Lian Xu
Degree: BSc
Position: Grad Students
Research Type: Experiment
Email: xu.lian@u.nus.edu
Contact: tel:(65) 9449 1152
CA2DM Publications:
2023 |
Liu, Yuan; Lian, Xu; Yu, Xiaojiang; Niu, Yuxiang; Yang, Jinlin; Ding, Yishui; Chen, Wei Interaction Mechanisms Between Nitrogen-Containing Groups and Alkali Metals with Molecular Model System of HATCN Journal Article BATTERIES & SUPERCAPS, 7 (1), 2023. @article{ISI:001110665200001, title = {Interaction Mechanisms Between Nitrogen-Containing Groups and Alkali Metals with Molecular Model System of HATCN}, author = {Yuan Liu and Xu Lian and Xiaojiang Yu and Yuxiang Niu and Jinlin Yang and Yishui Ding and Wei Chen}, doi = {10.1002/batt.202300351}, times_cited = {0}, year = {2023}, date = {2023-11-29}, journal = {BATTERIES & SUPERCAPS}, volume = {7}, number = {1}, publisher = {WILEY-V C H VERLAG GMBH}, address = {POSTFACH 101161, 69451 WEINHEIM, GERMANY}, abstract = {To enable the practical implementation of alkali metal batteries (AMBs), significant endeavors have been focused on enhancing the stability of alkali metal anodes (AMAs) using a range of strategies, such as optimizing electrolyte compositions, constructing anode deposition hosts, and establishing artificial protective layers. Despite significant progress in enhancing battery performance, limited attention has been given to comprehending the interaction mechanisms between alkali metals and protective materials, which is pivotal for the informed development of novel protective materials. Thus, aiming to enhance the comprehension of interaction processes between AMAs and organic protective materials containing various nitrogen groups, we conducted a mechanism study utilizing 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HATCN) as the model material, based on in-situ x-ray and ultraviolet photoelectron spectroscopy (XPS/UPS), and near edge x-ray absorption fine structure (NEXAFS), as well as density functional theory (DFT) calculations. Through the investigation of interaction processes between HATCN and Li/Na, we find that Li or Na interacts with the two different nitrogen-containing groups of HATCN in the same order: preferentially interacts with the inner imine groups of HATCN before interacting with the outer nitrile groups. Interestingly, our findings also reveal that the two distinct nitrogen-containing groups exhibit a smaller difference in their sodiophilicity compared to their difference in lithiophilicity. These valuable insights shed light on the intricate interactions between nitrogen-containing protective materials and AMAs, paving the way for the development of more effective protective materials in the future.}, keywords = {}, pubstate = {published}, tppubtype = {article} } To enable the practical implementation of alkali metal batteries (AMBs), significant endeavors have been focused on enhancing the stability of alkali metal anodes (AMAs) using a range of strategies, such as optimizing electrolyte compositions, constructing anode deposition hosts, and establishing artificial protective layers. Despite significant progress in enhancing battery performance, limited attention has been given to comprehending the interaction mechanisms between alkali metals and protective materials, which is pivotal for the informed development of novel protective materials. Thus, aiming to enhance the comprehension of interaction processes between AMAs and organic protective materials containing various nitrogen groups, we conducted a mechanism study utilizing 1,4,5,8,9,11-hexaazatriphenylenehexacarbonitrile (HATCN) as the model material, based on in-situ x-ray and ultraviolet photoelectron spectroscopy (XPS/UPS), and near edge x-ray absorption fine structure (NEXAFS), as well as density functional theory (DFT) calculations. Through the investigation of interaction processes between HATCN and Li/Na, we find that Li or Na interacts with the two different nitrogen-containing groups of HATCN in the same order: preferentially interacts with the inner imine groups of HATCN before interacting with the outer nitrile groups. Interestingly, our findings also reveal that the two distinct nitrogen-containing groups exhibit a smaller difference in their sodiophilicity compared to their difference in lithiophilicity. These valuable insights shed light on the intricate interactions between nitrogen-containing protective materials and AMAs, paving the way for the development of more effective protective materials in the future. |
Liu, Yuan; Lian, Xu; Jiang, Chonglai; Sun, Zejun; Yang, Jinlin; Ding, Yishui; Chen, Wei BATTERIES-BASEL, 9 (1), 2023. @article{ISI:000916644300001, title = {In-Situ Photoelectron Spectroscopy Investigation of Sulfurization-Induced Sodiophilic Sites with Model Systems of \textit{α}-sexithiophene and \textit{p}-sexiphenyl}, author = {Yuan Liu and Xu Lian and Chonglai Jiang and Zejun Sun and Jinlin Yang and Yishui Ding and Wei Chen}, doi = {10.3390/batteries9010021}, times_cited = {0}, year = {2023}, date = {2023-01-01}, journal = {BATTERIES-BASEL}, volume = {9}, number = {1}, publisher = {MDPI}, address = {ST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLAND}, abstract = {Uncontrollable sodium dendrite growth results in poor cycling performance and severe safety issues, hindering practical applications of sodium metal batteries (SMBs). To stabilize sodium metal anodes (SMAs), various strategies have been developed including employing anode hosts and electrolyte additives to establish protective layers. Nevertheless, the understanding of interaction mechanisms between protective materials and SMAs is still limited, which is crucial for the rational design of protective materials. In this work, we investigated the interaction mechanism between sodium metal and sulfur-containing functional groups with comparative model systems of alpha-sexithiophene (6T) and p-sexiphenyl (6P) through in-situ photoelectron spectroscopy investigations and density functional theory (DFT) calculations. Our results show that sodium atoms tend to interact with sulfur atoms and their connected carbon atoms simultaneously as well as the aromatic carbon atoms of the end groups of 6T molecules, while no chemical interaction between Na and 6P molecules is observed. The observed sulfurization-induced sodiophilic sites can shed light on the rational design of sulfur-containing protective materials and the relevant interface engineering to stabilize SMAs.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Uncontrollable sodium dendrite growth results in poor cycling performance and severe safety issues, hindering practical applications of sodium metal batteries (SMBs). To stabilize sodium metal anodes (SMAs), various strategies have been developed including employing anode hosts and electrolyte additives to establish protective layers. Nevertheless, the understanding of interaction mechanisms between protective materials and SMAs is still limited, which is crucial for the rational design of protective materials. In this work, we investigated the interaction mechanism between sodium metal and sulfur-containing functional groups with comparative model systems of alpha-sexithiophene (6T) and p-sexiphenyl (6P) through in-situ photoelectron spectroscopy investigations and density functional theory (DFT) calculations. Our results show that sodium atoms tend to interact with sulfur atoms and their connected carbon atoms simultaneously as well as the aromatic carbon atoms of the end groups of 6T molecules, while no chemical interaction between Na and 6P molecules is observed. The observed sulfurization-induced sodiophilic sites can shed light on the rational design of sulfur-containing protective materials and the relevant interface engineering to stabilize SMAs. |
2022 |
Liu, Yuan; Lian, Xu; Xie, Zhangdi; Yang, Jinlin; Ding, Yishui; Chen, Wei Probing fluorination promoted sodiophilic sites with model systems of F16CuPc and CuPc Journal Article FRONTIERS OF OPTOELECTRONICS , 15 (1), 2022, ISSN: 2095-2759. @article{ISI:000788600500002, title = {Probing fluorination promoted sodiophilic sites with model systems of F16CuPc and CuPc }, author = {Yuan Liu and Xu Lian and Zhangdi Xie and Jinlin Yang and Yishui Ding and Wei Chen}, doi = {10.1007/s12200-022-00026-3}, times_cited = {0}, issn = {2095-2759}, year = {2022}, date = {2022-12-01}, journal = {FRONTIERS OF OPTOELECTRONICS }, volume = {15}, number = {1}, publisher = {HIGHER EDUCATION PRESS }, address = {CHAOYANG DIST, 4, HUIXINDONGJIE, FUSHENG BLDG, BEIJING 100029, PEOPLES R CHINA }, abstract = {Sodium metal batteries (SMBs) are receiving broad attention due to the high specific capacity of sodium metal anodes and the material abundance on earth. However, the growth of dendrites results in poor battery performance and severe safety problems, inhibiting the commercial application of SMBs. To stabilize sodium metal anodes, various methods have been developed to optimize the solid electrolyte interphase (SEI) layer and adjust the electroplating/stripping behavior of sodium. Among the methods, developing anode host materials and adding electrolyte additives to build a protective layer are promising and convenient. However, the understanding of the interaction process between sodium metal and those organic materials is still limited, but is essential for the rational design of advanced anode hosts and electrolyte additives. In this study, we use copper(II) hexadecafluorophthalocyanine (F16CuPc), and copper(II) phthalocyanine (CuPc), as model systems to unravel the sodium interaction with polar functional groups by in-situ photoelectron spectroscopy and density functional theory (DFT) calculations. It is found that sodium atoms prefer to interact with the inner pyrrolic nitrogen sites of CuPc, while they prefer to interact with the outer aza bridge nitrogen atoms, owing to Na-F interaction at the Na/F16CuPc interface. Besides, for the both organic molecules, the central Cu(II) ions are reduced to Cu(I) ions by charge transfer from deposited sodium. The fluorine-containing groups are proven to promote the interaction process of sodium in organic materials, which sheds light on the design of functional interfaces in host materials and anode protective layers for sodium metal anodes. }, keywords = {}, pubstate = {published}, tppubtype = {article} } Sodium metal batteries (SMBs) are receiving broad attention due to the high specific capacity of sodium metal anodes and the material abundance on earth. However, the growth of dendrites results in poor battery performance and severe safety problems, inhibiting the commercial application of SMBs. To stabilize sodium metal anodes, various methods have been developed to optimize the solid electrolyte interphase (SEI) layer and adjust the electroplating/stripping behavior of sodium. Among the methods, developing anode host materials and adding electrolyte additives to build a protective layer are promising and convenient. However, the understanding of the interaction process between sodium metal and those organic materials is still limited, but is essential for the rational design of advanced anode hosts and electrolyte additives. In this study, we use copper(II) hexadecafluorophthalocyanine (F16CuPc), and copper(II) phthalocyanine (CuPc), as model systems to unravel the sodium interaction with polar functional groups by in-situ photoelectron spectroscopy and density functional theory (DFT) calculations. It is found that sodium atoms prefer to interact with the inner pyrrolic nitrogen sites of CuPc, while they prefer to interact with the outer aza bridge nitrogen atoms, owing to Na-F interaction at the Na/F16CuPc interface. Besides, for the both organic molecules, the central Cu(II) ions are reduced to Cu(I) ions by charge transfer from deposited sodium. The fluorine-containing groups are proven to promote the interaction process of sodium in organic materials, which sheds light on the design of functional interfaces in host materials and anode protective layers for sodium metal anodes. |
2021 |
Lian, Xu; Ma, Zhirui; Zhang, Zhonghan; Yang, Jinlin; Liu, Yuan; Gu, Chengding; Sun, Shuo; Ding, Honghe; Hu, Jun; Zhu, Junfa; Li, Shuzhou; Chen, Wei Fluorination-Guided Li-Anchoring Behaviors on Phthalocyanines Journal Article JOURNAL OF PHYSICAL CHEMISTRY C, 125 (15), pp. 8236-8243, 2021, ISSN: 1932-7447. @article{ISI:000644438400022, title = {Fluorination-Guided Li-Anchoring Behaviors on Phthalocyanines}, author = {Xu Lian and Zhirui Ma and Zhonghan Zhang and Jinlin Yang and Yuan Liu and Chengding Gu and Shuo Sun and Honghe Ding and Jun Hu and Junfa Zhu and Shuzhou Li and Wei Chen}, doi = {10.1021/acs.jpcc.1c00831}, times_cited = {0}, issn = {1932-7447}, year = {2021}, date = {2021-04-12}, journal = {JOURNAL OF PHYSICAL CHEMISTRY C}, volume = {125}, number = {15}, pages = {8236-8243}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {Understanding the interactions between metallic lithium (Li) and the anchoring sites/groups is essential for the design of stable host materials and artificial interphases in lithium metal batteries (LMBs). Here, we investigate the interactions of lithium with the polar organic functional groups in copper(II) hexadecafluorophthalocyanine (F16CuPc) and copper-(II) phthalocyanine (CuPc) through the combination of in-situ X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy UPS), synchrotron-based near-edge X-ray absorption fine structures (NEXAFS), and density functional theory (DFT) calculations. It is revealed that the highly polar C-F bonds can anchor the Li atom via ionic Li-F interaction around the outer aza bridge N atoms in F16CuPc, while Li tends to interact with the inner pyrrolic N atoms around the central Cu in CuPc. The central Cu(II) ions in both molecules are reduced to Cu(I) upon interaction with Li. Electrons are transferred from Li to the lowest unoccupied molecular orbitals (LUMO) of both F-16 CuPc and CuPc molecules, as revealed by the UPS and NEXAFS measurements. Our systematic study can shed light on the design of anode materials by adding polar functional groups for applications in lithium metal batteries (LMBs).}, keywords = {}, pubstate = {published}, tppubtype = {article} } Understanding the interactions between metallic lithium (Li) and the anchoring sites/groups is essential for the design of stable host materials and artificial interphases in lithium metal batteries (LMBs). Here, we investigate the interactions of lithium with the polar organic functional groups in copper(II) hexadecafluorophthalocyanine (F16CuPc) and copper-(II) phthalocyanine (CuPc) through the combination of in-situ X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy UPS), synchrotron-based near-edge X-ray absorption fine structures (NEXAFS), and density functional theory (DFT) calculations. It is revealed that the highly polar C-F bonds can anchor the Li atom via ionic Li-F interaction around the outer aza bridge N atoms in F16CuPc, while Li tends to interact with the inner pyrrolic N atoms around the central Cu in CuPc. The central Cu(II) ions in both molecules are reduced to Cu(I) upon interaction with Li. Electrons are transferred from Li to the lowest unoccupied molecular orbitals (LUMO) of both F-16 CuPc and CuPc molecules, as revealed by the UPS and NEXAFS measurements. Our systematic study can shed light on the design of anode materials by adding polar functional groups for applications in lithium metal batteries (LMBs). |
Ma, Zhirui; Lian, Xu; Yuan, Kaidi; Sun, Shuo; Gu, Chengding; Zhang, Jia Lin; Lyu, Jing; Zhong, Jian-Qiang; Liu, Lei; Li, Hexing; Chen, Wei Pressure-dependent band-bending in ZnO: A near-ambient-pressure X-ray photoelectron spectroscopy study Journal Article JOURNAL OF ENERGY CHEMISTRY, 60 , pp. 25-31, 2021, ISSN: 2095-4956. @article{ISI:000644065700003, title = {Pressure-dependent band-bending in ZnO: A near-ambient-pressure X-ray photoelectron spectroscopy study}, author = {Zhirui Ma and Xu Lian and Kaidi Yuan and Shuo Sun and Chengding Gu and Jia Lin Zhang and Jing Lyu and Jian-Qiang Zhong and Lei Liu and Hexing Li and Wei Chen}, doi = {10.1016/j.jechem.2020.12.018}, times_cited = {3}, issn = {2095-4956}, year = {2021}, date = {2021-01-19}, journal = {JOURNAL OF ENERGY CHEMISTRY}, volume = {60}, pages = {25-31}, publisher = {ELSEVIER}, address = {RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS}, abstract = {ZnO-based catalysts have been intensively studied because of their extraordinary performance in lower olefin synthesis, methanol synthesis and water-gas shift reactions. However, how ZnO catalyzes these reactions are still not well understood. Herein, we investigate the activations of CO2, O-2 and CO on single crystalline ZnO polar surfaces at room temperature, through in-situ near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS). It is revealed that O-2 and CO2 can undergo chemisorption on ZnO polar surfaces at elevated pressures. On the ZnO (0001) surface, molecular CO2 (O-2) can chemically interact with the top layer Zn atoms, leading to the formation of CO2 delta- (O-2(delta-)) or partially dissociative atomic oxygen (O-) and hence the electron depletion layer in ZnO. Therefore, an apparent upward band-bending in ZnO (0001) is observed under the CO2 and O-2 exposure. On the ZnO (000 (1) over bar) surface, the molecular chemisorbed CO2 (O-2) mainly bond to the surface oxygen vacancies, which also results in an upward band-bending in ZnO (0001). In contrast, no band-bending is observed for both ZnO polar surfaces upon CO exposure. The electron-acceptor nature of the surface bounded molecules/atoms is responsible for the reversible binding energy shift of Zn 2p(3/2) and O 1s in ZnO. Our findings can shed light on the fundamental understandings of CO2 and O-2 activation on ZnO surfaces, especially the role of ZnO in heterogeneous catalytic reactions. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.}, keywords = {}, pubstate = {published}, tppubtype = {article} } ZnO-based catalysts have been intensively studied because of their extraordinary performance in lower olefin synthesis, methanol synthesis and water-gas shift reactions. However, how ZnO catalyzes these reactions are still not well understood. Herein, we investigate the activations of CO2, O-2 and CO on single crystalline ZnO polar surfaces at room temperature, through in-situ near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS). It is revealed that O-2 and CO2 can undergo chemisorption on ZnO polar surfaces at elevated pressures. On the ZnO (0001) surface, molecular CO2 (O-2) can chemically interact with the top layer Zn atoms, leading to the formation of CO2 delta- (O-2(delta-)) or partially dissociative atomic oxygen (O-) and hence the electron depletion layer in ZnO. Therefore, an apparent upward band-bending in ZnO (0001) is observed under the CO2 and O-2 exposure. On the ZnO (000 (1) over bar) surface, the molecular chemisorbed CO2 (O-2) mainly bond to the surface oxygen vacancies, which also results in an upward band-bending in ZnO (0001). In contrast, no band-bending is observed for both ZnO polar surfaces upon CO exposure. The electron-acceptor nature of the surface bounded molecules/atoms is responsible for the reversible binding energy shift of Zn 2p(3/2) and O 1s in ZnO. Our findings can shed light on the fundamental understandings of CO2 and O-2 activation on ZnO surfaces, especially the role of ZnO in heterogeneous catalytic reactions. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved. |
2020 |
Ma, Zhirui; Yang, Ke; Lian, Xu; Sun, Shuo; Gu, Chengding; Zhang, Jia Lin; West, Damien; Zhang, Shengbai; Liu, Lei; Yuan, Kaidi; Sun, Yi-Yang; Li, Hexing; Chen, Wei Polarity- and Pressure-Dependent Hydrogen Dynamics on ZnO Polar Surfaces Revealed by Near-Ambient-Pressure X-ray Photoelectron Spectroscopy Journal Article JOURNAL OF PHYSICAL CHEMISTRY C, 124 (46), pp. 25431-25436, 2020, ISSN: 1932-7447. @article{ISI:000592958800029, title = {Polarity- and Pressure-Dependent Hydrogen Dynamics on ZnO Polar Surfaces Revealed by Near-Ambient-Pressure X-ray Photoelectron Spectroscopy}, author = {Zhirui Ma and Ke Yang and Xu Lian and Shuo Sun and Chengding Gu and Jia Lin Zhang and Damien West and Shengbai Zhang and Lei Liu and Kaidi Yuan and Yi-Yang Sun and Hexing Li and Wei Chen}, doi = {10.1021/acs.jpcc.0c08881}, times_cited = {0}, issn = {1932-7447}, year = {2020}, date = {2020-11-19}, journal = {JOURNAL OF PHYSICAL CHEMISTRY C}, volume = {124}, number = {46}, pages = {25431-25436}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {ZnO-based catalysts have been widely used in industrial reactions involving syngas conversions. Hydrogen dynamics on the surface of the catalyst is an essential process for understanding the mechanisms of such reactions. As a polar material, however, the role of ZnO surface polarity on hydrogen dynamics has not been studied under operando conditions. Here, we investigate the behavior of polar (0001) and (000 (1) over bar) surfaces of single-crystal ZnO under different H-2 pressures using near-ambient-pressure X-ray photoelectron spectroscopy. We found that the (000 (1) over bar) surface shows a monotonic and irreversible band bending with increasing H-2 pressure. In contrast, the (0001) surface shows two opposite responses depending on H-2 pressure, which are reversible in pressure cycles. This polarity-and pressure-dependent hydrogen dynamics is clearly understood with the assistance from first-principles calculations. In particular, the amphoteric behavior of atomic H is identified to play a key role.}, keywords = {}, pubstate = {published}, tppubtype = {article} } ZnO-based catalysts have been widely used in industrial reactions involving syngas conversions. Hydrogen dynamics on the surface of the catalyst is an essential process for understanding the mechanisms of such reactions. As a polar material, however, the role of ZnO surface polarity on hydrogen dynamics has not been studied under operando conditions. Here, we investigate the behavior of polar (0001) and (000 (1) over bar) surfaces of single-crystal ZnO under different H-2 pressures using near-ambient-pressure X-ray photoelectron spectroscopy. We found that the (000 (1) over bar) surface shows a monotonic and irreversible band bending with increasing H-2 pressure. In contrast, the (0001) surface shows two opposite responses depending on H-2 pressure, which are reversible in pressure cycles. This polarity-and pressure-dependent hydrogen dynamics is clearly understood with the assistance from first-principles calculations. In particular, the amphoteric behavior of atomic H is identified to play a key role. |
Lian, Xu; Ma, Zhirui; Zhang, Zhonghan; Yang, Jinlin; Liu, Yuan; Gu, Chengding; Guo, Rui; Wang, Yanan; Ye, Xin; Sun, Shuo; Zheng, Yue; Ding, Honghe; Hu, Jun; Cao, Xu; Mao, Hongying; Zhu, Junfa; Li, Shuzhou; Chen, Wei Alkali metal storage mechanism in organic semiconductor of perylene-3,4,9, 10-tetracarboxylicdianhydride Journal Article APPLIED SURFACE SCIENCE, 524 , 2020, ISSN: 0169-4332. @article{ISI:000540437600002, title = {Alkali metal storage mechanism in organic semiconductor of perylene-3,4,9, 10-tetracarboxylicdianhydride}, author = {Xu Lian and Zhirui Ma and Zhonghan Zhang and Jinlin Yang and Yuan Liu and Chengding Gu and Rui Guo and Yanan Wang and Xin Ye and Shuo Sun and Yue Zheng and Honghe Ding and Jun Hu and Xu Cao and Hongying Mao and Junfa Zhu and Shuzhou Li and Wei Chen}, doi = {10.1016/j.apsusc.2020.146396}, times_cited = {0}, issn = {0169-4332}, year = {2020}, date = {2020-09-15}, journal = {APPLIED SURFACE SCIENCE}, volume = {524}, publisher = {ELSEVIER}, address = {RADARWEG 29a, 1043 NX AMSTERDAM, NETHERLANDS}, keywords = {}, pubstate = {published}, tppubtype = {article} } |
Lian, Xu; Ma, Zhirui; Zhang, Zhonghan; Yang, Jinlin; Sun, Shuo; Gu, Chengding; Liu, Yuan; Ding, Honghe; Hu, Jun; Cao, Xu; Zhu, Junfa; Li, Shuzhou; Chen, Wei An in-situ spectroscopy investigation of alkali metal interaction mechanism with the imide functional group Journal Article NANO RESEARCH, 13 (12), pp. 3224-3229, 2020, ISSN: 1998-0124. @article{ISI:000559369900001, title = {An \textit{in-situ} spectroscopy investigation of alkali metal interaction mechanism with the imide functional group}, author = {Xu Lian and Zhirui Ma and Zhonghan Zhang and Jinlin Yang and Shuo Sun and Chengding Gu and Yuan Liu and Honghe Ding and Jun Hu and Xu Cao and Junfa Zhu and Shuzhou Li and Wei Chen}, doi = {10.1007/s12274-020-2991-6}, times_cited = {0}, issn = {1998-0124}, year = {2020}, date = {2020-08-12}, journal = {NANO RESEARCH}, volume = {13}, number = {12}, pages = {3224-3229}, publisher = {TSINGHUA UNIV PRESS}, address = {B605D, XUE YAN BUILDING, BEIJING, 100084, PEOPLES R CHINA}, abstract = {Organic anode materials have attracted considerable interest owing to their high tunability by adopting various active functional groups. However, the interaction mechanisms between the alkali metals and the active functional groups in host materials have been rarely studied systematically. Here, a widely used organic semiconductor of perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) was selected as a model system to investigate how alkali metals interact with imide functional groups and induce changes in chemical and electronic structures of PTCDI. The interaction at the alkali/PTCDI interface was probed byin-situX-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), synchrotron-based near edge X-ray absorption fine structure (NEXAFS), and corroborated by density functional theory (DFT) calculations. Our results indicate that the alkali metal replaces the hydrogen atoms in the imide group and interact with the imide nitrogen of PTCDI. Electron transfer induced gap states and downward band-bending like effects are identified on the alkali-deposited PTCDI surface. It was found that Na shows a stronger electron transfer effect than Li. Such a model study of alkali insertion/intercalation in PTCDI gives insights for the exploration of the potential host materials for alkali storage applications.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Organic anode materials have attracted considerable interest owing to their high tunability by adopting various active functional groups. However, the interaction mechanisms between the alkali metals and the active functional groups in host materials have been rarely studied systematically. Here, a widely used organic semiconductor of perylene-3,4,9,10-tetracarboxylic diimide (PTCDI) was selected as a model system to investigate how alkali metals interact with imide functional groups and induce changes in chemical and electronic structures of PTCDI. The interaction at the alkali/PTCDI interface was probed byin-situX-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS), synchrotron-based near edge X-ray absorption fine structure (NEXAFS), and corroborated by density functional theory (DFT) calculations. Our results indicate that the alkali metal replaces the hydrogen atoms in the imide group and interact with the imide nitrogen of PTCDI. Electron transfer induced gap states and downward band-bending like effects are identified on the alkali-deposited PTCDI surface. It was found that Na shows a stronger electron transfer effect than Li. Such a model study of alkali insertion/intercalation in PTCDI gives insights for the exploration of the potential host materials for alkali storage applications. |
2019 |
Guo, Rui; Zheng, Yue; Ma, Zhirui; Lian, Xu; Sun, Haicheng; Han, Cheng; Ding, Honghe; Xu, Qian; Yu, Xiaojiang; Zhu, Junfa; Chen, Wei Surface passivation of black phosphorus via van der Waals stacked PTCDA Journal Article APPLIED SURFACE SCIENCE, 496 , 2019, ISSN: 0169-4332. @article{ISI:000488957400074, title = {Surface passivation of black phosphorus \textit{via} van der Waals stacked PTCDA}, author = {Rui Guo and Yue Zheng and Zhirui Ma and Xu Lian and Haicheng Sun and Cheng Han and Honghe Ding and Qian Xu and Xiaojiang Yu and Junfa Zhu and Wei Chen}, doi = {10.1016/j.apsusc.2019.143688}, times_cited = {0}, issn = {0169-4332}, year = {2019}, date = {2019-12-01}, journal = {APPLIED SURFACE SCIENCE}, volume = {496}, publisher = {ELSEVIER}, address = {RADARWEG 29, 1043 NX AMSTERDAM, NETHERLANDS}, abstract = {Two-dimensional (2D) black phosphorus (BP) has received great attention due to its anisotropic mechanical, optical and electronic properties. However, the air-instability of BP seriously limits its further applications. Various approaches have been explored to improve the device stability of BP, including the encapsulation by inert 2D counterparts, and surface passivation by AlOx via atomic layer deposition and by organic layers either van der Waals stacked or covalently bonded onto the surface. Here we systematically investigate the surface passivation effect of perylenetetracarboxylic dianhydride (PTCDA) on BP through a variety of in-situ characterization techniques. PTCDA molecule on BP adopts a lying down configuration with the molecular pi-plane almost parallel to the BP surface, arising from the formation of multiple intermolecular hydrogen bonds. The evaporation of PTCDA on BP does not modify the intrinsic structure and electrical transport property of BP, as revealed by in-situ ultraviolet photoelectron spectroscopy (UPS)/x-ray photoelectron spectroscopy (XPS), and further corroborated by in-situ field-effect-transistor (FET) evaluation. After the air-exposure of PTCDA covered BP in dark, no obvious degradation on BP was observed by XPS. However, the electron mobility of the passivated BP FET significantly decreased by 80% after 20 h exposure despite lifetime of the passivated device was prolonged.}, keywords = {}, pubstate = {published}, tppubtype = {article} } Two-dimensional (2D) black phosphorus (BP) has received great attention due to its anisotropic mechanical, optical and electronic properties. However, the air-instability of BP seriously limits its further applications. Various approaches have been explored to improve the device stability of BP, including the encapsulation by inert 2D counterparts, and surface passivation by AlOx via atomic layer deposition and by organic layers either van der Waals stacked or covalently bonded onto the surface. Here we systematically investigate the surface passivation effect of perylenetetracarboxylic dianhydride (PTCDA) on BP through a variety of in-situ characterization techniques. PTCDA molecule on BP adopts a lying down configuration with the molecular pi-plane almost parallel to the BP surface, arising from the formation of multiple intermolecular hydrogen bonds. The evaporation of PTCDA on BP does not modify the intrinsic structure and electrical transport property of BP, as revealed by in-situ ultraviolet photoelectron spectroscopy (UPS)/x-ray photoelectron spectroscopy (XPS), and further corroborated by in-situ field-effect-transistor (FET) evaluation. After the air-exposure of PTCDA covered BP in dark, no obvious degradation on BP was observed by XPS. However, the electron mobility of the passivated BP FET significantly decreased by 80% after 20 h exposure despite lifetime of the passivated device was prolonged. |