Boron-Doped Boron Nitride Photocatalyst for Visible Light-Driven H2 Evolution and CO2 Photoreduction
Developing robust, multifunctional photocatalysts that can facilitate both hydrogen evolution via photoreforming of water and gas phase CO2 photoreduction is highly desirable with the long-term vision of integrated photocatalytic setups. Here, we present a step-change in the family of boron oxynitride materials by introducing the first example of a B-doped boron oxynitride (B-BNO). This material resolves an on-going bottleneck associated with BN-based materials, i.e. the lack of photoactivity under visible light. Detailed EPR studies revealed distinct hyperfine interactions between the free oxygen radicals and 3 neighbouring boron nuclei. This confirmed isolated OB3 sites, which contribute to band gap narrowing, as the radical species and origin of paramagnetism in BNO materials. We show that B-BNO can facilitate both liquid phase H2 evolution and gas phase CO2 photoreduction, using UV-Vis and deep visible irradiation (λ > 550 nm), without any co-catalysts. The evolution rates, quantum efficiencies, and selectivities observed for both reactions with B-BNO exceed those of its porous BNO counterpart, P25 TiO2 and bulk g-C3N4.