Nickel selenide/g-CN heterojunction photocatalyst promotes CC coupling for photocatalytic CO reduction to ethane.

Photocatalytic CO reduction to generate high value-added and renewable chemicals is of great potential in facilitating the realization of closed-loop and carbon-neutral hydrogen economy. Stabilizing and accelerating the formation of COCO* intermediate is crucial to achieve high-selectivity ethane production. Herein, a novel 3D/2D NiSe/g-CN heterostructure that mesoscale hedgehog nickel selenide (NiSe) grown on the ultrathin g-CN nanosheets were synthesized via a successively high temperature calcination process and in-situ thermal injection method for the first time. The optimum 2.7 % NiSe/g-CN heterostructure achieved moderate CH generation rate of 46.1 μmol·g·h and selectivity of 97.5 % without any additional photosensitizers and sacrificial agents under light illumination. Based on the results of the theoretical calculations and experiments, the improvement of photocatalytic CO to CH production and selectivity should be ascribed to the increased visible light absorption ability, unique 3D/2D heterostructures with promoted adsorption of CO molecules on the Ni active sites, the type II heterojunction with improved charge transfer dynamics and lowered interfacial transfer resistance, as well as the formation of COCO* key intermediate. This work provides an inspiration to construct efficient photocatalysts for the direct transformation of CO to multicarbon products (C).