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.