Palladium hexagonal nanoparticles/carbon nanotubes/cellulose nanocrystals integrated over paper for wearable hydrogen sensing with fast response by bridging behavior

Wearable hydrogen (H2) sensing with fast response and excellent flexibility is highly desired for those workers who are exposed to flammable and explosive H2, however, it needs further exploring. Here, wearable H2 sensing with fast response at room temperature (∼25 °C) has been developed by integrating palladium hexagonal nanoparticles/carbon nanotubes/cellulose nanocrystals over filter paper (P-Pd HNPs/CNTs/CNCs). By optimizing the wet-chemical approach, Pd HNPs (edge length, ∼7.33 nm) have been synthesized via the simultaneous reduction of CNCs and ethanol, resulting in a random dispersion around the surface of cross-linked CNTs. Beneficially, P-Pd HNPs/CNTs/CNCs shows fast response/recovery time (3 s/3 s) to 0.5 v/v% H2 and can detect 50 ppm H2. Additionally, it exhibits excellent wearable sensing durability, including the resistance to freezing, pressing and peeling off the sensing materials. Theoretically, such fast-response H2 sensing can be interpreted that H2 is adsorbed over Pd to form PdHx intermediates, and the “bridging behavior” between CNCs and CNTs facilitates the H2 diffusion and promotes electron hopping and tunneling. Potentially, this “bridging behavior” that contributes to fast-response H2 sensing might be extended to other sensing materials for wearable gas detection. [Display omitted] •Pd nanoparticles/carbon nanotubes/cellulose nanocrystals over paper is prepared.•The “bridging behavior” is discovered to boost the H2 sensing response.•The simulation on detecting the leaked H2 is conducted with the wearable sensing.