A significantly enhanced gas-phase photocatalytic conversion of carbon dioxide into methane on Cu/TiO2 nanoparticles upon introducing Bi2O3 as a promoter in the vicinity of Cu was observed. The maximum rate of CH4 generation of 11.90 mmol g(-1) h(-1) recorded in the case of Cu-Bi2O3/TiO2 is approximately one order of magnitude higher than that obtained with Cu/TiO2 nanoparticles. The enhanced performance was attributed to facilitated migration of CO* from Cu to the Bi2O3 surface.