Strategies for distinguishing thermal and non-thermal effects in photo-assisted CO2 hydrogenation reactions

The catalytic hydrogenation of waste CO 2 , a major greenhouse gas, into value-added fuels and chemicals offers a sustainable route to mitigate climate change. However, conventional thermal hydrogenation demands high energy input, while purely photocatalytic processes often suffer from low reaction efficiency. Over the past decade, photo-assisted thermal catalysis has emerged as a promising alternative, synergistically harnessing thermal and photochemical (non-thermal) effects from solar irradiation to drive CO 2 conversion. Despite numerous advances, individual contributions of heat and light, as well as their combined effects, remain poorly understood due to complex light-matter interactions and the lack of techniques for accurate nanoscale temperature measurements. This review summarizes recent progress in photo-assisted CO 2 hydrogenation, with a particular focus on strategies to disentangle and quantify thermal versus non-thermal contributions. It first discusses the fundamentals of light absorption and energy transfer in representative catalytic materials, followed by examples illustrating light-induced thermal and non-thermal effects in CO 2 conversion. Subsequently, it highlights state-of-the-art experimental and analytical approaches, including nanoscale thermometry, direct and indirect illumination, kinetic isotope effect studies, in situ spectroscopy, and ultrafast spectroscopic techniques, used to decouple these effects. Finally, it outlines key challenges and future perspectives for achieving precise control and quantitative understanding of the interplay between thermal and non-thermal processes. This review offers key insights and methods to deepen understanding and improve control of photo-assisted CO 2 hydrogenation, paving the way for green, sustainable, and energy-efficient solar-driven CO 2 conversion. This review summarizes recent advances in photothermal CO 2 hydrogenation, emphasizing strategies to distinguish and quantify thermal and non-thermal effects. It discusses light absorption and energy transfer in representative catalysts, showcases examples of light-driven thermal and non-thermal pathways in CO 2 conversion, highlights modern methods for separating these effects, and outlines key challenges and future directions for achieving precise control and deeper understanding of their interplay. • The significance of photothermal CO 2 hydrogenation was emphasized. • Complex light-matter interactions in catalytic systems were analyzed. • Representative examples of thermal and non-thermal pathways in CO 2 hydrogenation were illustrated. • The latest techniques for distinguishing thermal and non-thermal effects were summarized. • Key challenges and future perspectives for decoupling these contributions were proposed.