The synergistic effect of Ni(OH)(2) and CuxO on TiO2 enhanced the H-2 production 4 times higher than bare TiO2 at the optimum loading of 1.0 wt% Ni(OH)(2) and 0.5 wt% CuxO (1.0 wt% Ni(OH)(2)-CT) under natural sunlight. CuxO-TiO2 heterojunctions improved the visible activity and charge transfer efficiency of TiO2. The layered morphology of non-precious Ni(OH)(2) cocatalyst with intercalated H2O molecules enhanced H-2 production by improving the surface charge transfer reaction with additional formation of H+ ions through the redox reactions. Based on the characterization and experimental results, the double charge transfer and direct Z-scheme mechanisms were proposed for the charge carrier pathway in CuxO-TiO2 heterojunction. On the whole, the improved visible light response, efficient interfacial charge transfer and production of additional excited free electrons/H+ ions enhanced the overall H-2 production on Ni(OH)(2)-CT, which was also confirmed with various experimental and characterization results. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.