Room-temperature electrochemical deposition of nanostructured ZnO films on FTO substrate and their photoelectrochemical activity

The possibility of fabrication of nanostructured ZnO layers on conductive glass substrates via simple room-temperature electrodeposition was studied in detail. The process was carried out in zinc nitrate electrolyte at different potentials for various durations. The morphology, composition, and semiconducting properties of the deposits were examined by various techniques. As-synthesized materials were found to be amorphous and co-deposition of the metallic Zn at more negative potentials was confirmed. Nevertheless, thermal treatment in air results in the successful conversion of the as-deposited precipitate to the wurtzite ZnO. The potential of −1.5 V vs. SCE was identified as optimal to achieve both full coverage of the glass substrate, as well as uniform morphology of the deposits. In general, the photoelectrochemical performance of such kind of ZnO photoanodes was found to be significantly dependent on the electrodeposition duration since this parameter strongly affected the thickness, surface morphology, as well as semiconducting properties of the obtained material. In consequence, the photoanode deposited at −1.5 V vs. SCE for 40 min exhibited the most promising photoelectrochemical activity under studied conditions.