Metal catalysts, especially noble metals, have frequently been prepared upon downsizing from nanoparticles to subnanoclusters to catalyze the important reaction of partial oxidation of methane (POM) in order to optimize the catalytic performance and conserve metal resources. Here, benefiting from mass spectrometric experiments in conjunction with photoelectron spectroscopy and quantum chemical calculations, we successfully determine that metal cluster anions composed of only three Rh atoms (Rh3 -) can catalyze the POM reaction with O2 to produce 2H2 + CO2 under thermal collision conditions (∼300 K). The interdependence between CH4 and O2 to protect Rh3 - from collapse and to promote conversion of CH4 → 2H2 has been clarified. This study not only provides a promising metal cluster displaying good catalytic behavior in POM reaction under mild conditions but also reveals a strictly molecular-level mechanism of direct partial oxidation for the production of hydrogen, a promising renewable energy source in the 21st century.
© 2021 The Authors. Published by American Chemical Society.