On the impact of Cu dispersion on CO2 photoreduction over Cu/TiO2

► We explore copper promoted photoreduction of carbon dioxide over titania. ► Photocatalytic methane production is a strong function of copper loading. ► Optimum methane yields occur at ultra-low copper concentrations < 0.03 wt.%. ► We propose 2-dimensional Cu2O islands are the active photoreduction sites.