Construction of p-n type heterojunction of Cu2-xS@Zn3.74Ga1.02S5.24 hollow nanospheres promoting hole transfer for enhanced photocatalytic H2 production

Slow hole transfer is one of the important reasons for limited charge separation. This work reports a strategy to construct a p-n heterojunction biomimetic hollow composite (Cu2-xS@ZGS) by combining Cu2-xS (composed of Cu7.2S4 and Cu1.96S) with Zn3.74Ga1.02S5.24 (ZGS) to promote charge space separation and improve the photocatalytic hydrogen production activity of ZGS. Cu2-xS@ZGS shows significantly enhanced photocatalytic hydrogen production. The hydrogen production rate of 7 %Cu2-xS@ZGS is 44 and 3 times higher than that of Cu2-xS and ZGS under simulated sunlight and is 36, 30, and 25 times higher than that of Cu2S, Cu2-xS, and ZGS under visible-light-driven, respectively. The biomimetic hollow structure provides the site of spatial separation for the redox reaction. The Cu2-xS/ZGS p-n heterojunction promotes the migration of photogenerated holes to the inner Cu2-xS, where oxidation reactions occur, and it promotes the migration of photogenerated electrons to the outer ZGS, where the proton reduction reaction occurs, improving the spatial separation efficiency of charges. In addition, the Cu vacancies of Cu2-xS further promote the rapid transfer of h+ and the S vacancies of ZGS expose the active site to enhance hydrophilicity. This study provides design ideas and synthesis guidance for heterojunction catalysts that achieve photogenerated charge spatial separation.