Structural Effects and Interactions of Carbon Dioxide Molecules Adsorbed on Ni, Zn, and Cd Nitroprussides

A thorough structural characterization of the synthesized Ni-, Zn-, and Cd-nitroprussides (NPs) with X-ray diffraction (XRD), thermogravimetric analysis, diffuse reflectance infrared Fourier transform spectrometry (DRIFTS), Mossbauer spectroscopy, and magnetic measurements was performed. However, the innovative part of the research was the study of the structural effects and the interactions of the CO2 molecule with the Ni-, Zn-, Cd-NP frameworks. DRIFTS of adsorbed molecules, high pressure adsorption, and in situ XRD adsorption experiments were performed. The DRIFTS spectra displayed peaks assigned to CO2 physical adsorption and the formation of adducts (M2+···O═C═O). The fitting of the adsorption data to the Dubinin–Radushkevich equation and a Langmuir-type equation for volume filling allowed the calculation of the micropore volume and the isosteric heats of adsorption. The calculated parameters indicated an unusual behavior of the adsorption process in Cd-NP at high pressure. This fact was caused by th...