Synthesis of Cobalt-Nickel Nanoparticles via a Liquid-Phase Reduction Process

T Usami,M Okido,M K Gouda,S A Salman,K Kuroda,A Mahdy,Brajesh Kumar

doi:10.1155/2021/9401024

Abstract

Cobalt-nickel nanoparticles (Co-Ni-NPs) show promising electrochemical performance in oxygen and hydrogen evolution reactions (OER and HER) due to their physicochemical properties such as electronic configuration and great electrochemical stability. Therefore, developing new economically and environmentally friendly methods of synthesizing Co-Ni-NPs has become a practical requirement. Co-Ni-NPs were produced by employing the liquid-phase reduction method. Nickel and cobalt sulfate solutions in hydrazine monohydrate with various mixing ratios were used as raw materials. Nickel plays an important role in the nucleation process via increasing the reduction reaction rate throughout the formation of Co-Ni-NPs. Furthermore, the acceleration of the Co-Ni-NPs formation process may be attributed to the partial dissolution of Ni(OH)2 in the presence of N2H4 and/or citrate-anions and the formation of the Ni-N2H4 or Ni-Cit complexes in contrast to Co(OH)2.

Highlights

Electrocatalysts accelerate the kinetics for the electrochemical reactions by reducing the required overpotentials [13, 14]. e noble metal electrocatalysts, such as platinum for hydrogen evolution reaction (HER) and ruthenium oxide for oxygen evolution reaction (OER), showed excellent performance [15, 16]
E cathodic polarization measurement is shown in Figure 3. is figure shows that it is easy to extract Co from cobalt solution; the extraction speed of Ni from Co solution seems to progress at a slower rate. e presence of montmorillonite NPs was likely precipitated on the working electrodes, reducing the active area of the working electrode metals in contact with the electrolyte leading to a decrease of cathodic current
E noble metal salts such as Ag2NO3, PdCl2, and H2PtCl6 are used as nucleating agents in the liquid-phase reduction method to form fine particles [39]

Summary

Introduction

Magnetic NPs have attracted increasing interest from researchers of many fields due to their promising applications in high-density magnetic storage media, magnetic refrigeration systems, ferrofluids, and biomedicine [1,2,3]. Nickel (Ni) and cobalt (Co) have attracted attention among the various magnetic NPs because of their excellent properties and industrial applications. Transition-metal-based materials, especially Co and Ni, are considered the most promising electrocatalysts for HER and OER due to their low cost and advanced catalytic performance comparable with the noble metals [11, 13, 16,17,18,19]. Liquid-phase reduction methods are relatively simple and do not require special equipment. They are considered less expensive and quicker to implement, which are desirable qualities for future attempts at large-scale production [24,25,26,27]. The effect of the mixing ratio of nickel-based and cobalt-based solutions on the NPs was investigated

Experimental Methods

Results and Discussion

Conclusion