Pd-Doped WO3 Nanoplates for Hydrogen Sensing: Experimental Studies and Density Functional Theory Investigations

In this article, a hydrogen sensor with excellent performance was synthesized using the hydrothermal method, with Pd-modified WO3 nanoplates as the sensing layer. At an optimum operating temperature of 200 °C, the hydrogen gas sensing capabilities of WO3 and Pd-WO3 composite sensors were investigated. The findings indicate that in contrast to the WO3 sensor, the Pd-WO3 composite sensor exhibits superior hydrogen sensing performance, showcasing remarkable selectivity, reliable repeatability, sustained long-term stability, and quick response and recovery (8 s/10 s@100 ppm). The first-principles density functional theory was used to explain the sensing mechanism of the Pd-WO3 composite. The improved sensing performance of Pd-WO3 composite sensors was explained from the perspectives of the Schottky junction formed between Pd nanoparticles and WO3, the catalytic effect of metal Pd nanoparticles, and gas adsorption–desorption. This article confirms that Pd-modified WO3 nanoplates are good candidates for efficient hydrogen gas sensing.