Defects-free single-crystalline zinc oxide nanostructures for efficient photoelectrochemical solar hydrogen generation

Abstract The article reports a novel and highly efficient methodology for the development of surface defects-free zinc oxide (ZnO) nanostructures, which are highly useful for various optoelectronic and electronic devices. Using this approach, we have developed high-quality ZnO nanostructures with comparable physical and chemical properties to high-temperature grown ones. Initially, ZnO nanostructures were developed by low-temperature chemical bath deposition, and the surface defects passivated structures were obtained by atomic layer deposition of homo-molecular clusters, i.e., Zn and O atomic layers. The surface passivated ZnO nanostructures exhibited excellent chemical stoichiometry between their constituents with enhanced crystalline quality. These nanostructures also showed improved light transmittance in the wavelengths range of 450–1000 nm, and light emission in the ultraviolet region. Further, the surface passivated nanostructures exhibited remarkable device performance as photoanodes with a greatly improved photocurrent density, more than 3 times, and reduced cathodic current of 6.17 × 10−7 A@-0.4 V. Significantly, the light-to-dark current ratio of the PEC devices fabricated with passivated ZnO nanostructures is found to be 1761.