A “One-Pot” Route for the Synthesis of Snowflake-like Dendritic CoNi Alloy-Reduced Graphene Oxide-Based Multifunctional Nanocomposites: An Efficient Magnetically Separable Versatile Catalyst and Electrode Material for High-Performance Supercapacitors

Abstract

In this paper, a simple “one pot” methodology to synthesize snowflake-like dendritic CoNi alloy-reduced graphene oxide (RGO) nanocomposites has been reported. First-principles quantum mechanical calculations based on density functional theory (DFT) have been conducted to understand the electronic structures and properties of the interface between Co, Ni, and graphene. Detailed investigations have been conducted to evaluate the performance of CoNi alloy and CoNi-RGO nanocomposites for two different types of applications: (i) as the catalyst for the reduction reaction of 4-nitrophenol and Knoevenagel condensation reaction and (ii) as the active electrode material in the supercapacitor applications. Here, the influence of microstructures of CoNi alloy particles (spherical vs snowflake-like dendritic) and the effect of immobilization of CoNi alloy on the surface of RGO on the performance of CoNi-RGO nanocomposites have been demonstrated. CoNi alloy having a snowflake-like dendritic microstructure exhibited better performance than that of spherical CoNi alloy, and CoNi-RGO nanocomposites showed improved properties compared to CoNi alloy. The kapp value of the (CoNiD)60RGO40-catalyzed reduction reaction of 4-nitrophenol is 20.55 × 10–3 s–1, which is comparable and, in some cases, superior to many RGO-based catalysts. The (CoNiD)60RGO40-catalyzed Knoevenagel condensation reaction showed the % yield of the products in the range of 80–93%. (CoNiD)60RGO40 showed a specific capacitance of 501 F g–1 (at 6 A g–1), 21.08 Wh kg–1 energy density at a power density of 1650 W kg–1, and a retention of ∼85% of capacitance after 4000 cycles. These results indicate that (CoNiD)60RGO40 could be considered as a promising electrode material for high-performance supercapacitors. The synergistic effect, derived from the hierarchical structure of CoNiD-RGO nanocomposites, is the origin for its superior performance. The easy synthetic methodology, high catalytic efficiency, and excellent supercapacitance performance make (CoNiD)60RGO40 an appealing multifunctional material.

A review on the use of DFT for the prediction of the properties of nanomaterials

“…14) also supported this fact by demonstrating the higher conductivity of Co-Ni-graphene nanocomposite. 129 Similar observations were attained when we have carried out DFT calculations for the Ag-Ni-rGO catalysts, to explain why The enhancement of catalytic efficiency of core-shell Ag@Pt nanoparticles due to their immobilization on the sepiolite nanobers towards the reduction of 4-NP has been reported by Ying Ma et al 138 DFT calculations were performed to determine the plausible reaction mechanism and to realize the electronic structure and interaction of Ag cores and Pt shells in the Ag@Pt nanoparticles. The higher TDOS of Ag@Pt than that of Ag suggested the higher catalytic activity of Ag@Pt.…”

“…136 We have also developed CoNi-rGO and AgNi-rGO nanocatalysts for the reduction of 4-NP. 129,131 Our experimental results indicated that the catalytic activity of pure metal nanoparticles (i.e., Co, Ni, Ag) was less than that of bimetallic alloy catalysts (e.g., Co-Ni, Ag-Ni) and when the bimetallic alloy nanoparticles were anchored on the RGO support, the catalytic efficiency was further enhanced. We have performed DFT calculations to know the interfacial interactions (i) between metal nanoparticles in the bimetallic alloy system (e.g., Co-Ni, Ag-Ni) and (ii) between alloy nanoparticles and the graphene in the nanocatalysts.…”

“…), alloy nanoparticles, metal nanoparticles anchored on support matrix. [128][129][130][131][132][133][134] This reduction reaction is a simple six electron transfer reaction and trustworthy. It yields a single product and the reaction kinetics can be monitored easily.…”

“…Fig.11The band structure and density of states of Co-Ni interface. This figure is reproduced from ref 129. with permission from the American Chemical Society, copyright 2019.…”

Functionalized hybrid magnetic catalytic systems on micro- and nanoscale utilized in organic synthesis and degradation of dyes

“…The synthesis of the snowake-like dendritic (CoNi D ) 60 RGO 40 nanocomposite and its catalytic and supercapacitor applications were presented in this study. 276 Multifunctional and stimuli-responsive MNP-and derivative nanocomposite-based systems have emerged from nanobiotechnology with signicant impacts on drug delivery, cancer diagnosis and treatment. These systems overcome the limitations of conventional therapeutic methods for cancer in recent decades.…”