2D NbIrTe4 and TaRhTe4 monolayers: two fascinating topological insulators as electrocatalysts for oxygen reduction

Abstract

By means of density functional theory calculations, it is revealed that freestanding 2D topological insulator nanomaterials, namely NbIrTe₄ and TaRhTe₄ monolayers, can be exfoliated from their bulk phases with a layered structure, and both of them are dynamically, thermodynamically and mechanically stable. In addition, obvious hybridization and electron transfer between O 2p and Te 5p orbitals can effectively activate adsorbed oxygen on the two monolayer surfaces and subsequent steps of the oxygen reduction reaction are preferentially carried out through the four-electron (4e) dissociation paths. Especially, the overpotentials of the dominant dissociation paths on the 2D NbIrTe₄ and TaRhTe₄ monolayers can be very small, in the range of 0.18 to 0.47 V and 0.23 to 0.44 V, respectively; these values are comparable to or even lower than that on Pt (111) (0.48 V). Besides, the two 2D monolayers can also exhibit high selectivity, effectively preventing the formation of the by-product, H₂O₂. Moreover, the relevant mechanisms behind the high oxygen reduction activity are analyzed in detail, and it is also found that the topological state has an important influence on the excellent oxygen reduction catalytic activity of the two monolayers. This work can provide new ideas for realizing highly efficient oxygen reduction catalysts to replace precious metal Pt-based materials.