Tang Wei
CA2DM Publications:
2019 |
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. |
2018 |
Li, Xing; Gao, Qiang; Wang, Juefan; Chen, Yifeng; Chen, Zhi-Hui; Xu, Hai-Sen; Tang, Wei; Leng, Kai; Ning, Guo-Hong; Wu, Jishan; Xu, Qing-Hua; Quek, Su Ying; Lu, Yixin; Loh, Kian Ping Tuneable near white-emissive two-dimensional covalent organic frameworks Journal Article NATURE COMMUNICATIONS, 9 , 2018, ISSN: 2041-1723. @article{ISI:000435082400012, title = {Tuneable near white-emissive two-dimensional covalent organic frameworks}, author = {Xing Li and Qiang Gao and Juefan Wang and Yifeng Chen and Zhi-Hui Chen and Hai-Sen Xu and Wei Tang and Kai Leng and Guo-Hong Ning and Jishan Wu and Qing-Hua Xu and Su Ying Quek and Yixin Lu and Kian Ping Loh}, doi = {10.1038/s41467-018-04769-6}, times_cited = {0}, issn = {2041-1723}, year = {2018}, date = {2018-06-13}, journal = {NATURE COMMUNICATIONS}, volume = {9}, publisher = {NATURE PUBLISHING GROUP}, address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND}, abstract = {Most two-dimensional (2D) covalent organic frameworks (COFs) are non-fluorescent in the solid state even when they are constructed from emissive building blocks. The fluorescence quenching is usually attributed to non-irradiative rotation-related or p-p stacking-caused thermal energy dissipation process. Currently there is a lack of guiding principle on how to design fluorescent, solid-state material made of COF. Herein, we demonstrate that the eclipsed stacking structure of 2D COFs can be used to turn on, and tune, the solid-state photoluminescence from non-emissive building blocks by the restriction of intramolecular bond rotation via intralayer and interlayer hydrogen bonds among highly organized layers in the eclipse-stacked COFs. Our COFs serve as a platform whereby the size of the conjugated linkers and side-chain functionalities can be varied, rendering the emission colour-tuneable from blue to yellow and even white. This work provides a guide to design new solid-state emitters using COFs.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Most two-dimensional (2D) covalent organic frameworks (COFs) are non-fluorescent in the solid state even when they are constructed from emissive building blocks. The fluorescence quenching is usually attributed to non-irradiative rotation-related or p-p stacking-caused thermal energy dissipation process. Currently there is a lack of guiding principle on how to design fluorescent, solid-state material made of COF. Herein, we demonstrate that the eclipsed stacking structure of 2D COFs can be used to turn on, and tune, the solid-state photoluminescence from non-emissive building blocks by the restriction of intramolecular bond rotation via intralayer and interlayer hydrogen bonds among highly organized layers in the eclipse-stacked COFs. Our COFs serve as a platform whereby the size of the conjugated linkers and side-chain functionalities can be varied, rendering the emission colour-tuneable from blue to yellow and even white. This work provides a guide to design new solid-state emitters using COFs. |
Gao, Qiang; Li, Xing; Ning, Guo-Hong; Xu, Hai-Sen; Liu, Cuibo; Tian, Bingbing; Tang, Wei; Loh, Kian Ping Covalent Organic Framework with Frustrated Bonding Network for Enhanced Carbon Dioxide Storage Journal Article 150 CHEMISTRY OF MATERIALS, 30 (5), pp. 1762-1768, 2018, ISSN: 0897-4756. @article{ISI:000427661500036, title = {Covalent Organic Framework with Frustrated Bonding Network for Enhanced Carbon Dioxide Storage}, author = {Qiang Gao and Xing Li and Guo-Hong Ning and Hai-Sen Xu and Cuibo Liu and Bingbing Tian and Wei Tang and Kian Ping Loh}, doi = {10.1021/acs.chemmater.8b00117}, times_cited = {150}, issn = {0897-4756}, year = {2018}, date = {2018-03-13}, journal = {CHEMISTRY OF MATERIALS}, volume = {30}, number = {5}, pages = {1762-1768}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Two-dimensional covalent organic framework (COF) materials can serve as excellent candidates for gas storage due to their high density of periodically arranged pores and channels, which can be tethered with functional groups. However, post-functionalization tends to disturb the structure of the COF; thus, it is attractive to develop synthetic approaches that generate built-in functionalities. Herein, we develop a new strategy for the construction of 2D-COFs with built-in, unreacted periodic bonding networks by solvent-directed divergent synthesis. Tetraphenylethane (TPE), which combines both pi-rigidity for stacking and rotational flexibility, is selected as the central core for COF construction. By solvent control, two distinct COF structures could be constructed, arising from a [4 + 4] condensation pathway (TPE-COF-I) or an unusual [2 + 4] pathway (TPE-COF-II). TPE-COF-II contains unreacted linker units arranged around its pores and shows greatly enhanced carbon dioxide adsorption performance (23.2 wt %, 118.8 cm(3) g(-1) at 1 atm, 273 K), which is among the best COF materials for CO2 adsorption reported to date.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two-dimensional covalent organic framework (COF) materials can serve as excellent candidates for gas storage due to their high density of periodically arranged pores and channels, which can be tethered with functional groups. However, post-functionalization tends to disturb the structure of the COF; thus, it is attractive to develop synthetic approaches that generate built-in functionalities. Herein, we develop a new strategy for the construction of 2D-COFs with built-in, unreacted periodic bonding networks by solvent-directed divergent synthesis. Tetraphenylethane (TPE), which combines both pi-rigidity for stacking and rotational flexibility, is selected as the central core for COF construction. By solvent control, two distinct COF structures could be constructed, arising from a [4 + 4] condensation pathway (TPE-COF-I) or an unusual [2 + 4] pathway (TPE-COF-II). TPE-COF-II contains unreacted linker units arranged around its pores and shows greatly enhanced carbon dioxide adsorption performance (23.2 wt %, 118.8 cm(3) g(-1) at 1 atm, 273 K), which is among the best COF materials for CO2 adsorption reported to date. |
Gao, Qiang; Li, Xing; Ning, Guo-Hong; Leng, Kai; Tian, Bingbing; Liu, Cuibo; Tang, Wei; Xu, Hai-Sen; Loh, Kian Ping Highly photoluminescent two-dimensional imine-based covalent organic frameworks for chemical sensing Journal Article CHEMICAL COMMUNICATIONS, 54 (19), pp. 2349-2352, 2018, ISSN: 1359-7345. @article{ISI:000428065300005, title = {Highly photoluminescent two-dimensional imine-based covalent organic frameworks for chemical sensing}, author = {Qiang Gao and Xing Li and Guo-Hong Ning and Kai Leng and Bingbing Tian and Cuibo Liu and Wei Tang and Hai-Sen Xu and Kian Ping Loh}, doi = {10.1039/c7cc09866a}, times_cited = {0}, issn = {1359-7345}, year = {2018}, date = {2018-03-07}, journal = {CHEMICAL COMMUNICATIONS}, volume = {54}, number = {19}, pages = {2349-2352}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {The strong pi-pi interactions in the stacking layers of two-dimensional covalent organic frameworks (2D-COFs), together with rotationally labile imine linkages, make most of the solid state imine-linked COFs non-fluorescent due to fluorescence quenching processes. Here, we report the successful synthesis of highly photoluminescent imine-based 2D-COFs by integrating a non-planar building unit with a pyrene-based unit and transforming the COF into spherical, sub-micron particles. High photoluminescence quantum yields (PLQY) were achieved with COF sub-micron particles dispersed in organic solvents. The as-prepared COF sub-micron particles can be used as a chemical sensor for the detection of explosive chemicals, with high sensitivity and selectivity (up to ppm level).}, keywords = {}, pubstate = {published}, tppubtype = {article} } The strong pi-pi interactions in the stacking layers of two-dimensional covalent organic frameworks (2D-COFs), together with rotationally labile imine linkages, make most of the solid state imine-linked COFs non-fluorescent due to fluorescence quenching processes. Here, we report the successful synthesis of highly photoluminescent imine-based 2D-COFs by integrating a non-planar building unit with a pyrene-based unit and transforming the COF into spherical, sub-micron particles. High photoluminescence quantum yields (PLQY) were achieved with COF sub-micron particles dispersed in organic solvents. The as-prepared COF sub-micron particles can be used as a chemical sensor for the detection of explosive chemicals, with high sensitivity and selectivity (up to ppm level). |
Chen, Jianyi; Zhao, Xiaoxu; Grinblat, Gustavo; Chen, Zhongxin; Tan, Sherman J R; Fu, Wei; Ding, Zijing; Abdelwahab, Ibrahim; Li, Yi; Geng, Dechao; Liu, Yanpeng; Leng, Kai; Liu, Bo; Liu, Wei; Tang, Wei; Maier, Stefan A; Pennycook, Stephen John; Loh, Kian Ping Homoepitaxial Growth of Large-Scale Highly Organized Transition Metal Dichalcogenide Patterns Journal Article ADVANCED MATERIALS, 30 (4), 2018, ISSN: 0935-9648. @article{ISI:000422932800013, title = {Homoepitaxial Growth of Large-Scale Highly Organized Transition Metal Dichalcogenide Patterns}, author = {Jianyi Chen and Xiaoxu Zhao and Gustavo Grinblat and Zhongxin Chen and Sherman J R Tan and Wei Fu and Zijing Ding and Ibrahim Abdelwahab and Yi Li and Dechao Geng and Yanpeng Liu and Kai Leng and Bo Liu and Wei Liu and Wei Tang and Stefan A Maier and Stephen John Pennycook and Kian Ping Loh}, doi = {10.1002/adma.201704674}, times_cited = {0}, issn = {0935-9648}, year = {2018}, date = {2018-01-25}, journal = {ADVANCED MATERIALS}, volume = {30}, number = {4}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {Controllable growth of highly crystalline transition metal dichalcogenide (TMD) patterns with regular morphology and unique edge structure is highly desired and important for fundamental research and potential applications. Here, single-crystalline MoS2 flakes are reported with regular trigonal symmetric patterns that can be homoepitaxially grown on MoS2 monolayer via chemical vapor deposition. The highly organized MoS2 patterns are rhombohedral (3R)-stacked with the underlying MoS2 monolayer, and their boundaries are predominantly terminated by zigzag Mo edge structure. The epitaxial MoS2 crystals can be tailored from compact triangles to fractal flakes, and the pattern formation can be explained by the anisotropic growth rates of the S and Mo edges under low sulfur chemical potential. The 3R-stacked MoS2 pattern demonstrates strong second and third-harmonic-generation signals, which exceed those reported for monolayer MoS2 by a factor of 6 and 4, correspondingly. This homoepitaxial growth approach for making highly organized TMD patterns is also demonstrated for WS2.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Controllable growth of highly crystalline transition metal dichalcogenide (TMD) patterns with regular morphology and unique edge structure is highly desired and important for fundamental research and potential applications. Here, single-crystalline MoS2 flakes are reported with regular trigonal symmetric patterns that can be homoepitaxially grown on MoS2 monolayer via chemical vapor deposition. The highly organized MoS2 patterns are rhombohedral (3R)-stacked with the underlying MoS2 monolayer, and their boundaries are predominantly terminated by zigzag Mo edge structure. The epitaxial MoS2 crystals can be tailored from compact triangles to fractal flakes, and the pattern formation can be explained by the anisotropic growth rates of the S and Mo edges under low sulfur chemical potential. The 3R-stacked MoS2 pattern demonstrates strong second and third-harmonic-generation signals, which exceed those reported for monolayer MoS2 by a factor of 6 and 4, correspondingly. This homoepitaxial growth approach for making highly organized TMD patterns is also demonstrated for WS2. |
Tian, Bingbing; Tang, Wei; Su, Chenliang; Li, Ying Reticular V2O5•0.6H2O Xerogel as Cathode for Rechargeable Potassium Ion Batteries Journal Article ACS APPLIED MATERIALS & INTERFACES, 10 (1), pp. 642-650, 2018, ISSN: 1944-8244. @article{ISI:000422814400069, title = {Reticular V_{2}O_{5}•0.6H_{2}O Xerogel as Cathode for Rechargeable Potassium Ion Batteries}, author = {Bingbing Tian and Wei Tang and Chenliang Su and Ying Li}, doi = {10.1021/acsami.7b15407}, times_cited = {0}, issn = {1944-8244}, year = {2018}, date = {2018-01-10}, journal = {ACS APPLIED MATERIALS & INTERFACES}, volume = {10}, number = {1}, pages = {642-650}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Potassium ion batteries (KIBs), because of their low price, may exhibit advantages over lithium ion batteries as potential candidates for large-scale energy storage systems. However, owing to the large ionic radii of K-ions, it is challenging to find a suitable intercalation host for KIBs and thus the rechargeable KIB electrode materials are still largely unexplored. In this work, a reticular V2O5 center dot 0.6H(2)O xerogel was synthesized via a hydrothermal process as a cathode material for rechargeable KIBs. Compared with the orthorhombic crystalline V2O5, the hydrated vanadium pentoxide (V2O5 center dot 0.6H(2)O) exhibits the ability of accommodating larger alkali metal ions of K+ because of the enlarged layer space by hosting structural H2O molecules in the interlayer. By intercalation of H2O into the V2O5 layers, its potassium electrochemical activity is significantly improved. It exhibits an initial discharge capacity of similar to 224.4 mA h g(-1) and a discharge capacity of similar to 103.5 mA h g(-1) even after 500 discharge/charge cycles at a current density of 50 mA g(-1), which is much higher than that of the V2O5 electrode without structural water. Meanwhile, X-ray diffraction and X-ray photoelectron spectroscopy combined with energy dispersive spectroscopy techniques are carried out to investigate the potassiation/depotassiation process of the V2O5 center dot 0.6H(2)O electrodes, which confirmed the potassium intercalation storage mechanisms of this hydrated material. The results demonstrate that the interlayer-spacing-enlarged V2O5 center dot 0.6H(2)O is a promising cathode candidate for KIBs.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Potassium ion batteries (KIBs), because of their low price, may exhibit advantages over lithium ion batteries as potential candidates for large-scale energy storage systems. However, owing to the large ionic radii of K-ions, it is challenging to find a suitable intercalation host for KIBs and thus the rechargeable KIB electrode materials are still largely unexplored. In this work, a reticular V2O5 center dot 0.6H(2)O xerogel was synthesized via a hydrothermal process as a cathode material for rechargeable KIBs. Compared with the orthorhombic crystalline V2O5, the hydrated vanadium pentoxide (V2O5 center dot 0.6H(2)O) exhibits the ability of accommodating larger alkali metal ions of K+ because of the enlarged layer space by hosting structural H2O molecules in the interlayer. By intercalation of H2O into the V2O5 layers, its potassium electrochemical activity is significantly improved. It exhibits an initial discharge capacity of similar to 224.4 mA h g(-1) and a discharge capacity of similar to 103.5 mA h g(-1) even after 500 discharge/charge cycles at a current density of 50 mA g(-1), which is much higher than that of the V2O5 electrode without structural water. Meanwhile, X-ray diffraction and X-ray photoelectron spectroscopy combined with energy dispersive spectroscopy techniques are carried out to investigate the potassiation/depotassiation process of the V2O5 center dot 0.6H(2)O electrodes, which confirmed the potassium intercalation storage mechanisms of this hydrated material. The results demonstrate that the interlayer-spacing-enlarged V2O5 center dot 0.6H(2)O is a promising cathode candidate for KIBs. |
Liu, Cuibo; Chen, Zhongxin; Su, Chenliang; Zhao, Xiaoxu; Gao, Qiang; Ning, Guo-Hong; Zhu, Hai; Tang, Wei; Leng, Kai; Fu, Wei; Tian, Bingbing; Peng, Xinwen; Li, Jing; Xu, Qing-Hua; Zhou, Wu; Loh, Kian Ping Controllable deuteration of halogenated compounds by photocatalytic D2O splitting Journal Article NATURE COMMUNICATIONS, 9 , 2018. @article{ISI:000419446600008, title = {Controllable deuteration of halogenated compounds by photocatalytic D_{2}O splitting}, author = {Cuibo Liu and Zhongxin Chen and Chenliang Su and Xiaoxu Zhao and Qiang Gao and Guo-Hong Ning and Hai Zhu and Wei Tang and Kai Leng and Wei Fu and Bingbing Tian and Xinwen Peng and Jing Li and Qing-Hua Xu and Wu Zhou and Kian Ping Loh}, doi = {10.1038/s41467-017-02551-8}, times_cited = {0}, year = {2018}, date = {2018-01-08}, journal = {NATURE COMMUNICATIONS}, volume = {9}, publisher = {NATURE PORTFOLIO}, address = {HEIDELBERGER PLATZ 3, BERLIN, 14197, GERMANY}, abstract = {Deuterium labeling is of great value in organic synthesis and the pharmaceutical industry. However, the state-of-the-art C-H/C-D exchange using noble metal catalysts or strong bases/acids suffers from poor functional group tolerances, poor selectivity and lack of scope for generating molecular complexity. Herein, we demonstrate the deuteration of halides using heavy water as the deuteration reagent and porous CdSe nanosheets as the catalyst. The deuteration mechanism involves the generation of highly active carbon and deuterium radicals via photoinduced electron transfer from CdSe to the substrates, followed by tandem radicals coupling process, which is mechanistically distinct from the traditional methods involving deuterium cations or anions. Our deuteration strategy shows better selectivity and functional group tolerances than current C-H/C-D exchange methods. Extending the synthetic scope, deuterated boronic acids, halides, alkynes, and aldehydes can be used as synthons in Suzuki coupling, Click reaction, C-H bond insertion reaction etc. for the synthesis of complex deuterated molecules.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Deuterium labeling is of great value in organic synthesis and the pharmaceutical industry. However, the state-of-the-art C-H/C-D exchange using noble metal catalysts or strong bases/acids suffers from poor functional group tolerances, poor selectivity and lack of scope for generating molecular complexity. Herein, we demonstrate the deuteration of halides using heavy water as the deuteration reagent and porous CdSe nanosheets as the catalyst. The deuteration mechanism involves the generation of highly active carbon and deuterium radicals via photoinduced electron transfer from CdSe to the substrates, followed by tandem radicals coupling process, which is mechanistically distinct from the traditional methods involving deuterium cations or anions. Our deuteration strategy shows better selectivity and functional group tolerances than current C-H/C-D exchange methods. Extending the synthetic scope, deuterated boronic acids, halides, alkynes, and aldehydes can be used as synthons in Suzuki coupling, Click reaction, C-H bond insertion reaction etc. for the synthesis of complex deuterated molecules. |
2017 |
Tian, Bingbing; Tang, Wei; Leng, Kai; Chen, Zhongxin; Tan, Sherman Jun Rong; Peng, Chengxin; Ning, Guo-Hong; Fu, Wei; Su, Chenliang; Zheng, Guangyuan Wesley; Loh, Kian Ping Phase Transformations in TiS2 during K Intercalation Journal Article ACS ENERGY LETTERS, 2 (8), pp. 1835-1840, 2017, ISSN: 2380-8195. @article{ISI:000407771500018, title = {Phase Transformations in TiS_{2} during K Intercalation}, author = {Bingbing Tian and Wei Tang and Kai Leng and Zhongxin Chen and Sherman Jun Rong Tan and Chengxin Peng and Guo-Hong Ning and Wei Fu and Chenliang Su and Guangyuan Wesley Zheng and Kian Ping Loh}, doi = {10.1021/acsenergylett.7b00529}, times_cited = {0}, issn = {2380-8195}, year = {2017}, date = {2017-08-01}, journal = {ACS ENERGY LETTERS}, volume = {2}, number = {8}, pages = {1835-1840}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {The electrochemical performances of TiS2 in potassium ion batteries (KIBs) are poor due to the large size of K ions, which induces irreversible structural changes and poor kinetics. To obtain detailed insights into the kinetics of phase changes, we investigated the electrochemical properties, phase transformations, and stability of potassium-intercalated TiS2 (KxTiS2, 0 <= x <= 0.88). In situ XRD reveals staged transitions corresponding to distinct crystalline phases during K ion intercalation, which are distinct from those of Li and Na ions. Electrochemical (cyclic voltammetry and galvanostatic charge/discharge) studies show that the phase transitions among various intercalated stages slow down the kinetics of the discharge/charge in bulk TiS2 hosts. By chemically prepotassiating the bulk TiS2 (K0.25TiS2) to reduce the domain size of the crystal, these phase transitions are bypassed and more facile ion insertion kinetics can be obtained, which leads to improved Coulombic efficiency, rate capability, and cycling stability.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The electrochemical performances of TiS2 in potassium ion batteries (KIBs) are poor due to the large size of K ions, which induces irreversible structural changes and poor kinetics. To obtain detailed insights into the kinetics of phase changes, we investigated the electrochemical properties, phase transformations, and stability of potassium-intercalated TiS2 (KxTiS2, 0 <= x <= 0.88). In situ XRD reveals staged transitions corresponding to distinct crystalline phases during K ion intercalation, which are distinct from those of Li and Na ions. Electrochemical (cyclic voltammetry and galvanostatic charge/discharge) studies show that the phase transitions among various intercalated stages slow down the kinetics of the discharge/charge in bulk TiS2 hosts. By chemically prepotassiating the bulk TiS2 (K0.25TiS2) to reduce the domain size of the crystal, these phase transitions are bypassed and more facile ion insertion kinetics can be obtained, which leads to improved Coulombic efficiency, rate capability, and cycling stability. |
Tang, Wei; Chen, Zhongxin; Tian, Bingbing; Lee, Hyun-Wook; Zhao, Xiaoxu; Fan, Xiaofeng; Fan, Yanchen; Leng, Kai; Peng, Chengxin; Kin, Min-Ho; Li, Meng; Lin, Ming; Su, Jie; Chen, Jianyi; Jeong, Hu Young; Yin, Xuesong; Zhang, Qianfan; Zhou, Wu; Loh, Kian Ping; Zheng, Guangyuan Wesley In Situ Observation and Electrochemical Study of Encapsulated Sulfur Nanoparticles by MoS2 Flakes Journal Article JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 139 (29), pp. 10133-10141, 2017, ISSN: 0002-7863. @article{ISI:000417342500032, title = {\textit{In Situ} Observation and Electrochemical Study of Encapsulated Sulfur Nanoparticles by MoS_{2} Flakes}, author = {Wei Tang and Zhongxin Chen and Bingbing Tian and Hyun-Wook Lee and Xiaoxu Zhao and Xiaofeng Fan and Yanchen Fan and Kai Leng and Chengxin Peng and Min-Ho Kin and Meng Li and Ming Lin and Jie Su and Jianyi Chen and Hu Young Jeong and Xuesong Yin and Qianfan Zhang and Wu Zhou and Kian Ping Loh and Guangyuan Wesley Zheng}, doi = {10.1021/jacs.7b05371}, times_cited = {0}, issn = {0002-7863}, year = {2017}, date = {2017-07-26}, journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, volume = {139}, number = {29}, pages = {10133-10141}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Sulfur is an attractive cathode material for next-generation lithium batteries due to its high theoretical capacity and low cost. However, dissolution of its lithiated product (lithium polysulfides) into the electrolyte limits the practical application of lithium sulfur batteries. Here we demonstrate that sulfur particles can be hermetically encapsulated by leveraging on the unique properties of two-dimensional materials such as molybdenum disulfide (MoS2). The high flexibility and strong van der Waals force in MoS2 nanoflakes allows effective encapsulation of the sulfur particles and prevent its sublimation during in situ TEM studies. We observe that the lithium diffusivities in the encapsulated sulfur particles are in the order of 10(-17) m(2) Composite electrodes made from the MoS2-encapsulated sulfur spheres show outstanding electrochemical performance, with an initial capacity of 1660 mAh g(-1) and long cycle life of more than 1000 cycles.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Sulfur is an attractive cathode material for next-generation lithium batteries due to its high theoretical capacity and low cost. However, dissolution of its lithiated product (lithium polysulfides) into the electrolyte limits the practical application of lithium sulfur batteries. Here we demonstrate that sulfur particles can be hermetically encapsulated by leveraging on the unique properties of two-dimensional materials such as molybdenum disulfide (MoS2). The high flexibility and strong van der Waals force in MoS2 nanoflakes allows effective encapsulation of the sulfur particles and prevent its sublimation during in situ TEM studies. We observe that the lithium diffusivities in the encapsulated sulfur particles are in the order of 10(-17) m(2) Composite electrodes made from the MoS2-encapsulated sulfur spheres show outstanding electrochemical performance, with an initial capacity of 1660 mAh g(-1) and long cycle life of more than 1000 cycles. |
Peng, Chengxin; Ning, Guo-Hong; Su, Jie; Zhong, Guiming; Tang, Wei; Tian, Bingbing; Su, Chenliang; Yu, Dingyi; Zu, Lianhai; Yang, Jinhu; Ng, Man-Fai; Hu, Yong-Sheng; Yang, Yong; Armand, Michel; Loh, Kian Ping Reversible multi-electron redox chemistry of π-conjugated N-containing heteroaromatic molecule-based organic cathodes Journal Article NATURE ENERGY, 2 (7), 2017, ISSN: 2058-7546. @article{ISI:000406499200004, title = {Reversible multi-electron redox chemistry of π-conjugated N-containing heteroaromatic molecule-based organic cathodes}, author = {Chengxin Peng and Guo-Hong Ning and Jie Su and Guiming Zhong and Wei Tang and Bingbing Tian and Chenliang Su and Dingyi Yu and Lianhai Zu and Jinhu Yang and Man-Fai Ng and Yong-Sheng Hu and Yong Yang and Michel Armand and Kian Ping Loh}, doi = {10.1038/nenergy.2017.74}, times_cited = {0}, issn = {2058-7546}, year = {2017}, date = {2017-07-01}, journal = {NATURE ENERGY}, volume = {2}, number = {7}, publisher = {NATURE PUBLISHING GROUP}, address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND}, abstract = {Even though organic molecules with well-designed functional groups can be programmed to have high electron density per unit mass, their poor electrical conductivity and low cycle stability limit their applications in batteries. Here we report a facile synthesis of pi-conjugated quinoxaline-based heteroaromatic molecules (3Q) by condensation of cyclic carbonyl molecules with o-phenylenediamine. 3Q features a number of electron-deficient pyrazine sites, where multiple redox reactions take place. When hybridized with graphene and coupled with an ether-based electrolyte, an organic cathode based on 3Q molecules displays a discharge capacity of 395 mAh g(-1) at 400 mA g(-1) (1C) in the voltage range of 1.2-3.9 V and a nearly 70% capacity retention after 10,000 cycles at 8 A g(-1). It also exhibits a capacity of 222 mAh g(-1) at 20C, which corresponds to 60% of the initial specific capacity. Our results offer evidence that heteroaromatic molecules with multiple redox sites are promising in developing high-energy-density, long-cycle-life organic rechargeable batteries.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Even though organic molecules with well-designed functional groups can be programmed to have high electron density per unit mass, their poor electrical conductivity and low cycle stability limit their applications in batteries. Here we report a facile synthesis of pi-conjugated quinoxaline-based heteroaromatic molecules (3Q) by condensation of cyclic carbonyl molecules with o-phenylenediamine. 3Q features a number of electron-deficient pyrazine sites, where multiple redox reactions take place. When hybridized with graphene and coupled with an ether-based electrolyte, an organic cathode based on 3Q molecules displays a discharge capacity of 395 mAh g(-1) at 400 mA g(-1) (1C) in the voltage range of 1.2-3.9 V and a nearly 70% capacity retention after 10,000 cycles at 8 A g(-1). It also exhibits a capacity of 222 mAh g(-1) at 20C, which corresponds to 60% of the initial specific capacity. Our results offer evidence that heteroaromatic molecules with multiple redox sites are promising in developing high-energy-density, long-cycle-life organic rechargeable batteries. |
Tian, Bingbing; Ding, Zijing; Ning, Guo-Hong; Tang, Wei; Peng, Chengxin; Liu, Bo; Su, Jie; Su, Chenliang; Loh, Kian Ping Amino group enhanced phenazine derivatives as electrode materials for lithium storage Journal Article CHEMICAL COMMUNICATIONS, 53 (20), pp. 2914-2917, 2017, ISSN: 1359-7345. @article{ISI:000398997200003, title = {Amino group enhanced phenazine derivatives as electrode materials for lithium storage}, author = {Bingbing Tian and Zijing Ding and Guo-Hong Ning and Wei Tang and Chengxin Peng and Bo Liu and Jie Su and Chenliang Su and Kian Ping Loh}, doi = {10.1039/c6cc09084b}, times_cited = {0}, issn = {1359-7345}, year = {2017}, date = {2017-03-11}, journal = {CHEMICAL COMMUNICATIONS}, volume = {53}, number = {20}, pages = {2914-2917}, publisher = {ROYAL SOC CHEMISTRY}, address = {THOMAS GRAHAM HOUSE, SCIENCE PARK, MILTON RD, CAMBRIDGE CB4 0WF, CAMBS, ENGLAND}, abstract = {The development of organic molecule-based batteries is hampered by stability issues caused by the dissolution of the active organic materials in electrolytes. Herein, phenazine (PNZ) and 2,3-diamino-phenazine (DAP) are investigated as organic electrode materials. The presence of amino functional groups in DAP dramatically enhances its electrochemical performances due to suppressed dissolution in the electrolyte.}, keywords = {}, pubstate = {published}, tppubtype = {article} } The development of organic molecule-based batteries is hampered by stability issues caused by the dissolution of the active organic materials in electrolytes. Herein, phenazine (PNZ) and 2,3-diamino-phenazine (DAP) are investigated as organic electrode materials. The presence of amino functional groups in DAP dramatically enhances its electrochemical performances due to suppressed dissolution in the electrolyte. |
Chen, Zhongxin; Leng, Kai; Zhao, Xiaoxu; Malkhandi, Souradip; Tang, Wei; Tian, Bingbing; Dong, Lei; Zheng, Lirong; Lin, Ming; Yeo, Boon Siang; Loh, Kian Ping Interface confined hydrogen evolution reaction in zero valent metal nanoparticles-intercalated molybdenum disulfide Journal Article NATURE COMMUNICATIONS, 8 , 2017, ISSN: 2041-1723. @article{ISI:000394588600001, title = {Interface confined hydrogen evolution reaction in zero valent metal nanoparticles-intercalated molybdenum disulfide}, author = {Zhongxin Chen and Kai Leng and Xiaoxu Zhao and Souradip Malkhandi and Wei Tang and Bingbing Tian and Lei Dong and Lirong Zheng and Ming Lin and Boon Siang Yeo and Kian Ping Loh}, doi = {10.1038/ncomms14548}, times_cited = {0}, issn = {2041-1723}, year = {2017}, date = {2017-02-23}, journal = {NATURE COMMUNICATIONS}, volume = {8}, publisher = {NATURE PUBLISHING GROUP}, address = {MACMILLAN BUILDING, 4 CRINAN ST, LONDON N1 9XW, ENGLAND}, abstract = {Interface confined reactions, which can modulate the bonding of reactants with catalytic centres and influence the rate of the mass transport from bulk solution, have emerged as a viable strategy for achieving highly stable and selective catalysis. Here we demonstrate that 1T'-enriched lithiated molybdenum disulfide is a highly powerful reducing agent, which can be exploited for the in-situ reduction of metal ions within the inner planes of lithiated molybdenum disulfide to form a zero valent metal-intercalated molybdenum disulfide. The confinement of platinum nanoparticles within the molybdenum disulfide layered structure leads to enhanced hydrogen evolution reaction activity and stability compared to catalysts dispersed on carbon support. In particular, the inner platinum surface is accessible to charged species like proton and metal ions, while blocking poisoning by larger sized pollutants or neutral molecules. This points a way forward for using bulk intercalated compounds for energy related applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Interface confined reactions, which can modulate the bonding of reactants with catalytic centres and influence the rate of the mass transport from bulk solution, have emerged as a viable strategy for achieving highly stable and selective catalysis. Here we demonstrate that 1T'-enriched lithiated molybdenum disulfide is a highly powerful reducing agent, which can be exploited for the in-situ reduction of metal ions within the inner planes of lithiated molybdenum disulfide to form a zero valent metal-intercalated molybdenum disulfide. The confinement of platinum nanoparticles within the molybdenum disulfide layered structure leads to enhanced hydrogen evolution reaction activity and stability compared to catalysts dispersed on carbon support. In particular, the inner platinum surface is accessible to charged species like proton and metal ions, while blocking poisoning by larger sized pollutants or neutral molecules. This points a way forward for using bulk intercalated compounds for energy related applications. |
Chen, Jianyi; Zhao, Xiaoxu; Tan, Sherman J R; Xu, Hai; Wu, Bo; Liu, Bo; Fu, Deyi; Fu, Wei; Geng, Dechao; Liu, Yanpeng; Liu, Wei; Tang, Wei; Li, Linjun; Zhou, Wu; Sum, Tze Chien; Loh, Kian Ping Chemical Vapor Deposition of Large-Size Monolayer MoSe2 Crystals on Molten Glass Journal Article 12 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 139 (3), pp. 1073-1076, 2017, ISSN: 0002-7863. @article{ISI:000393541000013, title = {Chemical Vapor Deposition of Large-Size Monolayer MoSe_{2} Crystals on Molten Glass}, author = {Jianyi Chen and Xiaoxu Zhao and Sherman J R Tan and Hai Xu and Bo Wu and Bo Liu and Deyi Fu and Wei Fu and Dechao Geng and Yanpeng Liu and Wei Liu and Wei Tang and Linjun Li and Wu Zhou and Tze Chien Sum and Kian Ping Loh}, doi = {10.1021/jacs.6b12156}, times_cited = {12}, issn = {0002-7863}, year = {2017}, date = {2017-01-25}, journal = {JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, volume = {139}, number = {3}, pages = {1073-1076}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {We report the fast growth of high-quality millimeter-size monolayer MoSe2 crystals on molten glass using an ambient pressure CVD system. We found that the isotropic surface of molten glass suppresses nucleation events and greatly improves the growth of large crystalline domains. Triangular monolayer MoSe2 crystals with sizes reaching 2.5 mm, and with a room-temperature carrier mobility up to 95 cm2(/)(V.s), can be synthesized in 5 min. The method can also be used to synthesize millimeter-size monolayer MoS2 crystals. Our results demonstrate that "liquid-state" glass is a highly promising substrate for the low-cost growth of high-quality large-size 2D transition metal dichalcogenides (TMDs).}, keywords = {}, pubstate = {published}, tppubtype = {article} } We report the fast growth of high-quality millimeter-size monolayer MoSe2 crystals on molten glass using an ambient pressure CVD system. We found that the isotropic surface of molten glass suppresses nucleation events and greatly improves the growth of large crystalline domains. Triangular monolayer MoSe2 crystals with sizes reaching 2.5 mm, and with a room-temperature carrier mobility up to 95 cm2(/)(V.s), can be synthesized in 5 min. The method can also be used to synthesize millimeter-size monolayer MoS2 crystals. Our results demonstrate that "liquid-state" glass is a highly promising substrate for the low-cost growth of high-quality large-size 2D transition metal dichalcogenides (TMDs). |
2016 |
Tian, Bingbing; Ning, Guo-Hong; Gao, Qiang; Tan, Li-Min; Tang, Wei; Chen, Zhongxin; Su, Chenliang; Loh, Kian Ping Crystal Engineering of Naphthalenediimide-Based Metal-Organic Frameworks: Structure-Dependent Lithium Storage Journal Article ACS APPLIED MATERIALS & INTERFACES, 8 (45), pp. 31067-31075, 2016, ISSN: 1944-8244. @article{ISI:000388429600047, title = {Crystal Engineering of Naphthalenediimide-Based Metal-Organic Frameworks: Structure-Dependent Lithium Storage}, author = {Bingbing Tian and Guo-Hong Ning and Qiang Gao and Li-Min Tan and Wei Tang and Zhongxin Chen and Chenliang Su and Kian Ping Loh}, doi = {10.1021/acsami.6b11772}, times_cited = {0}, issn = {1944-8244}, year = {2016}, date = {2016-11-16}, journal = {ACS APPLIED MATERIALS & INTERFACES}, volume = {8}, number = {45}, pages = {31067-31075}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Metal-organic frameworks (MOFs) possess great structural diversity because of the flexible design of linker groups and metal nodes. The structure property correlation has been extensively investigated in areas like chiral catalysis, gas storage and absorption, water purification, energy storage, etc. However, the use of MOFs in lithium storage is hampered by stability issues, and how its porosity helps with battery performance is not well understood. Herein, through anion and thermodynamic control, we design a series of naphthalenediimide-based MOFs 1-4 that can be used for cathode materials in lithium-ion batteries (LIBs). Complexation of the N,N'-di(4-pyridyl)-1,4,5,8-naphthalenediimide (DPNDI) ligand and CdX2 (X = NO3- or ClO4-) produces complexes MOFs 1 and 2 with a one-dimensional (1D) nonporous network and a porous, noninterpenetrated two-dimensional (2D) square-grid structure, respectively. With the DPNDI ligand and Co(NCS)(2), a porous 1D MOF 3 as a kinetic product is obtained, while a nonporous, noninterpenetrated 2D square-grid structure MOF 4 as a thermodynamic product is formed. The performance of LIBs is largely affected by the stability and porosity of these MOFs. For instance, the initial charge discharge curves of MOFs 1 and 2 show a specific capacity of similar to 47 mA h g(-1) with a capacity retention ratio of >70% during 50 cycles at 100 mA g(-1), which is much better than that of MOFs 3 and 4. The better performances are assigned to the higher stability of Cd(II) MOFs compared to that of Co (II) MOFs during the electrochemical process, according to X-ray diffraction analysis. In addition, despite having the same Cd(II) node in the framework, MOF 2 exhibits a lithium-ion diffusion coefficient (Du) larger than that of MOF 1 because of its higher porosity. X-ray photoelectron spectroscopy and Fourier transform infrared analysis indicate that metal nodes in these MOFs remain intact and only the DPNDI ligand undergoes the revisible redox reaction during the lithiation-delithiation process.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Metal-organic frameworks (MOFs) possess great structural diversity because of the flexible design of linker groups and metal nodes. The structure property correlation has been extensively investigated in areas like chiral catalysis, gas storage and absorption, water purification, energy storage, etc. However, the use of MOFs in lithium storage is hampered by stability issues, and how its porosity helps with battery performance is not well understood. Herein, through anion and thermodynamic control, we design a series of naphthalenediimide-based MOFs 1-4 that can be used for cathode materials in lithium-ion batteries (LIBs). Complexation of the N,N'-di(4-pyridyl)-1,4,5,8-naphthalenediimide (DPNDI) ligand and CdX2 (X = NO3- or ClO4-) produces complexes MOFs 1 and 2 with a one-dimensional (1D) nonporous network and a porous, noninterpenetrated two-dimensional (2D) square-grid structure, respectively. With the DPNDI ligand and Co(NCS)(2), a porous 1D MOF 3 as a kinetic product is obtained, while a nonporous, noninterpenetrated 2D square-grid structure MOF 4 as a thermodynamic product is formed. The performance of LIBs is largely affected by the stability and porosity of these MOFs. For instance, the initial charge discharge curves of MOFs 1 and 2 show a specific capacity of similar to 47 mA h g(-1) with a capacity retention ratio of >70% during 50 cycles at 100 mA g(-1), which is much better than that of MOFs 3 and 4. The better performances are assigned to the higher stability of Cd(II) MOFs compared to that of Co (II) MOFs during the electrochemical process, according to X-ray diffraction analysis. In addition, despite having the same Cd(II) node in the framework, MOF 2 exhibits a lithium-ion diffusion coefficient (Du) larger than that of MOF 1 because of its higher porosity. X-ray photoelectron spectroscopy and Fourier transform infrared analysis indicate that metal nodes in these MOFs remain intact and only the DPNDI ligand undergoes the revisible redox reaction during the lithiation-delithiation process. |
Chen, Jianyi; Zhou, Wu; Tang, Wei; Tian, Bingbing; Zhao, Xiaoxu; Xu, Hai; Liu, Yanpeng; Geng, Dechao; Tan, Sherman Jun Rong; Fu, Wei; Loh, Kian Ping Lateral Epitaxy of Atomically Sharp WSe2/WS2 Heterojunctions on Silicon Dioxide Substrates Journal Article CHEMISTRY OF MATERIALS, 28 (20), pp. 7194-7197, 2016, ISSN: 0897-4756. @article{ISI:000386421900004, title = {Lateral Epitaxy of Atomically Sharp WSe_{2}/WS_{2} Heterojunctions on Silicon Dioxide Substrates}, author = {Jianyi Chen and Wu Zhou and Wei Tang and Bingbing Tian and Xiaoxu Zhao and Hai Xu and Yanpeng Liu and Dechao Geng and Sherman Jun Rong Tan and Wei Fu and Kian Ping Loh}, doi = {10.1021/acs.chemmater.6b03639}, times_cited = {2}, issn = {0897-4756}, year = {2016}, date = {2016-10-25}, journal = {CHEMISTRY OF MATERIALS}, volume = {28}, number = {20}, pages = {7194-7197}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, keywords = {}, pubstate = {published}, tppubtype = {article} } |