Humidity-resilient trace hydrogen detection using AuPd-Functionalized zinc oxide nanohybrids on surface-engineered silicon substrate

The accelerating growth of the hydrogen (H₂) economy is pivotal for achieving large-scale decarbonization of current energy resources. Ensuring safe and efficient handling of this potentially hazardous resource has led to an increasing demand for fast, selective and reliable H₂ sensors. In this work, we report a nanohybrid H₂ sensing platform comprising uniformly dispersed AuPd bimetallic nanoparticles (BNPs) embedded in a ZnO-based metal oxide semiconductor (MOS) matrix infiltrated within an anodized porous silicon (PSi) framework. This hybrid design (PSi-MOS#AuPd) synergistically merges the strong chemisorption affinity and rapid desorption kinetics of Pd with the enhanced catalytic activity and electronic modulation imparted by Au[sbnd]Pd interactions. Precise control over BNPs thickness (~ 8.6 nm) ensures uniform dispersion and effectively mitigates the inherent volume expansion of Pd during hydrogenation, maintaining structural integrity and catalytic efficiency. The PSi support characterized by high porosity (~1.1 μm) and superhydrophobicity (θ_w = 153.6° ± 0.2°), promotes efficient gas diffusion and enhances humidity resilience. The resulting sensor exhibits remarkable performance, including high sensitivity ~46 %@50 ppm, low-operating temperature (~90 °C), rapid response time (~14 s), excellent stability over 60 days and strong selectivity against interfering gases (H₂S, NH₃, NO₂, and CO) under varying humidity conditions (25–85 % RH). This work paves the way for the advancement of H₂ sensors and highlights the potential of substrate engineering and bimetallic synergy in enhancing gas sensing technology for safety-critical applications.