Low-Coordination Single Au Atoms on Ultrathin ZnIn 2 S 4 Nanosheets for Selective Photocatalytic CO 2 Reduction towards CH 4 .

Selective CO 2 photoreduction to hydrocarbon fuels such as CH 4 is promising and sustainable for carbon-neutral future. However, lack of proper binding strengths with reaction intermediates makes it still a challenge for photocatalytic CO 2 methanation with both high activity and selectivity. Here, low-coordination single Au atoms (Au 1 -S 2 ) on ultrathin ZnIn 2 S 4 nanosheets was synthesized by a complex-exchange route, enabling exceptional photocatalytic CO 2 reduction performance. Under visible light irradiation, Au 1 /ZnIn 2 S 4 catalyst exhibits a CH 4 yield of 275 μmol g -1  h -1 with a selectivity as high as 77 %. As revealed by detailed characterizations and density functional theory calculations, Au 1 /ZnIn 2 S 4 with Au 1 -S 2 structure not only display fast carrier transfer to underpin its superior activity, but also greatly reduce the energy barrier for protonation of *CO and stabilize the *CH 3 intermediate, thereby leading to the selective CH 4 generation from CO 2 photoreduction.