“…Furthermore, elements doping is a simple and effective way to enhance the photon-to-electron conversion rate. To date, non-metallic elements such as C [14] , N [15] , O [16] , P [17] , S [18] , B [15] , F [19] , I [20] and metal elements, such as Fe [21] , Co [22] , Ni [23] , Zn [24] , Mn [25] , have been investigated, and great progresses also have been achieved. Amongst, O-doping is an economic and effective measure, which can be obtained by direct calcination in air.…”