Molecular and Structural Insights into H<sub>2</sub> Indicator Supraparticles: Lowering the Limit of Detection by Tuning Incorporated Catalyst Nanoparticles
Kailun Zhang, Jakob Reichstein, Philipp Groppe, Simon Schoetz, Nina Stockinger, Jörg Libuda, Karl Mandel, Susanne Wintzheimer, Tanja Retzer
Abstract
With the increasing interest in H 2 -based energy storage, H 2 detectors gain significant importance. Here, we report on safe, i.e., spark-free, reliable, and highly reactive gasochromic H 2 indicator supraparticles (SPs). They are assembled from different types of noble metal nanoparticles (NPs), SiO 2 NPs, and the dye resazurin via spray-drying. Their sensing principle is based on the adsorption and activation of H 2 on catalytically active noble metal NPs incorporated in the mesoporous supraparticulate framework. Upon stepwise hydrogenation of resazurin molecules with molecular mobility via activated H species, the indicator displays a fast color change visible to the naked eye. We investigate the effect of incorporating different catalytically active NPs into indicator SPs on their sensor performance at different H 2 concentrations. We find that the size and material of the catalyst NPs have a strong influence on the sensor response of the H 2 indicator as it changes the amount of activated H species available in the system. Enhancing the amount of interstitial H 2 O in the mesopores of the SPs increases their reaction volume but impairs the reproducibility of their sensor response. Among the studied materials, dispersed Pt NP-containing SPs give the overall best results in terms of overall performance toward H 2 detection.