Fast and selective detection of volatile organic compounds using a novel pseudo spin-ladder compound CaCu2O3

Spin-ladders are a class of unique materials in low dimensional systems with a complex structure and intriguing properties originating from quantum fluctuations. Spin-ladder compounds with an even and odd number of legs have quite generic features and have the potential for promising technological applications. In this paper, a novel pseudo spin-ladder CaCu2O3 compound (2-leg) based conductometric gas sensor has been proposed, for the first time, for the detection of volatile organic compounds (VOCs). Nanostructured CaCu2O3 rods were synthesized by a hydrothermal method and annealed in air at different temperatures (200, 400 and 600 degrees C). Powder XRD, SEM-EDX, XPS, photoluminescence (PL) and electrical characterisation studies indicated that CaCu2O3 crystallized in an orthorhombic structure with a tiny rod-shaped morphology. The gas sensing properties of the nanostructured CaCu2O3 were then investigated by fabricating thick-film conductometric sensors and exposing them to ethanol and acetone, chosen as the representative VOC target gases. CaCu2O3 annealed at a low temperature (200 degrees C) showed excellent performance towards both ethanol and acetone monitoring. At the optimal operating temperature of 200 degrees C, the sensor showed a response, S = R-g/R-a, of 2.6 towards 10 ppm ethanol and 2.4 towards acetone with a fast response/recovery time of 25 and 150 s for both VOCs tested. In addition, the proposed sensor shows high selectivity against some common interfering gases.