Nanoengineered PDMS/Pd/ZnO-Based Sensor to Improve Detection of H₂ Dissolved Gas in Oil at Room Temperature

The current research aims to synthesize zinc oxide decorated with palladium nanoparticles and develop a stable sensor with high sensitivity to hydrogen gas dissolved in oil. ZnO nanorods (NR) were synthesized by a hydrothermal method directly onto a commercial sensor board with gold interdigital electrodes, followed by functionalization with Pd nanoparticles (NP) by drop casting. SEM images show ZnO NRs with an average diameter of ∼220 nm and Pd spherical NPs with diameters of 35-75 nm. Finally, the sensing properties were examined by immersing the sensor into insulating mineral oil in a closed system, where different H₂ concentrations (from 0 up to 500 ppm) were injected into the headspace and then dissolved in the mineral oil, according to the Ostwald coefficient. All measurements were carried out at room temperature. The electrical characterization showed that our sensor had good repeatability, stability, and sensitivity to detect lower concentrations (less than 10 ppm). Additionally, a nanoengineered porous layer of PDMS was prepared over the sensor board through spin coating and heat treatment, and then the sensitivity of our sensor board reached ∼2.8 ppm of H₂ gas. Our findings indicate that the methodology applied improves gas detection performance in industrial applications and its potential use for real-time monitoring.