Preparation and characterization of different concentrations of palladium-loaded graphitic carbon nitride-based nanocomposites as an efficient hydrogen gas sensor at room temperature

This paper reports the deposition of Pd/g-C₃N₄-based thin films at different percentages of Pd loading (10%, 20%, and 40%) on an Astro-glass substrate in a temperature range of 350–400°C, using a simplistic nebulizer-based ultrasonic spray pyrolysis technique. A mist of the precursor solution was produced utilizing a nebulizer. Dry airflow was used to transfer the formed mist on the thermally activated substrate, which allows deposition. The crystallinity and morphology of the deposited film were confirmed by x-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), respectively. X-ray photoelectron spectroscopy (XPS) and energy-dispersive x-ray spectroscopy (EDS) were performed to identify the chemical characteristics of the deposited film. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were performed to examine the thermal stability of the film. The surface area of the deposited film was analyzed using Brunauer–Emmett–Teller (BET) theory and the electrochemical route by Cu underpotential deposition (Cu-UPD). Response time for the 10% Pd/g-C₃N₄ film was beyond the measurable limit due to the high resistance of the film, whereas 40% Pd/g-C₃N₄ and 20% Pd/g-C₃N₄ showed response and recovery which is discussed in the results section. The sensitivity of the 20% Pd/g-C₃N₄ was found to be highest amongst all different loaded composites. These films were used for efficient hydrogen gas sensing at room temperature.