Recent advances in atomic-level active centres for photocatalytic methane conversion

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Photocatalytic conversion of methane (CH 4 ) to value-added chemicals and fuels under mild conditions offers an attractive strategy. However, this reaction still faces numerous challenges because CH 4 has strong C–H bonds and low polarity, while many target products are more reactive than CH 4 . This can lead to overoxidation, deep dehydrogenation, C–C bond breaking, or carbon deposition during the formation of partially oxidized and C 2 products. Notably, atomic-level active centres (AACs), including single-atom sites, dual-atom sites, and atomically dispersed aggregates, as well as atomic–nanoparticle interface motifs, can regulate these processes at the atomic scale, providing a potential solution for methane activation. These AACs can effectively regulate charge transfer, reactant activation, intermediate binding, product desorption, and active site isolation. This review discusses recent advances in AAC-mediated photocatalytic CH 4 conversion, focusing on four main reaction pathways: methane oxidation to C 1 oxygenates, oxidative C–C coupling to C 2 oxygenates, non-oxidative C–C coupling to C 2 hydrocarbons, and dry reforming to syngas. The discussion of these reaction pathways focuses on how to control reaction pathways and product selectivity by modulating the support environment, site nuclearity, metal-support interactions, local microenvironments, and reactor structure. We also pay particular attention to mechanistic evidence, including in situ spectroscopy, isotope labelling, theoretical calculations, and product-based indirect inferences. Furthermore, this paper proposes a standardized evaluation framework for comparing reaction conditions, photon utilisation, product selectivity, carbon balance, stability, and deactivation behaviour. Finally, we extend our discussion to the design of photoreactors and actual solar-powered operation to clarify the remaining gap between laboratory-scale and real-world solar methane conversion.