PtNi Nanocrystal–Ionic Liquid Interfaces: An Innovative Platform for High-Performance and Reliable H₂ Detection

The transition to hydrogen (H₂) as a clean alternative energy source demands rigorous safety, especially in its storage, transportation, and application due to its inherently explosive nature. Moreover, H₂ emissions into the atmosphere can disrupt the atmospheric balance of greenhouse gases, such as methane, ozone, and water vapor, leading to indirect contributions to short-term global temperature increases. To address this, the development of high-performance H₂ gas sensors is crucial for the early detection and warning of potential leakages, both ensuring safety and assessing their environmental impact. In this study, we present a real-time, high-performance electrochemical H₂ sensor featuring an innovative electrochemical interface between octahedral PtNi alloy nanocrystals and two distinct ionic liquid electrolytes: 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([Bmpy][NTf₂]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][NTf₂]). We demonstrated that the PtNi/[Bmpy][NTf₂] interface achieves exceptional sensitivity, with a limit of detection of 107.1 ppm, as well as rapid response time of 17 s and recovery time of 21 s, excellent selectivity, and long-term stability, with only a 1.1% degradation observed over a 120 day test period. Experimental analysis and theoretical calculations reveal that [Bmpy][NTf₂] surpasses [Bmim][NTf₂] due to its better wettability, lower H₂ solvation energy, and favorable H₂ dissociation kinetics for the H₂ oxidation reaction (HOR). These characteristics enhance H₂ solubility and facilitate H₂ oxidation on the PtNi nanocrystal surface, making [Bmpy][NTf₂] superior to [Bmim][NTf₂] as the electrolyte for H₂ sensing application. This study advances high-sensitivity durable H₂ sensor technology and offers insights into the interactions between metal alloy nanocrystals and ionic liquids, guiding the design of next-generation H₂ sensors for environmental monitoring, industrial safety, and sustainable energy systems.