Eco-friendly ferrite nanocomposite photoelectrode for improved solar hydrogen generation

For the first time, a ferrite nanocomposite photoelectrode (FNCP) has been fabricated and investigated for photoelectrochemical hydrogen production from water under simulated solar light. The ZnFe2O4:Fe2O3 nanocomposite photoanode has been fabricated via a single step methodology using a novel approach involving the solution precursor plasma spraying technique. The FNCP is achieved by optimal phase formation during the deposition of the ferrite film (similar to 10 mm) over a stainless steel substrate. It exhibits an enhanced photoactivity 6 times higher compared to pure ZnFe2O4 (ZFO), under simulated-solar (AM1.5 G) illumination. Its Mott-Schottky characterization reveals an n-type semiconducting behaviour, indicating an order of magnitude higher donor density (N-d similar to 10(17) cm(-3)) than the pure phase ZnFe2O4 electrode. It also exhibits a low band gap of 1.94 eV demonstrating that it can more efficiently absorb visible light photons than other systems comprising of bare zinc ferrite or iron oxide. The FNCP yielded a solar-to-hydrogen conversion efficiency of 1.25% under simulated solar radiation (AM1.5 G) with a hydrogen evolution rate of 99 mu mol h(-1). Electrochemical impedance spectroscopy of the FNCP revealed a significantly improved charge transfer characteristic compared to ZnFe2O4. An enhanced photoactivity for the oxidation of water from the FNCP is attributed to its improved optical absorption and better charge transfer properties induced by the existence of Fe2O3 in ZnFe2O4.