Dual Mechanisms of Pd-Doped In2O3/CeO2 Nanofibers for Hydrogen Gas Sensing

A hydrogen sensing structure composed of Pd-doped In2O3/CeO2 nanofibers was synthesized by electrospinning and DC sputtering. Unexpectedly, the nanofibers show ultrahigh hydrogen sensing properties, and the response (Ra /Rg ) to 100 ppm H2 gas reaches a value of 16,411 at a low temperature of only 100 °C. Meanwhile, the sensor also shows absolute selectivity for hydrogen gas. Pd doping is found to catalyze the metallization of the In2O3 surface, which indicates that the ultrahigh sensitivity is affected by metallization of In2O3 homojunctions. Finally, a dual-mechanism for hydrogen sensing is proposed, which is helpful to improve the understanding and design of gas sensing materials.