Nickel Selenide/G-C3n4 Heterojunction Photocatalyst Promotes C-C Coupling for Photocatalytic Co2 Reduction to Ethane

Abstract

Photocatalytic CO2 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 NiSe2/CNNS heterostructure that mesoscale hedgehog nickel selenide (NiSe2) nanoparticles grown on the ultrathin g-C3N4 nanosheets were firstly synthesized via a successively high temperature calcination process and in-situ thermal injection method. The optimal 2.7% NiSe2/CNNS heterostructure achieves moderate C2H6 generation rate of 46.1 μmol·g-1·h-1 and selectivity of 97.5% without any additional photosensitizers and sacrificial agents under light illumination. Based on a combination of the theoretical calculations and experimental results, the improvement of photocatalytic CO2 to C2H6 production and selectivity could be ascribed to increased visible light absorption ability, unique 3D/2D heterostructures with promoted adsorption of CO2 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 inspiration to construct efficient photocatalysts for the direct transformation of CO2 to multicarbon products (C2+).

Keywords: g-C3N4, NiSe2, Photocatalytic CO2 reduction, C2H6, Selectivity.