Versatile Gasochromic Hydrogen Detection via Supraparticle‐Based Applied Composite Materials

Gasochromic hydrogen indicators combine easily readable color changes with low-cost, low-maintenance operation, making them attractive for reliable hydrogen monitoring in real-world settings. In this study, gasochromic indicator supraparticles are synthesized from silica and platinum nanoparticles with resazurin as the gasochromic element. These powders, although responsive, are impractical in the field due to handling losses and limited mechanical robustness. Therefore, the supraparticles are implemented into a polymethylmethacrylate (PMMA) matrix to create millimeter-sized beads, so-called suprabeads, and self-supporting thin films. The gasochromic behavior of the powder, suprabeads, and thin films is systematically compared. All formats exhibit the same color transition sequence under hydrogen exposure - purple to pink to colorless - with the pink state recovered in air. The effects of hydrogen concentration, relative humidity, and light exposure on the gasochromic response are thoroughly analyzed, and detailed electron microscopy studies linked structural information to the performance in all application scenarios. No significant differences in the color change mechanism are observed between the different applications; however, increasing the polymer-matrix thickness slowed the indicators’ response while improving resistance to desiccation. The findings highlight the potential of these materials for hydrogen sensing in real-world scenarios alongside the hydrogen economy.