23February2019

Nano-Micro Letters

Bimetallic Nickel Cobalt Sulfide as Efficient Electrocatalyst for Zn–Air Battery and Water Splitting

Jingyan Zhang1, Xiaowan Bai2, Tongtong Wang1, Wen Xiao3, Pinxian Xi4, Jinlan Wang2,
Daqiang Gao1,*, John Wang3,*

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Nano-Micro Lett. (2019) 11: 2

First Online: 09 January 2019 (Article)

DOI:10.1007/s40820-018-0232-2

*Corresponding author. E-mail: gaodq@lzu.edu.cn ; msewangj@nus.edu.sg

 

Abstract

 


Toc

The development of efficient earth-abundant electrocatalysts for oxygen reduction, oxygen evolution, and hydrogen evolution reactions (ORR, OER, and HER) is important for future energy conversion and energy storage devices, for which both rechargeable Zn–air batteries and water splitting have raised great expectations. Herein, we report a single-phase bimetallic nickel cobalt sulfide ((Ni,Co)S2) as an efficient electrocatalyst for both OER and ORR. Owing to the synergistic combination of Ni and Co, the (Ni,Co)S2 exhibits superior electrocatalytic performance for ORR, OER, and HER in an alkaline electrolyte, and the first principle calculation results indicate that the reaction of an adsorbed O atom with a H2O molecule to form a *OOH is the potential limiting step in the OER. Importantly, it could be utilized as an advanced air electrode material in Zn–air batteries, which shows an enhanced charge–discharge performance (charging voltage of 1.71 V and discharge voltage of 1.26 V at 2 mA cm−2), large specific capacity (842 mAh g Zn −1 at 5 mA cm−2), and excellent cycling stability (480 h). Interestingly, the (Ni,Co)S2-based Zn–air battery can efficiently power an electrochemical water-splitting unit with (Ni,Co)S2 serving as both the electrodes. This reveals that the prepared (Ni,Co)S2 has promising applications in future energy conversion and energy storage devices.


 

Keywords

(Ni,Co)S2 nanosheet arrays; DFT calculations; Zn–air batteries; Water splitting

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