The efficient removal of atmospheric pollutants such as oxides of carbon and nitrogen is of great concern for society since it those oxides are directly related to the human health as well as climate changes. Cerium dioxide is a reducible oxide, which often is crucial component in various adsorption or catalytic systems for removal of nitrogen oxide, the so-called deNO_x processes, as well as for adsorption or conversion of carbon monoxide. By this reason, understanding of atomistic details of the interaction of CO or NO_x with ceria-based systems is important for developing of new air purification technologies and improving the existing ones. This is the goal of the present work, which was done with the support by the project EXTREME, funded by the Bulgarian Ministry of Education and Science, D01-76/30.03.2021.

The main feature of cerium dioxide is the oxygen storage capacity, allowing release and accommodation of oxygen depending on the reaction conditions [1]. In order to clarify the specific sorption and catalytic properties of cerium dioxide based systems we performed series of periodic quantum chemical calculations. The calculations were performed with DFT+U approach using periodic code VASP with the gradient corrected PW91 exchange-correlation functional. 

In relation to deNOx processes we modeled the interaction of NO and NO₂ with cerium dioxide surface and nanoparticles and studied the formation of various surface species for which we estimated the reaction energies and vibrational frequencies to be compared with experimental data. On reduced ceria we considered two new surface species, nitric oxide dianion and surface azides [2]. In addition, we clarified the vibrational frequencies of specific types of hyponitrites, nitrites and nitrites [3].

For CO adsorption on cerium dioxide we studied also several surface intermediates – different types of carbonates, hydrogen carbonates, and formates [4]. For carbon monoxide we also clarified the reaction paths for catalytic oxidation on platinum, supported on cerium dioxide as we considered both isolated ionic platinum species and small platinum clusters as active sites for the process [5].