Ultrathin sulfate-intercalated NiFe-layered double hydroxide nanosheets for efficient electrocatalytic oxygen evolution.

Xiao-Xiao Jiang,Zhong-Yin Zhao,Hong-Wei Gu,Cong Li,Zheng Niu,Fei-Long Li,Chen Cao,Jian-Ping Lang,Jiang-Yan Xue

doi:10.1039/d0ra00845a

Abstract

As an important two-dimensional material, layered double hydroxides (LDHs) show considerable potential in electrocatalytic reactions. However, the great thickness of the bulk LDH materials significantly limits their catalytic activity. In this work, we report ultrathin NiFe-LDH nanosheets with sulfate interlayer anions (Ni6Fe2(SO4)(OH)16·7H2O) (U-LDH(SO42−)), which can be synthesized in gram-scale by a simple solvothermal method. The U-LDH(SO42−) shows excellent stability and great electrocatalytic performance in OER with a current density of 10 mA cm−2 at a low overpotential of 212 mV and a small Tafel slope of 65.2 mV dec−1, exhibiting its great potential for a highly efficient OER electrocatalyst.

Highlights

We report ultrathin NiFe-layered double hydroxides (LDHs) nanosheets with sulfate interlayer anions (Ni6Fe2(SO4)(OH)16$7H2O) (U-LDH(SO42À)), which can be synthesized in gram-scale by a simple solvothermal method
The gradual hydrolysis of the acetate anions and the release of OHÀ ions ensured a slow reaction between metal ions with OHÀ, thereby controlling nuclei formation and subsequent crystal growth to allow uniform precipitation.[39]
The 2D ultrathin morphology of U-LDH(SO42À) showing uniform and exible nanosheets was established by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) (Fig. 1a and b)

Summary

Introduction

Current energy issues require the development of increasingly efficient and environmentally friendly energy conversion and storing devices.[1,2] Water splitting, which includes the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), is considered to be a most promising approach for energy production.[3,4,5,6] the sluggish kinetics of OER concerning multistep proton-coupled electron transfer processes has become a challenging topic and hampers efficiency of the electrocatalytic water splitting.[7,8,9] noble-metal-based electrocatalysts (e.g. IrO2 and RuO2) possess high OER performance,[10] the scarcity and high cost of such catalysts greatly hinder their industrial applications.Layered double hydroxides (LDHs) with unique twodimensional (2D) lamellar structures have been extensively investigated as OER electrocatalysts.[11,12,13] the pristine LDHs show unsatisfactory performances in OER owing to their limited active sites and poor intrinsic activities.[11,14,15] To date, more efforts have been devoted to improve the OER activity of LDH materials, including the incorporation of high-valent metals (such as V,16 Mn,[17] Cr18), the fabrication of vacancies and defects,[19] and the hybridization with highly conductive carbon materials.[20]. We report ultrathin NiFe-LDH nanosheets with sulfate interlayer anions (Ni6Fe2(SO4)(OH)16$7H2O) (U-LDH(SO42À)), which can be synthesized in gram-scale by a simple solvothermal method.

Results

Conclusion