Photoactivated Pd-Loaded WO₃ for Enhanced H₂ S Sensing

Abstract

In this article, pristine WO3 and Pd-loaded WO3 are synthesized via facile hydrothermal method and integrated with the Internet of Things (IoT)-enabled portable resistance readout circuit for real-time sensing performance measurement of the fabricated sensor toward <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{S}$ </tex-math></inline-formula> . A series of characterizations are performed to investigate the crystal structure, surface morphology, active surface area, and elemental composition of the synthesized materials. Pristine WO3 nanoplates show a 9.13 sensing response toward 100-ppm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{H}_{{2}}\text{S}$ </tex-math></inline-formula> exposure, while loading of 0.25 and 0.5 mol% Pd further improves the response up to 14.37 and 23.45, respectively. However, further loading of Pd (1 mol%) on WO3 nanoplates reduces the sensing response to 15.29. The fabricated 0.5 mol% Pd-loaded WO3 sensor is investigated under thermal and photoenergy excitations. Moreover, the temperature optimization of 0.5 mol% Pd-loaded WO3 exhibits a higher sensing response of 47.8 at 100 °C. Furthermore, under visible and ultraviolet (UV) illumination, the 0.5 mol% Pd-loaded WO3 sensor response increases from 47.8 to 57.3 and 63. The fabricated 0.5 mol% Pd-loaded WO3 sensor exhibits remarkable response, shorter response–recovery time, and ultraselectivity toward analyte gas.