A Low Temperature Chemiresistive Hydrogen Sensor Based on Pd: Iron Pthalocyanine (FePc) Thin Films

Abstract

Energy transition is advancing rapidly, with hydrogen (H<inf>2</inf>) gas emerging as a leading clean fuel. Various stakeholders are engaged in building H<inf>2</inf>-compatible infrastructure for production, storage, and transport. Due to H<inf>2</inf> gas explosive nature, reliable systems are essential for safe operations. In this context, our group has already developed a Hydrogen Sensor Device (0.5% to LEL working at 150 °C) based on Pd thin film working on Pellister sensing principle. As a step forward, we have investigated Pd modified FePc thin films as low temperature H<inf>2</inf> sensor device based on chemiresistive sensing principle. The films were prepared by thermal evaporation of FePc at 200 °C (80 nm, β phase) substrate temperature followed by sputter deposition of Pd film (10 nm). The Pd: FePc films exhibited room temperature (RT) sensing (lowest detection limit of 0.3% H<inf>2</inf>) with best sensing characteristics at 100 °C (sensitivity 1.4 times for 2% H<inf>2</inf> with a response time of 200 s). The sensing behavior may be attributed to the catalytic behavior of Pd in facilitation of oxygen adsorption on low coordinated Fe atoms in FePc. The same is inferred using Kelvin probe studies on pure and Pd modified FePc films. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.