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 CuSeO3-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 CuII-Ov species in CuSeO3-x. Our study suggests that the ensemble of CuII-Ov 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. Methane-to-methanol conversion with O2 has long been considered kinetically challenging. Here the authors report CuSeO3-x as a new class of plasmonic semiconductors capable of harnessing low-energy near-infrared photons to achieve efficient conversion at 25 °C.
Zhang et al. (2025) studied this question.