Defect-enriched BiOIO3/Ti3C2 MXene 2D/2D Schottky-type heterostructure for efficient and selective CH4 production via CO2 photoreduction: Unveiling the roles of defect inclusion and Ti3C2 MXene co-catalyst

The photoreduction of CO2 using solar energy to produce energy-efficient fuels is a sustainable technology that addresses energy needs while reducing carbon emissions. However, synthesizing efficient and robust photocatalysts for this process is challenging. This study introduces a viable approach for highly selective CO2 photoreduction to CH4 production by integrating defect-enriched BiOIO3 (DEBI) with a Ti3C2 (TC) MXene co-catalyst, forming an efficient 2D/2D Schottky-type heterostructure. The DEBI, enhanced with precise defect engineering, showed improved light absorption and charge separation efficiency. In tandem, the TC MXene co-catalyst facilitated rapid electron transfer and significantly minimized charge recombination. Consequently, the DEBI/TC-2 heterostructure, with an optimal 2 wt% TC MXene loading, achieved a CH4 yield of 52.8 μmol h−1g−1, representing a remarkable 20.5- and 6.3-fold increase over pristine BiOIO3 and DEBI, respectively. The Schottky-type 2D/2D heterostructure also demonstrated an impressive apparent quantum yield of 0.72%, 99% CH4 selectivity over H2 generation, and remarkable stability across multiple cycles. This study underscores the synergistic advantages of defect engineering and MXene co-catalyst integration in a single system, proposing a novel direction for designing highly efficient photocatalysts for solar-driven CO2 reduction in energy-efficient fuel production.