Temperature-controlled deposition of NiO-ZnO composite thin films: optical and photoelectrochemical properties
摘要
Developing cost-effective, eco-friendly and highly efficient electrocatalysts is a pre-requisite for advanced sustainable energy conversion systems. In the present work, NiO-ZnO composite thin films were fabricated by aerosol-assisted chemical vapor deposition method at 450, 475, 500 and 525 °C. This study was focused on improving the efficacy and durability of fabricated composites for photo and electrochemical water splitting. The influence of temperature on physio-chemical properties was meticulously characterized by X-ray diffraction spectroscopy, field-emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The composite thin film deposited at 500 °C exhibited 10 mA cm−2 current density with a low bias overpotential of 1.37 V versus reversible hydrogen electrode for catalytic water oxidation. The synergistic effect of NiO and ZnO in a composite created a robust photoanode indicating 2.03 mA cm−2 current density at + 0.8 V versus saturated calomel electrode. Moreover, the small value of Tafel slope (1.2 V dec−1), tailored bandgap (2.81 eV) and efficient stability demonstrated a significant improvement in charge separation and transfer over the extended period. This research opens the door for more investigation into composite thin films as potential solutions towards global energy problems in addition to advance photocatalytic or electrocatalytic materials for energy conversion.
Graphical abstract