Catalytic synergy of WS₂-anchored PdSe₂ for highly sensitive hydrogen gas sensor

Hydrogen (H₂) is widely used in industrial processes and is one of the well-known choices for storage of renewable energy. H₂ detection has become crucial for safety in manufacturing, storage, and transportation due to its strong explosivity. To overcome the issue of explosion, there is a need for highly selective and sensitive H₂ sensors that can function at low temperatures. In this research, we have adequately fabricated an unreported van der Waals (vdWs) PdSe₂/WS₂ heterostructure, which exhibits exceptional properties as a H₂ sensor. The formation of these heterostructure devices involves the direct selenization process using chemical vapor deposition (CVD) of Pd films that have been deposited on the substrate of SiO₂/Si by DC sputtering, followed by drop casting of WS₂ nanoparticles prepared by a hydrothermal method onto device substrates including pre-patterned electrodes. The confirmation of the heterostructure has been done through the utilization of powder X-ray diffraction (XRD), depth-dependent X-ray photoelectron spectroscopy (XPS) and field-emission scanning electron microscopy (FE-SEM) techniques. Also, the average roughness of thin films is decided by Atomic Force Microscopy (AFM). The comprehensive research shows that the PdSe₂/WS₂ heterostructure-based sensor produces a response that is equivalent to 67.4% towards 50 ppm H₂ at 100 °C. The response could be a result of the heterostructure effect and the superior selectivity for H₂ gas in contrast to other gases, including NO₂, CH₄, CO and CO₂, suggesting tremendous potential for H₂ detection. Significantly, the sensor exhibits fast response and a recovery time of 31.5 s and 136.6 s, respectively. Moreover, the explanation of the improvement in gas sensitivity was suggested by exploiting the energy band positioning of the PdSe₂/WS₂ heterostructure, along with a detailed study of variations in the surface potential. This study has the potential to provide a road map for the advancement of gas sensors utilizing two-dimensional (2D) vdWs heterostructures, which exhibit superior performance at low temperatures.