The growth of Sn whiskers from Ti_(2)SnC/Sn-X(X=Sn,Bi,Pb,Ga)samples was studied in this work to understand the effect of alloying elements on whiskering behaviors.The mobility of source Sn atoms relating with the form...The growth of Sn whiskers from Ti_(2)SnC/Sn-X(X=Sn,Bi,Pb,Ga)samples was studied in this work to understand the effect of alloying elements on whiskering behaviors.The mobility of source Sn atoms relating with the formation and migration of defects was found to be the critical factor dominating the growth rate,with the gathering of which to grow whiskers on the surface acts as an effective means to lower the enthalpy.As a result,the source Sn atoms would migrate to whisker root spontaneously,making the growth of whiskers the nature of materials,and external factors like compressive stress or oxidation are no more necessary but facilitate the whiskering process by promoting the mobility of source Sn atoms.展开更多
To realize efficient atmospheric CO_(2) chemisorption and activation,abundant Ti^(3+) sites and oxygen vacancies in TiO_(2) ultrathin layers were designed.Positron annihilation lifetime spectroscopy and theoretical ca...To realize efficient atmospheric CO_(2) chemisorption and activation,abundant Ti^(3+) sites and oxygen vacancies in TiO_(2) ultrathin layers were designed.Positron annihilation lifetime spectroscopy and theoretical calculations first unveil each oxygen vacancy is associated with the formation of two Ti^(3+)sites,giving a Ti^(3+)-V_(o)-Ti^(3+) configuration.The Ti^(3+)-V_(o)-Ti^(3+) sites could bond with CO_(2) molecules to form a stable configuration,which converted the endoergic chemisorption step to an exoergic process,verified by in-situ Fourier-transform infrared spectra and theoretical calculations.Also,the adjacent Ti^(3+)sites not only favor CO_(2) activation into COOH*via forming a stable Ti^(3+)–C–O–Ti^(3+) configuration,but also facilitate the rate-limiting COOH^(*)scission to CO^(*)by reducing the energy barrier from 0.75 to 0.45 e V.Thus,the Ti^(3+)-V_(o)-TiO_(2) ultrathinlayers could directly capture and photofix atmospheric CO_(2) into near-unity CO,with the corresponding CO_(2)-to-CO conversion ratio of ca.20.2%.展开更多
基金This work is financially supported by the National Natural Science Foundation of China(NSFC)(Nos.51902051,51731004 and 11875248)the China Postdoctoral Science Foundation(No.2019M661687).
文摘The growth of Sn whiskers from Ti_(2)SnC/Sn-X(X=Sn,Bi,Pb,Ga)samples was studied in this work to understand the effect of alloying elements on whiskering behaviors.The mobility of source Sn atoms relating with the formation and migration of defects was found to be the critical factor dominating the growth rate,with the gathering of which to grow whiskers on the surface acts as an effective means to lower the enthalpy.As a result,the source Sn atoms would migrate to whisker root spontaneously,making the growth of whiskers the nature of materials,and external factors like compressive stress or oxidation are no more necessary but facilitate the whiskering process by promoting the mobility of source Sn atoms.
基金This work was supported by the National Key R&D Program of China(2019YFA0210004,2017YFA0207301,2017YFA0303500)the National Natural Science Foundation of China(21975242,U2032212,21890754,21805267,21703222,11975225)+7 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDB36000000)Youth Innovation Promotion Association of CAS(CX2340007003)Key Research Program of Frontier Sciences of CAS(QYZDY-SSW-SLH011)Major Program of Development Foundation of Hefei Center for Physical Science and Technology(2020HSC-CIP003)Users with Excellence Program of Hefei Science Center CAS(2020HSCUE001)The University Synergy Innovation Program of Anhui Province(GXXT-2020-001)the Fok Ying-Tong Education Foundation(161012)Supercomputing USTC and National Supercomputing Center in Shenzhen are acknowledged for computational support.
文摘To realize efficient atmospheric CO_(2) chemisorption and activation,abundant Ti^(3+) sites and oxygen vacancies in TiO_(2) ultrathin layers were designed.Positron annihilation lifetime spectroscopy and theoretical calculations first unveil each oxygen vacancy is associated with the formation of two Ti^(3+)sites,giving a Ti^(3+)-V_(o)-Ti^(3+) configuration.The Ti^(3+)-V_(o)-Ti^(3+) sites could bond with CO_(2) molecules to form a stable configuration,which converted the endoergic chemisorption step to an exoergic process,verified by in-situ Fourier-transform infrared spectra and theoretical calculations.Also,the adjacent Ti^(3+)sites not only favor CO_(2) activation into COOH*via forming a stable Ti^(3+)–C–O–Ti^(3+) configuration,but also facilitate the rate-limiting COOH^(*)scission to CO^(*)by reducing the energy barrier from 0.75 to 0.45 e V.Thus,the Ti^(3+)-V_(o)-TiO_(2) ultrathinlayers could directly capture and photofix atmospheric CO_(2) into near-unity CO,with the corresponding CO_(2)-to-CO conversion ratio of ca.20.2%.