Plasma Engraved Bi2MoO6 for Enhanced Photocatalytic Nitrate Reduction Reaction

Photocatalytic nitrate removal to produce recyclable netrogen (N2) without using chemical reductants is regarded as an environmentally friendly and effective technology for denitrification. However, the sluggish cathode reaction kinetics severely hampered the efficiency of nitrate reduction reaction (NO3RR). Developing high performance photocatalyst is highly pursued for boosting NO3RR. In this study, Bi2MoO6 nanosheets with massive oxygen vacancies are fabricated through hydrothermal reaction and subsequent plasma modification. Maximal nitrate conversion yield of 38% with the high N2 selectivity of 80.0% is achieved for photocatalytic NO3RR. The underlying photocatalytic mechanism is systemically investigated through comprehensive approaches. The enhanced nitrate conversion efficiency is mainly attributed to the synergistic effect between deliberately generated oxygen vacancies and Mo active sites, capturing O and N atoms of nitrate, respectively, thus promoting the adsorption of nitrate and cleavage of N–O bond. Furthermore, the H “repulsion” effect of Bi efficiently suppresses hydrogenation reaction, resulting in greatly enhanced N2 selectivity.Graphical Abstract The generation of oxygen vacancy leads to the cleavage of N-O bond in NO3-, which also enhances the adsorption of nitrate. The specific adsorption of nitrogen on active Mo site is enhanced, and the repulsion of element Bi to protons enhances the selectivity of N2 in the product.