Mg-Doping Engineered Interfacial Electronic Structures in Ordered Porous Nanoreactors for Enhanced Solar Photothermal CO2 Methanation

Abstract Solar-driven photothermal catalytic CO2 conversion into valuable chemicals offers a promising route toward carbon neutrality, yet integrating broadband solar absorption with high catalytic activity remains a critical challenge. Herein, we demonstrate an interfacial electronic structure engineering strategy via Mg doping in the three-dimensionally ordered macroporous (3DOM) NiOx/Mg-CeO2 catalyst to promote solar photothermal CO2 methanation. Mg dopants, serving as electron donors, effectively tailor the electronic structures of the Ni species and CeO2 support, reinforcing their interfacial electronic interaction and stabilizing the highly dispersed NiOx clusters within the porous CeO2 framework. The optimized electronic configurations promote interfacial charge transfer from NiOx to CeO2 under light irradiation, enriching the electron density at Ce active sites and facilitating CO2 activation. Simultaneously, the broadband photoabsorption and strong photothermal effect of NiOx clusters accelerate surface reaction kinetics via local heating under illumination. The optimized NiOx/Mg-CeO2 catalyst delivers a CH4 production rate of 172.44 mmol g−1 h−1 with 90.3% selectivity under simulated solar irradiation in a continuous flow system, and reaches a production rate of 25.32–30.97 mmol·g−1·h−1 when exposed to outdoor sunlight within a closed reactor. Theoretical calculations reveal that Mg doping induces interfacial charge redistribution, which significantly reduces the thermodynamic energy barriers for the formation of *CHO and *CH intermediates, thereby promoting selective CO2 hydrogenation to CH4. This work provides some insights into engineering the interfacial electronic structures of supported catalysts for efficient solar-driven CO2 conversion.