Pd-Induced Lattice Heterogeneity (Interface Compression/Bulk Stretching) in W18O49 Nanowires for Synergistically Enhanced H2 Sensing

Abstract

Hydrogen (H2) sensing demands high sensitivity, fast kinetics, and stability. Herein, we report Pd-modified W18O49 nanocomposites with unique lattice heterogeneity (interfacial lattice compression coupled with bulk lattice expansion) induced by metal-support interaction. XRD and HRTEM confirm the structural modulation: Pd loading narrows W18O49’s band gap, enhances charge transfer, and optimizes oxygen vacancies. The 2%-Pd-W18O49 exhibits superior H2 sensing performance at 130 °C: a high response (∼160 to 300 ppm H2), ultra-fast response/recovery (7/10 s), excellent selectivity over interfering gases (CO, ethanol, etc.), and long-term stability of 380 days (after a simple annealing process). Synergistic effects of Pd-catalyzed H2 dissociation and lattice heterogeneity dominate the enhancement, overcoming the reduced specific surface area. This work highlights lattice heterogeneity as a novel design parameter for high-performance metal oxide semiconductor H2 sensors, promising safe H2 applications.