Energy and mass flow in photocatalytic water splitting by coupling photothermal effect

Solar photocatalytic water splitting for hydrogen production represents an ideal approach to address the current energy and environmental challenges, while also achieving “carbon peak and carbon neutrality” goals. The incorporation of photothermal effect into photocatalysis enables dual utilization of both light and heat energies, resulting in improved solar-to-hydrogen efficiency. In this review, we first discussed the behavior of energy flow and mass flow, and the characteristics of photogenerated carrier throughout the photocatalytic water splitting process, with particular focus on the behaviors induced by photothermal effect. Subsequently, we elaborate on strategies for designing high-efficiency photothermal catalytic systems and novel photothermal–photocatalytic integrated systems based upon concentrating-photothermal coupling effects. We then illustrate the development and large-scale demonstrations that utilize concentrated solar irradiation. Finally, we outline the challenges and highlight the future research directions of photothermal catalysis toward hydrogen production from water. This review aims to provide fundamental references and principal strategies for efficient utilization of solar energy in photothermal catalytic processes.