TiO2/BiOBr 2D-2D heterostructure via in-situ approach for enhanced visible-light photocatalytic N2 fixation

Highlights: • The TiO₂/BiOBr 2D-2D heterojunction catalytic material was synthesized by in-situ growth method. • TiO₂/BiOBr 2D-2D heterojunction catalyst has excellent photocatalytic nitrogen fixation performance that the NH₃ yield can be 1.43 mmol/g/h. • The improved performance can be attributed to the formation of 2D-2D heterojunction between TiO₂ nanosheets and BiOBr nanosheets, which accelerates electron transfer through this 2D channel. • The applicability of this strategy can be demonstrated for other 2D photocatalytic materials. Two-dimensional (2D)-2D heterojunctions have great potential for solar energy utilization and photocatalytic nitrogen fixation due to their unique electron transport pathways. Herein, TiO₂/BiOBr 2D-2D heterojunction photocatalysts with different composite ratios were synthesized. The TiO₂/BiOBr heterojunction demonstrated excellent photocatalytic nitrogen fixation activity and good cycling stability during the experiment. The maximum NH₃ production rate of the prepared 15% TiO₂/BiOBr heterojunction catalyst was 1.43 mmol/g/h, which was more than about 4 times as much as that of pure BiOBr. The high photocatalytic nitrogen fixation performance can be mainly ascribed to the 2D interface between TiO₂ and BiOBr nanosheets in the heterojunction. As demonstrated by transient photocurrents, electrochemical impedance spectra and photoluminescence quenching studies, 2D interface can speed up the transfer of photogenerated electrons and provide more electrons to participate in the nitrogen fixation reaction, thus improving the performance of photocatalytic nitrogen fixation. Our results demonstrated that the construction of 2D-2D heterojunctions can be an effective strategy to improve solar energy utilization.