Katlego Makgopa | Tshwane University of Technology (original) (raw)

Papers by Katlego Makgopa

Environmental chemistry for a sustainable world, 2019

The fundamental properties of supercapacitors (SCs) with descriptions restricted to the metal oxi... more The fundamental properties of supercapacitors (SCs) with descriptions restricted to the metal oxides systems and the effect on the electrochemical performance and synthesis are described in this chapter. Metal oxides such as manganese oxide (MnO), vanadium oxide (V2O5) and ruthenium oxide (RuO) have demonstrated great potential in the field of energy storage due to their structural as well as electrochemical properties, thus attracting huge attention in the past decade and in recent years. The major contributing factor to the electrochemical properties is their capability to achieve relatively high pseudocapacitive performance derived from their theoretical values resulting from their multiple valence state changes. The developments of the metal oxide (MO)-based electrode materials and their composites are being explored from the synthetic point of view as well as their emerging applications as energy storage materials. Therefore, the need to further exploration of MO-based electrodes is motivated by their considerably low-cost and environmentally friendly nature as compared to other supercapacitive electrode materials. This chapter accounts to the overview of various nanostructured metal oxide materials for application as energy storage materials in supercapacitors.

Nano-Horizons

The study of nanoparticles has grown in significance during the last several years. Nanoparticles... more The study of nanoparticles has grown in significance during the last several years. Nanoparticles are a kind of material that is composed of very tiny particles. Nanoparticle characteristics vary greatly depending on their size and form. The surface of a nanoparticle significantly affects its optical, mechanical, magnetic, and other characteristics. Nanoparticles are categorised according to their size, origin and chemical composition. We created nanoparticles using both top-down and bottom-up techniques. In this article, we discuss various different methods for creating nanomaterials, such as sol-gel processes, gas condensation, vacuum deposition and vaporisation, chemical vapour deposition and condensate, mechanical attrition, chemical precipitation, electrodeposition, and chemical vapour condensation. When it comes to creating nanoparticles, green synthesis is one of the most effective approaches. In this article, we explore eco-friendly techniques for manufacturing alloy nanopar...

Chemical engineering journal advances, May 1, 2023

Cleaner chemical engineering, Sep 1, 2022

Nanostructure science and technology, 2016

The operating life of a fuel cell is expected to be thousands of hours. One of the critical compo... more The operating life of a fuel cell is expected to be thousands of hours. One of the critical components of the fuel cell that will allow for such long-life cycle is the catalyst-support material. The support material is expected, amongst others, to be electrically conductive, strongly interact with the catalyst, possess large surface area, and be corrosion-resistant. This chapter provides the readers with the physico-chemical properties of the traditional support materials (i.e., carbons) and also the emerging support materials being reported in the literature as a means of alleviating some of the challenges associated with carbon supports. The need for the emerging materials arises mainly from the electrochemical corrosion of carbon materials as catalyst-supports in fuel cells (FCs) leading to electrical isolation of the catalyst particles and Ostwald ripening as well as decrease in the electrochemically-active surface area (EASA) of the catalyst. Although the chapter summarizes much of the historically significant work on various catalyst supports for Direct Alcohol Fuel Cells (DAFCs), as far as possible, the most recent developments are accentuated. References are made to other reports that have reviewed similar subject matter for specific cases of supports used in the field for ease of reference by readers. In addition, the basics of fuel cell technology is included which will hopefully serve as an introductory note to scientists and entrepreneurs who are technically new to the field.

Zeitschrift Fur Kristallographie-new Crystal Structures, Nov 6, 2020

C 18 H 16 O 3 N 4 Re, monoclinic, P2 1 /c (no. 14), a = 9.8409(6) Å, b = 14.0933(9) Å, c = 13.915... more C 18 H 16 O 3 N 4 Re, monoclinic, P2 1 /c (no. 14), a = 9.8409(6) Å, b = 14.0933(9) Å, c = 13.9153(9) Å, β = 90.558(2)°, V = 1929.8(2) Å 3 , Z = 4, R gt (F) = 0.0266, wR ref (F 2) = 0.0584, T = 100(2) K. CCDC no.: 2036274 The molecular structure is shown in the Figure. Table 1 contains crystallographic data, and Table 2 contains the list of the atoms including atomic coordinates and displacement parameters.

Journal of The Electrochemical Society, 2010

Journal of Electronic Materials, Feb 11, 2023

Materials Chemistry and Physics, Apr 1, 2018

Highlights  Revalorisation of waste tyres as a means to sustainable value added porous carbon. ... more Highlights  Revalorisation of waste tyres as a means to sustainable value added porous carbon.  K 2 CO 3 activation and carbonization of the hydrochar to produce porous carbons.  Electrodes based on the porous carbon exhibit good electrochemical performance.  Investigate the influence of redox-mediated electrolytes on the porous carbon.

Zeitschrift für Kristallographie - New Crystal Structures

C13H7BrN3O6Re, monoclinic, P21/n (no. 14), a = 7.2645(1) Å, b = 10.0607(1) Å, c = 20.7717(2) Å, β... more C13H7BrN3O6Re, monoclinic, P21/n (no. 14), a = 7.2645(1) Å, b = 10.0607(1) Å, c = 20.7717(2) Å, β = 97.1800(10)°, V = 1506.22(3) Å3, Z = 4, R gt(F) = 0.0359, wR ref(F 2) = 0.0810, T = 150 K.

Chemical Engineering Journal Advances

Advances in material research and technology, 2022

Polymers

The accumulation of toxic heavy metal ions continues to be a global concern due to their adverse ... more The accumulation of toxic heavy metal ions continues to be a global concern due to their adverse effects on the health of human beings and animals. Adsorption technology has always been a preferred method for the removal of these pollutants from wastewater due to its cost-effectiveness and simplicity. Hence, the development of highly efficient adsorbents as a result of the advent of novel materials with interesting structural properties remains to be the ultimate objective to improve the adsorption efficiencies of this method. As such, advanced materials such as metal–organic frameworks (MOFs) that are highly porous crystalline materials have been explored as potential adsorbents for capturing metal ions. However, due to their diverse structures and tuneable surface functionalities, there is a need to find efficient characterization techniques to study their atomic arrangements for a better understanding of their adsorption capabilities on heavy metal ions. Moreover, the existence o...

Cleaner Chemical Engineering

ECS Meeting Abstracts, 2012

not Available.

Electrochimica Acta, Apr 1, 2022

Journal of Electronic Materials

ECS Transactions, 2013

ABSTRACT An aqueous asymmetric electrochemical capacitor was developed using manganese dioxide / ... more ABSTRACT An aqueous asymmetric electrochemical capacitor was developed using manganese dioxide / multiwalled carbon nanotubes (MnO 2 /MWCNT) nanocomposites. The nanostructured MnO 2 was generated from micron-sized commercial electrolytic manganese dioxide (EMD) via a hydrothermal reaction, with the addition of the surfactant sodium dodecylsulphate (SDS), and acid treatment. The capacitance of the nano-sized MnO 2 was improved. The MnO 2 /MWCNT hybrid showed excellent specific capacitance (170 F g -1), energy density (18 Wh kg -1), power density (4 kW kg -1), satisfactory cycle life, and a high frequency response (8 kHz).

Journal of Materials Science, 2013

Few-layer graphene was synthesized on a nickel foam template by chemical vapour deposition (CVD).... more Few-layer graphene was synthesized on a nickel foam template by chemical vapour deposition (CVD). The resulting three-dimensional (3D) graphene was loaded with nickel oxide nanostructures using the successive ionic layer adsorption and reaction (SILAR) technique. The composites were characterized and investigated as electrode material for supercapacitors. Raman spectroscopy measurements on the sample revealed that the 3D graphene consisted of mostly few layers, while X-ray diffractometry (XRD) and scanning electron microscopy (SEM) revealed the presence of nickel oxide. The electrochemical properties were investigated using cyclic voltammetry, electrochemical impedance spectroscopy and potentiostatic charge-discharge in aqueous KOH electrolyte. The novelty of this work is the use of the 3D porous cell structure of the nickel foam which allows for the growth of highly conductive graphene and subsequently provides support for uniform adsorption of the NiO onto the graphene. The NF-G/NiO electrode material showed excellent properties as a pseudocapacitive device with a high specific capacitance value of 783 Fg-1 at a scan rate of 2 mVs-1. The device also exhibited excellent cycle stability, with 84% retention of the initial capacitance after 1,000 cycles. The results demonstrate that composites made using 3D graphene are versatile and show considerable promise as electrode materials for supercapacitor applications.