Coral-like carbon-wrapped NiCo alloys derived by emulsion aggregation strategy for efficient oxygen evolution reaction

Xiaolu Zhang; Kuixing Ding; Baicheng Weng; Shijun Liu; Wei Jin; Xiaobo Ji; Jiugang Hu

doi:10.1016/j.jcis.2020.03.124

Coral-like carbon-wrapped NiCo alloys derived by emulsion aggregation strategy for efficient oxygen evolution reaction

J Colloid Interface Sci. 2020 Aug 1:573:96-104. doi: 10.1016/j.jcis.2020.03.124. Epub 2020 Apr 1.

Authors

Xiaolu Zhang¹, Kuixing Ding¹, Baicheng Weng², Shijun Liu¹, Wei Jin³, Xiaobo Ji¹, Jiugang Hu⁴

Affiliations

¹ College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China.
² College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China; Department of Physics and Astronomy, and Wright Center for Photovoltaics Innovation and Commercialization, University of Toledo, Toledo, OH 43606, USA.
³ School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, China. Electronic address: wjin@ipe.ac.cn.
⁴ College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China; Hunan Provincial Key Laboratory of Efficient and Clean Utilization of Manganese Resources, Central South University, Changsha 410083, China. Electronic address: hujiugang@csu.edu.cn.

PMID: 32276232
DOI: 10.1016/j.jcis.2020.03.124

Abstract

The transition metal-based catalysts have great potential to boost the electrocatalytic reactions due to their flexible electronic configuration and low cost. This work developed a facile emulsion aggregation strategy to synthesize coral-like carbon-wrapped NiCo alloy (Co_0.5Ni_0.5/rGO) with high oxygen evolution reaction (OER) activity. The effect of alloy composition and GO content on the OER activity was evaluated in the 1 mol L^-1 KOH solution. The OER mechanism of the Co_0.5Ni_0.5/rGO catalyst was disclosed by X-ray photoelectron spectra (XPS) and synchrotron radiation X-ray absorption spectra (XAS). The emulsion containing amphipathic graphene oxide (GO) and hydrophobic nickel/cobalt complexes induces the formation of the carbon-wrapped nanostructure. The coral-like Co_0.5Ni_0.5/rGO catalyst exhibits the low overpotential of 288 mV at the current density of 10 mA cm^-2 and good durability, both of which are superior to the standard RuO₂. The synergistic effect between nickel and cobalt effectively regulates the electronic structure and OER activity of the alloy catalysts. Moreover, the interaction between NiCo alloys and carbon shells can reduce the interfacial resistance.

Keywords: Carbon-coated composites; Coral-like; Emulsion aggregation; NiCo alloys; Oxygen evolution reaction.