Photocatalytic CH4-to-Ethanol Conversion on Asymmetric Multishelled Interfaces

The selective oxidation of methane (CH4) features attractive potentials in both mitigating global warming and producing value-added chemicals. However, due to the short-life and unpaired concentrations of reactive intermediates (such as ·OH, ·CH3, and CO), the selective formation of multicarbon products like ethanol has remained challenging. In this work, we developed a hollow multishelled CeO2@PdO@FeOx nanosphere catalyst with two asymmetric and closely connected interfaces, featuring efficient in-tandem photo-oxidation of CH4 into ethanol with O2 as the oxidant. The outer FeOx surface promotes the photoreduction of the oxazole atoms in O2. In the meantime, the two asymmetric PdO/FeOx and CeO2/PdO catalytic interfaces enable selective photoactivation of CH4 to ·CH3 and then to CO, respectively, and the hollow multishelled structure further facilitates the directional transport and coupling of the as-generated ·CH3 and CO to produce ethanol. Under 100 mW·cm–2 light intensity and ambient conditions, the hollow multishelled CeO2@PdO@FeOx nanosphere photocatalyst exhibited a peak CH4-to-ethanol yield of 728 μmol·g–1·h–1 without photosensitizers or sacrificial agents, almost three times higher than the previous best reports on photocatalytic CH4 oxidation to ethanol, suggesting the attractive potential of the asymmetric multishelled catalytic interfaces.