Regulation of charge transfer direction and key steps via Y modification of redox-active sites on borocarbonitride for photocatalytic CO2 reduction

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Hexagonal borocarbonitride (h-BCN) have garnered significant attention for their unique optoelectronic properties in solar-to-fuel conversions. However, the efficiency of h-BCN in the field of photocatalytic CO2 reduction is limited by high reaction energy barriers and serious charge recombination. Here, a Y-modified h-BCN were synthesized through an organic-inorganic hybrid precursor pyrolysis method. Both theoretical simulation and experimental analysis demonstrated that the Y-modified sample exhibits an inhomogeneous charge distribution that favours rapid charge transfer and can decrease the reaction barrier of the rate-control step. Further investigations indicated that adding Y changes the electronic structure of BCN, which leads to rapid charge transfer/separation and an increased lifespan for photoinduced electrons. As a result, 2.5%Y/BCN exhibited improved CO2 photoreduction activity with a fuel yield of 50.35 μmol g−1. Notably, this outstanding performance was achieved without the use of any cocatalyst or sacrificial agent. In the meanwhile, cycle test shows the photocatalyst's great stability. The findings provide a useful suggestions for BCN-based photocatalysts.