Interfacial Mo-S bond-reinforced hierarchical S-scheme heterostructure of Bi2MoO6@ZnIn2S4 for highly-selective and efficient CO2 photoreduction into CO

Developing highly-selective and efficient photocatalysts for converting CO2 into carbon-based fuels by solar energy is desirable, whereas it is still a severe challenge. Herein, we present a unique interfacial Mo-S bond bridged hierarchical S-scheme heterostructured photocatalysts, prepared by in-situ loading ZnIn2S4 nanoflakes (ZIS-NFs) on the Bi2MoO6 porous micro-spheres (BMO-PMs) assembled from numerous nanosheets. The interfacial Mo-S bonds can reinforce the separation and migration of photoinduced charge carriers via the S-scheme mechanism in the BMO@ZIS heterostructure. Besides, its hierarchical heterostructure can improve the visible light response ability, and afford plenty of active sites so as to benefit the CO2 adsorption and activation. Specifically, the combined results of experiment and density functional theory (DFT) calculations indicate that the fine heterostructure can not only convert the endoergic rate-determining step of bare ZIS (namely, CO2* hydrogenation to form COOH*) to an exoergic reaction process and lower the overall activation energy barrier, but also boost the desorption of CO* from the ZIS surface. As a result, in existence of H2O vapor without any sacrificial agents, the optimum photocatalyst (BMO@ZIS-0.4) manifests the outstanding CO2 photoreduction activity, with a CO yield and selectivity of 23.11 mu mol g- 1h- 1 and 93.1 %, respectively, higher than those of the most reported photocatalysts. This work offers an in-depth insight for fabricating the interfacial chemical bond modulated hierarchical S-scheme heterostructure with a remarkable performance of CO2 conversion.