In\nSitu Fabrication\nof 2D-2D Bi/BiOBr Ohmic Heterojunction\nfor Enhanced Photocatalytic Nitrogen Fixation

The performance of BiOBr in photocatalytic\nnitrogen (N<sub>2</sub>) fixation is suboptimal, attributed to the\nweak chemisorption\nand\nactivation of N<sub>2</sub> by surface atoms. In our study, we achieved\nthe formation of two-dimensional (2D) bismuth (Bi) on BiOBr nanosheets\nthrough in situ annealing in hydrogen atmosphere and successfully\nconstructed a unique 2D-2D Bi/BiOBr ohmic heterojunction using a one-step\nmethod. Notably, the Bi/BiOBr heterojunction was utilized for photocatalytic\nN<sub>2</sub> fixation under visible light (λ > 400 nm) in\nultrapure\nwater, demonstrating an exceptional N<sub>2</sub> fixation rate of\n376.16 μmol g<sup>–1</sup> h<sup>–1</sup>. This\nrate is 7.7 and 4.1 times higher than those of BiOBr and BiOBr-OVs,\nrespectively. The improved photocatalytic efficiency is attributed\nto the significantly enhanced N<sub>2</sub> adsorption capability\nand more effective separation of photogenerated carriers, both stemming\nfrom the distinctive 2D/2D architecture of the Bi/BiOBr heterojunction.\nThis work demonstrates that 2D Bi offers active sites that facilitate\nphotocatalytic N<sub>2</sub> fixation and introduces an approach to\nthe design and construction of 2D/2D photocatalysts for applications\nspanning catalysis, optoelectronics, electronics, and beyond.