Production of hydrogen using photoELECTROCHEMICAL WATER SPLITTING is a promising method for production of clean and renewable energy source. Using positive and negative semiconductors respectively as photocathode and photoanode, WATER can be splitted into hydrogen and oxygen. In this study, hematite was synthesized using ELECTROCHEMICAL deposition. The diffraction pattern obtained using x-ray diffraction showed hematite having rhombohedral crystal structure. Surface morphology obtained by scanning electron microscope showed a two-layer structure, lower layer with cracks and upper layer consisting of particles. Photocurrent density was obtained using linear sweep voltammetry under chopped illumination and it was obtained at 0. 6V vs Ag/AgCl as 2. 5 μ A. cm-2. Nyquist plot of hematite at potentials of 0V and 0. 6V was obtained using ELECTROCHEMICAL impedance spectroscopy and an equivalent circuit was fitted to EIS data and the value of the parameters was obtained. Also, using Mott-schottky plot, the flat band potential and the carrier density were obtained to be-0. 35V vs Ag/AgCl and 8. 4×1018 cm-3.

Cu-doped ZnO nanotube arrays decorated with silver nanoparticles (ZnO NTs: Cu/Ag) were synthesized on fluorine-doped tin oxide (FTO) substrates by electrodeposition technique and used as photoanodes to investigate photoELECTROCHEMICAL (PEC) WATER SPLITTING efficiency under visible light irradiation. The prepared photoanodes were characterized by field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction and UV-Visible absorption spectroscopy. Linear sweep voltammetry, ELECTROCHEMICAL impedance spectroscopy and Mott-Schottky analysis were used to evaluate PEC efficiency. The ZnO NT: Cu/Ag photoanode exhibits a significant photocurrent density of about180 µA/cm2 at 1.6 V vs. RHE compared to other films. Also, the results show that the charge transfer density increases to 1.03×1022cm-3 and the charge transfer resistance decreases to 17.6 Ω. The improved PEC performance of ZnO NTs: Cu/Ag is attributed to the localized surface plasmon resonance (LSPR) effect of Ag nanoparticles, the ability of Cu to absorb visible light, efficient separation and transfer charge carriers.

Titania nanotubes (TNT) prepared by anodization of Ti foils were used for WATER SPLITTING in a standalone cell. The concentration polarization between the anode side (1M NaOH) and cathode side (0.5 M H2SO4) ensured that the WATER SPLITTING reaction could take place with no external bias and separate H2 and O2 evolution could be achieved. The destruction of TNT structures under 365 nm UV irradiation as well as the absence of the stoichiometry between the anodic and cathodic gas collectors indicates the limits of the stability of TNT structures under these conditions.

Crystalline nanostructured zinc oxide and titanium dioxide thin layers were prepared using the spin-coating method. Their structural and optical properties were characterized using X-ray diffraction spectroscopy, scanning electron microscopy, UV-visible absorption spectroscopy, and photoluminescence spectroscopy. Additionally, their photoELECTROCHEMICAL properties were investigated by conducting three-electrode test and ELECTROCHEMICAL impedance spectroscopy. Finally, their short-term and long-term ELECTROCHEMICAL stability in acidic, alkaline, and neutral environments was studied. The results indicate that the synthesized materials are crystalline and nanostructured. The UV-visible absorption spectrum of zinc oxide exhibits a wider range, and its threshold voltage in the three-electrode test is closer to the theoretical value for WATER SPLITTING; its photocurrent is higher in alkaline environments, while acidic conditions lead to corrosion and degradation. In contrast, the ELECTROCHEMICAL impedance and recombination rate of electrons and holes in titanium dioxide are lower, resulting in a higher photocurrent and, consequently, increased efficiency; its photocurrent is greater in acidic conditions, with no corrosion observed. Ultimately, the chemical stability of titanium dioxide was assessed to be better than that of zinc oxide.

The reduction of fossil fuel usage and the simultaneous increase in the utilization of renewable fuels contribute to mitigating environmental pollution and reducing the Earth's atmospheric temperature. Today, the escalating global population poses a challenge of increased energy consumption, necessitating the adoption of simple and cost-effective methods for energy generation. WATER SPLITTING using solar light and photocatalysts for hydrogen production is one such approach. Recent years have witnessed significant advancements in the field of photocatalytic WATER SPLITTING, with progress extending from fundamental scientific research to practical and scalable applications. This review begins by examining the influential factors in the design of a photocatalyst, including sacrificial agents, nanoparticle effects, solar spectrum, and the introduction of photocatalysts operating in the UV region. Subsequently, recent advancements in two-dimensional materials and heterogeneous structures for WATER SPLITTING applications are summarized from a theoretical perspective. Specifically, various two-dimensional materials and heterogeneous structures employed for WATER SPLITTING are discussed. Finally, the focus shifts to recent progress in the development of new materials for light absorption in the visible region, insights, and strategies in the field. The discussion concludes with an emphasis on recent advancements in the development of new materials, absorption of light in the visible region, insights, and strategies for further exploration and development.