Selective CO2 Photoreduction to CH4 via Pdδ+‐Assisted Hydrodeoxygenation over CeO2 Nanosheets

Abstract

AbstractHere, noble‐metal‐doped two‐dimensional metal oxide nanosheets are designed to realize selective CO2 photoreduction to CH4. As a prototype, Pd‐doped CeO2 nanosheets are fabricated, where the active sites of Pdδ+ (2<δ<4) and Ce3+−Ov are revealed by quasi in situ X‐ray photoelectron spectra and in situ electron paramagnetic resonance spectra. Moreover, in situ Fourier‐transform infrared spectra of D2O photodissociation and desorption verify the existence of the Pd−OD bond, implying that Pdδ+ sites can participate in water oxidation to deliver H* species for facilitating the protonation of the intermediates. Furthermore, theoretical calculations suggest the Pd doping could regulate the formation energy barrier of the key intermediates CO* and CH3O*, thus making CO2 reduction to CH4 become the favorable process. Accordingly, Pd‐doped CeO2 nanosheets achieve nearly 100 % CH4 selectivity of CO2 photoreduction, with the raising CH4 evolution rate of 41.6 μmol g−1 h−1.