Effects of gas phase ion irradiation and vacuum annealing on the visible light photocatalytic properties of WO3

Oxygen vacancies were introduced into tungsten oxide (WO3) rods by irradiation with H2+, He+ or Ar+ ions and/ or vacuum annealing. The surface chemical bonding states and visible light photocatalytic properties of these materials were subsequently assessed. Although the irradiated surfaces were contaminated with carbon and silicon species during ion irradiation, vacuum annealing at 500 degrees C decreased the extent of carbon contamination and increased the concentration of lattice oxygen species related to a surface WO3-x phase. The irradiated WO3-x rods exhibited low photocatalytic efficiencies during the degradation of rhodamine 6G compared with pristine WO3 rods, possibly due to the existence of contamination and oxygen vacancies. Vacuum-annealed WO3-x rods having a green coloration exhibited high photocatalytic efficiency as a result of enhanced visible light absorption and the low concentration of both surface contamination and vacancies.

Automated summary

Oxygen vacancies were incorporated into tungsten oxide rods through ion irradiation and vacuum annealing, affecting the surface bonding states and visible light photocatalytic properties. Vacuum annealing reduced carbon contamination and increased the concentration of lattice oxygen species in the WO3-x phase. Irradiated WO3-x rods showed lower photocatalytic efficiency due to contamination and oxygen vacancies. Vacuum-annealed WO3-x rods with green coloration exhibited high photocatalytic efficiency due to enhanced visible light absorption and lower concentration of surface contamination and vacancies.