1 Department of Mechanical Engineering, Technical University of Denmark2 Materials and Surface Engineering, Department of Mechanical Engineering, Technical University of Denmark3 Department of Photonics Engineering, Technical University of Denmark4 Optical Microsensors and Micromaterials, Department of Photonics Engineering, Technical University of Denmark5 Université Grenoble Alpes6 Université Lille Nord de France7 Danish Technological Institute8 Danish Fundamental Metrology9 Centre for oil and gas – DTU, Center, Technical University of Denmark10 Danish Technological Institute
The photocatalytic behavior of magnetron sputtered anatase TiO2 coatings on copper, nickel, and gold was investigated with the aim of understanding the effect of the metallic substrate and coating-substrate interface structure. Stoichiometry and nanoscale structure of the coating were investigated using X-ray diffraction, Raman spectroscopy, atomic force microscope, and scanning and transmission electron microscopy. Photocatalytic behavior of the coating was explored by using optical spectrophotometry and electrochemical methods via photovoltage, photocurrent, and scanning kelvin probe microscopy measurements. The nature of the metal substrate and coating-substrate interface had profound influence on the photocatalytic behavior. Less photon energy was required for TiO2 excitation on a nickel substrate, whereas TiO2 coating on copper showed a higher band gap attributed to quantum confinement. However, the TiO2 coating on gold exhibited behavior typical of facile transfer of electrons to and from the CB, therefore requiring only a small amount of photon energy to make the TiO2 coating conductive.
A C S Applied Materials and Interfaces, 2014, Vol 6, Issue 24