화학공학소재연구정보센터
Solar Energy Materials and Solar Cells, Vol.191, 39-49, 2019
A novel growth control of nanoplates WO3 photoanodes with dual oxygen and tungsten vacancies for efficient photoelectrochemical water splitting performance
Recently, there has been attractive attention over the defect-engineering where the optimum extent of oxygen deficiency has been considered as an effective route towards enhancing the solar-driven water oxidation photocurrent. In this study, a nanoplate-like tungsten oxide with dual oxygen and tungsten vacancies (WO3-x) was successfully fabricated on tungsten foil by acid-mediated hydrothermal treatment to highly improve the photoelectrochemical (PEC) performance of WO3-x photoanode. Thermal annealing at 550 degrees C in air led to an oxygen deficient surface with a sub-stoichiometric by phase transformation from orthorhombic WO3 center dot nH(2)O to gamma-monoclinic. However, the optimum number of oxygen vacancies in WO3-x, fabricated at 2 h (W-2 h) with compact, porous and uniform nanoplate film that provide a large surface area for efficient charge collecting capability, caused an enhanced photocurrent density of 4.12 mA/cm(2) (41.2 mA/W) at 1.6 V vs. Ag/AgCl, as compared to W-3 h (2.59 rnA/cm(2) or 25.9 mA/W) and W-30 min (1.79 rnA/cm(2) or 17.9 mA/W). Finally, local variations in dual oxygen and tungsten vacancies and in the electronic band structure of a WO3-x. thin film was analyzed with ultraviolet photoelectron spectroscopy (UPS) and UV-visible diffuse reflectance spectroscopy (UV-DRS).