In Situ Fabrication of 2D-2D Bi/BiOBr Ohmic Heterojunction for Enhanced Photocatalytic Nitrogen Fixation

The performance of BiOBr in photocatalytic nitrogen (N₂) fixation is suboptimal, attributed to the weak chemisorption and activation of N₂ by surface atoms. In our study, we achieved the formation of two-dimensional (2D) bismuth (Bi) on BiOBr nanosheets through in situ annealing in hydrogen atmosphere and successfully constructed a unique 2D-2D Bi/BiOBr ohmic heterojunction using a one-step method. Notably, the Bi/BiOBr heterojunction was utilized for photocatalytic N₂ fixation under visible light (λ > 400 nm) in ultrapure water, demonstrating an exceptional N₂ fixation rate of 376.16 μmol g^-1 h^-1. This rate is 7.7 and 4.1 times higher than those of BiOBr and BiOBr-OVs, respectively. The improved photocatalytic efficiency is attributed to the significantly enhanced N₂ adsorption capability and more effective separation of photogenerated carriers, both stemming from the distinctive 2D/2D architecture of the Bi/BiOBr heterojunction. This work demonstrates that 2D Bi offers active sites that facilitate photocatalytic N₂ fixation and introduces an approach to the design and construction of 2D/2D photocatalysts for applications spanning catalysis, optoelectronics, electronics, and beyond.