Controlling Photocatalytic Methane Conversion Pathways: Challenges and Future Directions.

Photocatalytic methane conversion offers a sustainable route to transform the most inert C1 molecule into valuable oxygenates and hydrocarbons under ambient conditions. Recent progress has been made in the selective formation of methanol, ethanol, acetic acid, and C2 hydrocarbons, with notable efficiency. However, limited product diversity and an incomplete mechanistic understanding remain major barriers to further progress. This outlook deconstructs photocatalytic methane conversion into three elementary steps: formation of reactive species, coupling of reactive species, and transformation of intermediate products. This stepwise perspective enables a clearer identification of the factors governing individual reaction pathways and overall selectivity. By adopting a pathway-centric framework, the outlook integrates disparate observations from the literature into a unified mechanistic picture, elucidating how control over reactive-species generation, coupling modes, and intermediate evolution dictates reaction outcomes. From this analysis, general design principles and recurring control motifs are distilled, providing practical guidelines for the rational design of photocatalysts and reaction architectures aimed at more efficient and selective methane utilization.