The in situ photodeposition method of copper(0) nanoparticles on TiO2 is found to produce photoactive heterogeneous catalysts suitable for redox reactions. Several variables in the method that affect catalyst structure and activity have been investigated for H-2 generation as a model reaction. The counter-anion of the copper salt used plays a pivotal role in determining size, distribution and crystallinity of the nanopartides, as well as leaching, recyclability and stabilisation. Redox cycling between Cu(0) and Cu(II) was found to be extremely facile, with oxidation occurring aerobically and re-reduction under anaerobic irradiation in water. (C) 2016 Elsevier Inc. All rights reserved.