Standalone polymer ‘litmus-paper’-like sensor for specific hydrogen detection: Integrating naked-eye and fluorescence techniques

Hydrogen is a promising renewable fuel with broad applications, but its flammability and tendency to leak through metals create safety challenges, necessitating reliable, standalone, and affordable sensing systems. Current hydrogen sensors are often costly, suffer from cross-sensitivity to gases, and are typically not standalone. Our sensing approach is based on the hydrogenation of the fluorophore 1,4-bisphenylethnylbenzene (PEB). This approach encompasses two levels of visual sensing: rapid detection via surface color change and quantitative “litmus paper"-like analysis and cross-section observation, which provides a hydrogen exposure history and other parameters such as hydrogen partial pressure and exposure time. The sensor detection limit is 1 mbar (<1000 ppm), and its detection time is below 1 min. Moreover, the sensor demonstrates high specificity to hydrogen and is unaffected by the presence of other gases or humidity. These findings advance cost-effective, standalone visual hydrogen sensors for comprehensive qualitative and quantitative environmental analysis.