Photoinducing Different Mechanisms on a Co-Ni Bimetallic Alloy in Catalytic Dry Reforming of Methane

Abstract

Photothermal catalytic dry reforming of methane (DRM) is a promising process for simultaneous solar energy conversion and fossil fuel upgrading; however, its mechanistic difference from thermocatalysis has not been much investigated. Herein, we report a comprehensive mechanistic investigation of bimetal NiCo/SiO2 in photothermo- and thermocatalytic DRM. Co substitution in Ni/SiO2 poses a suppressing effect on thermocatalysis, while a promotion effect emerges after light irradiation. In situ diffuse reflectance infrared Fourier transform spectroscopy and theoretical simulations reveal that Co substitution thermodynamically inhibits the cleavage of C−H in methane, CO2 dissociation, and CO desorption in thermal catalysis. While energetic hot carriers are evidenced in the NiCo alloy under light irradiation, they directly activate reactant molecules and overcome the thermodynamic barriers to selectively promote the generation of *CHO to CO instead of *C to coke. Thus, NiCo/SiO2 achieves higher photo-to-thermal efficiency and prominent performance in photothermal catalytic DRM. This work unveils the intrinsic photo effects on non-noble bimetallic catalysts in photothermal catalytic DRM for developing robust photothermal DRM catalysts for practical applications.