Abstract
Nickel foam (NF) with a three-dimensional porous structure plays an important role in a wide variety of applications such as energy storage and conversion, catalysis, and sensor due to its high porosity, low density, and excellent conductivity. However, the main drawback of NF is that its ligaments are very smooth, and thus the surface area is relatively low. In this work, we propose a novel strategy, oxidization and reduction process, in situ to construct micron/nano pores on the ligaments of commercial NF to fabricate a typical hierarchical porous architecture. This process is simple and green, avoiding the use of sacrificial materials. Furthermore, MnO2 is coated on the micron/nano-porous Ni foam (MPNF) to construct an oxygen evolution reaction (OER) electrode through pulse electrodeposition. The designed MPNF-MnO2 electrode presents enhanced OER electrocatalysis activity with a low overpotential of 363.5 mV at the current density of 10 mA cm−2 in an alkaline solution, which is 66.4 mV lower than that of the NF-MnO2 electrode in the same operating conditions. Furthermore, the porous and wrinkled structures of the MPNF also improve the mechanical integrity of the electrode, resulting in super-long stability.
Highlights
Nickel foam (NF) is a three-dimensional (3D) porous metal composed of pores and ligament skeleton with the advantages of high porosity, good conductivity, and mechanical performance, which has very important applications in many fields such as energy storage and conversion, catalysis, and sensing (Yuan et al, 2012; Zhou et al, 2013; Huang et al, 2015; Tong et al, 2019; Zeng et al, 2020)
These wrinkle structures significantly increased the roughness of the nickel ligament surface, which is conducive to improve the contact area between micron/nano-porous Ni foam (MPNF) and active materials. Through this simple metal oxide–metal treatment, commercial NF was directly transformed to MPNF with hierarchical porous architecture
We proposed a simple and green approach to construct in situ micron/nano-porous and wrinkle structures on ligaments of commercial NF based on an oxidation–reduction strategy
Summary
Nickel foam (NF) is a three-dimensional (3D) porous metal composed of pores and ligament skeleton with the advantages of high porosity, good conductivity, and mechanical performance, which has very important applications in many fields such as energy storage and conversion, catalysis, and sensing (Yuan et al, 2012; Zhou et al, 2013; Huang et al, 2015; Tong et al, 2019; Zeng et al, 2020). Efficient Ni Foam Support for OER of active materials on NF support was a serious issue for the long-term stability of the electrode/catalyst (Yu et al, 2014). To overcome these problems, acid–base corrosion and dealloying have been developed for the treatment of NF. The porous Ni foam could be used as an efficient supercapacitor substrate to increase the loading capacity for the MnO2 electrode For these existing treatments for NF, a strong acid was often needed in the corrosion and dealloying treatment, which is harmful to the environment. The long-term stability of the composite electrodes was evaluated by chronopotentiometry
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