Safety Through Visibility: Tracing Hydrogen in Colors with Highly Customizable and Flexibly Applicable Supraparticle Additives

The flammability of H2-air mixtures demands timely detection and precise localization of H2 leakages to ensure safety and targeted maintenance measures in the anticipated hydrogen economy. Herein, H2 indicator supraparticles (SPs) are demonstrated that meet this demand by making H2 visible to the naked eye by a rapid (ir)reversible color change. Their toolbox-like manufacturing from SiO2 nanoparticles (NPs), Pt NPs, and indicator dye molecules via spray-drying allows for engineering their structure, texture, and detection performance by systematically tuning their composition. It is demonstrated that decreasing the SiO2 NP size, increasing the Pt NP concentration, and adjusting the amount of dye molecules improve the SPs' response times. This opens up the option for multidimensional customization of their detection performance. Furthermore, the toolbox of H2 indicator SPs containing the established resazurin system is expanded to other indicator dyes, which makes a color change and reversibility of choice feasible. H2 indicator SPs meet many of the target characteristics for H2 detectors, e.g., low limit of detection, cycle stability, and high selectivity. Moreover, the SPs' particulate nature allows for their flexible application as an additive, e.g., in coatings or clothing, which enables the detection and localization of H2 leakages in relevant application scenarios. Micrometer-sized H2 indicator supraparticles make H2 visible to the naked eye. Their scalable, toolbox-like manufacturing via spray-drying provides multiple options to customize their composition, structure, texture, and thereby, their detection performance. H2 indicator supraparticles stand out with pronounced, eye-readable, and readily tunable color change reactions, response times in the seconds' range, as well as their flexible application as an additive. image