Systematical study of depositing nanoparticles and nanowires in mesoporous silica using supercritical carbon dioxide and co-solvents: morphology control, thermodynamics and kinetics of adsorption
AgNO3 was successfully deposited into mesoporous silica including SBA-15 and KIT-6 using supercritical carbon dioxide as the solvent, ethanol or a mixture of ethanol and ethylene glycol as the co-solvent, followed by calcination after depressurization. A large number of experiments were conducted to find out the most important parameters influencing the metal loading and the morphology of the nanostructure. The morphology was found to vary a lot according to the deposition time, which is interesting, i.e. small nanoparticles, short nanorods, continuous nanowires, and big nanoparticles appeared in succession as the deposition time increased. Besides, the co-solvent was also found to influence significantly the deposition results. The samples prepared using the mixture of ethanol and ethylene glycol as the co-solvent presented the morphology of nanowires, while those prepared using only ethanol as the co-solvent presented a mixed morphology of both nanoparticles and nanowires. The role of ethylene glycol was discussed and a mechanism model demonstrating the formation of Ag nanowires or nanoparticles was proposed. Finally, the adsorption of AgNO3 (adsorbate) from supercritical carbon dioxide and co-solvent (solvent) on the SBA-15 support (adsorbent) was investigated by both experimental and simulating methods. It was found that the adsorption isotherm was well fitted by the Langmuir model, and the kinetic investigation based on a mass differential equation showed that the adsorption reached equilibrium after 10 000 s (about 2.8 h) which was consistent with our experimental result (2.5 h).
1.Dalian Univ Technol, State Key Lab Fine Chem, Sch Chem Machinery, Dalian 116023, Peoples R China 2.Chinese Acad Sci, Inst High Energy Phys, Beijing 100049, Peoples R China 3.Chinese Acad Sci, Dalian Inst Chem Phys, Dalian 116023, Peoples R China 4.Dalian Univ Technol, Sch Energy & Power Engn, Dalian 116023, Peoples R China
Recommended Citation:
Xu, Qin-qin,Wang, Ya-qiong,Wang, Ai-qin,et al. Systematical study of depositing nanoparticles and nanowires in mesoporous silica using supercritical carbon dioxide and co-solvents: morphology control, thermodynamics and kinetics of adsorption[J]. NANOTECHNOLOGY,2012,23(28).
