Low Temperature and Highly Selective H2 Sensing System Using WO3-ZnO Heterostructure Decorated with Pd Nanoparticle

In this paper, highly selective and highly sensitive hydrogen $(\mathrm{H}_{2})$ sensing heterostructure gas sensor device is reported with a low cost electronic circuit for easy transmission of hydrogen leakage information. Mixing two different materials $\text{WO}_{3}$ and ZnO at 1: 1 ratio with further modification by palladium (Pd)doping results high sensitivity 83.1 % and high selectiveness towards H2and low response and recovery time at 1000ppm (0.1%)H2concentration with respect to other fabricated bare WO3 and bare ZnO sensors. The sensor characteristics are studied using Scanning Electron Microscopy (SEM)and X-Ray Diffraction (XRD) methods which reveal particle size and mixing ratio information in nanoscale region. An easily implementable, low cost and reliable electronic circuit based on multivibrator interfacing with hydrogen sensor is also proposed in the present work which results highly accurate signal frequency variation from 14.1 KHz to 50.3 KHz for $\mathrm{H}_{2}$ concentration variation from 0.02%-0.1 % for Pd modified $\text{WO}_{3}-$ ZnO sensor.