Efficient methane oxidation to formaldehyde via photon–phonon cascade catalysis

The oxidation of methane to value-added chemicals provides an opportunity to use this abundant feedstock for sustainable petrochemistry. Unfortunately, such technologies remain insufficiently competitive due to a poor selectivity and a low yield rate for target products. Here we show a photon–phonon-driven cascade reaction that allows for methane conversion to formaldehyde with an unprecedented productivity of 401.5 μmol h−1 (or 40,150 μmol g−1 h−1) and a high selectivity of 90.4% at 150 °C. Specifically, with a ZnO catalyst decorated with single Ru atoms, methane first reacts with water to selectively produce methyl hydroperoxide via photocatalysis, followed by a thermodecomposition step yielding formaldehyde. Single Ru atoms, serving as electron acceptors, improve charge separation and promote oxygen reduction in photocatalysis. This reaction route with minimized energy consumption and high efficiency suggests a promising pathway for the sustainable transformation of light alkanes. Sustainable methane oxidation has the potential to green the petrochemical industry. Here the authors demonstrate a cascade catalysis process involving photoconversion and then thermal decomposition at mild temperatures to form formaldehyde with a high selectivity and a high yield rate.