Zhongxin Chen
Position: Grad Students
Research Type: Experiment
Office: MD1-Level 14
Email: chenzhongxin@u.nus.edu
CA2DM Publications:
2023 |
Chen, Zehong; Peng, Xinwen; Chen, Zhongxin; Li, Tingzhen; Zou, Ren; Shi, Ge; Huang, Yongfa; Cui, Peng; Yu, Jian; Chen, Yuling; Chi, Xiao; Loh, Kian Ping; Liu, Zhaoqing; Li, Xuehui; Zhong, Linxin; Lu, Jun Mass Production of Sulfur-Tuned Single-Atom Catalysts for Zn-Air Batteries Journal Article ADVANCED MATERIALS, 35 (15), 2023, ISSN: 0935-9648. @article{ISI:000941941800001, title = {Mass Production of Sulfur-Tuned Single-Atom Catalysts for Zn-Air Batteries}, author = {Zehong Chen and Xinwen Peng and Zhongxin Chen and Tingzhen Li and Ren Zou and Ge Shi and Yongfa Huang and Peng Cui and Jian Yu and Yuling Chen and Xiao Chi and Kian Ping Loh and Zhaoqing Liu and Xuehui Li and Linxin Zhong and Jun Lu}, doi = {10.1002/adma.202209948}, times_cited = {0}, issn = {0935-9648}, year = {2023}, date = {2023-03-02}, journal = {ADVANCED MATERIALS}, volume = {35}, number = {15}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {Single-atom catalysts (SACs) show great potential for rechargeable Zn-air batteries (ZABs); however, scalable production of SACs from sustainable resources is difficult owing to poor control of the local coordination environment. Herein, lignosulfonate, a by-product of the papermaking industry, is utilized as a multifunctional bioligand for the mass production of SACs with highly active M-N-4-S sites (M represents Fe, Cu, and Co) via strong metal-nitrogen/sulfur coordination. This effectively adjusts the charge distribution and promotes the catalytic performance, leading to highly durable and excellent performance in oxygen reduction and evolution reactions for ZABs. This study paves the way for the industrial production of cost-effective SACs in a sustainable manner.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Single-atom catalysts (SACs) show great potential for rechargeable Zn-air batteries (ZABs); however, scalable production of SACs from sustainable resources is difficult owing to poor control of the local coordination environment. Herein, lignosulfonate, a by-product of the papermaking industry, is utilized as a multifunctional bioligand for the mass production of SACs with highly active M-N-4-S sites (M represents Fe, Cu, and Co) via strong metal-nitrogen/sulfur coordination. This effectively adjusts the charge distribution and promotes the catalytic performance, leading to highly durable and excellent performance in oxygen reduction and evolution reactions for ZABs. This study paves the way for the industrial production of cost-effective SACs in a sustainable manner. |
2022 |
Chi, Xiao; Mandal, Lily; Liu, Cuibo; Fauzi, Angga Dito; Chaudhuri, Anindita; Whitcher, Thomas J; Jani, Hariom Kirit; Chen, Zhongxin; Xi, Shibo; Diao, Caozheng; Naradipa, Muhammad Avicenna; Yu, Xiaojiang; Yang, Ping; Castro-Neto, Antonio Helio; Breese, Mark B H; Loh, Kian Ping; Venkatesan, Thirumalai Venky; Rusydi, Andrivo Unravelling a new many-body large-hole polaron in a transition metal oxide that promotes high photocatalytic activity Journal Article NPG ASIA MATERIALS, 14 (1), 2022, ISSN: 1884-4049. @article{ISI:000764082700003, title = {Unravelling a new many-body large-hole polaron in a transition metal oxide that promotes high photocatalytic activity}, author = {Xiao Chi and Lily Mandal and Cuibo Liu and Angga Dito Fauzi and Anindita Chaudhuri and Thomas J Whitcher and Hariom Kirit Jani and Zhongxin Chen and Shibo Xi and Caozheng Diao and Muhammad Avicenna Naradipa and Xiaojiang Yu and Ping Yang and Antonio Helio Castro-Neto and Mark B H Breese and Kian Ping Loh and Thirumalai Venky Venkatesan and Andrivo Rusydi}, doi = {10.1038/s41427-022-00364-w}, times_cited = {0}, issn = {1884-4049}, year = {2022}, date = {2022-12-01}, journal = {NPG ASIA MATERIALS}, volume = {14}, number = {1}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {A many-body large polaron, which is important for both fundamental physics and technological applications, has been predicted to occur in bismuth vanadate (BiVO4). Herein, using a combination of high-resolution spectroscopic ellipsometry, X-ray absorption spectroscopy at the V L-3,L-2- and O K-edges, and high-resolution X-ray diffraction supported by theoretical calculations, we reveal a new many-body large-hole polaron in W-doped BiVO4 films and the interplay of the large-hole polaron and indirect bandgap when determining the photocatalytic activity. With various W doping concentrations and temperatures, anomalous spectral weight transfers in the complex dielectric function are observed, revealing electronic correlations, particularly the on-site Coulomb interactions of O p (U-pp) and V d (U-dd), and screening in BiVO4. Due to the distortion of BiO8 dodecahedra and U-dd, Bi 6 s is lifted to the top of the valance band, which results in the formation of an indirect bandgap and a large-hole polaron. The large-hole polaron is found to form as a localized midgap state, consisting of O p hybridized with the V d and Bi sp orbitals, and this is important when determining the high photocatalytic activity of BiVO4 Our results show the importance of the interplay among the charge, orbital, and lattice degrees of freedom in forming the many-body large-hole polaron, which improves the conductivity and results in a transition metal oxide with high photocatalytic activity.}, keywords = {}, pubstate = {published}, tppubtype = {article} } A many-body large polaron, which is important for both fundamental physics and technological applications, has been predicted to occur in bismuth vanadate (BiVO4). Herein, using a combination of high-resolution spectroscopic ellipsometry, X-ray absorption spectroscopy at the V L-3,L-2- and O K-edges, and high-resolution X-ray diffraction supported by theoretical calculations, we reveal a new many-body large-hole polaron in W-doped BiVO4 films and the interplay of the large-hole polaron and indirect bandgap when determining the photocatalytic activity. With various W doping concentrations and temperatures, anomalous spectral weight transfers in the complex dielectric function are observed, revealing electronic correlations, particularly the on-site Coulomb interactions of O p (U-pp) and V d (U-dd), and screening in BiVO4. Due to the distortion of BiO8 dodecahedra and U-dd, Bi 6 s is lifted to the top of the valance band, which results in the formation of an indirect bandgap and a large-hole polaron. The large-hole polaron is found to form as a localized midgap state, consisting of O p hybridized with the V d and Bi sp orbitals, and this is important when determining the high photocatalytic activity of BiVO4 Our results show the importance of the interplay among the charge, orbital, and lattice degrees of freedom in forming the many-body large-hole polaron, which improves the conductivity and results in a transition metal oxide with high photocatalytic activity. |
2020 |
Zhang, Zheye; Zhao, Xiaoxu; Xi, Shibo; Zhang, Lili; Chen, Zhongxin; Zeng, Zhiping; Huang, Ming; Yang, Hongbin; Liu, Bin; Pennycook, Stephen J; Chen, Peng ADVANCED ENERGY MATERIALS, 10 (48), 2020, ISSN: 1614-6832. @article{ISI:000587349700001, title = {Atomically Dispersed Cobalt Trifunctional Electrocatalysts with Tailored Coordination Environment for Flexible Rechargeable Zn-Air Battery and Self-Driven Water Splitting}, author = {Zheye Zhang and Xiaoxu Zhao and Shibo Xi and Lili Zhang and Zhongxin Chen and Zhiping Zeng and Ming Huang and Hongbin Yang and Bin Liu and Stephen J Pennycook and Peng Chen}, doi = {10.1002/aenm.202002896}, times_cited = {0}, issn = {1614-6832}, year = {2020}, date = {2020-11-09}, journal = {ADVANCED ENERGY MATERIALS}, volume = {10}, number = {48}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {Designing multifunctional catalysts with high activity, stability, and low-cost for energy storage and conversion is a significant challenge. Herein, a trifunctional electrocatalyst is synthesized by anchoring individually dispersed Co atoms on N and S codoped hollow carbon spheres (CoSA/N,S-HCS), which exhibits outstanding catalytic activity and stability for the oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction. When equipped in liquid or flexible solid-state rechargeable Zn-air batteries, CoSA/N,S-HCS endows them with high power and energy density as well as excellent long-term cycling stability, outperforming benchmark batteries based on a commercial Pt/C + RuO2 dual catalyst system. Furthermore, a self-driven water splitting system powered by flexible Zn-air batteries is demonstrated using CoSA/N,S-HCS as the sole catalyst, giving a high H-2 evolution rate of 184 mmol h(-1). The state-of-art experimental characterizations and theoretical calculations reveal synergistic cooperation between atomically dispersed Co-N-4 active sites, nearby electron-donating S dopants, and the unique carbon support to single-atom catalysts (SACs). This work demonstrates a general strategy to design various multifunctional SAC systems with a tailored coordination environment.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Designing multifunctional catalysts with high activity, stability, and low-cost for energy storage and conversion is a significant challenge. Herein, a trifunctional electrocatalyst is synthesized by anchoring individually dispersed Co atoms on N and S codoped hollow carbon spheres (CoSA/N,S-HCS), which exhibits outstanding catalytic activity and stability for the oxygen reduction reaction, oxygen evolution reaction, and hydrogen evolution reaction. When equipped in liquid or flexible solid-state rechargeable Zn-air batteries, CoSA/N,S-HCS endows them with high power and energy density as well as excellent long-term cycling stability, outperforming benchmark batteries based on a commercial Pt/C + RuO2 dual catalyst system. Furthermore, a self-driven water splitting system powered by flexible Zn-air batteries is demonstrated using CoSA/N,S-HCS as the sole catalyst, giving a high H-2 evolution rate of 184 mmol h(-1). The state-of-art experimental characterizations and theoretical calculations reveal synergistic cooperation between atomically dispersed Co-N-4 active sites, nearby electron-donating S dopants, and the unique carbon support to single-atom catalysts (SACs). This work demonstrates a general strategy to design various multifunctional SAC systems with a tailored coordination environment. |
Yao, Chuanhao; Guo, Na; Xi, Shibo; Xu, Cong-Qiao; Liu, Wei; Zhao, Xiaoxu; Li, Jing; Fang, Hanyan; Su, Jie; Chen, Zhongxin; Yan, Huan; Qiu, Zhizhan; Lyu, Pin; Chen, Cheng; Xu, Haomin; Peng, Xinnan; Li, Xinzhe; Liu, Bin; Su, Chenliang; Pennycook, Stephen J; Sun, Cheng-Jun; Li, Jun; Zhang, Chun; Du, Yonghua; Lu, Jiong Atomically-precise dopant-controlled single cluster catalysis for electrochemical nitrogen reduction Journal Article NATURE COMMUNICATIONS, 11 (1), 2020, ISSN: 2041-1723. @article{ISI:000569891500016, title = {Atomically-precise dopant-controlled single cluster catalysis for electrochemical nitrogen reduction}, author = {Chuanhao Yao and Na Guo and Shibo Xi and Cong-Qiao Xu and Wei Liu and Xiaoxu Zhao and Jing Li and Hanyan Fang and Jie Su and Zhongxin Chen and Huan Yan and Zhizhan Qiu and Pin Lyu and Cheng Chen and Haomin Xu and Xinnan Peng and Xinzhe Li and Bin Liu and Chenliang Su and Stephen J Pennycook and Cheng-Jun Sun and Jun Li and Chun Zhang and Yonghua Du and Jiong Lu}, doi = {10.1038/s41467-020-18080-w}, times_cited = {0}, issn = {2041-1723}, year = {2020}, date = {2020-09-01}, journal = {NATURE COMMUNICATIONS}, volume = {11}, number = {1}, publisher = {NATURE PUBLISHING GROUP}, address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND}, abstract = {The ability to precisely engineer the doping of sub-nanometer bimetallic clusters offers exciting opportunities for tailoring their catalytic performance with atomic accuracy. However, the fabrication of singly dispersed bimetallic cluster catalysts with atomic-level control of dopants has been a long-standing challenge. Herein, we report a strategy for the controllable synthesis of a precisely doped single cluster catalyst consisting of partially ligand-enveloped Au4Pt2 clusters supported on defective graphene. This creates a bimetal single cluster catalyst (Au4Pt2/G) with exceptional activity for electrochemical nitrogen (N-2) reduction. Our mechanistic study reveals that each N-2 molecule is activated in the confined region between cluster and graphene. The heteroatom dopant plays an indispensable role in the activation of N-2 via an enhanced back donation of electrons to the N-2 LUMO. Moreover, besides the heteroatom Pt, the catalytic performance of single cluster catalyst can be further tuned by using Pd in place of Pt as the dopant. The fabrication of singly dispersed metal cluster catalysts with atomic-level control of dopants is a long-standing challenge. Here, the authors report a strategy for the synthesis of a precisely doped single cluster catalyst which shows exceptional activity for electrochemical dinitrogen reduction.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The ability to precisely engineer the doping of sub-nanometer bimetallic clusters offers exciting opportunities for tailoring their catalytic performance with atomic accuracy. However, the fabrication of singly dispersed bimetallic cluster catalysts with atomic-level control of dopants has been a long-standing challenge. Herein, we report a strategy for the controllable synthesis of a precisely doped single cluster catalyst consisting of partially ligand-enveloped Au4Pt2 clusters supported on defective graphene. This creates a bimetal single cluster catalyst (Au4Pt2/G) with exceptional activity for electrochemical nitrogen (N-2) reduction. Our mechanistic study reveals that each N-2 molecule is activated in the confined region between cluster and graphene. The heteroatom dopant plays an indispensable role in the activation of N-2 via an enhanced back donation of electrons to the N-2 LUMO. Moreover, besides the heteroatom Pt, the catalytic performance of single cluster catalyst can be further tuned by using Pd in place of Pt as the dopant. The fabrication of singly dispersed metal cluster catalysts with atomic-level control of dopants is a long-standing challenge. Here, the authors report a strategy for the synthesis of a precisely doped single cluster catalyst which shows exceptional activity for electrochemical dinitrogen reduction. |
Wu, Kunze; Zhang, Lei; Yuan, Yifei; Zhong, Linxin; Chen, Zhongxin; Chi, Xiao; Lu, Hao; Chen, Zehong; Zou, Ren; Li, Tingzhen; Jiang, Chengyu; Chen, Yongkang; Peng, Xinwen; Lu, Jun An Iron-Decorated Carbon Aerogel for Rechargeable Flow and Flexible Zn-Air Batteries Journal Article ADVANCED MATERIALS, 32 (32), 2020, ISSN: 0935-9648. @article{ISI:000544595300001, title = {An Iron-Decorated Carbon Aerogel for Rechargeable Flow and Flexible Zn-Air Batteries}, author = {Kunze Wu and Lei Zhang and Yifei Yuan and Linxin Zhong and Zhongxin Chen and Xiao Chi and Hao Lu and Zehong Chen and Ren Zou and Tingzhen Li and Chengyu Jiang and Yongkang Chen and Xinwen Peng and Jun Lu}, doi = {10.1002/adma.202002292}, times_cited = {0}, issn = {0935-9648}, year = {2020}, date = {2020-07-01}, journal = {ADVANCED MATERIALS}, volume = {32}, number = {32}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {Mechanically stable and foldable air cathodes with exceptional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities are key components of wearable metal-air batteries. Herein, a directional freeze-casting and annealing approach is reported for the construction of a 3D honeycomb nanostructured, N,P-doped carbon aerogel incorporating in situ grown FeP/Fe(2)O(3)nanoparticles as the cathode in a flexible Zn-air battery (ZAB). The aqueous rechargeable Zn-air batteries assembled with this carbon aerogel exhibit a remarkable specific capacity of 648 mAh g(-1)at a current density of 20 mA cm(-2)with a good long-term durability, outperforming those assembled with commercial Pt/C+RuO(2)catalyst. Furthermore, such a foldable carbon aerogel with directional channels can serve as a freestanding air cathode for flexible solid-state Zn-air batteries without the use of carbon paper/cloth and additives, giving a specific capacity of 676 mAh g(-1)and an energy density of 517 Wh kg(-1)at 5 mA cm(-2)together with good cycling stability. This work offers a new strategy to design and synthesize highly effective bifunctional air cathodes to be applied in electrochemical energy devices.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Mechanically stable and foldable air cathodes with exceptional oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities are key components of wearable metal-air batteries. Herein, a directional freeze-casting and annealing approach is reported for the construction of a 3D honeycomb nanostructured, N,P-doped carbon aerogel incorporating in situ grown FeP/Fe(2)O(3)nanoparticles as the cathode in a flexible Zn-air battery (ZAB). The aqueous rechargeable Zn-air batteries assembled with this carbon aerogel exhibit a remarkable specific capacity of 648 mAh g(-1)at a current density of 20 mA cm(-2)with a good long-term durability, outperforming those assembled with commercial Pt/C+RuO(2)catalyst. Furthermore, such a foldable carbon aerogel with directional channels can serve as a freestanding air cathode for flexible solid-state Zn-air batteries without the use of carbon paper/cloth and additives, giving a specific capacity of 676 mAh g(-1)and an energy density of 517 Wh kg(-1)at 5 mA cm(-2)together with good cycling stability. This work offers a new strategy to design and synthesize highly effective bifunctional air cathodes to be applied in electrochemical energy devices. |
Liu, Qiong; Chen, Zhongxin; Tao, Weijian; Zhu, Haiming; Zhong, Linxin; Wang, Fuxian; Zou, Ren; Lei, Yongqian; Liu, Cuibo; Peng, Xinwen JOURNAL OF MATERIALS CHEMISTRY A, 8 (23), pp. 11761-11772, 2020, ISSN: 2050-7488. @article{ISI:000542761900028, title = {Edge activation of an inert polymeric carbon nitride matrix with boosted absorption kinetics and near-infrared response for efficient photocatalytic CO_{2}reduction}, author = {Qiong Liu and Zhongxin Chen and Weijian Tao and Haiming Zhu and Linxin Zhong and Fuxian Wang and Ren Zou and Yongqian Lei and Cuibo Liu and Xinwen Peng}, doi = {10.1039/d0ta03870a}, times_cited = {0}, issn = {2050-7488}, year = {2020}, date = {2020-06-21}, journal = {JOURNAL OF MATERIALS CHEMISTRY A}, volume = {8}, number = {23}, pages = {11761-11772}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {The reduction of CO(2)into C(1)feedstocks (e.g., CO) by utilizing solar energy has attracted increasing attention for the efficient production of renewable energy. However, a significant challenge in the reduction of CO(2)is achieving high conversion efficiency due to the high C=O dissociation energy of CO(2)and difficultly in accessing the surface of photocatalysts. Herein, we fabricated a polymeric carbon nitride (PCN) catalyst with hydroxyethyl groups grafted on its edgeviaa facile bottom-up strategy, facilitating the efficient surface absorption of CO(2)and lowering the CO(2)transformation energy barrier; this was accompanied with exceptional extended optical absorption ability to the near-infrared region and increase in the density of states at the Fermi level. Thus, concentrated CO(2)molecules could contact the surface of PCN and be easily activated; this resulted in an excellent CO production rate of up to 209.24 mu mol h(-1)g(-1)in the modified PCN (i.e., 39.5-fold increase compared to that of pristine PCN) and a selectivity of 98.5% under white LED illumination, exceeding that of most PCN-based energy conversion systems reported to date. Notably, this PCN matrix also exhibited photocatalytic activity for the production of CO in the near-infrared region from 780 to 850 nm. These results pave the way for the development of structured photocatalysts with easy accessibility for CO(2)and broadband spectral response for the efficient photocatalytic reduction of CO2.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The reduction of CO(2)into C(1)feedstocks (e.g., CO) by utilizing solar energy has attracted increasing attention for the efficient production of renewable energy. However, a significant challenge in the reduction of CO(2)is achieving high conversion efficiency due to the high C=O dissociation energy of CO(2)and difficultly in accessing the surface of photocatalysts. Herein, we fabricated a polymeric carbon nitride (PCN) catalyst with hydroxyethyl groups grafted on its edgeviaa facile bottom-up strategy, facilitating the efficient surface absorption of CO(2)and lowering the CO(2)transformation energy barrier; this was accompanied with exceptional extended optical absorption ability to the near-infrared region and increase in the density of states at the Fermi level. Thus, concentrated CO(2)molecules could contact the surface of PCN and be easily activated; this resulted in an excellent CO production rate of up to 209.24 mu mol h(-1)g(-1)in the modified PCN (i.e., 39.5-fold increase compared to that of pristine PCN) and a selectivity of 98.5% under white LED illumination, exceeding that of most PCN-based energy conversion systems reported to date. Notably, this PCN matrix also exhibited photocatalytic activity for the production of CO in the near-infrared region from 780 to 850 nm. These results pave the way for the development of structured photocatalysts with easy accessibility for CO(2)and broadband spectral response for the efficient photocatalytic reduction of CO2. |
Hai, Xiao; Zhao, Xiaoxu; Guo, Na; Yao, Chuanhao; Chen, Cheng; Liu, Wei; Du, Yonghua; Yan, Huan; Li, Jing; Chen, Zhongxin; Li, Xing; Li, Zejun; Xu, Haomin; Lyu, Pin; Zhang, Jia; Lin, Ming; Su, Chenliang; Pennycook, Stephen J; Zhang, Chun; Xi, Shibo; Lu, Jiong Engineering Local and Global Structures of Single Co Atoms for a Superior Oxygen Reduction Reaction Journal Article 16 ACS CATALYSIS, 10 (10), pp. 5862-5870, 2020, ISSN: 2155-5435. @article{ISI:000535291500050, title = {Engineering Local and Global Structures of Single Co Atoms for a Superior Oxygen Reduction Reaction}, author = {Xiao Hai and Xiaoxu Zhao and Na Guo and Chuanhao Yao and Cheng Chen and Wei Liu and Yonghua Du and Huan Yan and Jing Li and Zhongxin Chen and Xing Li and Zejun Li and Haomin Xu and Pin Lyu and Jia Zhang and Ming Lin and Chenliang Su and Stephen J Pennycook and Chun Zhang and Shibo Xi and Jiong Lu}, doi = {10.1021/acscatal.0c00936}, times_cited = {16}, issn = {2155-5435}, year = {2020}, date = {2020-05-15}, journal = {ACS CATALYSIS}, volume = {10}, number = {10}, pages = {5862-5870}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {The ability to tune both local and global environments of a single metal active center on a support is crucial for the development of highly robust and efficient single-atom electrocatalysts (SAECs) that can surmount both thermodynamic and kinetic constraints in electrocatalysis. Here, we designed a core-shell-structured SAEC (Co-1-SAC) with superior oxygen reduction reaction (ORR) performance. Co-1-SAC consists of a locally engineered single Co-N3C1 site on a N-doped microporous amorphous carbon support enveloped by a globally engineered highly conductive mesoporous graphitic carbon shell. Theoretical calculations reveal that Co-N3C1 exhibits near-Fermi electronic states distinct from those of Co-N2C2 and Co-N-4, which facilitate both the electronic hybridization with O-2 and the subsequent protonation of adsorbed O-2* toward the formation of OOH*. Engineering Co-N3C1-SAC into a micro/mesoporous structure dramatically enhances the mass transport and electron transfer, which further boosts the ORR and Zn-air battery performance (slightly outperforming Pt/C). Our findings open an avenue toward engineering of the local and global environment of SACs for a wide range of efficient electrochemical conversions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The ability to tune both local and global environments of a single metal active center on a support is crucial for the development of highly robust and efficient single-atom electrocatalysts (SAECs) that can surmount both thermodynamic and kinetic constraints in electrocatalysis. Here, we designed a core-shell-structured SAEC (Co-1-SAC) with superior oxygen reduction reaction (ORR) performance. Co-1-SAC consists of a locally engineered single Co-N3C1 site on a N-doped microporous amorphous carbon support enveloped by a globally engineered highly conductive mesoporous graphitic carbon shell. Theoretical calculations reveal that Co-N3C1 exhibits near-Fermi electronic states distinct from those of Co-N2C2 and Co-N-4, which facilitate both the electronic hybridization with O-2 and the subsequent protonation of adsorbed O-2* toward the formation of OOH*. Engineering Co-N3C1-SAC into a micro/mesoporous structure dramatically enhances the mass transport and electron transfer, which further boosts the ORR and Zn-air battery performance (slightly outperforming Pt/C). Our findings open an avenue toward engineering of the local and global environment of SACs for a wide range of efficient electrochemical conversions. |
Dong, Lei; Zhang, Long; Lin, Shan; Chen, Zhongxin; Wang, Yannan; Zhao, Xiaoxu; Wu, Tianqi; Zhang, Jiajia; Liu, Wei; Lu, Hongbin; Loh, Kian Ping Building vertically-structured, high-performance electrodes by interlayer-confined reactions in accordion-like, chemically expanded graphite Journal Article NANO ENERGY, 70 , 2020, ISSN: 2211-2855. @article{ISI:000521052900022, title = {Building vertically-structured, high-performance electrodes by interlayer-confined reactions in accordion-like, chemically expanded graphite}, author = {Lei Dong and Long Zhang and Shan Lin and Zhongxin Chen and Yannan Wang and Xiaoxu Zhao and Tianqi Wu and Jiajia Zhang and Wei Liu and Hongbin Lu and Kian Ping Loh}, doi = {10.1016/j.nanoen.2020.104482}, times_cited = {1}, issn = {2211-2855}, year = {2020}, date = {2020-04-01}, journal = {NANO ENERGY}, volume = {70}, publisher = {ELSEVIER}, address = {RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS}, abstract = {Graphene has attracted major interests as electrode materials for energy storage applications. However, the major limitation of using blade- or spin-coated graphene films for fabricating electrode is that the basal plane of the flat-lying graphene is orthogonal to the direction of charge transport, causing sluggish charge transfer kinetics for the coated graphene film. Here we propose a general, scalable strategy to prepare vertically-structured hybrid electrodes using accordion-like, chemically expanded graphite (CEG). The coated CEG rods possess two-dimensional (2D) interlayer galleries that are vertically aligned with respect to the substrate because of their large length-diameter ratio, which facilitates high-efficiency ion transport. Due to its excellent wettability and high electrochemical surface areas, these interlayer galleries allow a high loading of redox-active (RA) materials, including metal (Pt), metal hydroxide (Ni(OH)(2), Fe2O3 and MnO2) or metal dichalcogenide (MoS2). As an example, Ni(OH)(2)-infiltrated CEG shows excellent rate-performance and long-term cycling stability when used as electrochemical electrodes in lithium-ion batteries and supercapacitors.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Graphene has attracted major interests as electrode materials for energy storage applications. However, the major limitation of using blade- or spin-coated graphene films for fabricating electrode is that the basal plane of the flat-lying graphene is orthogonal to the direction of charge transport, causing sluggish charge transfer kinetics for the coated graphene film. Here we propose a general, scalable strategy to prepare vertically-structured hybrid electrodes using accordion-like, chemically expanded graphite (CEG). The coated CEG rods possess two-dimensional (2D) interlayer galleries that are vertically aligned with respect to the substrate because of their large length-diameter ratio, which facilitates high-efficiency ion transport. Due to its excellent wettability and high electrochemical surface areas, these interlayer galleries allow a high loading of redox-active (RA) materials, including metal (Pt), metal hydroxide (Ni(OH)(2), Fe2O3 and MnO2) or metal dichalcogenide (MoS2). As an example, Ni(OH)(2)-infiltrated CEG shows excellent rate-performance and long-term cycling stability when used as electrochemical electrodes in lithium-ion batteries and supercapacitors. |
2019 |
Chen, Zhongxin; Liu, Cuibo; Liu, Jia; Li, Jing; Xi, Shibo; Chi, Xiao; Xu, Haisen; Park, In-Hyeok; Peng, Xinwen; Li, Xing; Yu, Wei; Liu, Xiaowang; Zhong, Linxin; Leng, Kai; Huang, Wei; Koh, Ming Joo; Loh, Kian Ping Cobalt Single-Atom-Intercalated Molybdenum Disulfide for Sulfide Oxidation with Exceptional Chemoselectivity Journal Article ADVANCED MATERIALS, 32 (4), 2019, ISSN: 0935-9648. @article{ISI:000498947900001, title = {Cobalt Single-Atom-Intercalated Molybdenum Disulfide for Sulfide Oxidation with Exceptional Chemoselectivity}, author = {Zhongxin Chen and Cuibo Liu and Jia Liu and Jing Li and Shibo Xi and Xiao Chi and Haisen Xu and In-Hyeok Park and Xinwen Peng and Xing Li and Wei Yu and Xiaowang Liu and Linxin Zhong and Kai Leng and Wei Huang and Ming Joo Koh and Kian Ping Loh}, doi = {10.1002/adma.201906437}, times_cited = {0}, issn = {0935-9648}, year = {2019}, date = {2019-11-28}, journal = {ADVANCED MATERIALS}, volume = {32}, number = {4}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {The identification of chemoselective oxidation process en route to fine chemicals and specialty chemicals is a long-standing pursuit in chemical synthesis. A vertically structured, cobalt single atom-intercalated molybdenum disulfide catalyst (Co-1-in-MoS2) is developed for the chemoselective transformation of sulfides to sulfone derivatives. The single-atom encapsulation alters the electron structure of catalyst owing to confinement effect and strong metal-substrate interaction, thus enhancing adsorption of sulfides and chemoselective oxidation at the edge sites of MoS2 to achieve excellent yields of up to 99% for 34 examples. The synthetic scopes can be extended to sulfide-bearing alkenes, alkynes, aldehydes, ketones, boronic esters, and amines derivatives as a toolbox for the synthesis of high-value, multifunctional sulfones and late-stage functionalization of pharmaceuticals, e.g., Tamiflu. The synthetic utility of cobalt single atom-intercalated MoS2, together with its reusability, scalability, and simplified purification process, renders it promising for industrial productions.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The identification of chemoselective oxidation process en route to fine chemicals and specialty chemicals is a long-standing pursuit in chemical synthesis. A vertically structured, cobalt single atom-intercalated molybdenum disulfide catalyst (Co-1-in-MoS2) is developed for the chemoselective transformation of sulfides to sulfone derivatives. The single-atom encapsulation alters the electron structure of catalyst owing to confinement effect and strong metal-substrate interaction, thus enhancing adsorption of sulfides and chemoselective oxidation at the edge sites of MoS2 to achieve excellent yields of up to 99% for 34 examples. The synthetic scopes can be extended to sulfide-bearing alkenes, alkynes, aldehydes, ketones, boronic esters, and amines derivatives as a toolbox for the synthesis of high-value, multifunctional sulfones and late-stage functionalization of pharmaceuticals, e.g., Tamiflu. The synthetic utility of cobalt single atom-intercalated MoS2, together with its reusability, scalability, and simplified purification process, renders it promising for industrial productions. |
Yu, Wei; Li, Jing; Herng, Tun Seng; Wang, Zishen; Zhao, Xiaoxu; Chi, Xiao; Fu, Wei; Abdelwahab, Ibrahim; Zhou, Jun; Dan, Jiadong; Chen, Zhongxin; Chen, Zhi; Li, Zejun; Lu, Jiong; Pennycook, Stephen J; Feng, Yuan Ping; Ding, Jun; Loh, Kian Ping Chemically Exfoliated VSe2 Monolayers with Room-Temperature Ferromagnetism Journal Article ADVANCED MATERIALS, 31 (40), 2019, ISSN: 0935-9648. @article{ISI:000481817000001, title = {Chemically Exfoliated VSe_{2} Monolayers with Room-Temperature Ferromagnetism}, author = {Wei Yu and Jing Li and Tun Seng Herng and Zishen Wang and Xiaoxu Zhao and Xiao Chi and Wei Fu and Ibrahim Abdelwahab and Jun Zhou and Jiadong Dan and Zhongxin Chen and Zhi Chen and Zejun Li and Jiong Lu and Stephen J Pennycook and Yuan Ping Feng and Jun Ding and Kian Ping Loh}, doi = {10.1002/adma.201903779}, times_cited = {0}, issn = {0935-9648}, year = {2019}, date = {2019-08-18}, journal = {ADVANCED MATERIALS}, volume = {31}, number = {40}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {Among van der Waals layered ferromagnets, monolayer vanadium diselenide (VSe2) stands out due to its robust ferromagnetism. However, the exfoliation of monolayer VSe2 is challenging, not least because the monolayer flake is extremely unstable in air. Using an electrochemical exfoliation approach with organic cations as the intercalants, monolayer 1T-VSe2 flakes are successfully obtained from the bulk crystal at high yield. Thiol molecules are further introduced onto the VSe2 surface to passivate the exfoliated flakes, which improves the air stability of the flakes for subsequent characterizations. Room-temperature ferromagnetism is confirmed on the exfoliated 2D VSe2 flakes using a superconducting quantum interference device (SQUID), X-ray magnetic circular dichroism (XMCD), and magnetic force microscopy (MFM), where the monolayer flake displays the strongest ferromagnetic properties. Se vacancies, which can be ubiquitous in such materials, also contribute to the ferromagnetism of VSe2, although density functional theory (DFT) calculations show that such effect can be minimized by physisorbed oxygen molecules or covalently bound thiol molecules.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Among van der Waals layered ferromagnets, monolayer vanadium diselenide (VSe2) stands out due to its robust ferromagnetism. However, the exfoliation of monolayer VSe2 is challenging, not least because the monolayer flake is extremely unstable in air. Using an electrochemical exfoliation approach with organic cations as the intercalants, monolayer 1T-VSe2 flakes are successfully obtained from the bulk crystal at high yield. Thiol molecules are further introduced onto the VSe2 surface to passivate the exfoliated flakes, which improves the air stability of the flakes for subsequent characterizations. Room-temperature ferromagnetism is confirmed on the exfoliated 2D VSe2 flakes using a superconducting quantum interference device (SQUID), X-ray magnetic circular dichroism (XMCD), and magnetic force microscopy (MFM), where the monolayer flake displays the strongest ferromagnetic properties. Se vacancies, which can be ubiquitous in such materials, also contribute to the ferromagnetism of VSe2, although density functional theory (DFT) calculations show that such effect can be minimized by physisorbed oxygen molecules or covalently bound thiol molecules. |
Chi, Kai; Chen, Zhongxin; Xiao, Fei; Guo, Wei; Xi, Wei; Liu, Jing; Yan, Huan; Zhang, Zheye; Xiao, Jian; Liu, Jia; Luo, Jun; Wang, Shuai; Loh, Kian Ping Maximizing the utility of single atom electrocatalysts on a 3D graphene nanomesh Journal Article JOURNAL OF MATERIALS CHEMISTRY A, 7 (26), pp. 15575-15579, 2019, ISSN: 2050-7488. @article{ISI:000474271200050, title = {Maximizing the utility of single atom electrocatalysts on a 3D graphene nanomesh}, author = {Kai Chi and Zhongxin Chen and Fei Xiao and Wei Guo and Wei Xi and Jing Liu and Huan Yan and Zheye Zhang and Jian Xiao and Jia Liu and Jun Luo and Shuai Wang and Kian Ping Loh}, doi = {10.1039/c9ta00942f}, times_cited = {0}, issn = {2050-7488}, year = {2019}, date = {2019-07-14}, journal = {JOURNAL OF MATERIALS CHEMISTRY A}, volume = {7}, number = {26}, pages = {15575-15579}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {Single atom catalysis has recently become the most active frontier in heterogeneous catalysis, however, its performance is practically limited by the exposure of single atoms to reactants. Herein, we synthesized a vertically aligned N-doped graphene nanomesh array (VNGNMA) with a high density of in-plane surface holes and out-of-plane interconnected, vertically aligned structures to facilitate the diffusion of reactants and maximize the utility of single atoms in the liquid phase. Pd and Pt single atom catalysts supported on a 3D graphene nanomesh outperformed benchmark Pt/C and conventional single atom catalysts for the hydrogen evolution reaction due to rapid mass transport.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Single atom catalysis has recently become the most active frontier in heterogeneous catalysis, however, its performance is practically limited by the exposure of single atoms to reactants. Herein, we synthesized a vertically aligned N-doped graphene nanomesh array (VNGNMA) with a high density of in-plane surface holes and out-of-plane interconnected, vertically aligned structures to facilitate the diffusion of reactants and maximize the utility of single atoms in the liquid phase. Pd and Pt single atom catalysts supported on a 3D graphene nanomesh outperformed benchmark Pt/C and conventional single atom catalysts for the hydrogen evolution reaction due to rapid mass transport. |
Peng, Xinwen; Zhang, Lei; Chen, Zhongxin; Zhong, Linxin; Zhao, Dengke; Chi, Xiao; Zhao, Xiaoxu; Li, Ligui; Lu, Xihong; Leng, Kai; Liu, Cuibo; Liu, Wei; Tang, Wei; Loh, Kian Ping Hierarchically Porous Carbon Plates Derived from Wood as Bifunctional ORR/OER Electrodes Journal Article ADVANCED MATERIALS, 31 (16), 2019, ISSN: 0935-9648. @article{ISI:000468005400026, title = {Hierarchically Porous Carbon Plates Derived from Wood as Bifunctional ORR/OER Electrodes}, author = {Xinwen Peng and Lei Zhang and Zhongxin Chen and Linxin Zhong and Dengke Zhao and Xiao Chi and Xiaoxu Zhao and Ligui Li and Xihong Lu and Kai Leng and Cuibo Liu and Wei Liu and Wei Tang and Kian Ping Loh}, doi = {10.1002/adma.201900341}, times_cited = {0}, issn = {0935-9648}, year = {2019}, date = {2019-04-19}, journal = {ADVANCED MATERIALS}, volume = {31}, number = {16}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {Porous carbon electrodes have emerged as important cathode materials for metal-air battery systems. However, most approaches for fabricating porous carbon electrodes from biomass are highly energy inefficient as they require the breaking down of the biomass and its subsequent reconstitution into powder-like carbon. Here, enzymes are explored to effectively hydrolyze the partial cellulose in bulk raw wood to form a large number of nanopores, which helps to maximally expose the inner parts of the raw wood to sufficiently dope nitrogen onto the carbon skeletons during the subsequent pyrolysis process. The resulting carbons exhibit excellent catalytic activity with respect to the oxygen reduction and oxygen evolution reactions. As-fabricated cellulose-digested, carbonized wood plates are mechanically strong, have high conductivity, and contain a crosslinked network and natural ion-transport channels and can be employed directly as metal-free electrodes without carbon paper, polymer binders, or carbon black. When used as metal-free cathodes in zinc-air batteries, they result in a specific capacity of 801 mA h g(-1) and an energy density of 955 W h kg(-1) with the long-term stability of the batteries being as high as 110 h. This work paves the way for the ready conversion of abundant biomass into high-value engineering products for energy-related applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Porous carbon electrodes have emerged as important cathode materials for metal-air battery systems. However, most approaches for fabricating porous carbon electrodes from biomass are highly energy inefficient as they require the breaking down of the biomass and its subsequent reconstitution into powder-like carbon. Here, enzymes are explored to effectively hydrolyze the partial cellulose in bulk raw wood to form a large number of nanopores, which helps to maximally expose the inner parts of the raw wood to sufficiently dope nitrogen onto the carbon skeletons during the subsequent pyrolysis process. The resulting carbons exhibit excellent catalytic activity with respect to the oxygen reduction and oxygen evolution reactions. As-fabricated cellulose-digested, carbonized wood plates are mechanically strong, have high conductivity, and contain a crosslinked network and natural ion-transport channels and can be employed directly as metal-free electrodes without carbon paper, polymer binders, or carbon black. When used as metal-free cathodes in zinc-air batteries, they result in a specific capacity of 801 mA h g(-1) and an energy density of 955 W h kg(-1) with the long-term stability of the batteries being as high as 110 h. This work paves the way for the ready conversion of abundant biomass into high-value engineering products for energy-related applications. |
Chen, Zhongxin; Liu, Cuibo; Zhao, Xiaoxu; Yan, Huan; Li, Jing; Lyu, Pin; Du, Yonghua; Xi, Shibo; Chi, Kai; Chi, Xiao; Xu, Haisen; Li, Xing; Fu, Wei; Leng, Kai; Pennycook, Stephen J; Wang, Shuai; Loh, Kian Ping Promoted Glycerol Oxidation Reaction in an Interface-Confined Hierarchically Structured Catalyst Journal Article ADVANCED MATERIALS, 31 (2), 2019, ISSN: 0935-9648. @article{ISI:000455111100007, title = {Promoted Glycerol Oxidation Reaction in an Interface-Confined Hierarchically Structured Catalyst}, author = {Zhongxin Chen and Cuibo Liu and Xiaoxu Zhao and Huan Yan and Jing Li and Pin Lyu and Yonghua Du and Shibo Xi and Kai Chi and Xiao Chi and Haisen Xu and Xing Li and Wei Fu and Kai Leng and Stephen J Pennycook and Shuai Wang and Kian Ping Loh}, doi = {10.1002/adma.201804763}, times_cited = {0}, issn = {0935-9648}, year = {2019}, date = {2019-01-01}, journal = {ADVANCED MATERIALS}, volume = {31}, number = {2}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {Confined catalysis in a 2D system is of particular interest owing to the facet control of the catalysts and the anisotropic kinetics of reactants, which suppress side reactions and improve selectivity. Here, a 2D-confined system consisting of intercalated Pt nanosheets within few-layered graphene is demonstrated. The strong metal-substrate interaction between the Pt nanosheets and the graphene leads to the quasi-2D growth of Pt with a unique (100)/(111)/(100) faceted structure, thus providing excellent catalytic activity and selectivity toward one-carbon (C1) products for the glycerol oxidation reaction. A hierarchically porous graphene architecture, grown on carbon cloth, is used to fabricate the confined catalyst bed in order to enhance the mass-diffusion limitation in interface-confined reactions. Owing to its unique 3D porous structure, this graphene-confined Pt catalyst exhibits an extraordinary mass activity of 2910 mA mg(Pt)(-1) together with a formate selectivity of 79% at 60 degrees C. This paves the way toward rational designs of heterogeneous catalysts for energy-related applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Confined catalysis in a 2D system is of particular interest owing to the facet control of the catalysts and the anisotropic kinetics of reactants, which suppress side reactions and improve selectivity. Here, a 2D-confined system consisting of intercalated Pt nanosheets within few-layered graphene is demonstrated. The strong metal-substrate interaction between the Pt nanosheets and the graphene leads to the quasi-2D growth of Pt with a unique (100)/(111)/(100) faceted structure, thus providing excellent catalytic activity and selectivity toward one-carbon (C1) products for the glycerol oxidation reaction. A hierarchically porous graphene architecture, grown on carbon cloth, is used to fabricate the confined catalyst bed in order to enhance the mass-diffusion limitation in interface-confined reactions. Owing to its unique 3D porous structure, this graphene-confined Pt catalyst exhibits an extraordinary mass activity of 2910 mA mg(Pt)(-1) together with a formate selectivity of 79% at 60 degrees C. This paves the way toward rational designs of heterogeneous catalysts for energy-related applications. |
2018 |
Zhang, Long; Chen, Zhongxin; Dongfang, Nanchen; Li, Mengxiong; Diao, Caozheng; Wu, Qingsong; Chi, Xiao; Jiang, Peilu; Zhao, Zedong; Dong, Lei; Che, Renchao; Loh, Kian Ping; Lu, Hongbin Nickel-Cobalt Double Hydroxide as a Multifunctional Mediator for Ultrahigh-Rate and Ultralong-Life Li-S Batteries Journal Article ADVANCED ENERGY MATERIALS, 8 (35), 2018, ISSN: 1614-6832. @article{ISI:000453273200008, title = {Nickel-Cobalt Double Hydroxide as a Multifunctional Mediator for Ultrahigh-Rate and Ultralong-Life Li-S Batteries}, author = {Long Zhang and Zhongxin Chen and Nanchen Dongfang and Mengxiong Li and Caozheng Diao and Qingsong Wu and Xiao Chi and Peilu Jiang and Zedong Zhao and Lei Dong and Renchao Che and Kian Ping Loh and Hongbin Lu}, doi = {10.1002/aenm.201802431}, times_cited = {0}, issn = {1614-6832}, year = {2018}, date = {2018-12-01}, journal = {ADVANCED ENERGY MATERIALS}, volume = {8}, number = {35}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {The performance of lithium-sulfur (Li-S) batteries is largely hindered by the shuttle effect caused by the dissolution of lithium polysulfides (LiPSs) and the sluggish reaction kinetics of LiPSs. Here, it is demonstrated that the nickel-cobalt double hydroxide (NiCo-DH) shells that encapsulate sulfur nanoparticles can play multiple roles in suppressing the shuttle effect and accelerating the redox kinetics of LiPSs by combining with graphene and carbon nanotubes to construct the conductive networks. The NiCo-DH shell that intimately contacts with sulfur physically confines the loss of sulfur and promotes the charge transfer and ion diffusion. More importantly, it can react with LiPSs to produce the surface-bound intermediates, which are able to anchor the soluble LiPSs and accelerate the redox kinetics. Such composite electrodes can load high contents of sulfur (>85 wt%) and the resulting Li-S battery exhibits a superior capacity (1348.1 mAh g(-1) at 0.1 C), ultrahigh rate performance (697.7 mAh g(-1) at 5 C), and ultralong cycle life (1500 cycles) with a decay rate of 0.015% per cycle.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The performance of lithium-sulfur (Li-S) batteries is largely hindered by the shuttle effect caused by the dissolution of lithium polysulfides (LiPSs) and the sluggish reaction kinetics of LiPSs. Here, it is demonstrated that the nickel-cobalt double hydroxide (NiCo-DH) shells that encapsulate sulfur nanoparticles can play multiple roles in suppressing the shuttle effect and accelerating the redox kinetics of LiPSs by combining with graphene and carbon nanotubes to construct the conductive networks. The NiCo-DH shell that intimately contacts with sulfur physically confines the loss of sulfur and promotes the charge transfer and ion diffusion. More importantly, it can react with LiPSs to produce the surface-bound intermediates, which are able to anchor the soluble LiPSs and accelerate the redox kinetics. Such composite electrodes can load high contents of sulfur (>85 wt%) and the resulting Li-S battery exhibits a superior capacity (1348.1 mAh g(-1) at 0.1 C), ultrahigh rate performance (697.7 mAh g(-1) at 5 C), and ultralong cycle life (1500 cycles) with a decay rate of 0.015% per cycle. |
Leng, Kai; Abdelwahab, Ibrahim; Verzhbitskiy, Ivan; Telychko, Mykola; Chu, Leiqiang; Fu, Wei; Chi, Xiao; Guo, Na; Chen, Zhihui; Chen, Zhongxin; Zhang, Chun; Xu, Qing-Hua; Lu, Jiong; Chhowalla, Manish; Eda, Goki; Loh, Kian Ping Molecularly thin two-dimensional hybrid perovskites with tunable optoelectronic properties due to reversible surface relaxation Journal Article NATURE MATERIALS, 17 (10), pp. 908-+, 2018, ISSN: 1476-1122. @article{ISI:000445410900016, title = {Molecularly thin two-dimensional hybrid perovskites with tunable optoelectronic properties due to reversible surface relaxation}, author = {Kai Leng and Ibrahim Abdelwahab and Ivan Verzhbitskiy and Mykola Telychko and Leiqiang Chu and Wei Fu and Xiao Chi and Na Guo and Zhihui Chen and Zhongxin Chen and Chun Zhang and Qing-Hua Xu and Jiong Lu and Manish Chhowalla and Goki Eda and Kian Ping Loh}, doi = {10.1038/s41563-018-0164-8}, times_cited = {0}, issn = {1476-1122}, year = {2018}, date = {2018-10-01}, journal = {NATURE MATERIALS}, volume = {17}, number = {10}, pages = {908-+}, publisher = {NATURE PUBLISHING GROUP}, address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND}, abstract = {Due to their layered structure, two-dimensional Ruddlesden-Popper perovskites (RPPs), composed of multiple organic/inorganic quantum wells, can in principle be exfoliated down to few and single layers. These molecularly thin layers are expected to present unique properties with respect to the bulk counterpart, due to increased lattice deformations caused by interface strain. Here, we have synthesized centimetre-sized, pure-phase single-crystal RPP perovskites (CH3(CH2)(3)NH3)(2)(CH3NH3)n(-1)Pb(n)I(3n+1) (n = 1-4) from which single quantum well layers have been exfoliated. We observed a reversible shift in excitonic energies induced by laser annealing on exfoliated layers encapsulated by hexagonal boron nitride. Moreover, a highly efficient photodetector was fabricated using a molecularly thin n = 4 RPP crystal, showing a photogain of 10(5) and an internal quantum efficiency of similar to 34%. Our results suggest that, thanks to their dynamic structure, atomically thin perovskites enable an additional degree of control for the bandgap engineering of these materials}, keywords = {}, pubstate = {published}, tppubtype = {article} } Due to their layered structure, two-dimensional Ruddlesden-Popper perovskites (RPPs), composed of multiple organic/inorganic quantum wells, can in principle be exfoliated down to few and single layers. These molecularly thin layers are expected to present unique properties with respect to the bulk counterpart, due to increased lattice deformations caused by interface strain. Here, we have synthesized centimetre-sized, pure-phase single-crystal RPP perovskites (CH3(CH2)(3)NH3)(2)(CH3NH3)n(-1)Pb(n)I(3n+1) (n = 1-4) from which single quantum well layers have been exfoliated. We observed a reversible shift in excitonic energies induced by laser annealing on exfoliated layers encapsulated by hexagonal boron nitride. Moreover, a highly efficient photodetector was fabricated using a molecularly thin n = 4 RPP crystal, showing a photogain of 10(5) and an internal quantum efficiency of similar to 34%. Our results suggest that, thanks to their dynamic structure, atomically thin perovskites enable an additional degree of control for the bandgap engineering of these materials |