Chemical Structure of Nanosize Copper Wires in MCM-41
X-ray absorption near edge structural (XANES) and X-ray absorption fine structural (EXAFS) spectroscopies have been used to study chemical structure of nanosize copper extracted in the channels of MCM-41. The component-fitted XANES spectra show that about 95% of copper are adsorbed on the surfaces of MCM-41 at 298 K. A small amount of nanosize CuO in MCM-41 is also found. The adsorbed copper (Cu(II)(ads)) in the channels of MCM-41 may be oxidized and form nanosize CuO as calcined at 573 and 923 K. By EXAFS, it is observed that the nanosize CuO in MCM-41 possesses a Cu-O bond distance of 1.97 Å with a coordination number (CN) of 2.6, indicating the existence of linear type Cu3O4 cluster. Interestingly, calcinations of the nanosize CuO in MCM-41 at 923 K has led to a formation nanowire-type CuO (in the channels of MCM-41) with a length of 50-100 nm and width of about 5-9 nm.
Alan K.T. Lau, J. Lu, Vijay K. Varadan, F.K. Chang, J.P. Tu and P.M. Lam
H. L. Huang et al., "Chemical Structure of Nanosize Copper Wires in MCM-41", Advanced Materials Research, Vols. 47-50, pp. 1125-1128, 2008