Metal-alcohol coordination promoted reduction of bismuth (III) in bismuth-based semiconductors for enhanced photocatalytic activity

Metal ion doping is an extensively researched method to enhance photocatalytic activity of bismuth-based semiconductors, but function of the metal ions need be further clarified. Herein, metal-alcohol coordination was evidenced to promote reduction of Bi^III in Bi-based semiconductors (e.g., Bi₂MoO₆ hierarchical microspheres) to generated oxygen vacancies (Ovs) and Bi metal (Bi⁰). Ovs and Bi⁰, rather than widely recognized doping metal ions, play a key role for remarkable enhancement of photocatalytic activity of Bi₂MoO₆, for example of ∼16-fold higher photocatalytic nitrogen reduction activity, which arises from that the Ovs and Bi⁰ can enhance photoexcited charge separation and work as surface active sites. The Ovs possess much greater efficacy than the Bi⁰. Formation of Bi⁰ also induces prominent morphological variation of the microspheres. This work discloses an interesting but neglected phenomenon in alcohothermal synthesis of “metal-doped” Bi-based semiconductors and aims at drawing high attention of relevant researchers.