Single-atom catalysts(SACs)have attracted much attention in the field of electrocatalysis due to their100%atomic utilization efficiency,clear active center and adjustable support.The application of SACs to anodic oxyg...Single-atom catalysts(SACs)have attracted much attention in the field of electrocatalysis due to their100%atomic utilization efficiency,clear active center and adjustable support.The application of SACs to anodic oxygen evolution substitution reactions with high conversion efficiency and selectivity is undoubtedly promising.Therefore,a full understanding of the interactions between metal single-atom active sites and supports,and an in-depth understanding of the active centers and catalytic mechanisms of SACs in the electro-oxidation of small molecules are the keys to the development of high-performance catalysts.This review focuses on the synthesis of different support SACs and the interactions between single atoms and supports at the inter-face,and introduces the reaction mechanism of SACs in the electro-oxidation of different small-molecule substrates,such as ethanol,urea and hydrazine,with the aim of providing insights and ideas for the design of more efficient and ideal catalysts.Finally,we discuss the current challenges and future opportunities in the field.展开更多
Based on first principle calculations, a comprehensive study of substitutional oxygen defects in hexagonal silicon nitride （β-Si3N4） has been carried out. Firstly, it is found that substitutional oxygen is most lik...Based on first principle calculations, a comprehensive study of substitutional oxygen defects in hexagonal silicon nitride （β-Si3N4） has been carried out. Firstly, it is found that substitutional oxygen is most likely to form clusters at three sites in Si3N4 due to the intense attractive interaction between oxygen defects. Then, by using three analytical tools （trap energy, modified Bader analysis and charge density difference）, we discuss the trap abilities of the three clusters. The result shows that each kind of cluster at the three specific sites presents very different abilities to trap charge carriers （electrons or holes）： two of the three clusters can trap both kinds of charge carriers, confirming their amphoteric property; While the last remaining one is only able to trap hole carriers. Moreover, our studies reveal that the three clusters differ from each other in terms of endurance during the program/erase progress. Taking full account of capturing properties for the three oxygen clusters, including trap ability and endurance, we deem holes rather than electrons to be optimal to act as operational charge carriers for the oxygen defects in Si3N4-based charge trapping memories.展开更多
Exposure to oxygen alters the physical and chemical properties of two-dimensional(2D)transition metal dichalcogenides(TMDs).In particular,oxygen in the ambient may influence the device stability of 2D TMDs over time.E...Exposure to oxygen alters the physical and chemical properties of two-dimensional(2D)transition metal dichalcogenides(TMDs).In particular,oxygen in the ambient may influence the device stability of 2D TMDs over time.Engineering the doping of 2D TMDs,especially hole doping is highly desirable towards their device function.Herein,controllable oxygen-induced p-type doping in a range of hexagonal(MoTe2,WSe2,MoSe2 and PtSe2)and pentagonal(PdSe2)2D TMDs are demonstrated.Scanning tunneling microscopy,electrical transport and X-ray photoelectron spectroscopy are used to probe the origin of oxygen-derived hole doping.Three mechanisms are postulated that contribute to the hole doping in 2D TMDs,namely charge transfer from absorbed oxygen molecules,surface oxides,and chalcogen atom substitution.This work provides insights into the doping effects of oxygen,enabling the engineering of 2D TMDs properties for nanoelectronic applications.展开更多
基金financially supported by the Fundamental Research Funds for the Central Universities(No.2682022ZTPY049)the National Natural Science Foundation of China(Nos.U22A20120 and 22171157)。
文摘Single-atom catalysts(SACs)have attracted much attention in the field of electrocatalysis due to their100%atomic utilization efficiency,clear active center and adjustable support.The application of SACs to anodic oxygen evolution substitution reactions with high conversion efficiency and selectivity is undoubtedly promising.Therefore,a full understanding of the interactions between metal single-atom active sites and supports,and an in-depth understanding of the active centers and catalytic mechanisms of SACs in the electro-oxidation of small molecules are the keys to the development of high-performance catalysts.This review focuses on the synthesis of different support SACs and the interactions between single atoms and supports at the inter-face,and introduces the reaction mechanism of SACs in the electro-oxidation of different small-molecule substrates,such as ethanol,urea and hydrazine,with the aim of providing insights and ideas for the design of more efficient and ideal catalysts.Finally,we discuss the current challenges and future opportunities in the field.
基金supported by the National Youth Science Foundation of China(No.61006064)
文摘Based on first principle calculations, a comprehensive study of substitutional oxygen defects in hexagonal silicon nitride （β-Si3N4） has been carried out. Firstly, it is found that substitutional oxygen is most likely to form clusters at three sites in Si3N4 due to the intense attractive interaction between oxygen defects. Then, by using three analytical tools （trap energy, modified Bader analysis and charge density difference）, we discuss the trap abilities of the three clusters. The result shows that each kind of cluster at the three specific sites presents very different abilities to trap charge carriers （electrons or holes）： two of the three clusters can trap both kinds of charge carriers, confirming their amphoteric property; While the last remaining one is only able to trap hole carriers. Moreover, our studies reveal that the three clusters differ from each other in terms of endurance during the program/erase progress. Taking full account of capturing properties for the three oxygen clusters, including trap ability and endurance, we deem holes rather than electrons to be optimal to act as operational charge carriers for the oxygen defects in Si3N4-based charge trapping memories.
基金This work was financially supported by the National Natural Science Foundation of China(No.51472164)Shenzhen Peacock Plan(No.KQTD2016053112042971)+3 种基金the Educational Commission of Guangdong Province(Nos.2015KGJHZ006 and 2016KCXTD006)the Science and Technology Planning Project of Guangdong Province(No.2016B050501005)A.T.S.W.acknowledges funding support from MOE Tier 2 grant R 144-000-382-112,A*STAR Pharos Program(No.1527300025)facility support from the NUS Centre for Advanced 2D Materials(CA2DM).
文摘Exposure to oxygen alters the physical and chemical properties of two-dimensional(2D)transition metal dichalcogenides(TMDs).In particular,oxygen in the ambient may influence the device stability of 2D TMDs over time.Engineering the doping of 2D TMDs,especially hole doping is highly desirable towards their device function.Herein,controllable oxygen-induced p-type doping in a range of hexagonal(MoTe2,WSe2,MoSe2 and PtSe2)and pentagonal(PdSe2)2D TMDs are demonstrated.Scanning tunneling microscopy,electrical transport and X-ray photoelectron spectroscopy are used to probe the origin of oxygen-derived hole doping.Three mechanisms are postulated that contribute to the hole doping in 2D TMDs,namely charge transfer from absorbed oxygen molecules,surface oxides,and chalcogen atom substitution.This work provides insights into the doping effects of oxygen,enabling the engineering of 2D TMDs properties for nanoelectronic applications.
