Visible light-assisted room temperature gas sensing with ZnO-Ag heterostructure nanoparticles

Noble metal-metal oxide nanohybrids play an ever-increasing role in photocatalytic applications. Here, a ZnO-Ag nanoparticle prepared by a modified polymer-network gel method was utilized for room temperature light-assisted NO2 gas detection. Since a heterojunction forms between the two materials and surface oxygen vacancies increase, the sensitivities of the sensors to NO2 gas (0.5-5 ppm) under various light (lambda = 365-520 nm) illumination conditions are enhanced in comparison with those of pure ZnO sensor. Surface plasmon resonance (SPR) was found to result in the excellent visible-light performance of this ZnO-Ag nanostructure. More importantly, by tuning the working wavelength using different LED light sources, we can obtain an optimized sensitivity. When blue-green LED (470 nm, 75 mW/cm(2)) is used, the 3 mol% Ag-loaded ZnO sensor shows the highest sensitivity as well as superior stability and selectivity. The effect of humidity on the sensor performance is also discussed in detail. (c) 2017 Elsevier B.V. All rights reserved.