Interface engineering on Janus Pd–Au heterojunction co-catalysts for selective photocatalytic reduction of CO2 to CH4

Abstract

Photocatalytic reduction of CO₂ to renewable fuels offers opportunities for long-term energy storage and environmental protection. However, the lack of highly active and selective catalysts impedes the application of this reaction. Here, Janus Pd–Au heterojunctions are proposed as advanced co-catalysts for the conversion of CO₂ to CH₄, which achieve an unprecedented average CH₄ production rate of 48.2 μmol g_cat⁻¹ h⁻¹ with a high selectivity of 91.4%. The experimental results indicate that the interfaces between Pd and Au play multiple roles in the enhancement of CO₂-to-CH₄ conversion: (1) Au atoms around the interface provide the sites for the reduction of CO₂ to *CO intermediates and then to CH₄; (2) *H intermediates are produced on adjacent Pd atoms on the other side of the interface, which further accelerate the rate-limiting process in conversion of *CO to CH₄; (3) charge re-distribution through the Pd–Au interface leads to substantial suppression of H₂ and CO evolution on electron-deficient Pd and electron-rich Au, respectively. This work provides fresh insights into the rational interface design of high-performance bimetallic co-catalysts for selective CO₂ photoreduction.