Formaldehyde detection with chemical gas sensors based on WO3 nanowires decorated with metal nanoparticles under dark conditions and UV light irradiation.

• UV light irradiation of doped WO 3 gas sensing layers reduced response time to formaldehyde. • The gas induced baseline shift was diminished under UV light irradiation. • UV light irradiation induces similar effect as the doping of WO 3 gas sensing layers with metal nanoparticles. • Energy induced by the UV light, accelerates the adsorption-desorption processes in WO 3 gas sensing layers. We report results of formaldehyde gas (CH 2 O) detection under dark conditions and UV light irradiation with pristine tungsten trioxide nanowires (WO 3 NWs) and metal nanoparticles decorated WO 3 NWs gas sensing layers. The resistive layers were deposited by one step aerosol assisted chemical vapor deposition (AACVD) on commercial alumina substrates with 10-pair interdigitated platinum electrodes. The elaborated gas sensors, based on pristine WO 3 and on WO 3 decorated with Au, Pt, Au/Pt, Ni and Fe nanoparticles, were investigated towards three concentrations of formaldehyde gas (5, 10 and 15 ppm) under dark conditions and under UV light irradiation at the wavelength of 394 nm. Two main effects were observed: firstly, under UV light irradiation the response time for CH 2 O desorption was significantly reduced with the exception of the nanomaterial with Fe NPs dopant; secondly, the gas induced baseline shift was reduced under UV light irradiation conditions. These results can be explained by the additional energy induced by the UV light, accelerating the adsorption-desorption processes. The results obtained confirmed that both the decoration of WO 3 NWs with selected metal nanoparticles as well as sensors operation under UV light irradiation are a practical and affordable way to enhance gas sensing towards formaldehyde detection, although both strategies applied together did not introduce an amplified synergetic effect. [ABSTRACT FROM AUTHOR]