Unique NiCo bimetal boosting 98% CH4 selectivity and high catalysis stability for photothermal CO2 hydrogenation

Abstract

A highly dispersed NiCo alloy catalyst derived from NiCo bimetallic–organic framework nanosheets was synthesized for efficient photothermal catalysis for CO₂ hydrogenation to methane. The NiCo bimetal catalyst achieves a CH₄ production rate of 55.60 mmol g⁻¹ h⁻¹ with only a 18.82% decline in performance after 86 hours under atmospheric pressure at selected 290 °C and continuous flow reaction. In situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) reveals the synergistic and complementary roles of light and heat in photothermal catalysis. The thermochemical process drives the reverse water–gas shift reaction to form a *CO intermediate, a key intermediate for the formation of CH₄, and light irradiation-generating strong near field from the surface plasma resonance of NiCo bimetals promotes the subsequent *CO hydrogenation step to form *CHO, the rate-determining step for the hydrogenation of CO₂ into CH₄. Meanwhile, density functional theory (DFT) calculations suggest that the NiCo bimetallic catalyst can also lower the energy barrier of *CO hydrogenation, facilitating the formation of *CHO.