ZnCo2S4/Zn0.2Cd0.8 S Z-scheme heterojunction: Efficient photocatalytic H2 evolution coupling selective oxidation of benzyl alcohol

The Z-scheme heterojunction photocatalysts possess excellent photocatalytic activity benefitting from their properly matched edge potentials. In this work, ZnCo 2 S 4 nanoparticles are anchored on Zn 0.2 Cd 0.8 S solid solution nanowires and assembled into binary ZnCo 2 S 4 /Zn 0.2 Cd 0.8 S nanocomposites. The as-synthesized ZnCo 2 S 4 /Zn 0.2 Cd 0.8 S nanocomposites act as bifunctional photocatalysts, which can be used for high-performance H 2 production coupling synthesis of high-value-added benzaldehyde in low concentration benzyl alcohol solution. Under visible light irradiation, 20%-ZnCo 2 S 4 /Zn 0.2 Cd 0.8 S nanocomposite shows the highest H 2 evolution rate of 23.02 mmol g −1 h −1 in the first photocatalytic cycle, which is 395.0 and 526.7 times higher than that of Zn 0.2 Cd 0.8 S and ZnCo 2 S 4 under the same conditions. Eventually, after six-time cycles, the conversion rate and selectivity of benzyl alcohol oxidation to benzaldehyde are 54.3% and 92.2%, respectively. The enhancement of photocatalytic performance is mainly attributed to the Z-scheme heterojunction between ZnCo 2 S 4 and Zn 0.2 Cd 0.8 S, which promote the separation and transfer of photogenerated charge carriers. This work provides strong support for the rational design of Z-scheme nano-heterojunction of highly efficient photocatalytic application in H 2 evolution and fine chemicals production. The bifunctional ZnCo 2 S 4 /Zn 0.2 Cd 0.8 S Z-scheme heterojunction photocatalysts show efficient H 2 evolution rate and high-value-added benzaldehyde synthesis activity under visible light irradiation. • An efficient bifunctional ZnCo 2 S 4 /Zn 0.2 Cd 0.8 S heterojunction is prepared. • ZnCo 2 S 4 /Zn 0.2 Cd 0.8 S shows excellent H 2 evolution and benzaldehyde synthesis activity. • The photocatalytic mechanism between ZnCo 2 S 4 and Zn 0.2 Cd 0.8 S is proposed.