Enhanced Photocatalytic Activity for H(2) Evolution under Irradiation of UV–Vis Light by Au-Modified Nitrogen-Doped TiO(2)

BACKGROUND PURPOSE: Photocatalytic water splitting for hydrogen evolution is a potential way to solve many energy and environmental issues. Developing visible-light-active photocatalysts to efficiently utilize sunlight and finding proper ways to improve photocatalytic activity for H(2) evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO(2) by N doping and Au loading. METHODS: Au/N-doped TiO(2) photocatalysts were synthesized and successfully used for photocatalytic water splitting for H(2) evolution under irradiation of UV and UV–vis light, respectively. The samples were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence spectroscopy (PL), and photoelectrochemical characterizations. RESULTS: DRS displayed an extension of light absorption into the visible region by doping of N and depositing with Au, respectively. PL analysis indicated electron-hole recombination due to N doping and an efficient inhibition of electron-hole recombination due to the loaded Au particles. Under the irradiation of UV light, the photocatalytic hydrogen production rate of the as-synthesized samples followed the order Au/TiO(2) > Au/N-doped TiO(2) > TiO(2) > N-doped TiO(2). While under irradiation of UV–vis light, the N-TiO(2) and Au/N-TiO(2) samples show higher H(2) evolution than their corresponding nitrogen-free samples (TiO(2) and Au/TiO(2)). This inconsistent result could be attributed to the doping of N and the surface plasmonic resonance (SPR) effect of Au particles extending the visible light absorption. The photoelectrochemical characterizations further indicated the enhancement of the visible light response of Au/N-doped TiO(2). CONCLUSION: Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO(2) and increased the utilization of solar energy, greatly boosting the photocatalytic activity for hydrogen production under UV–vis light.