Thermally Stable AgPd@ZnO Bimetallic Alloy Nanoparticles for Ethanol Sensors with Long-Term Stability

Bimetallic alloy nanoparticles (NPs) typically provide some unique properties in gas sensing due to the synergistic effects that arise from the two distinct metals, especially selective catalytic oxidation of hazardous volatile organic compounds. However, their practical uses are being held back by the high catalyst cost and the deterioration of catalytic capabilities at elevated temperatures. In this work, extremely thermally stable ZnO-supported AgPd bimetallic alloy core-shell NPs were synthesized, demonstrating resistance to surface oxidation due to the synergistic effect of Ag and Pd atoms. The AgPd_alloy@ZnO core-shell NPs outperform the pristine ZnO and Pd@ZnO NPs in ethanol sensing, with a response of 704.08 to 100 ppm ethanol at 300 °C. Besides, the sensor demonstrates excellent selectivity, anti-interfering response, repeatability, long-term stability, and humidity effect. The lattice mismatch, upshifts in the d-band center, and oxidation resistance behavior of AgPd_alloyameliorate their electronic structure, which enhances the catalytic properties and the gas sensing performances in AgPd_alloy@ZnO NPs. Most importantly, compared to other noble metal NPs, Ag is very inexpensive and cost-effective, which is a great advantage from an economic perspective.