Realizing a high OER activity in new single-atom catalysts formed by introducing TMNx (x = 3 and 4) units into carbon nanotubes using high-throughput calculations

Abstract

Exploring highly efficient electrocatalysts for the oxygen evolution reaction (OER) is of great significance for hydrogen production through water splitting. By means of high-throughput density functional theory (DFT) calculations, we investigated the OER catalytic activity of a series of one-dimensional carbon nanotube (CNT)-based systems containing TMN₄ or TMN₃ functional units. Through the screening of 3d/4d/5d transition metals (TMs) from Group IVB to Group VIII, eight newly obtained TMN_x@CNT (x = 3 and 4) systems were found to exhibit excellent OER activity, with very low overpotentials in the range 0.29–0.51 V, where the Co, Rh, Ir, Ti, Fe, and Ru atoms could be used as active sites. It was found that under the framework of TMN₃@CNTs, the pre-adsorption of some species from water dissociation on the relevant TM sites (TM = Ti, Fe, and Ru) could lead to a high OER catalytic activity, which was different from the general situation where OER reactions directly occur on the clean surfaces of the remaining systems with Co/Rh/Ir metal centers. Moreover, the catalytic mechanisms were analyzed in detail. This work can be conducive to obtaining low-cost and high-performance OER single-atom electrocatalysts based on excellent CNT nanomaterials.