Highly porous Co-doped NiO nanorods: facile hydrothermal synthesis and electrocatalytic oxygen evolution properties.

Nguyen Duc Cuong,Wantana Klysubun,Phong D Tran,Ho Van Minh Hai,Tran Thai Hoa,Quyen T Nguyen,Duong Tuan Quang,Tien D Tran

doi:10.1098/rsos.202352

Abstract

Highly porous 3d transition metal oxide nanostructures are opening up the exciting area of oxygen evolution reaction (OER) catalysts in alkaline medium thanks to their good thermal and chemical stability, excellent physiochemical properties, high specific surface area and abundant nanopores. In this paper, highly porous Co-doped NiO nanorods were successfully synthesized by a simple hydrothermal method. The porous rod-like nanostructures were preserved with the added cobalt dopant ranging from 1 to 5 at% but were broken into aggregated nanoparticles at higher concentrations of additional cobalt. The catalytic activity of Co-doped NiO nanostructures for OER in an alkaline medium was assayed. The 5%Co-NiO sample showed a drastically enhanced activity. This result could originate from the combination of advantageous characteristics of highly porous NiO nanorods such as large surface area and high porosity as well as the important role of Co dopant that could provide more catalytic active sites, leading to an enhanced catalytic activity of the nanocatalyst.

Highlights

Hydrogen has been considered as a sustainable energy carrier thanks to its high energy density and environmental benignity [1,2]
The results demonstrate that the advantages of nanostructures such as large specific surface area, the increase of edges and defective sites on the surface and high porosity may enhance the intrinsic properties of electrocatalytic materials, subsequently increasing the catalytic oxygen evolution reaction (OER) activity
We investigated the contribution of the Co dopant to the electrochemical catalytic activity of the NiO nanorods for the OER in alkaline solution

Summary

Introduction

Hydrogen has been considered as a sustainable energy carrier thanks to its high energy density and environmental benignity [1,2]. Ultrathin porous Co3O4 nanoplates with large specific surface area, small crystalline size and high porosity possess great catalytic activity for OER, which may be supported by their structural features that provide more surface-active sites and efficient chemical diffusion [17]. The results demonstrate that the advantages of nanostructures such as large specific surface area, the increase of edges and defective sites on the surface and high porosity may enhance the intrinsic properties of electrocatalytic materials, subsequently increasing the catalytic OER activity. The remarkable features of highly porous NiO nanorods such as large surface area and high porosity may provide better charge transfer, more catalytic active sites on the surface and efficient chemical diffusion.

Synthesis of highly porous undoped and Co-doped NiO nanorods

Material characterizations

Catalytic assay

Results and discussion

Catalytic activity of Co-doped highly porous NiO nanorods

Conclusion