A first-principles based microkinetic study of ZnMn1.5TM0.5O4 (TM = 3d transition metal) for NO oxidation

Abstract

A highly-efficient NO oxidation catalyst is urgently needed due to serious NO pollution. Herein, we perform first principles calculations and microkinetic analysis to investigate NO oxidation properties of pristine and 3d transition metal doped ZnMn2O4 that exhibits similar Mn-Mn dimer features to SmMn2O5. It is found that two different categories of NO oxidation mechanism with different O2 adsorption and dissociation behaviors occur on pristine and B-site doped ZnMn2O4. The microkinetic analysis shows that Cu, Fe, Zn, Ti, Cr and Ni doping can effectively promote the reaction rates of NO oxidation, with Cu and Fe doped ZnMn2O4 showing the best low-temperature NO oxidation performance. Sc, V, and Co doping are predicted not to be beneficial to performance enhancement. A general relation between NO oxidation reactivity and NO adsorption energies is proposed to quantitatively depict the key factors influencing NO oxidation performance. The relation provides a specific strategy for the optimization of NO oxidation that ZnMn1.5TM0.5O4 (TM = 3d transition metal) with first and second NO adsorption energies (Ead) in the ranges of −2.40 ∼ −2.00 eV and −1.50 ∼ −0.25 eV respectively have good NO oxidation performance, respectively. Our paper paves a feasible road for the applications of ZnMn1.5TM0.5O4 as the NO oxidation catalyst.