In this combined quantum chemical and EPR study we have investigated the formation of CO2- radicals by contact of CO2 molecules with a K precovered MgO surface. K atoms have been deposited on polycrystalline MgO samples, and then exposed to CO2. The typical EPR signal of the isolated K atoms disappears when the reaction with CO2 takes place and a new paramagnetic species attributed to CO2- is observed. DFT cluster model calculations show that there is a spontaneous electron transfer from the adsorbed K atom to the CO2 molecule, with formation of K+CO2-surface complexes. These species have the same electronic characteristics and spin distribution of gas-phase M+CO2- (M = Li, Na, K) molecules, but are stabilized by the presence of the ionic surface. The most stable MgO sites where the adsorption of CO2 occurs and the computed EPR properties are discussed.
Preda, G., Pacchioni, G., Chiesa, M., Giamello, E. (2009). The reactivity of CO2 with K atoms adsorbed on MgO powders. PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 11(37), 8156-8164 [10.1039/b906192d].
The reactivity of CO2 with K atoms adsorbed on MgO powders
PREDA, GLORIA;PACCHIONI, GIANFRANCO;
2009
Abstract
In this combined quantum chemical and EPR study we have investigated the formation of CO2- radicals by contact of CO2 molecules with a K precovered MgO surface. K atoms have been deposited on polycrystalline MgO samples, and then exposed to CO2. The typical EPR signal of the isolated K atoms disappears when the reaction with CO2 takes place and a new paramagnetic species attributed to CO2- is observed. DFT cluster model calculations show that there is a spontaneous electron transfer from the adsorbed K atom to the CO2 molecule, with formation of K+CO2-surface complexes. These species have the same electronic characteristics and spin distribution of gas-phase M+CO2- (M = Li, Na, K) molecules, but are stabilized by the presence of the ionic surface. The most stable MgO sites where the adsorption of CO2 occurs and the computed EPR properties are discussed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.