Hydrogen spillover breaks the sensitivity–recovery trade-off in room-temperature H₂ sensors

Hydrogen energy serves as a sustainable energy carrier crucial for global decarbonization. High-performance room-temperature sensing technologies are required to ensure its safe deployment. However, the strong Pd-H interactions make it challenging for Pd-based hydrogen sensors to simultaneously achieve high sensitivity and rapid recovery, especially at room temperature. In this study, a hydrogenation–oxidation strategy is proposed to enable precise modification of oxygen species at the Pd–graphene interface, which produces ultrahigh sensitivity and fast recovery speed in response to H₂ at room temperature. Through in situ characterization and DFT calculations, we confirm that interfacial oxygen species promote hydrogen spillover to the graphene support and inhibit their diffusion into the Pd bulk, which breaks the sensitivity–recovery trade-off. The oxygen-modified Pd/graphene sensor (Pd_A-Gr-O_H20%) achieves a five-fold increase in sensitivity at room temperature (410.8% response to 2% H₂), a 10-fold decrease in recovery time, and an ultra-broad detection range of 10 ppb-2%, along with excellent repeatability and selectivity. This research provides a novel and efficient strategy to fabricate highly sensitive and fast room-temperature H₂ sensors through interfacial engineering.