Pd-Sensitized SnO2@WO3 Nanosheets via Cluster-Nucleus Coassembly: Enhanced Hydrogen Spillover for High-Efficiency H2 Sensing

The risk of hydrogen explosions in industrial and hydrogen energy facilities presents serious safety threats. An inherent trade-off between response magnitude and response/recovery kinetics plagues chemiresistive H2 sensors: monocomponent materials are incapable of concurrently realizing high-efficiency H2 activation and ultrafast gas-solid interfacial charge transfer/desorption. Herein, we synthesized SnO2@WO3 hexagonal nanosheets via hydrothermal cluster-nucleus coassembly and decorated them with Pd nanoparticles by wet-chemical reduction. The Pd/SnO2@WO3 sensor exhibits a response (Rair/Rgas) of 22.4 toward 1000 ppm H2 at 220 °C, along with response/recovery times as short as 1.4/3.2 s, and a detection limit as low as 200 ppb. The enhanced sensing performance originates from the coupling of preferential H2 dissociation on Pd with efficient migration and conversion of active hydrogen at the defect-rich SnO2@WO3 heterointerface, which accelerates interfacial oxygen consumption and electron reinjection. A backpropagation artificial neural network (BP-ANN) regression model enables high-precision quantification of single-channel H2 signals; the sensor is integrated into a wearable printed circuit board (PCB) module for H2 leakage warning. These results show this material platform is suitable for wearable hydrogen safety monitoring in real-world environments.