Incorporation of Cu, Fe, Ag, and Au nanoparticles in mercapto-silica (MOS) and their CO2 adsorption capacities

Metal-organic-silica (MOS) nanocomposites of metal nanoparticles of copper, iron, silver, and gold are incorporated into mercaptopropyl-modified silica by surface chemical modification methods. A silica surface modified with mercaptopropyl functional groups (MP-S) was treated with a concentrated solution of metal salts to form metal complex-mercaptopropyl-silica composites (Cu2+-MP-S, Fe3+-MP-S, Ag1+-MP-S, Au3+-MP-S). The metal nanoparticle silica nanocomposites (Cu-MP-S, Fe-MP-S, Ag-MP-S, and Au-MP-S) were obtained by the chemical reduction of immobilized metal ions using sodium borohydride. The nanocomposites' physicochemical properties were investigated by CHN elemental analysis, FTIR, TGA, EDAX, and transmission electron microscopy. Cu, Fe, Ag, and Au nanoparticles showed a uniform dispersion through the silica support with diameters ranging from 3 nm to 200 nm. The CO2 adsorption capacities for metal ions and nanoparticle nanocomposites have considerably increased by 20% and 100%, respectively. Cu-MP-S shows the maximum capacity of 0.52 mmol/g as measured by TGA analysis. In addition, the preparation procedure is favorable for the synthesis of a variety of metal-silica composites for their potential application in greenhouse gas sequestration. (C) 2013 Elsevier Ltd. All rights reserved.