Facet-selective deposition of a silver-manganese dual cocatalyst on potassium hexatitanate photocatalyst for highly selective reduction of carbon dioxide by water

Previously a silver-manganese dual cocatalyst loaded on a potassium hexatitanate crystal photocatalyst was reported to be efficient for photocatalytic reduction of CO2 to CO by using water as an electron source. In the present study, variously prepared silver-manganese dual cocatalysts were investigated to figure out their states and functions of Ag and MnOx species. Although an impregnation method provided various states of these species such as AgOx particles, core-shell structures, and oxidized aggregates, they gave negative effects on the photocatalytic activity. On the other hand, a simultaneous photodeposition method fabricated Ag and MnOx species on the long and short facets of the rod-like crystal, respectively, and these species functioned as each efficient promoter for the reductive and oxidative reactions in the photocatalysis. It was firstly evidenced that the clear separation of the reaction sites with the proper promoters is essential for the high efficiency in the photocatalytic CO2 reduction.