Role of passivated N–F pairs in enhancing photoactivity of ZnWO4 (0 1 0) surface: Emphasis on correlation between codoping forms and compensation mechanisms

We perform first-principles density function theory calculations to study the correlation between codoping forms and compensation mechanism in N–F pairs at ZnWO4 (0 1 0) surface. Our study considers substitutional as well as adsorptive and interstitial codoping forms at ZnWO4 (0 1 0) surface, and the results show that all the NsFs, NsFad, NadFs, and NadFad codoping forms can passivate the partially occupied states formed in the corresponding monodoped systems to enhance the photoactivity of ZnWO4 (0 1 0) surface and decrease the transition energy of photoexcited electrons from the impurity levels to the conduction band minimum to low-energy area. There are four different compensation mechanisms in N–F pairs at ZnWO4 (0 1 0) surface, corresponding to the four codoping forms, and different compensation mechanisms in N–F pairs result in different effects on photoactivity of ZnWO4, such as the NadFad has little sense to photocatalytic process, due to the electrons only transferring between the Nad–Obπ* states. We expected that this knowledge could introduce some more general useful codoping concepts to the design of visible-light photocatalysts.

Graphical abstractWe reveal the correlation between codoping forms and compensation mechanisms in N–F pairs and their different effects on enhancing photoactivity of ZnWO4 (0 1 0) surface.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► N–F codoping passivates the partially occupied states acted as trap of electrons. ► NadFs codoping achieves good visible-light photoactivity of ZnWO4. ► NadFad-codoped ZnWO4 (0 1 0) surface has little sense to photocatalytic process.