Bi4O5Br2 anchored on Ti3C2 MXene with ohmic heterojunction in photocatalytic NH3 production: Insights from combined experimental and theoretical calculations

Nitrogen-to-ammonia conversion under mild conditions offers a tremendous prospect as a sustainable technology for synthesizing ammonia (NH3) in the future. In this study, we elaborately designed Bi4O5Br2/Ti3C2 heterojunction combined with electrostatic adsorption with in-situ growth to form a photocatalyst with a 2D/2D structure. This unique structure substantially improved the exposure of active edge sites for photocatalytic dinitrogen reduction reaction. Notably, Ti3C2 MXene acted as an efficient cocatalyst for the conversion of N2 to NH3 of Bi4O5Br2/Ti3C2 with a yield of 277.74 μmol g−1h−1 without the use of a sacrificial agent; this yield was five times higher than that of Bi4O5Br2. Density functional theory calculations demonstrated that the ohmic contact was at the Bi4O5Br2/Ti3C2 interface. The ohmic heterojunction could expedite the separation of spatial carriers and extraction of photoexcited charge carriers, which had outstanding reducibility to cleavage the N≡N bond. This work provides a novel strategy for designing highly efficient Bi4O5Br2-based photocatalysts through the integration of multifunctional materials. This work also offers guidance for implementing high-performance nitrogen-to-ammonia conversion by introducing interfacial modifiers.