Photothermal methane dry reforming: catalyst architectures, mechanistic pathways, and future challenges.

Abstract

Photothermal dry reforming of methane (PT-DRM) presents a promising strategy for simultaneously mitigating greenhouse gas emissions and valorizing carbon resources by converting CH4 and CO2 into syngas under solar irradiation. By integrating photonic and thermal activation, this hybrid catalytic approach addresses the kinetic and thermodynamic limitations of conventional DRM, enabling efficient activation of chemically inert molecules through mechanisms such as localized surface plasmon resonance, semiconductor bandgap excitation, and interfacial charge transfer. This review provides a comprehensive analysis of PT-DRM catalyst architectures, which are systematically categorized into nanoparticle-based catalysts, fully exposed active site systems, and hybrid nanostructures. We highlight how variations in morphology, dispersion, and electronic configuration govern light-heat synergy, intermediate evolution, and suppression of side reactions. Moreover, we dissect the mechanistic pathways involved, including lattice oxygen cycling, oxygen vacancy dynamics, and dual-site redox mechanisms, with emphasis on how these pathways diverge across structural motifs and reaction environments. Despite these advances, several unresolved challenges persist, such as the difficulty in decoupling photonic and thermal effects, the instability of active sites under operando conditions, the suppression of side reactions, and the lack of real-time diagnostic tools to probe nanoscale thermal gradients and intermediate transformations. By bridging structure-activity relationships with photophysical and interfacial phenomena, this review aims to guide the rational design of next-generation PT-DRM catalysts and accelerate the development of solar-driven syngas production technologies.