(189z) Palladium-Platinum Nanosheets for Hydrogen Sensing

Hydrogen is being extensively investigated for use as a carbon-free energy carrier, especially in fuel cell vehicles and for long-term energy storage. Given that H₂ can create explosive mixtures in air at concentrations as low as 4%, safe use of H₂ at a consumer level will require inexpensive, low-power hydrogen sensors that can be widely deployed. Here, we used a new technique for making ribbon-like palladium-platinum nanosheets (PdPt NSs). We created sensors via drop-casting dispersions of these nanosheets onto interdigitated electrodes. In these chemoresistive sensors, the resistance increases in the presence of hydrogen, due to rapid uptake of hydrogen by the PdPt nanosheets at room temperature, forming a hydride with higher resistivity than the hydrogen-free nanosheet. The most promising PdPt nanosheet sensors, with 5:8 and 7:6 Pd:Pt ratios showed response times of 16 s and 14 s, and responses of 6.0% and 4.4%, respectively, to 1 vol% H₂ in air. These sensors could readily measure as little as 100 ppm of H₂ in air while maintaining positive response (increasing resistance upon exposure to H₂). These sensors have potential to broadly support the safe use of H₂ as an energy carrier because they function at ambient temperature.