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 BiIII 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.