Au@Pd core–shell nanoparticles: A highly active electrocatalyst for amperometric gaseous ethanol sensors

Au@Pd core–shell nanoparticles (NPs) were synthesized using seed-mediated method, and three samples with different shell structures were obtained by tuning the Au core size. The shape-dependent catalytic activities of Au@Pd core–shell NPs toward ethanol oxidation in alkaline electrolytes were systematically explored. The electrochemical experiments showed that the Au@Pd-2 core–shell NPs (with Au core size of 9.8 nm and loose Pd shell) exhibited a distinctly higher activity and poison-resistance for the ethanol oxidation than other core–shell structures. Based on the Au@Pd-2 core–shell NPs and Pd NPs, two amperometric ethanol gas sensors were fabricated. During the sensor tests, the ethanol sensor based on Au@Pd-2 NPs showed good performance for ethanol in the range of 50–600 ppm with sensitivity of 178.5 nA ppm−1 and less than 5% signal loss in 60 days.