Ag-modified α-FeO spherical particles interspersed on hierarchical flower-like NiAl-LDH microspheres with Z-scheme for significantly enhanced CO photoreduction into CO.

The conversion of carbon dioxide (CO) into value-added C1 and/or C2 chemicals by photocatalytic technology has been regarded as a "one stone-two birds" solution for environmental degradation and energy shortage. In this work, a novel Z-scheme mechanism photocatalyst of Ag-modified α-FeO spherical particles interspersed on hierarchical flower-like layered nickel-aluminum hydroxides (NiAl-LDH) microspheres (α-FeO/Ag/NiAl-LDH, designated as FALDH) is successfully prepared by a combined in-situ hydrothermal and grating strategy. As expected, the optimal sample of FALDH-5/10 exhibits significantly enhanced photocatalytic performance for CO reduction with a highest CO yield up to 46.7 μmol g under simulated sunlight without any sacrificial reagents and photosensitizers, compared with the pristine NiAl-LDH, binary Ag/NiAl-LDH and α-FeO/NiAl-LDH, as well as surpassing the previously reported LDH-based counterparts. The high activity is ascribed to strong interaction between the NiAl-LDH microspheres and highly-dispersed Ag/α-FeO particles, boosted CO adsorption capacity and optimized bandgap from α-FeO, and increased utilization efficiency of light from Ag. This study offers a new idea for more efficient stimulating the photocatalytic activity of LDHs by the construction of Z-scheme heterojunction with the aid of plasmonic metal(s) for CO photoreduction, and is expected to be employed to other photocatalytic applications effectively.