Cobalt oxide thin films were successfully grown directly on fluorine-doped tin oxide glass substrates through a simple, green, and low-cost hydrothermal method. An investigation into the physicochemical characteristics and photoelectrochemical (PEC) properties of the developed cobalt oxide thin film was comprehensively performed. At various annealing temperatures, different morphologies and crystal phases of cobalt oxide were observed. Microflowers (Co₃O₄) and microflowers with nanowire petals (Co₃O₄/CoO) were produced at 450 °C and 550 °C, respectively. Evaluation of the PEC performance of the samples in KOH (pH 13), Na₂SO₄ (pH 6.7), and H₂SO₄ (pH 1) revealed that the highest photocurrent −2.3 mA cm⁻² generated at −0.5 V vs. reversible hydrogen electrode (RHE) was produced by Co₃O₄ (450 °C) in H₂SO₄ (pH 1). This photocurrent corresponded to an 8-fold enhancement compared with that achieved in neutral and basic electrolytes and was higher than the results reported by other studies. This promising photocurrent generation was due to the abundant source of protons, which was favorable for the hydrogen evolution reaction (HER) in H₂SO₄ (pH 1). The present study showed that Co₃O₄ is photoactive under acidic conditions, which is encouraging for HER compared with the mixed-phase Co₃O₄/CoO.

The presence of Ti³⁺ in the structure of TiO₂ nanotube arrays (NTs) has been shown to enhance the photoelectrochemical (PEC) water-splitting performance of these NTs, leading to improved results compared to pristine anatase TiO₂ NTs. To further improve the properties related to PEC performance, we successfully produced TiO₂ NTs using a two-step electrochemical anodization technique, followed by annealing at a temperature of 450 °C. Subsequently, Mo₂C was decorated onto the NTs by dip coating them with precursors at varying concentrations and times. The presence of anatase TiO₂ and Ti₃O₅ phases within the TiO₂ NTs was confirmed through X-ray diffraction (XRD) analysis. The TiO₂ NTs that were decorated with Mo₂C demonstrated a photocurrent density of approximately 1.4 mA cm⁻², a value that is approximately five times greater than the photocurrent density exhibited by the bare TiO₂ NTs, which was approximately 0.21 mA cm⁻². The observed increase in photocurrent density can be ascribed to the incorporation of Mo₂C as a cocatalyst, which significantly enhances the photocatalytic characteristics of the TiO₂ NTs. The successful deposition of Mo₂C onto the TiO₂ NTs was further corroborated by the characterization techniques utilized. The utilization of field emission scanning electron microscopy (FESEM) allowed for the observation of Mo₂C particles on the surface of TiO₂ NTs. To validate the composition and optical characteristics of the decorated NTs, X-ray photoelectron spectroscopy (XPS) and UV absorbance analysis were performed. This study introduces a potentially effective method for developing efficient photoelectrodes based on TiO₂ for environmentally sustainable hydrogen production through the use of photoelectrochemical water-splitting devices. The utilization of Mo₂C as a cocatalyst on TiO₂ NTs presents opportunities for the advancement of effective and environmentally friendly photoelectrochemical (PEC) systems.

Electrodeposition (ED) is applied in several applications since it is one of the most user‐friendly and cost-effective techniques. The increasing popularity of this technique is due to its capacity to control the morphology and chemical composition of the target materials. Copper (Cu) is one of the metals that can be discovered in the greatest abundance on earth. It has been used as an alternative to noble metals to improve the photo electrochemical (PEC) activity for hydrogen generation. This research involved the electrochemical deposition of Cu metal onto fluorine-doped tin oxide (FTO) glass using direct and pulse ED. The objective of this study is to investigate the PEC performance of Cu metal electrodeposited on FTO glass by evaluating its efficiency under light illumination. The deposition of the Cu films was successful, resulting in a thin layer of Cu films onto the FTO. The PEC response of metallic Cu was analysed by doing an LSV study on the thin films, in relation to the ED technique, applied voltage, ED time, and pulse cycle. The results show that the FTO/Cu −0.8 V samples produced via pulse ED have the highest PEC activity. The deposition of strongly adhering and improved morphology of Cu thin film is important especially for interconnect in semiconductor applications.