Engineering Synergistic Pd-Ni Co-Modified System for Highly Efficient Hydrogen Sensing

The development of hydrogen sensors with low operating temperatures, high sensitivity, and high selectivity is critically important for ensuring safety during hydrogen production, transportation, and storage. Palladium-functionalized metal oxide semiconductors are widely recognized for their excellent hydrogen selectivity. However, the oxidation and agglomeration of Pd severely deteriorate long-term sensing performance. Herein, a bimetallic modulation strategy is proposed by introducing NiO as a secondary dopant to construct Pd-NiO/WO₃ nanospheres, enabling synergistic regulation of Pd valence states, dispersion, and catalytic activity. Benefiting from the bimetallic synergistic effect, the Pd-NiO/WO₃ nanospheres exhibit markedly enhanced hydrogen sensing performance at a low operating temperature of 160 °C, delivering a high response of 25 toward 50 ppm H₂ (1.67 times higher than that of Pd-WO₃), along with fast response-recovery kinetics, excellent hydrogen selectivity, and good long-term stability. Mechanistic investigations reveal that NiO enhances oxygen adsorption and effectively suppresses Pd oxidation, thereby optimizing Pd loading states and promoting catalytic hydrogen dissociation. Furthermore, machine learning-assisted gas discrimination achieved a classification accuracy of 95.8%, further enhancing hydrogen selectivity. Notably, the Pd-NiO/WO₃ sensor demonstrates reliable detection of hydrogen generated from a water-splitting device, highlighting its practical applicability. This work provides an effective strategy for engineering synergistic co-modified system toward high-performance hydrogen sensing.