Three-Dimensional Porous Carbon/Nitrogen Framework-Decorated Palladium Nanoparticles for Stable and...

Hydrogen (H₂) as a high-energy-density carrier is of great potential in the upcoming hydrogen economy. Nevertheless, H₂/air mixtures are explosive at H₂ concentrations above 4 v/v % and reliable and wide-concentration-range H₂ sensors are thus highly desired. Here, hydrogen sensing has been developed using palladium nanoparticles of ∼11.2 nm in diameter chemically decorated on the carbon/nitrogen three-dimensional porous framework of 308 m² g^-1 in specific surface area (Pd NPs@CN 3D framework). Theoretically, the Pd NPs and CN 3D framework are used to construct the Mott-Schottky heterojunctions, in which the CN 3D framework possesses a higher work function, promoting electron transfer to Pd NPs and therefore highly active dissociation of H₂. Beneficially, the Pd NPs@CN 3D framework exhibits a wide concentration range of 200 ppm (S ≈ 0.2% and T_res ≈ 15 s) to 40 v/v % (S ≈ 73.8% and T_res ≈ 9 s) H₂ sensing at room temperature. Remarkably, the H₂ sensor prototype built with the Pd NPs@CN 3D framework shows excellent long-term stability that maintains reliable H₂ sensing after 142 days. Such stable hydrogen sensing provides an experimental basis for the wide-concentration-range detection of H₂ leakage in the future hydrogen economy.