Boosting photocatalytic nitrogen fixation over Ni/Fe co-doped BiOBr in pure water under the synergistic effect of enhanced internal electric field and oxygen vacancies

Abstract

To improve energy and environmental problems, the green and energy-saving photocatalytic ammonia synthesis reaction has received extensive research. The production of photocatalysts that possess high electron-hole separation rates has become an urgent problem. In this paper, we successfully synthesized Ni/Fe bimetallic co-doped nanoflower-like BiOBr materials enriched with oxygen vacancies through a simple one-step hydrothermal strategy. The effects of the introduction of transition metals Ni and Fe on the photocatalytic performance of BiOBr were examined using a variety of test methods. The findings demonstrated that Ni/Fe doping induced BiOBr lattice distortion and enhanced the internal electric field (IEF) and oxygen vacancy (OV) concentration of BiOBr. Furthermore, the Fe3+/Fe2+ redox pathway can be utilized as a photocatalytic active site to improve charge aggregation and accelerate the reaction process. The metal doping and vacancy defects assist in the adsorption and activation of nitrogen, synergistically promoting the photocatalytic performance of BiOBr. In purified water without any organic scavengers, the Ni/Fe-BiOBr exhibiting optimal nitrogen fixation efficiency generated a production of ammonia of 433.8 μmol g−1 h−1, which surpasses the unmodified BiOBr by about 5.7 times. This paper offers new perspectives into how extremely effective photocatalysts for nitrogen fixation might be developed in the future.