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 (Bi-0). Ovs and Bi-0, rather than widely recognized doping metal ions, play a key role for remarkable enhancement of photocatalytic activity of Bi2MoO6, for example of similar to 16-fold higher photocatalytic nitrogen reduction activity, which arises from that the Ovs and Bi-0 can enhance photoexcited charge separation and work as surface active sites. The Ovs possess much greater efficacy than the Bi-0. Formation of Bi-0 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.