Photoelectrical response of mesoporous nickel oxide decorated with size controlled platinum nanoparticles under argon and oxygen gas.

The visible light photoelectrical properties of a p-type mesoporous nickel oxide (MNO) support was investigated upon the decoration of size controlled, 1.6 nm, 6.4 nm and 7.9 nm Pt nanoparticles. The near room temperature photoelectrical response of the MNO was 3 times higher after decoration of 1.6 nm Pt nanoparticles with a loading of 1 wt%. MNO decorated with smaller Pt nanoparticles showed the highest photoresponse. The surrounding atmosphere has striking effect on the photoelectrical behavior, as adsorbed oxygen induced 32% lower photoelectrical response compared to that of argon. The noble metal nanoparticles show both electronic and chemical sensitization: the first functioning as an electron sink resulting in a new band structure of the photocatalyst, and the second interacting chemically with the oxygen and argon adsorbed from the environment. A model is proposed using heterojunctions theory comprising a new induced oxygen potential that may explain the lower photoresponse in the presence of oxygen. [ABSTRACT FROM AUTHOR]