Nitrogen oxides (NOx), emitted by automobiles as well as other sources, such as nitric acid production plants, are major contributors to air pollution and important ozone-depleting substances. Thus, developing economical catalysts that convert NOx to benign gases is of paramount importance. Ni/Cu dilute alloys have recently emerged as promising catalysts for N-O and C-O scission, as well as for N + N association towards N2.1 In this work, we adopt theoretical methods to assess the potential of Ni/Cu dilute alloys as catalysts for the decomposition of N2O, as well as for the NO + CO reaction. We thus employ density functional theory (DFT) and microkinetic modelling to study two catalytic surfaces: in the first, Ni atoms are isolated in the host Cu(111) surface, thereby forming a single-atom alloy (Ni/Cu(111) SAA), while on the second, the same atoms are organised as Ni-Ni dimers (Ni2Cu(111)). For comparison purposes, the reactions of interest are also simulated on pure Cu(111), i.e. the host surface, and on Rh(111), the latter being a well-established PGM catalyst in emissions control catalysis. Our DFT calculations reveal the intricacies of the underlying pathways that lead to N2O formation and decomposition via the different binding configurations of this species. We further use the DFT data to parameterize a microkinetic model, which yields insight on the catalytic performance of the different materials. Our results suggest that the addition of trace amounts of Ni on Cu(111) may bring about significant improvement to the catalytic performance with regard to the catalytic decomposition of N2O. Additionally, Ni2Cu(111) is predicted to exhibit equivalent or even better, under certain conditions, performance compared to Rh(111) for the NO + CO reaction. This work contributes to long-standing efforts toward the design of efficient PGM-free catalytic materials for the elimination of noxious gases.

Theoretical investigations of NOx reduction over Ni/Cu dilute alloys

ACS Spring Meeting 2021

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