Atomic-level insight into super-efficient electrocatalytic oxygen evolution on iron and vanadium co-doped nickel (oxy)hydroxide

Jian Jiang,Fanfei Sun,Zheng Jiang,Wensheng Yan,Jijun Zhao,Wei Hu,Hao Zhang,Jinchao Dong,Jianfeng Li,Mei Wang,Si Zhou

doi:10.1038/s41467-018-05341-y

Abstract

It is of great importance to understand the origin of high oxygen-evolving activity of state-of-the-art multimetal oxides/(oxy)hydroxides at atomic level. Herein we report an evident improvement of oxygen evolution reaction activity via incorporating iron and vanadium into nickel hydroxide lattices. X-ray photoelectron/absorption spectroscopies reveal the synergistic interaction between iron/vanadium dopants and nickel in the host matrix, which subtly modulates local coordination environments and electronic structures of the iron/vanadium/nickel cations. Further, in-situ X-ray absorption spectroscopic analyses manifest contraction of metal–oxygen bond lengths in the activated catalyst, with a short vanadium–oxygen bond distance. Density functional theory calculations indicate that the vanadium site of the iron/vanadium co-doped nickel (oxy)hydroxide gives near-optimal binding energies of oxygen evolution reaction intermediates and has lower overpotential compared with nickel and iron sites. These findings suggest that the doped vanadium with distorted geometric and disturbed electronic structures makes crucial contribution to high activity of the trimetallic catalyst.

Highlights

It is of great importance to understand the origin of high oxygen-evolving activity of state-ofthe-art multimetal oxides/(oxy)hydroxides at atomic level
Ni3Fe0.5V0.5 features an apparently smaller charge transfer resistance and displays considerably higher specific activity compared to Ni3V and Ni3Fe, which implies a concerted effect of Fe and V on the oxygen evolution reaction (OER) performance of Ni-basedhydroxides
The FT and WT analyses of extended X-ray absorption fine structure (EXAFS) data attest the substitution of Fe and V atoms for the Ni sites in Ni(OH)[2] lattices, which is supported by the results obtained from theoretical calculations

Summary

Introduction

It is of great importance to understand the origin of high oxygen-evolving activity of state-ofthe-art multimetal oxides/(oxy)hydroxides at atomic level. Density functional theory calculations indicate that the vanadium site of the iron/ vanadium co-doped nickel (oxy)hydroxide gives near-optimal binding energies of oxygen evolution reaction intermediates and has lower overpotential compared with nickel and iron sites. These findings suggest that the doped vanadium with distorted geometric and disturbed electronic structures makes crucial contribution to high activity of the trimetallic catalyst. In light of the reports mentioned above, we prepared a series of Fe/V co-doped, Fe- or V-doped, and pure Ni (oxy)hydroxides as ultrathin nanosheets (NSs) on hydrophilic carbon fiber paper (CFP), and made comparative studies on these OER catalysts by X-ray photoelectron spectroscopy (XPS) and ex-situ/in-situ XAS, combined with density functional theory (DFT) calculations. DFT calculations indicate that the V site of the Fe/V co-doped Ni (oxy)hydroxide gives near-optimal binding energies (BEs) of OER intermediates, and point to the higher OER activity of V site compared to that of Ni and Fe sites

Methods

Results

Conclusion