Highly exposed NiFeOx nanoclusters supported on boron doped carbon nanotubes for electrocatalytic oxygen evolution reaction

Abstract

The development of efficient and cost-effective electrocatalysts for oxygen evolution reaction (OER) is crucial for the overall water splitting. Herein, we prepared a highly exposed NiFeOx ultra-small nanoclusters supported on boron-doped carbon nonotubes catalyst, which achieves a 10 mA/cm2 anodic current density at a low overpotential of 213 mV and the Tafel slope of 52 mV/dec in 1.0 mol/L KOH, superior to the pristine NiFeOx-CNTs and other state-of-the-art OER catalysts in alkaline media. A combination study (XPS, sXAS and XAFS) verifies that the local atomic structure of Ni and Fe atoms in the nanoclusters are similar to NiO and Fe2O3, respectively, and the B atoms which are doped into the crystal lattice of CNTs leads to the optimization of Ni 3d eg orbitals. Furthermore, in-situ X-ray absorption spectroscopies reveal that the high valence state of Ni atoms are served as the real active sites. This work highlights that the precise control of highly exposed multicomponent nanocluster catalysts paves a new way for designing highly efficient catalysts at the atomic scale.