Experimental evaluation of photocatalytic and photoelectrochemical hydrogen fuel production with metal-based catalysts, electrodes and coatings in a novel manner

• Copper oxide mesh-based photoelectrodes are developed. • Transition metal coatings are applied to enhance photoelectrochemical performance. • Photoelectrochemical and photocatalytic effects are combined in an integrated manner. In this work, transition-metal based photoelectrodes are developed and tested across three permutations, including pristine copper oxide mesh, titania coated, and nickel-zinc-iron oxide (NiZnFeO)/titania coated copper oxide mesh. Additionally, NiZnFeO photocatalyst’s performance for photocatalytic hydrogen production is assessed. Subsequently, an integrated cell combining both photocatalytic and photoelectrochemical effects is considered. The novelty of this work is assessing the combination of NiZnFeO photocatalyst with titania in photoelectrochemical settings as well as developing an integrated hybrid system combining both photoelectrochemical and photocatalytic effects. For the photoelectrochemical system, the highest current density is attributed to the titania-coated copper oxide mesh photoelectrode, with values of −1.17 mA/cm 2 and −2.92 mA/cm 2 , for dark and light conditions, respectively, at −0.6 V vs Ag/AgCl, and with an onset potential of −0.18 V vs Ag/AgCl. Additionally, the integrated cell shows a current density of −1.71 mA/cm 2 at −0.6 V vs Ag/AgCl. The optimization study on a NiZnFeO photocatalyst is conducted with the objective function of maximizing hydrogen concentration to fine-tune factors such as catalyst loading, sacrificial agent molarity, and temperature. The highest obtained hydrogen concentration after 30 min and under simulated solar light is 26 ppm, at an energy efficiency of 1.83 %, with optimum conditions of 15 mg/100 ml catalyst loading, 1 M of triethanolamine sacrificial agent, and 35 °C temperature.