Humidity Sensing Enhancement and Structural Evolution of Tungsten Doped Zinc Oxide Nano-Sensors Fabricated Through Co-Precipitation Synthesis

Abstract In this work, pure and tungsten (W) doped ZnO nano-crystals have been synthesized through the co-precipitation technique. The prepared samples are employed to study the effect of tungsten doping on the structural, morphological, and humidity sensing properties of ZnO nanomaterials. The structural and morphological studies have been carried out using X-ray Diffraction (XRD) and Field Emission Scanning Electron Microscopy (FESEM), respectively. The XRD of the synthesized nanomaterials reveals a hexagonal wurtzite structure and a reduction of crystallite size from 44.46 nm to 37.38 nm with increase in doping concentration. The SEM images reveal a cuboidal columnar growth. Finally, the samples have been exposed to a humidity range from 10% to 90% RH and observed that the sensitivity of the sensor is enhanced as the concentration of tungsten is increased. The sample doped with 1.75 mol% tungsten demonstrates the highest sensitivity of 144% among all the samples with good stability.