Infrared and Computational Studies on Interactions of Carbon Dioxide and Titania Nanoparticles with Acetate Groups

Abstract

Understanding the nature of the interactions between growing colloidal nanoparticles and CO2 molecules is of importance for designing and synthesizing well-defined oxide nanoarchitectures during sol−gel processing in supercritical CO2 (scCO2). In this research, attenuated total reflective Fourier transform infrared (ATR-FTIR) spectrometry was used for studying the interactions between CO2 molecules and metal acetate bidentate groups. Freshly synthesized aerogels formed using Ti and Zr alkoxides were treated with CO2 and subsequently depressurized to remove the strong infrared absorbance of bulk CO2. The IR spectra from the depressurized TiO2 and ZrO2 samples were compared to the IR spectra from the respective calcined samples showing that the ν2 bending peak of the CO2 split due to Lewis acid and base interactions. Further verification of the spectral assignments and the bonding analysis were obtained by theoretical calculations using the density functional theory (DFT) method and TiO2 nanocluster models....