Pd loading induced excellent NO2 gas sensing of 3DOM In2O3 at room temperature

Abstract

Pd loaded three dimensionally ordered macroporous (3DOM) In2O3 sensors were fabricated by reduction precipitation method with a uniform distribution of Pd nanoparticles (NPs). The response of 0.5 wt% Pd loaded 3DOM In2O3 is 980 for 500 ppb NO2 which is over 5 times higher than that of pure In2O3 at room temperature. Our work presents a relatively simple but more efficient approach for NO2 detection without extra heating. Pd inducing surface-modification effectively modulates the thickness of electron depletion layer, which is the dominant sensing mechanism for enhancing NO2 performance. When Pd NPs are loaded on the surface of 3DOM In2O3 support, not only the amount of surface deficiency and carrier concentration increase, but also electrons flow further from In2O3 to Pd NPs. All of these results in the formation of Pd-In2O3 Schottky contact and eventually widen the depletion layer on the In2O3 support. Apparently, our work presents a relatively simple but more efficient approach for NO2 detection without extra heating, indicating that Pd loaded 3DOM In2O3 sensors would be more suitable for future applications.