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 (τres = 19 s, τrec = 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.