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 title compound, C₁₂H₁₄N₂O₃S, adopts a cis–trans geometry of the thiourea group and is stabilized by intramolecular hydrogen bonds between the carbonyl O atoms and the H atom of the thioamide group and by a C—H...S interaction. Molecules are linked by two intermolecular hydrogen bonds (C—H...O and N—H...O), forming a one-dimensional chain parallel to the c axis.