High-Performance Nanostructured Palladium-Based Hydrogen Sensors—Current Limitations and Strategies for Their Mitigation

Abstract

Hydrogen gas is rapidly approaching a global breakthrough as a carbon-free energy vector. In such a hydrogen economy, safety sensors for hydrogen leak detection will be an indispensable element along the entire value chain, from the site of hydrogen production to the point of consumption, due to the high flammability of hydrogen–air mixtures. To stimulate and guide the development of such sensors, industrial and governmental stakeholders have defined sets of strict performance targets, which are yet to be entirely fulfilled. In this Perspective, we summarize recent efforts and discuss research strategies for the development of hydrogen sensors that aim at meeting the set performance goals. In the first part, we describe the state-of-the-art for fast and selective hydrogen sensors at the research level, and we identify nanostructured Pd transducer materials as the common denominator in the best performing solutions. As a consequence, in the second part, we introduce the fundamentals of the Pd–hydrogen interaction to lay the foundation for a detailed discussion of key strategies and Pd-based material design rules necessary for the development of next generation high-performance nanostructured Pd-based hydrogen sensors that are on par with even the most stringent and challenging performance targets.

Advanced development of metal oxide nanomaterials for H2gas sensing applications

“…after by researchers recent years. 314 The combination between polymers and MOx provides the sensors for both flexibility and robustness. Moreover, the hybridization of organic and inorganic materials also enhances the performance of the sensors at room temperature.…”

Grain-Growth Mediated Hydrogen Sorption Kinetics and Compensation Effect in Single Pd Nanoparticles

“…11), thereby corroborating recent results correlating grain boundary length with hysteresis width. 11 Finally, from an application perspective, the found evolution of structure and kinetics over time both identifies a potentially critical feature responsible for the deterioration of (Pd-based) solid-state hydrogen storage materials and hydrogen sensors over time and a so far unexplored design rule for the development of ultrafast hydrogen sensors in par with the US DoE response time target 18,41 , namely the optimization and stabilization of grain structure.…”

“…[6][7][8][9][10][11][12][13][14] Therefore, the understanding of the influence of grain boundaries on kinetic processes, for example during nanoscale phase transformations, is widely lacking. This is problematic since phase transformations in nanostructured materials are a central concept in energy storage technologies like batteries 15,16 and hydrides 17 , in hydrogen sensors 18,19 , as well as in heterogeneous catalysis, for example through metal catalyst oxidation. [20][21][22] To overcome this current lack of understanding, single particle experiments hold the key since they have been successfully deployed to investigate the impact of nanostructure dimensions and geometry on the thermodynamics of phase transformation processes, where they have focused on hysteresis effects 7,8,11 and the role of defects like dislocations and voids 9,10,12 .…”

Tantalum‐Palladium: Hysteresis‐Free Optical Hydrogen Sensor Over 7 Orders of Magnitude in Pressure with Sub‐Second Response

“…Optical metal‐hydride hydrogen sensors are an attractive candidate for large‐scale implementation in the future hydrogen economy. [ 8–12 ] Their working principle is based on the fact that the optical properties change when metal hydrides partly hydrogenate when they are exposed to a hydrogen atmosphere. These changes are probed by for example measuring the fraction of transmitted or reflected light or the frequency shift of the (localized) surface plasmon resonance peak and from one of these optical signals the partial hydrogen pressure P H 2 can be determined.…”

“…Compared to conventional ways of detecting hydrogen such as catalytic resistor detectors and electrochemical devices, optical fiber hydrogen sensors are inherently safe and can be made small and inexpensive. [ 8,9,11–18 ]…”