Porous sol gel silica films doped with crystalline NiO nanoparticles for gas sensing applications

摘要

A reliable sol gel route to synthesize NiO dopedSiO2 films with different NiO content is here described.The films showed detectable and reversible changes in bothoptical and electrical properties when exposed to somereducing/oxidizing gaseous species at temperatures in the250◦C–350◦C range. A functional characterization protocolhas been designed and some of the sensing properties ofthe materials have been investigated for detecting NO2,CH4, CO and H2. An optical transmittance increase up to2% has been detected for 1% CO in dry air atmospheres,while relative resistance response (RR = Rgas/Rair) valuesup to 4.97 for 850 ppm H2/air mixtures have been registeredfor conductometric gas sensing. Films at all NiO molarconcentrations in the 10% NiO - 40% range showed anoptical response to the target gas, while only 30% and 40%NiO films provided a detectable gas induced resistancechange.