Dual-state stepwise methane-to-methanol conversion by water droplets with excellent yield and selectivity.

Leveraging the continuous and rapid deposition and evaporation processes of water microdroplets on photocatalyst surfaces, this study presents an innovative dual-state stepwise methane conversion approach. This method significantly enhances the photocatalytic methane oxidation rate and selectivity, addressing the challenges of low methane solubility and poor liquid product selectivity typically found in aqueous-phase methane oxidation. By increasing the looping frequency per unit time, we achieved a state-of-the-art methane oxidation rate of 640 µmol g-1 h-1 using water as the sole oxidant, while maintaining approximately 95% selectivity toward liquid products, including 90% for methanol. This water microdroplet-assisted strategy not only establishes a framework for achieving both high yield and selectivity in photocatalytic methane oxidation but also pioneers a more efficient and sustainable approach for broadly applicable gases and water-involved photochemical conversion processes.