Bismuth-rich bismuth oxyiodide microspheres with abundant oxygen vacancies as an efficient photocatalyst for nitrogen fixation

Abstract

Solar-driven reduction of dinitrogen (N₂) to ammonia (NH₃) is still challenging due to the highly stable N–N triple bond. Herein, orthorhombic phase H-Bi₅O₇I microspheres with abundant oxygen vacancies (OVs) were successfully prepared via a simple calcination and hydrogen reduction strategy. Based on the combined bismuth-rich strategy and the introduction of OVs in H-Bi₅O₇I, a remarkable photocatalytic nitrogen fixation performance was achieved under visible light irradiation in the absence of any organic scavengers or noble-metal cocatalysts. H-Bi₅O₇I exhibits an NH₄⁺ generation rate of 162.48 μmol g⁻¹ h⁻¹, which is 2.0 and 7.4 times higher than that of Bi₅O₇I and BiOI. It is because H-Bi₅O₇I with abundant OVs has a more proper band gap, better electron capturing ability and more effective separation and transfer rate for the photogenerated charge carriers. This study may provide a new direction and useful insight for the design of defect assisted N₂ fixation photocatalysts.