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.