Abstract

Solar-light-driven CO<inf>2</inf> photoreduction offers a promising route for mitigating carbon emissions while enabling sustainable fuel generation. Aurivillius-type bismuth titanate (Bi<inf>4</inf>Ti<inf>3</inf>O<inf>12</inf>) is an attractive photocatalyst owing to its structural stability and ferro-/piezoelectric properties; however, its application in gas-phase CO<inf>2</inf> conversion is severely limited by low surface area, weak CO<inf>2</inf> adsorption, and poor visible-light absorption. To overcome these constraints, a visible-light-responsive heterojunction photocatalyst was constructed by coupling Bi<inf>4</inf>Ti<inf>3</inf>O<inf>12</inf> with high-surface-area CeO<inf>2</inf> via wet impregnation, followed by photodeposition of Pt nanoparticles (NPs). The optimized 1.0%-Pt/20%-Ce/BTO catalyst exhibits a pronounced enhancement in photocatalytic performance, delivering completely selective CH<inf>4</inf> formation with a yield of 6.64 µmol g⁻¹ after 7 h of simulated solar irradiation, corresponding to activity enhancements of 7.7- and 9.5-fold compared to pristine Bi<inf>4</inf>Ti<inf>3</inf>O<inf>12</inf> and CeO<inf>2</inf>, respectively. Structural and spectroscopic analyses reveal that Pt nanoparticles (∼3.2 nm) act as efficient electron traps and enhance visible-light absorption. The enhanced activity and selectivity arise from synergistic effects of improved CO<inf>2</inf> adsorption, efficient charge separation across the heterojunction, prolonged charge-carrier lifetime, and the reversible Ce³⁺/Ce⁴⁺ redox couple in CeO<inf>2</inf>. This study demonstrates a straightforward and effective strategy for designing visible-light-driven heterostructures for highly selective gas-phase CO<inf>2</inf> photoreduction.