“…However, for pure TiO 2 NTs, the low solar energy utilization efficiency and high recombination rate of photogenerated carriers result in low light quantum yield and low photocathodic protection performance. Recently, quite a few attempts have been made to enhance the solar photovoltaic transform efficiency of TiO 2 NTs, including precious metal modification (such as Ag [6], Cu [7] and Bi [8]), doping of non-metal elements (such as N [9] and F [10,11]) or metal elements (such as Cr [12], Ni [13] and Fe [14,15]), and in combination with specific semiconductors with a narrow band gap (such as WO 3 [16], CdS [17], CdSe [18], Bi 2 S 3 [19] and Ag 2 S [20]).…”