Molecular and Structural Insights into H-2 Indicator Supraparticles: Lowering the Limit of Detection by Tuning Incorporated Catalyst Nanoparticles

With the increasing interest in H-2-based energystorage,H-2 detectors gain significant importance. Here, we reporton safe, i.e., spark-free, reliable, and highly reactivegasochromic H-2 indicator supraparticles (SPs). They areassembled from different types of noble metal nanoparticles (NPs),SiO2 NPs, and the dye resazurin via spray-drying. Theirsensing principle is based on the adsorption and activation of H-2 on catalytically active noble metal NPs incorporated in themesoporous supraparticulate framework. Upon stepwise hydrogenationof 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 catalyticallyactive NPs into indicator SPs on their sensor performance at differentH(2) concentrations. We find that the size and material ofthe catalyst NPs have a strong influence on the sensor response ofthe H-2 indicator as it changes the amount of activatedH species available in the system. Enhancing the amount of interstitialH(2)O in the mesopores of the SPs increases their reactionvolume but impairs the reproducibility of their sensor response. Amongthe studied materials, dispersed Pt NP-containing SPs give the overallbest results in terms of overall performance toward H-2 detection.

Automated summary

In this study, we report on the development of safe and reliable gasochromic H-2 indicator supraparticles assembled from noble metal nanoparticles, SiO2 nanoparticles, and resazurin dye. The indicator shows a fast color change upon hydrogenation and the incorporation of different catalytically active nanoparticles affects its sensor performance. Among the studied materials, Pt NP-containing supraparticles show the best overall performance for H-2 detection.