Selective conversion of CO2 to CH4 enhanced by WO3/In2O3 S-scheme heterojunction photocatalysts with efficient CO2 activation

Abstract

Solar-powered CO₂ reduction is a promising approach for mitigating the energy crisis and environmental issues. However, its efficiency is hindered by challenges including difficult CO₂ activation, rapid charge recombination, and uncontrollable selectivity. Here, we develop WO₃/In₂O₃ S-scheme heterojunction photocatalysts by depositing In₂O₃ nanoparticles onto WO₃ nanosheets for CO₂ photoreduction. The Fermi level difference triggers electron transfer upon coupling, generating an internal electric field pointing from In₂O₃ to WO₃ at the interface. This impels oriented charge transfer and effective separation of the powerful photoinduced carriers. With the unique S-scheme mechanism and the efficient activation of CO₂ molecules on the In₂O₃ surface, the resulting WO₃/In₂O₃ heterostructures exhibit enhanced CO₂ photoreduction performance with ∼53.7% selectivity for CH₄, without any molecule cocatalyst or scavenger. In situ irradiation X-ray photoelectron spectroscopy, in situ diffuse reflectance infrared Fourier transform spectroscopy, along with density functional theory simulations are conducted to elucidate the photocatalytic and CO₂-reduction mechanism, and the enhanced CH₄-selectivity.