Enhancement of the photocatalytic efficiency of WO3 nanoparticles via hydrogen plasma treatment

Surface defect engineering is able to effectively enhance the photocatalytic performance of WO3 nanoparticles. In this paper, radio frequency hydrogen plasma was employed to create surface defects on WO3 nanoparticles. X-ray photoelectron spectroscopy (XPS) and electron spin resonance (ESR) analysis confirmed that hydrogen plasma modification increases the density of oxygen vacancies on the surface of WO3. The broadening of characteristic WO3 peaks in Raman spectra indicates the increase of oxygen vacancies by increasing voltage in hydrogen plasma treatment. The sample treated with hydrogen plasma at 20 volts shows enhancement in photocurrent density by an order of magnitude, attributable to the band-gap narrowing and subsequent increase of quantum yield in the visible range. Consistent results were also obtained from photocatalytic O-2 evolution from water oxidation.