Electronic Coupling and Defect Engineering in Pd–HPW–ZnO Ternary Heterostructures for Ultrasensitive Triethylamine Detection

Rational design of interfacial electronic structures and defect sites is pivotal for advancing chemiresistive gas sensing, yet achieving synergistic modulation remains a formidable challenge. Herein, we report a ternary Pd-HPW-ZnO heterostructure constructed via the integration of phosphotungstic acid (HPW) clusters and Pd nanoparticles onto porous ZnO nanosheets. This unique architecture establishes a robust electronic coupling network, where HPW acts as an electron sink, inducing electron depletion in both ZnO and Pd species to form electron-deficient Pd sites. This electronic modulation, corroborated by XPS and DFT calculations, significantly optimizes the Pd d-band center and enhances the surface Lewis acidity. Furthermore, the synergistic interaction triggers a substantial enrichment of oxygen vacancies and facilitates the spillover of active oxygen species. Consequently, the optimized sensor exhibits an extraordinary response of 2016.70 to 50 ppm triethylamine (TEA) at a low operating temperature of 110 °C, surpassing pristine ZnO by nearly 60-fold. The sensor also demonstrates ultrafast response/recovery kinetics (16/150 s), excellent selectivity against interfering volatiles, and robust long-term stability. This work provides a paradigm for boosting sensing performance through precise interfacial electronic regulation and defect engineering in multicomponent heterostructures.