Near-infrared photon-triggered CH₄-to-CH₃OH conversion over plasmonic oxyselenides

The direct oxidation of methane into methanol exploiting O₂ as oxidant offers an ideal route for methane utilization. Although the reaction is strongly preferred in thermodynamics, conventional catalytic systems always demand intense energy input like high temperatures or high-energy photons (>2.8 eV) to conquer the large kinetic barrier in the conversion process. In this study, we demonstrate that by creation of a suitable plasmonic photocatalyst, namely oxygen-vacancy-rich CuSeO_3-x, the low-energy near-infrared (NIR) photons can serve as the sole energy input to complete CH₄-to-CH₃OH conversion with remarkable activity (Apparent quantum yield of 1.5% at 800 nm with Au cocatalyst) and near unity selectivity (ca. 96%) at 25 °C. Such fascinating performance is attributed to a small activation energy measured at 0.28 eV, enabled by the existence of Cu^II-O_v species in CuSeO_3-x. Our study suggests that the ensemble of Cu^II-O_v constitutes an exceptional active site, which can harness the plasmon-induced hot electrons and meantime brings a kinetically advantageous route for reducing O₂ into •OH radicals greatly favoring methane activation.