Efficient photocatalytic nitrogen fixation to ammonia over bismuth monoxide quantum dots-modified defective ultrathin graphitic carbon nitride

The photocatalytic nitrogen reduction offers a promising strategy for ammonia (NH3) production, with the kinetics of the reaction depending on the transfer of photoinduced electrons to the adsorbed N2 molecules. However, the energetic electrons may flow into the defect states of the photocatalyst, thereby impeding nitrogen fixation. Herein, were report a novel heterojunction photocatalyst system for photocatalytic NH3 production, comprising BiO quantum dots (QDs) and nitrogen defective ultrathin carbon nitride (UCNx), which overcomes this limitation. Efficient spatial charge separation is achieved through nitrogen vacancies and the intimate heterojunction contact between the BiO QDs and UCNx. Benefitting from efficient charge separation, the adsorbed N2 on nitrogen vacancies and Bi2+ sites can effectively receive energetic electrons and in turn boost NH3 production. The optimal hybrid catalyst (BiCNx-5) shows excellent photocatalytic performance, with NH3 production rate of 576.11 μmol g−1 h−1 under visible light illumination (λ > 420 nm). This study provides a platform for the future design of effective photocatalysts for NH3 production.