Photocatalytic CH4-to-Ethanol Conversion on Asymmetric Multishelled Interfaces

Abstract

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@FeO_x 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 FeO_x surface promotes the photoreduction of the oxazole atoms in O₂. In the meantime, the two asymmetric PdO/FeO_x 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@FeO_x 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.