Sensitizing effect of montmorillonite on the gas sensing property of CuO particles to n-butanol

Individual montmorillonite (MMT) platelets as an electronic additive were inserted into CuO particle matrix to derive CuO-MMT nanocomposites via a 2-methylimidazole ligand-assisted hydrolysis method in combination with thermal decomposition. The analyses by XRD, FTIR, and XPS confirmed the presence of monoclinic copper oxide and aluminosilicate in the nanocomposites. MMT platelets were observed to be surrounded among quasi spherical CuO particles closely, even generating some large-sized aggregates. While CuO particles had a decrease in surface area after the loading of MMT, their electrical resistance was modulated to gradually increase. The CuO-MMT(0.050) based sensor showed the highest response of-31 (Rg/Ra) to 200 ppm n-butanol at 260 degrees C. The limit of detection was estimated to be-0.75 ppm for CuO-MMT(0.050), which was lower than that of CuO (-3.12 ppm). Additionally, the nanocomposite-base sensor was also relatively tolerant against humidity. The improved sensing property could be attributed to the resistance modulation, nanoscale junction, and interface oxygen vacancies upon the addition of MMT. This work suggests that aluminosilicate clays can serve as a promising additive with the ability to enhance the gas sensing property of p-type metal oxides.