Enhancing the hydrogen photo-production using zinc oxide films doped with iron, tin, and aluminum

Abstract

Hydrogen is recognized as the most promising renewable energy source and can be efficiently produced through water photo-electrolysis green process. This study investigates the performance of ZnO nanorods doped with Fe, Al, and Sn at a 2 % molar ratio for hydrogen photo-production. The films were prepared using a combination of successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) methods. X-ray diffraction (XRD) analysis confirmed the hexagonal structure of the doped ZnO films with preferential growth along the (002) orientation, while energy-dispersive X-ray spectroscopy (EDX) confirmed their high purity. The doping with Al maintains the ZnO nanorods morphology while Fe, and Sn doping induced changes to overlapped nanoflakes/nanoflowers morphology. Optical analysis revealed a clear trend in the energy band gap, with Fe-ZnO film exhibiting the lowest value (2.95 eV), followed by Al-ZnO (3.03 eV), Sn-ZnO (3.07 eV), and ZnO (3.11 eV). The Fe-ZnO film also demonstrated the best performance as a photoelectrode for hydrogen generation, achieving optimized incident photon-to-current efficiency (IPCE) and applied bias photon-to-current efficiency (ABPE) values of 1.45 % and 0.20 % respectively, under 500 nm monochromatic illumination, with high reproducibility, and durability. These findings represent one step forward to developing ZnO-doped photoanodes for efficient and sustainable hydrogen green production.