Controlled nitrogen doping and film colorimetrics in porous TiO2 materials using plasma processing.
Nitrogen doping of TiO(2) films (N:TiO(2)) has been shown to improve the visible-light sensitivity of TiO(2), thereby increasing the performance of both photovoltaic and photocatalytic devices. Inductively coupled rf plasmas containing a wide range of nitrogen precursors were used to create nitrogen-doped TiO(2) films. These treatments resulted in anatase-phased materials with as high as 34% nitrogen content. As monitored with high-resolution X-ray photoelectron spectroscopy spectra, the nitrogen binding environments within the films were controlled by varying the plasma processing conditions. XPS peak assignments for multiple N 1s binding environments were made based on high resolution Ti 2p and O 1s XPS spectra, Fourier transform infrared spectroscopy (FTIR) data, and literature N 1s XPS peak assignments. The N:TiO(2) films produced via plasma treatments displayed colors ranging from gray to brown to blue to black, paralleling the N/Ti ratios of the films. Three possible mechanisms to explain the color changes in these materials are presented.
Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872, USA.
Daniel J V
DJ
Pulsipher
Ina T
IT
Martin
Ellen R
ER
Fisher
D002384:Catalysis; D003124:Colorimetry / Q000379:methods*; D008422:Materials Testing; D015233:Models, Statistical; D009584:Nitrogen / Q000737:chemistry*; D055095:Optics and Photonics; D010777:Photochemistry / Q000379:methods*; D056951:Photoelectron Spectroscopy / Q000379:methods; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
C009495:titanium dioxide; D014025:Titanium; D009584:Nitrogen