Unlocking clean energy: Exploring FeVO4 nanopebble thin film as an outstanding photoanode for efficient water splitting

This study presents a two-step synthesis approach utilizing the hydrothermal method and drop casting for the fabrication of FeVO4 (FVO) thin films onto FTO-coated glass substrates, employing sacrificial basic FeOOH (FOH) nanostructured thin films. X-ray diffraction (XRD) and Raman spectroscopy confirmed the formation of FVO nanopebble thin films. Morphological and elemental analyses revealed that the thickness and grain size of the FVO nanopebbles increased, reaching maximum values depending on the parent FOH nanostructures. Additionally, the optimized FVO nanopebbles exhibited a high content of oxygen vacancies. Furthermore, a gradual increase in grain size and film thickness observed through the phenomenon of red-shifting in the optical band gap. The well-optimized FVO photoanode delivers the highest photocurrent density of 0.3 mA cm−2 at an applied bias of 1.6 V (vs. RHE) under standard illumination, demonstrating exceptional stability under these conditions. Moreover, the photoanode exhibited exceptional injection efficiency of 96.7% compared to separation efficiency, as evidenced by photoelectrochemical impedance spectroscopy (PEIS) studies. Furthermore, the optimized photoelectrode exhibited a hydrogen evolution rate of 11.96 μmol h−1cm−2 with a faradaic efficiency of 98.73% after one hour. Overall, the synthesized FVO nanopebble thin films shows promising potential for efficient photoelectrochemical water splitting applications.