Decoration of the internal structure of mesoporous chromium terephthalate MIL-101 with NiO using atomic layer deposition

Mesoporous chromium terephthalate MIL-101 was modified with NiO via atomic layer deposition (ALD) process using bis(cyclopentadienyl)nickel (Ni(Cp)2) as a metal precursor and O2 as an oxidizing agent, respectively. Based on the results of transmission electron microscopy (TEM), N2 and Ar isotherms, X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma-atomic emission spectroscopy (ICP-AES), we show that the deposited NiO nanoparticles were distributed inside internal mesoporous cages as well as on the external surface of MIL-101(Cr). Studies using in situ X-ray photoelectron spectroscopy show that NiO selectively occupied ligand sites without affecting metal sites of MIL-101. The NiO deposition using ALD enhanced thermal stability of MIL-101 compared to that without NiO and provided catalytic activity for CO oxidation, i.e., ALD provided novel chemical functionality to the metal-organic frameworks (MOFs).