One-pot reflux method synthesis of cobalt hydroxide nanoflake-reduced graphene oxide hybrid and their NOx gas sensors at room temperature

The different morphology cobalt hydroxide (Co(OH)(2)) nanoflake-reduced graphene oxide (rGO) hybrid were controllably synthesized by one-pot reflux method. The structural and surface properties of the materials were investigated by scanning and transmission electron microscopy, powder X-ray diffraction and Fourier transform infrared spectroscopy. It was found that the nanostructures were actually composed of thin nanosheets or nanopetals, which consisted of many ultrafine nanoparticles with 5-7 nm diameters. The gas-performance results of the composites for NOx demonstrated that they had superior performance compared to the pure alpha-Co(OH)(2), especially the alpha-Co(OH)(2)/rGO-10 composite (mass ratio of Co(NO3)(2)center dot 6H(2)O/GO was 10:1) showed higher NOx gas sensing performance with lower detection limit of 0.97 ppm and high sensitivity of 70% to 100 ppm NOx at room temperature. The mechanism of it was preliminary attribute to the effective combination between alpha-Co(OH)(2) and rGO, which restrained alpha-Co(OH)(2) from growing up and aggregating, The pore structure of composite material could be quickly adsorption gas molecules leading to rapid electron transfer. (C) 2014 Elsevier B.V. All rights reserved.