Decoration of cyanamide groups to tune the surface electronic structures of semiconductor photocatalysts for efficient solar driven CO₂ reduction

The using of reductive cocatalysts to dictate the transfer path of electrons towards targeting products is indispensable for photocatalytic CO2 reduction reaction (CRR). However, the development of low-cost and highly selective cocatalysts for photocatalytic CRR remains a daunting challenge. Herein, a functional molecule decoration strategy is proposed to tune the surface electronic structures of semiconductor photocatalysts, in order to promote their photocatalytic performance in CRR. We employ cyanamide groups as the chemical modifiers to regulate the CRR performance of solid solution metal sulphide photocatalysts. The synthesized photocatalysts exhibit excellent photocatalytic performance in CRR, and the highest CO evolution rate exceeds 1400 mu mol g(-1)h(-1), being among the best results reported to date. Multiple characterizations in combination with theoretical simulations further demonstrate that the decorated cyanamides do not act as active sites, but changes the electronic structures of the neighboring surface lattice metal atoms and decreases the kinetic barrier of the rate determining *CO2 ->*COOH step, thereby making the surface much more active for photocatalytic CRR. These findings explicitly verify the effectiveness of the functional molecule decoration strategy in promoting the CRR performance of photocatalysts, and also open up a new pathway for the development of highly efficient and selective catalysts for specific catalytic reactions.