采用RHEED与STM技术对GaAs(001)-(2×6)表面重构下的表面形貌进行研究,研究发现GaAs(001)-(2×6)重构表面是GaAs(001)-β2(2×4)重构表面经530℃,1.33μPa As BEP退火获得,在(2×6)重构下的GaAs(001)表面形貌已经进入...采用RHEED与STM技术对GaAs(001)-(2×6)表面重构下的表面形貌进行研究,研究发现GaAs(001)-(2×6)重构表面是GaAs(001)-β2(2×4)重构表面经530℃,1.33μPa As BEP退火获得,在(2×6)重构下的GaAs(001)表面形貌已经进入表面存在系列单层岛和坑覆盖的无序平坦状态。为了进一步确定(2×6)重构的原胞结构,采用球棍模型对其原胞结构进行模拟,提出新的As表面覆盖率计算方法、结合STM图片分析对球棍模型进行验证和筛选,首次在实验上证实(2×6)重构原胞中存在2个As Dimers和2个Ga Dimers,并以此重构原胞结构构建理论下的(2×6)重构表面,获得结果与STM图片高度吻合。展开更多
采用简单团簇模型结合密度泛函理论研究了CH3OH在Ga-rich Ga As(001)-(4×2)表面上的吸附与解离过程.计算结果表明,CH3OH在Ga-rich Ga As(001)-(4×2)表面上首先会形成两种化学吸附状态,然后CH3OH经解离生成CH3O自由基和H原子...采用简单团簇模型结合密度泛函理论研究了CH3OH在Ga-rich Ga As(001)-(4×2)表面上的吸附与解离过程.计算结果表明,CH3OH在Ga-rich Ga As(001)-(4×2)表面上首先会形成两种化学吸附状态,然后CH3OH经解离生成CH3O自由基和H原子吸附在表面不同位置上.通过比较各个吸附解离路径,发现解离后的H原子相对更容易吸附在位于表面第二层紧邻的As原子上.展开更多
The use of the internal magnetic field of ferromagnets can effectively promote charge separation and transfer(CST)in photoelectrochemical energy conversion.However,photoelectrochemical materials with a ferromagnetic f...The use of the internal magnetic field of ferromagnets can effectively promote charge separation and transfer(CST)in photoelectrochemical energy conversion.However,photoelectrochemical materials with a ferromagnetic field are scarce,and the internal magnetic field is negligible in nonferromagnetic mate-rials.To address this issue,we propose a rational method for preparing ferromagnetic TiO_(2)powder using controllable oxygen vacancies in anatase TiO_(2)with co-exposed{001}and{101}facets.Accordingly,an ex-cellent saturation magnetisation of 0.0014 emu/g in TiO_(2)is achieved owing to an asymmetric and uneven charge distribution.Compared with that of nonferromagnetic TiO_(2),the efficiency of photocatalytic hydro-gen generation of ferromagnetic TiO_(2)is improved by 0.64 times.The enhancement of photocatalytic hy-drogen generation is due to the different forces exerted on the electrons and holes in the magnetic field,which significantly improve the photogenerated CST efficiency of ferromagnetic TiO_(2).This result high-lights the significant role of the synergistic regulation of the crystal structure and defects in regulating the ferromagnetic characteristics of materials.The findings of this study provide guidance for leveraging point defects to promote CST for high-efficiency solar-energy conversion systems.展开更多
Curcurbit[n]uril(Q[n])-based supramolecular frameworks(QSFs) constructed from the outer surface interaction of Q[n]s(OSIQ) have the characteristic of simplicity,diversity and modulability.Their simplicity is reflected...Curcurbit[n]uril(Q[n])-based supramolecular frameworks(QSFs) constructed from the outer surface interaction of Q[n]s(OSIQ) have the characteristic of simplicity,diversity and modulability.Their simplicity is reflected in their simple composition and preparation methods used for QSFs.The diversity of supramolecular organic frameworks(SOFs) is reflected in the synthesis methods and structural characteristics of the as-obtained QSFs,as well as the variety of structural directing agents and basic building blocks used to prepare QSFs.The modulability is reflected by the controllable channel size in the QSFs,which can be adjusted using different sizes of Q[n]s.In this work,the first re ported cucurbituril Q[6]was selected as the basic building block and three Q[6]-based su p ramolecular frameworks were obtained from aqueous HCl solutions in the presence of [CdCl_(4)]^(2-)respectively.The OSIQs are the main driving forces for the formation of these frameworks.This study shows the diversity of the QSFs.展开更多
文摘采用RHEED与STM技术对GaAs(001)-(2×6)表面重构下的表面形貌进行研究,研究发现GaAs(001)-(2×6)重构表面是GaAs(001)-β2(2×4)重构表面经530℃,1.33μPa As BEP退火获得,在(2×6)重构下的GaAs(001)表面形貌已经进入表面存在系列单层岛和坑覆盖的无序平坦状态。为了进一步确定(2×6)重构的原胞结构,采用球棍模型对其原胞结构进行模拟,提出新的As表面覆盖率计算方法、结合STM图片分析对球棍模型进行验证和筛选,首次在实验上证实(2×6)重构原胞中存在2个As Dimers和2个Ga Dimers,并以此重构原胞结构构建理论下的(2×6)重构表面,获得结果与STM图片高度吻合。
文摘采用简单团簇模型结合密度泛函理论研究了CH3OH在Ga-rich Ga As(001)-(4×2)表面上的吸附与解离过程.计算结果表明,CH3OH在Ga-rich Ga As(001)-(4×2)表面上首先会形成两种化学吸附状态,然后CH3OH经解离生成CH3O自由基和H原子吸附在表面不同位置上.通过比较各个吸附解离路径,发现解离后的H原子相对更容易吸附在位于表面第二层紧邻的As原子上.
基金the China Postdoctoral Science Foundation(Grant No.2021M701829)It was also sup-ported by the Natural Science Foundation of Gansu Province in China(Grant No.22JR5RA484)+2 种基金Fundamental Research Funds for the Central University(Nos.lzujbky-2021-61 and SWU-KT22001)State Key Laboratory of New Ceramic and Fine Processing Ts-inghua University(No.KF202118)The authors would like to thank Tsinghua-Deqing Joint Research center for Materials Design and Industrial Innovation for the support.The authors would like to thank Shiyanjia Lab(www.shiyanjia.com)for the support provided for hydrogen generation,SS-SPV measurement,ESR test,DFT cal-culations,and modification polish.
文摘The use of the internal magnetic field of ferromagnets can effectively promote charge separation and transfer(CST)in photoelectrochemical energy conversion.However,photoelectrochemical materials with a ferromagnetic field are scarce,and the internal magnetic field is negligible in nonferromagnetic mate-rials.To address this issue,we propose a rational method for preparing ferromagnetic TiO_(2)powder using controllable oxygen vacancies in anatase TiO_(2)with co-exposed{001}and{101}facets.Accordingly,an ex-cellent saturation magnetisation of 0.0014 emu/g in TiO_(2)is achieved owing to an asymmetric and uneven charge distribution.Compared with that of nonferromagnetic TiO_(2),the efficiency of photocatalytic hydro-gen generation of ferromagnetic TiO_(2)is improved by 0.64 times.The enhancement of photocatalytic hy-drogen generation is due to the different forces exerted on the electrons and holes in the magnetic field,which significantly improve the photogenerated CST efficiency of ferromagnetic TiO_(2).This result high-lights the significant role of the synergistic regulation of the crystal structure and defects in regulating the ferromagnetic characteristics of materials.The findings of this study provide guidance for leveraging point defects to promote CST for high-efficiency solar-energy conversion systems.
基金the financial support of the National Natural Science Foundation of China(Nos.21761007,51663005 and 21871064)Science and Technology Plan Project of Guizhou Province(Nos.20175788 and 20185781)。
文摘Curcurbit[n]uril(Q[n])-based supramolecular frameworks(QSFs) constructed from the outer surface interaction of Q[n]s(OSIQ) have the characteristic of simplicity,diversity and modulability.Their simplicity is reflected in their simple composition and preparation methods used for QSFs.The diversity of supramolecular organic frameworks(SOFs) is reflected in the synthesis methods and structural characteristics of the as-obtained QSFs,as well as the variety of structural directing agents and basic building blocks used to prepare QSFs.The modulability is reflected by the controllable channel size in the QSFs,which can be adjusted using different sizes of Q[n]s.In this work,the first re ported cucurbituril Q[6]was selected as the basic building block and three Q[6]-based su p ramolecular frameworks were obtained from aqueous HCl solutions in the presence of [CdCl_(4)]^(2-)respectively.The OSIQs are the main driving forces for the formation of these frameworks.This study shows the diversity of the QSFs.
