Heteropoly blue-modified ultrathin bismuth oxychloride nanosheets with oxygen vacancies for efficient photocatalytic nitrogen fixation in pure water.

Photocatalytic nitrogen reduction is a promising green technology for ammonia synthesis under mild conditions. However, the poor charge transfer efficiency and weak N adsorption/activation capability severely hamper the ammonia production efficiency. In this work, heteropoly blue (r-PW) nanoparticles are loaded on the surface of ultrathin bismuth oxychloride nanosheets with oxygen vacancies (BiOCl-OVs) by electrostatic self-assembly method, and a series of xr-PW/BiOCl-OVs heterojunction composites have been prepared. Acting as a robust support, ultrathin two-dimensional (2D) structure of BiOCl-OVs inhibits the aggregation of r-PW nanoparticles, enhancing the interfacial contact between r-PW and BiOCl. More importantly, the existence of oxygen vacancies (OVs) provides abundant active sites for efficient N adsorption and activation. In combination of the enhanced light absorption and promoted photogenerated carriers separation of xr-PW/BiOCl-OVs heterojunction, under simulated solar light, the optimal 7r-PW/BiOCl-OVs exhibits an excellent photocatalytic N fixation rate of 33.53 µmol gh in pure water, without the need of sacrificial agents and co-catalysts. The reaction dynamics is also monitored by in situ FT-IR spectroscopy, and an associative distal pathway is identified. Our study demonstrates that construction of heteropoly blues-based heterojunction is a promising strategy for developing high-performance N reduction photocatalysts. It is anticipated that combining of different defects with heteropoly blues of different structures might provide more possibilities for designing highly efficient photocatalysis systems.