Sustainable valorization of methane via photocatalysis: A review on the advances in various conversion pathways

Directly burning methane for energy production wastes chemical potential and exacerbates CO2 emissions, while catalytic conversion into high-value fuel/chemicals provides economic and environmental sustainability. Photocatalytic CH4 conversion has emerged as a transformative technology, enabling selective oxidation under ambient conditions to directly synthesize value-added organic compounds. This addresses the dual challenges of climate mitigation and sustainable energy conversion. This review systematically examines the development of photocatalytic CH4 conversion, with three key dimensions. Firstly, we elucidate fundamental reaction mechanisms governing CH4 activation, emphasizing critical steps such as C–H bond scission via charge transfer, intermediate stabilization, and product desorption kinetics. Subsequently, we classify emerging photocatalytic pathways (partial oxidation, coupling, and reforming) and analyze material innovations. Finally, the challenges of the current photocatalytic CH4 conversion system and catalyst development were discussed, and perspectives were presented. The overarching objective of this work is to provide a comprehensive roadmap for the development of solar-driven CH4 conversion systems that are aligned with global carbon neutrality goals.