Epitaxial Metal-Organic Framework-Mediated Electron Relay for H₂ Detection on Demand

Hydrogen is regarded as one of the most promising clean substitutes for fossil fuels toward a carbon-zero society. However, the safety management of the upcoming hydrogen energy infrastructure has not been fully prepared, in contrast to the well-established natural gas and gasoline systems. On the frontline is the guard post of hydrogen detectors, which need to be deployed on various structural surfaces and environmental conditions. Conventional hydrogen detectors are usually bulky and environmentally sensitive, limiting their flexible and conformal deployment to various locations, such as pipelines and valves. Herein, we demonstrate the successful synthesis of a palladium-modified epitaxial metal-organic framework (MOF) on single-layer graphene to fabricate a heterostructure material (Epi-MOF-Pd). Device based on the heterostructure demonstrates high sensitivity toward low- concentration H₂ (155% resistance response to 1% H₂ within 12 s, a theoretical detection limit of 3 ppm). The 25 nm epitaxial MOF acquires electrons from the Pd nanoparticles after the trace amount of H₂ is chemically adsorbed and further relays the electrons to the highly conductive graphene. The Epi-MOF-Pd is both flexible and enduring, and maintains stable detection over 10 000 bending cycles. Through photolithography, device arrays with a density of 3000 units/cm² are successfully fabricated. This versatile material provides a prospective avenue for the mass production of high-performance chemical-sensitive electronics, which could significantly improve the hydrogen safety management on demand.