Self-oxidized AgCu nano-foam with unique phase structure for ethanol sensors breaking through the trade-off between sensitivity and upper linear limit

Comparing to gas ethanol sensors, electrochemical ethanol sensors are promising owing to the low operating temperature, high sensitivity and good accuracy. Common electrochemical ethanol sensors suffer from a general trade-off relationship between sensitivity and upper limit for linear detection. In this work, facile self-oxidized AgCu nano-foam is obtained by simply dealloying of Mg65Ag12.5Cu12.5Y10 metallic glass ribbon in citric acid, which breaks through the trade-off by showing an ultra-high upper linear limit of 1.5 M and good sensitivity of 109.6 mu A mM(-1) cm(-2). Combined experiment and simulation investigations confirm that the ligaments of the AgCu nano-foam is composed of surfaces with interlacing Ag and Cu2O grains that are driven by surface energy, and cores consist of Ag and Cu grains that result from phase separation. Such phase structures, coupled with the geometry merits, lead to fast oxidation dynamics, abundant electroactive sites, good reversibility and stable microstructure, which results in high upper linear limit and a sensitivity improvement of similar to 30 times comparing to Cu nano-foam. This work develops a candidate material for high performance sensing of concentrated ethanol, and verifies a promising strategy to prepare efficient catalysts by multilevel-design of geometry and phase structure.