Advances in Photothermal CO2 Hydrogenation to Methane: Mechanistic Insights into Catalytic System Design across Different Scales

Abstract

The ever-escalating accumulation of atmospheric CO2 and the growing demand for renewable energy conversion and storage have intensified research into solar-driven CO2 utilization technologies. Photothermal catalytic CO2 hydrogenation to methane has emerged as a promising approach for simultaneous carbon resource recycling and solar energy conversion, synergistically integrating the merits of photocatalysis and thermocatalysis. However, achieving high activity, selectivity, and long-term durability concurrently remains a central challenge, demanding precise control over photothermal conversion efficiency, charge transfer, and mass transport. Rational structural regulation spanning multiple length scales, from individual atoms to clusters, nanoparticles, and macroscopic reactors, is pivotal to overcoming such limitations. This review systematically summarizes research progress from a multiscale catalytic system design perspective, covering single atoms, nanoclusters, nanoparticles, supports, and macroscopic reactors. At each scale, the corresponding structure–activity relationships are analyzed, and the modulation mechanisms of active sites, photothermal effects, charge migration, and mass transport are elaborated. On this basis, we critically evaluate the advantages and bottlenecks of current research and put forward design guidelines and future development directions for next-generation high-performance catalytic systems. This review aims to provide both theoretical insights and practical references for the rational design of advanced photothermal CO2 methanation catalysts.