Nitrogen and oxygen binary vacancies modulated g-C3N4/BiO2−x for visible-NIR-driven nitrogen photofixation

In order to achieve efficient development of green and sustainable industries and improve energy efficiency, the growth of highly efficient catalysts with photoresponse from ultraviolet (UV) to near-infrared (NIR) region is of great significance for the reduction of nitrogen to ammonia. Herein, we reported binary nanohybrids composed of nitrogen vacancy-rich two dimensional (2 D) g-C ₃N ₄ and oxygen vacancy-rich 2 D BiO _2−x (CN/BiO). Both experimental results and DFT calculations indicated that the synergistic effect of the heterostructure in CN/BiO effectively suppresses the recombination of photogenerated electron-hole pairs. Advancing from the efficient charge separation, N ₂ adsorbed on the nitrogen vacancy and oxygen vacancy sites can effectively receive high-energy electrons, which in turn promote NH ₃ production. Impressively, the CN/BiO exhibited remarkable ammonia yield rate of 602.1 μmol g ⁻¹ h ⁻¹ with > 420 nm light irradiation. More crucially, superior activity under NIR light was indeed accomplished for CN/BiO with the NH ₃ production rates up to 89.4 μmol g ⁻¹ h ⁻¹ using > 780 nm light irradiation. This study provided a novel synthetic route to prepare highly active and full-spectrum light-driven heterojunction photocatalysts toward sustainable and scalable solar-to-NH ₃ production.