AlMnPdPtAu Quasicrystal Modulated Carbon Nanotubes for H₂ Sensors: Experimental and DFT Computational Analysis

Hydrogen (H₂) sensors are crucial for safety in H₂ storage and fuel cell systems. AlMnPdPtAu high-entropy alloy (HEA) quasicrystal nanosheets with high surface area, tunable electronic structure, and atomic disorder exhibit enhanced H₂ adsorption and sensor response. This work demonstrates highly sensitive and selective H₂ sensors developed by a low-cost screen printing method using the AlMnPdPtAu quasicrystal and CNTs. The sensor demonstrates high sensitivity with a relative response of 103% (1 ppm) to 130.4% (100 ppm) and rapid dynamics (τ_res = 19 s, τ_rec = 81 s at 100 ppm of H₂) at room temperature. Structural analysis by high-resolution transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy confirmed the interface formation between the AlMnPdPtAu HEA quasicrystal and CNTs. Raman spectroscopy revealed structural and electronic interactions within the composite, while X-ray photoelectron spectroscopy identified chemical states and surface interactions at the AlMnPdPtAu QC@CNT interface. The density functional theory study highlighted dissociative H₂ adsorption modes and spillover effects at the QC@CNT interface, where H atoms bond with Mn atoms in the quasicrystal, facilitating H atom migration and stabilization. The adsorption energy and Bader charge transfer values are calculated to determine the binding strength of the H atom to the sensing material and the extent of electronic interaction, influencing sensitivity.