Modulating the catalytic activity of metal-organic frameworks for CO oxidation with N2O through an oriented external electric field

Abstract One of the most promising ways to solve various environmental issues caused by toxic gasses is to effectively reduce them to less hazardous gasses. Here, we investigate the effect of an oriented external electric field (OEEF) on the oxidation of CO with N2O over the metal-organic framework Fe3(btc)2 (btc=1,3,5-benzentricarboxylate) by deriving the relevant reaction profiles with density functional theory calculations. We apply the OEEF to Fe3(btc)2 in the range of -0.010 to +0.010 a.u. The reaction is assumed to proceed in two steps: the breaking of the N O bond of N2O and C O bond formation. The applied OEEF is found to mainly affect the transition states and intermediates along the reaction path. A strong correlation between the activation barriers for N O bond breaking, the rate-determining step of the reaction, and the magnitude of the OEEF is observed. The activation energies are reduced from 16.0 to 10.5 and 4.0 kcal/mol by applying positive OEEFs of +0.005 and +0.010 a.u., respectively. In contrast, by applying negative OEEFs of -0.005 and -0.010 a.u., the barriers increase to 20.1 and 23.1 kcal/mol, respectively. Based on charge transfer analysis, the applied positive OEEF enhances the charge transfer from the catalytic site to antibonding molecular orbitals of N2O, thus facilitating N O bond breaking. The results show that an OEEF can customize the catalytic performance of CO oxidation with N2O over MOF catalysts.