Selective optical detection of H2 and CO with SiO2 sol–gel films containing NiO and Au nanoparticles

Abstract

NiO is a p-type semiconductor widely studied for its promising implementation inchemo-optical gas sensors. Reducing/oxidizing gases induce a change in opticalabsorption of NiO. It has been found that Au doping induces a remarkableincrease in the NiO sensitivity, and at the same time silica films obtained by thesol–gel technique have been demonstrated to be a suitable support matrix forgas-sensitive materials due to their extremely high specific surface area (up to600 m2 g−1). The aim of this workis the synthesis of SiO2 films containing both NiO and Au nanoparticles and their morphological and functional characterizationas active gas-sensing materials suitable for optical detectors. The possibility to selectively recognizeH2 and CO is studied exploiting the wavelength dependence of the gas-induced opticaltransmittance variation.