Mesoporous TiO2 exhibiting better surface area 188 m2 g−1 and structural properties. Formation of photostable Cu+/Cu-TiO2 ternary hybrid nanocomposite catalyst. Water decomposition under direct sunlight irradiation using methanol as h+ scavenger. Improved apparent quantum yield (AQE = 11.39%) of Cu-mpTiO2 for H2 evolution. Efficient photostability and recyclability of Cu-mpTiO2 for several cycles.