Palladium/Palladium Oxide Nanosheet Heterostructures by Partial Reduction for Sub-Parts per Million Hydrogen Detection at Room Temperature

To address the energy crisis and mitigate greenhouse gas emissions, substantial investments are advancing hydrogen (H 2 ) technologies. Reliable, efficient room-temperature H 2 sensors are critical for ensuring safe H 2 production and utilization. Here, we report a palladium/palladium oxide (Pd/PdO) nanosheet composite capable of detecting H 2 concentrations as low as 0.5 ppm at room temperature. The sensor exhibits exceptional stability, maintaining this detection limit after four months under ambient conditions. The superior H 2 sensing performance stems from two key features: (1) the ultrathin nanosheet morphology, which offers abundant reactive sites, and (2) Pd nanoregions that enhance chemical and electronic sensitization. Together, these attributes synergistically elevate room-temperature H 2 detection. This work demonstrates a promising strategy for advancing H 2 sensor performance, supporting the transition to a hydrogen-based economy.