Facile synthesis of a Z-scheme CeO2/C3N4 heterojunction with enhanced charge transfer for CO2 photoreduction

Using solar energy to convert CO2 into value-added fuel is crucial for the goal of global carbon neutrality. Effective separation of photogenerated charges is important for improving photocatalytic CO2 reduction efficiency. Herein, we report a facile in situ exfoliation and conversion strategy to synthesize a novel CeO2/C3N4 heterostructure by uniformly distributing CeO2 nanoparticles onto ultrathin porous C3N4 nanosheets. The ultrathin porous structure of C3N4 not only increases the specific surface area to provide more active sites but also effectively shortens the migration distance of photogenerated electron holes to avoid their recombination. In addition, the well-dispersed CeO2 on C3N4 shows an intimate interface contact, which allows more charges to be transferred through the increased interface surface area. The as-synthesized CeO2/C3N4 heterojunction with well-matched band gaps and a Z-scheme structure prolongs the lifetime of photo-induced charge carriers and maximizes the redox ability of the photocatalyst. Without a noble metal cocatalyst or a sacrificial agent, the CO2 photoreduction performance of the CeO2/C3N4 heterojunction is approximately 5-fold enhanced compared with that of bulk C3N4. This study provides a facile strategy for the design and practical application of direct Z-scheme pho-tocatalysts for sustainable energy conversion.