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 the low dimensional systems with complex structure and intriguing properties originating from quantum fluctuations. The spin-ladder compounds with even and odd number of legs have quite generic features and have 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 hydrothermal method and annealed in air at different temperatures (200, 400 and 600°C). Powder XRD, SEM-EDX, XPS, photoluminescence (PL) and electrical characterisation studies indicated that the CaCu2O3 crystallized in orthorhombic structure with tiny rod-shaped morphology. Gas sensing properties of nanostructured CaCu2O3 were then investigated by fabricating thick-film conductometric sensors and exposing them to ethanol and acetone, chosen as representative VOCs target gases. CaCu2O3 annealed at low temperature (200°C) showed excellent performance towards both ethanol and acetone monitoring. At the optimal operating temperature of 200°C, the sensor showed a response, S = Rg/Ra, of 2.6 towards 10 ppm ethanol and 2.4 to acetone with 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.