Bismuth nanoparticles and oxygen vacancies synergistically modified HNb3O8 nanosheets for enhanced photocatalytic N2 reduction towards NH3.

Abstract

Due to the high stability of the N2 molecule and the low charge separation efficiency, the photocatalytic reduction of N2 to high-value chemicals (NH3) under mild conditions remains a great challenge. Herein, a composite photocatalyst (Bi/HNb3O8-Vo nanosheets) with Bi nanoparticles modified the HNb3O8-Vo nanosheets are designed for the conversion of N2 into NH3. In this design, the introduction of oxygen vacancies on the catalyst surface facilitates the formation of defective energy levels within the band gap of HNb3O8-Vo NS, which promotes the absorption of visible light, and enhances the charge carrier transport and separation. Bi nanoparticles co-catalyst not only facilitates the separation and migration of photogenerated charges, but also acts as reaction sites to adsorb and activate N2 molecule. Consequently, the optimized 5% Bi/HNb3O8-Vo photocatalysts show a NH3 yield of 372.7μmol/L g-1h-1 under full spectral irradiation without sacrificial agent, which is much higher than that of HNb3O8 NS (92.2μmol/L g-1h-1). This work provides a new way for the design of efficient N2 reduction photocatalysts through the synergistic effect of surface vacancies and metal co-catalysts.