Fabrication of high sensitive proto-type NOx sensor based on Pd nanoparticles loaded on WO3

Herein, we report, development of a proto-type NOx sensor using optimized Pd nanoparticles loaded WO3(Pd@WO3). The WO3 powder was synthesized hydrothermally using sodium tungstate dihydrate and adipic acid as precursors. The structural and morphological analyses of as-prepared samples were performed using XRD, FESEM and FETEM analysis. The results revealed the formation of irregular shaped monoclinic WO3 particles decorated with Pd nanoparticles of similar to 10-15 nm size. The NOx sensing characterization of WO3 and Pd@WO3 was performed at different ppm levels and at different temperature. The WO3 nanostructures were found to exhibit maximum response towards NOx gas at room temperature which enhances drastically after Pd loading. The NOx sensor device has been fabricated using optimized Pd loaded WO3 material which showed higher % response towards NOx. The response and recovery time observed were 1 and 2 s respectively. The cross sensitivity observed for other gases and organic vapors was negligible.