Smart hydrogen barrier films based on large-sized 2D MXenes and highly amorphous polyvinyl alcohol crosslinked with polyacrylic acid

This study introduces an innovative smart nanocomposite designed to provide exceptional hydrogen-barrier performance while functioning as a pressure sensor for real-time hydrogen permeation monitoring. The material combines highly amorphous poly(vinyl alcohol) (HAVOH) and polyacrylic acid (PAA) with large, defect-free few-layer MXene (fl-Ti 3 C 2 T x ) as a 2D filler. Crosslinking between HAVOH and PAA enhances water resistance, and MXene incorporation significantly improves thermal stability and hydrogen impermeability. The optimal formulation (H 50 P 50 MX 3 ) achieves permeability values below the detection limit at 41 °C and 41% RH, outperforming pristine HAVOH by a wide margin. Even under harsher conditions (50 °C, 50% RH), the composite maintains superior barrier properties, whereas HAVOH exceeds the instrument's upper detection limit. After laser processing, the material also exhibits strong pressure-sensing capabilities, making it a promising candidate for hydrogen storage systems with built-in leakage detection.