Flower-like microspheres Z-scheme BiSnO/NiAl-LDH heterojunction for boosting photocatalytic CO reduction under visible light.

Fabrication of efficient photocatalysts with great visible light utilization ability, rapid carriers' separation, and suitable redox potential is essential for improving photocatalytic CO reduction. Herein, flower-like microspheres BiSnO/NiAl-layered double hydroxide (BSO/LDH) heterojunctions were prepared by hydrothermal process for CO reduction. The BiSnO nanoparticles were dispersed on NiAl-LDH nanosheets, with tight contact interface, which facilitated charges transfer and exposing more catalytic active sites. Results of photochemical deposition of metal/metal oxide demonstrated that interfacial charges transfer of the BSO/LDH followed Z-scheme mechanism, endowing more desired redox potential and more efficient carriers separation. The 30%-BSO/LDH showed the highest CO and CH yields of 37.91 and 1.18 μmol g h under visible light irradiation, 3.4 and 2.0 times higher than those from the NiAl-LDH, respectively. The main intermediates during CO reduction were carboxylate (COOH*) and aldehyde group (CHO*), and CO reduction pathways and mechanism were proposed accordingly. This study provided referential strategy for designing efficient heterojunction photocatalysts for CO conversion.