“…2 To improve the utilization of solar light, a lot of researchers have shown that doping TiO 2 with non-metal elements such as C, N, F, S and B could be an effective strategy. [3][4][5][6][7] In order to further achieve photocatalytic activity, co-doping TiO 2 with two or three non-metal elements has attracted much attention, such as N-F, 5,8 N-B, 9 C-N, 10 S-N, 11,12 S, N and C, 3,13 and so on. Density functional theory (DFT) calculations have shown that the doping S, N elements could lower the band gap of TiO 2 effectively.…”