PH-controllable Regeneration and Visible-light Photocatalytic Redox of Carbon and Nitrogen Codoped Zn3Nb2O8 towards Multiple Contaminants

The visible light photocatalytic activity and stability of bare Zn3Nb2O8 and carbon doped Zn3Nb2O8 (C-Zn3Nb2O8) was enhanced with nitrogen and carbon co-doped Zn3Nb2O8 (N/C-Zn3Nb2O8) for the oxidative and reductive degradation of pH-sensitive substrates, such as Cr(VI), Cu(II), methyl orange, and tetracycline hydrochloride. Compared to pure Zn3Nb2O8, the band structure of N/C-Zn3Nb2O8 was optimized with conduction band at -0.37 eV and valence band at 1.61 eV due to the co-doping of nitrogen and carbon, which could stimulate the •OH and •O2− radicals. Moreover, N/C-Zn3Nb2O8 catalyst was highly improved by the synergistic effect of carbon and nitrogen dopants in the visible light absorption, the charge conductivity, and the electron-hole pair’s separation. In addition, N/C-Zn3Nb2O8 catalyst with negative charged surface and layered structure can selectively adsorb and degrade some pH-sensitive pollutants, thus achieving high photocatalytic activity in visible light irradiation and stable recyclability by designing regeneration test and controlling pH range.