Bifunctional phosphate-modulated Cu₂O/CeO₂ redox heterojunction: A promising approach for proficient CO₂ reduction

The construction of extremely dispersed redox-heterojunctions is a critical step toward improving of photocatalytic activity. Nonetheless, electron transfer faces momentous hurdles at the interfaces of these redox-heterojunction, mainly as a result of the considerable gap and potential-barrier between them. To address this obstacle, a bifunctional phosphate was deliberately introduced as an electron-bridge into the Cu₂O/CeO₂ redox-heterojunction system, aiming to necessitate a potential-barrier, establish a photoelectron transport route to improve the surface catalysis, and serve as a catalyst stabilizer, leading to improved dispersion of Cu₂O on the CeO₂ surface. The resultant intricately dispersed and optimized redox-heterojunction showcased an unparalleled advancement in apparent quantum efficiency (AQE), attaining an approximate value of 1.41 % at 420 nm during the photocatalytic CO₂ reduction. The experimental findings established a conspicuous association between the substantial increase in AQE and the diminished interfacial migration resistance, heightened dispersion, and abundance of more active-sites, all accredited to phosphate-modulation in the redox-heterojunction. The work emphasizes the significant importance of phosphate in bridging the conduction and valence bands of semiconductors, leading to enhanced photocarrier separation efficiency and improved molecular dispersion.