Enhanced photocatalytic activity for H2 evolution under irradiation of UV-vis light by Au-modified nitrogen-doped TiO2

PLoS One. 2014 Aug 4;9(8):e103671. doi: 10.1371/journal.pone.0103671. eCollection 2014.

Abstract

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 H2 evolution have always been hot topics for research. This study attempts to expand the use of sunlight and to enhance the photocatalytic activity of TiO2 by N doping and Au loading.

Methods: Au/N-doped TiO2 photocatalysts were synthesized and successfully used for photocatalytic water splitting for H2 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/TiO2 > Au/N-doped TiO2 > TiO2 > N-doped TiO2. While under irradiation of UV-vis light, the N-TiO2 and Au/N-TiO2 samples show higher H2 evolution than their corresponding nitrogen-free samples (TiO2 and Au/TiO2). 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 TiO2.

Conclusion: Comparative studies have shown that a combination of nitrogen doping and Au loading enhanced the visible light response of TiO2 and increased the utilization of solar energy, greatly boosting the photocatalytic activity for hydrogen production under UV-vis light.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Catalysis / radiation effects
  • Dielectric Spectroscopy
  • Electricity
  • Electrochemical Techniques
  • Gold / chemistry*
  • Hydrogen / chemistry*
  • Microscopy, Electron, Transmission
  • Nitrogen / chemistry*
  • Optical Phenomena
  • Photoelectron Spectroscopy
  • Spectrometry, X-Ray Emission
  • Spectrophotometry, Ultraviolet
  • Surface Properties
  • Titanium / chemistry*
  • Ultraviolet Rays*
  • Water / chemistry
  • X-Ray Diffraction

Substances

  • Water
  • titanium dioxide
  • Gold
  • Hydrogen
  • Titanium
  • Nitrogen

Grants and funding

This work has been partially supported by the National Nature Science Foundation of China (Grant nos. 51178412 and 51278456, http://www.nsfc.gov.cn) and the National Key Technologies R&D Program (Grant no. 2013BAC16B01, http://www.most.gov.cn). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.