Engineering defect-rich Fe-doped NiO coupled Ni cluster nanotube arrays with excellent oxygen evolution activity.

A novel structure of Fe-doped NiO coupled Ni cluster hollow nanotube arrays (Fe-NiO-Ni CHNAs) composed of defect-rich NiO phase and Ni clusters anchored on outside of nanotubes is presented. The d-band downshifted by Fe-doping, coupled of Ni clusters and defect-rich nature greatly improve electrocatalytic performances of Fe-NiO-Ni CHNAs toward oxygen evolution reaction. • A multi-level structure of Fe-doped NiO coupled Ni cluster hollow nanotube arrays (Fe-NiO-Ni CHNAs) was synthesized as a catalyst for OER. • Fe-NiO-Ni CHNAs exhibits overpotential of 245 mV at 10 mA cm−2 and outstanding durability that surpasses most of transition metal oxides. • The improved OER activity is mainly because Fe doping downshifts the d-band of metal sites. • Fe-NiO-Ni CHNAs obeyed the adsorbate evolution mechanism with a nonconcerted proton-electron transfer pathway. Herein we present a novel multi-level structure of Fe-doped NiO coupled Ni cluster hollow nanotube arrays (Fe-NiO-Ni CHNAs) grown on carbon fiber cloth as an efficient catalyst for oxygen evolution reaction. In this multi-level structure, rocksalt-type Fe-doped NiO phase hybrids with Ni clusters coupled into the nanospheres anchored to the outside of nanotube, forming a unique 3D corn-like structure. This novel multi-level structure represents a large specific area for catalytic reaction. X-ray absorption fine structure indicates that the defect-rich Fe-doped NiO phase has abundant coordinative unsaturated sites as active sites, and Fe doping downshifts the d-band of metal sites, which is the main contribution to the improved oxygen evolution reaction catalytic activity. The OER of Fe-NiO-Ni CHNAs obeys the adsorbate evolution mechanism with the nonconcerted proton-electron transfer pathway as a rate-determining step. Thus Fe-doped NiO CHNAs exhibits excellent OER performance and outstanding durability that surpasses most of transition metal oxides. [ABSTRACT FROM AUTHOR]