Facile preparation of porous Cu, Ni, and Cu–Ni alloy as electrodes for supercapacitor application

Abstract

Transition metal-based supercapacitors have attracted wide consideration as supercapacitors application owing to their higher electrical conductivity, rich redox chemistry, and cost effectiveness. However electrochemical energy storage capability of bimetallic alloys can be improved by generating porosity in their structure. In this work, we demonstrate the inverse Leidenfrost method that is low cost, benign, and scalable for the synthesis of porous Cu64Ni36 alloy. The powder X-ray diffraction results verify the formation of single-phase Cu, Ni, and Cu64Ni36 alloy having face-centered cubic structure. The porosity and surface area are determined by scanning electron microscopy and Brunauer-Emmett-Teller (BET) method, respectively. The surface area of Cu64Ni36 alloy is calculated to be 16 m2 g−1, BET also confirming the mesoporous nature of prepared Cu, Ni, and Cu64Ni36 alloy. Further, Temperature programmed reduction (TPR) and Temperature programmed oxidation (TPO) analysis describes that the prepared porous Cu64Ni36 alloy is stable towards oxidation up to 568 °C. The prepared porous were evaluated electrochemically as electrode materials for supercapacitor application. The cyclic voltammetry (CV) measurements show that all prepared porous materials show a pseudocapacitive mechanism for electrochemical energy storage. The porous Cu64Ni36 alloy electrode exhibits desirable specific capacitance (SC) value of 610 F g−1 at 1 A g−1 with 70.2% of retention after 5000 cycles at 20 A g−1. The solution and charge transfer resistance are measured to be 3.38 Ω and 0.16118 Ω, respectively using electrochemical impedance spectroscopy. The improved electrochemical energy storage behavior is attributed to the porosity and high conductivities of Cu64Ni36 alloy. Additionally, this work also offers a new direction for porous bimetallic alloys to study as supercapacitors. It demonstrates the promising behavior of mesoporous Cu64Ni36 alloy as an electrode material for supercapacitor application.