SnO_(2)(110)表面In掺杂对NO_(2)气敏吸附性能提升的理论研究

A Theoretical Study of the Enhancement of NO_(2) Sensing and Adsoption on Indium-Doped SnO_(2)(110)Surface

为了阐明In的掺杂能提高SnO_(2)(110)表面气敏性能的反应机制,采用密度泛函理论研究了NO_(2)分子在In掺杂SnO_(2)(110)表面的吸附行为.计算结果表明:In的掺杂可以提高材料表面的导电性,形成具有氧空位的缺陷表面,有利于发生活性氧在表面的预吸附过程.掺杂的In 5c/SnO_(2)(110)表面对NO_(2)表现出良好的吸附性,对NO_(2)气体的选择性和灵敏度提高的主要原因是In掺杂后氧空位缺陷表面的形成.此外,活性氧物种的预吸附对材料表面气敏性能的影响取决于NO_(2)在材料表面的具体吸附位点,其中Sn 5c位点的吸附促使电荷从表面转移到气体分子,导致表面电阻的增大以及氧空位的产生,从而表现出优异的气敏吸附性能.

To investigate the mechanism of NO_(2) sensing enhancement,the density functional theory was used to study the adsorption behavior of NO_(2) molecule on the surface of indium-doped SnO_(2)(110).Theoretical calculations showed that a new electronic state appeared near the Fermi level after indium doping,which increased the conductivity of SnO_(2),promoted the formation of SnO_(2)(110)defect surface with vacancies and facilitated the pre-adsorption process of active oxygen on the surface.Indium doping may significantly improve the adsorption of NO_(2) onto the surface.The increased selectivity and sensitivity of NO_(2) gas is mainly ascribed to the formation of defect surface with oxygen vacancies after indium doping.Moreover,the pre-adsorption of oxygen depends on the specific adsorption sites.The NO_(2) molecule located at the Sn 5c site of the surface gains charges from the surface,generating oxygen vacancies.That is why indium-doped SnO_(2)(110)exhibits excellent performance of NO_(2) gas-sensitive adsorption.