中文摘要：

通过基于密度泛函理论的第一性原理计算，对光催化水解半导体Ag2 ZnSnS4的改性方案做了理论研究。在与同类化合物的带边位置比较后发现， Cu与Ge共掺杂能够在Ag2 ZnSnS4中实现禁带宽度和带边位置的双重调节，从而使其能带结构优化到光催化水解最为理想的状态。另外， CuGaSe2可与Ag2 ZnSnS4形成type-II型带阶结构，制备它们的异质结同样可用于提升其光催化水解性能。

英文摘要：

By using the first-principles calculation based on density functional theory, we propose some approaches to improving the e？ciency for the photocatalyst Ag2ZnSnS4 from a theoretical aspect. Comparing its band edge positions with those of other similar compounds, we find that Cu, Ge codoping can adjust both the band gaps and band edge positions of Ag2ZnSnS4 at the same time, which can optimize its band structure for water splitting. In addition, Ag2ZnSnS4 has a type-II band offset with another photocatalyst CuGaSe2. Preparation of their homojunction can also improve their e？ciencies of photocatalysis hydrolyzation.