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.