Bismuth nanoparticles and oxygen vacancies synergistically attired Zn2SnO4 with optimized visible-light-active performance

As for the common synthesis methods of ameliorated Zn2SnO4 (ZSO), additional oxides refer to Zn or Sn or Zn/Sn would be introduced into the doped system synchronously, thereby the achievement of doped pure ZSO appears particularly difficult. In this study, a novel bismuth (Bi) nanoparticles modified ZSO composite with oxygen vacancies (OVs-BZSO) was fabricated via a facile one-pot hydrothermal approach. According to XRD and XPS analysis results, it was found that the metallic Bi nanoparticles were successfully introduced into ZSO. In addition, based on the results of XPS and EPR measurements, the existence of OVs in the ZSO was also affirmed. On this basis, the DFT calculation was employed to reveal the position of OVs, the electronic structure and charge transport properties of the interface between Bi and ZSO. Furthermore, it was observed that the introduction of OVs not only diminishes the bandgap induced by an intermediate gap but also services as active centers to favor the adsorptions of small molecules such as NO, O-2 and H2O as revealed by DFT simulations to promote the formation of reactive species. While the addition of metallic Bi nanoparticles into ZSO for one thing enhances the light harvesting capacity endowed by SPR effect as evidenced by UV-vis DRS result, for another accelerates the separation of photo-generated carriers by virtue of Schottky barrier formed at the metallic Bi and ZSO interface. Therefore, the synergistic effect of OVs and Bi nanoparticles can thermodynamically drive the adsorption/activation of NO molecules, benefitting the directional migration and effective separation of electrons in OVs-BZSO, all of which serviced the efficient NO removal rate with the illumination of visible light. Meanwhile, for OVs-BZSO, in-situ infrared spectroscopy results indicated that the formation of toxic by-products was greatly bridled, thus a fresh charge transfer path: Bi nanoparticles -> ZSO -> gas molecules and a unique NO reaction path were proposed accordingly. This study can provide new insights on controllable preparation and reaction mechanism of ZSO-based photocatalysts.