A DFT study of phenol adsorption on a low doping Mn–Ce composite oxide model

Abstract

Density functional theory calculations (DFT+U) were performed on a low doping Mn–Ce composite oxide prepared from experimental data, including X-ray diffraction (XRD) and temperature-programmed reduction (TPR). We considered a 12.5% Mn–doped CeO₂ solid solution with fluorite–type structure, where Mn replaces Ce⁴⁺ leading to an oxygen–deficient bulk structure. Then, we modeled the adsorption of phenol on the bare Ce_0.875Mn_0.125O_1.9375(111) surface. We also studied the effect of water adsorption and dissociation on phenol adsorption on this surface, and compared the predictions of DFT+U calculations with diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) measurements. The experimental results allowed us to both build a realistic model of the low doping Mn–Ce composite oxide and support the prediction that phenol is adsorbed as a phenoxy group with a tilt angle of about 70° with respect to the surface.