PW ₁₂ -Modified ZnO with Enhanced Carrier Transport for Triethylamine Gas Sensing

The synergy of defect engineering and bandgap engineering can modulate the gas-sensing properties of metal oxide semiconductors (MOS). Therefore, ZnO derived from pyrolyzed metal–organic frameworks (MOFs) was modified with phosphotungstic acid (PW12) to regulate the gas-sensing properties of PW12/ZnO composites. The experimental results show that PW12 modification induces lattice distortion in ZnO, increases the oxygen vacancy defect concentration, and enhances interfacial charge separation and transport capability. When the mass ratio of PW12 to zinc 2-methylimidazolate salt (ZIF-8) is 5%, the as-prepared PW12/ZnO composite (5-PW12/ZnO) exhibits superior carrier transport capability (carrier density of 1.41 × 1021 cm–3, carrier mobility of 53.86 cm2·V–1·s–1) compared to other samples, with the lowest interfacial charge transfer resistance (98 Ω). The response value (S) of the 5-PW12/ZnO at a working temperature of 307 °C to 50 ppm of triethylamine is 220. This value is 12.2 times higher than that of pure ZnO (S = 18). In addition, the composite demonstrates good selectivity, stability, and repeatability. The enhancement of carrier transport properties resulting from the synergistic regulation between defect engineering and bandgap engineering is the main reason for the improvement in the gas-sensing performance. This study offers a novel strategy for designing gas-sensing materials and elucidating their sensing mechanisms.