Structural Characterization of Chromium Atoms in MIL-101 Metal Organic Frameworks Using XANES/EXAFS Spectroscopy

Kuen-Song Lin；Abhijit Krishna Adhikari；Yu-Hsien Su；Chao-Lung Chiang；Khalilalrahman Dehvari

Chinese Journal of Physics

50卷2期（2012 / 04 / 01）

322 - 331

英文

MIL-101 is a chromium-based metal organic framework known to adsorb large amounts of gases such as H2, CO2 and CH4. The framework was synthesized through solvothermal route and the H2 adsorption capacity was measured using a standard gravimetric method. X-ray absorption spectroscopy was employed to understand the fine structure, neighbors, bond distances and coordination numbers. The BET specific surface area of MIL-101nf (treated with NH4F) was 3,241 m^2g^(−1) with a type I hysteresis loop measured from N2 adsorption. The hydrogen storage capacity was 0.163 wt% measured at 450 psig and room temperature. XANES spectra indicated that the valency of MIL-101 MOFs was Cr(III). EXAFS data revealed that MIL-101 had a first shell of Cr-O bonding with bond distance of 1.971 °A with the coordination number of 5.4.