Fabrication of bio-based acidic nonmetals co-doped TiO2 with core/shell structure and their unique photocatalytic performance for the rapid reduction of aqueous Cr(VI) under original pH and visible-light conditions

In this paper, bio-based acidic nonmetals co-doped titanium dioxide (C-SO 3 H/CN-TiO 2 ) with core/shell microstructure is successfully fabricated by a simple method. The synergistic effect of surface hydrogen ions (H + ) provided by sulfonic acid groups ( SO 3 H) functionalized bio-based carbon cores and photogenerated electrons generated by the visible-light excitation of nonmetals co-doped titanium dioxide (TiO 2 ) shells makes the as-prepared C-SO 3 H/CN-TiO 2 can rapidly reduce aqueous hexavalent chromium [Cr(VI)] under original pH condition. The addition of inorganic or organic acid is avoided during the photocatalytic reduction of aqueous Cr(VI). Therefore, the secondary pollution is effectively prevented during Cr(VI) reduction. The SO 3 H can be easily loaded on the surface of bio-based carbon cores by the thermal effect of light irradiation in concentrated H 2 SO 4 due to the aromatic carbon framework of bio-based carbon cores. The successful introduction of C and N elements into TiO 2 shells allows the as-prepared C-SO 3 H/CN-TiO 2 to exhibit a visible-light photocatalytic activity. Aqueous Cr(VI) having a concentration of 10 mg/L can be completely reduced after 180 min of visible-light irradiation under original pH condition.