Nano-Micro Letters

Hollow Nanocages of NixCo1-xSe for Efficient Zinc–Air Batteries and Overall Water Splitting

Zhengxin Qian1, Yinghuan Chen2, Zhenghua Tang2, 3, *, Zhen Liu4, Xiufang Wang1, Yong Tian1, *, Wei Gao1, *

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Nano-Micro Lett. (2019) 11: 28

First Online: 27 March 2019 (Article)

DOI:10.1007/s40820-019-0258-0

*Corresponding author. E-mail: tian_yong_tian@163.com (Yong Tian); gygaowei@126.com (Wei Gao); zhht@scut.edu.cn (Zhenghua Tang)

 

Abstract

 


Toc

Developing Earth-abundant, highly efficient, and anti-corrosion electrocatalysts to boost the oxygen evolution reaction (OER), oxygen reduction reaction (ORR), and hydrogen evolution reaction (HER) for the Zn–air battery (ZAB) and for overall water splitting is imperative. In this study, a series of NixCo1-xSe samples with hollow cages were prepared and studied as trifunctional electrocatalysts for the OER, ORR, and HER. A novel process starting with Cu2O cubes was developed to fabricate NixCo1-xSe nanocages, and a reasonable formation mechanism was proposed. In electrochemical measurements, Ni0.2Co0.8Se exhibited higher OER activity than its counterparts, as evidenced by the low overpotential of 280 mV at 10 mA cm-2. Additionally, in an HER test, it outperformed the other samples in the series, with a low overpotential of 73 mV at 10 mA cm-2. To investigate the applications of Ni0.2Co0.8Se, it was tested as an air-cathode of a self-assembled rechargeable ZAB and an all-solid-state ZAB and as a catalyst for overall water splitting. The rechargeable ZAB exhibited excellent performance, including an ultralong cycling lifetime of >50 h, a high round-trip efficiency of 60.86%, and a high power density of 223.5 mW cm-2, outperforming the precious-metal-based Pt/C+RuO2 catalyst. The self-made all-solid-state ZAB with Ni0.2Co0.8Se also demonstrated excellent performance, with a power density of 41.03 mW cm-2 and an open-circuit voltage of 1.428 V. In a practical demonstration of overall water splitting, Ni0.2Co0.8Se exhibited superior performance, as a cell voltage of only 1.592 V was needed to achieve a current density of 10 mA cm-2. These findings show that NixCo1-xSe with an optimized Ni-to-Co ratio is a promising cost-effective and high-efficiency electrocatalyst for practical applications of ZABs and overall water splitting in alkaline solutions.


 

Keywords

NixCo1-xSe hollow nanocages; Oxygen evolution reaction; Hydrogen evolution reaction; Rechargeable/all-solid-state zinc–air battery; Overall water splitting

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