Tarekegn Heliso Dolla

University of South Africa

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Patrick Ndungu

University of Pretoria

Thabo Matthews

University of Johannesburg

Nobanathi Wendy Maxakato

University of Johannesburg

K. Pruessner

University of KwaZulu-Natal

Ludwe L. Sikeyi

University of South Africa

Siyabonga Patrick Mbokazi

University of Johannesburg

Makhaokane Paulina Chabalala

University of Johannesburg

D.G. Billing

University of the Witwatersrand

Mkhulu Mathe

University of South Africa

Xinying Liu

Shandong University of Science and Technology

Cooperative Institutions

University of Johannesburg

University of South Africa

National Interuniversity Consortium of Materials Science and Technology

University of Pretoria

University of KwaZulu-Natal

Council for Scientific and Industrial Research

University of Milano-Bicocca

Mylan (Switzerland)

Milano University Press

Beijing Solar Energy Research Institute

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Acetylation of glycerol over bimetallic Ag–Cu doped rice husk silica based biomass catalyst for bio-fuel additives application

International Journal of Industrial Chemistry (2016)

R. Jothi Ramalingam T. Radhika Farook Adam Tarekegn Heliso Dolla

Acetylation of glycerol with acetic acid was carried out over bimetallic silver and copper deposited rice husk silica-alumina like ecofriendly green catalyst. Bio-additive like mono, di and tri acetyl glycerol synthesis from raw glycerol (one of the main product of biodiesel), which are gaining attention as additives for improving petroleum fuel properties towards biofuel additive development applications. Advantage of using bimetallic catalyst for glycerol acetylation due to possible synergistic effect between the metals and it enhances the catalytic conversion and selectivity compared to single metal catalyst. The prepared catalysts were characterised by XRD, FT-IR and TEM. Silver and copper incorporated RHS (rice husk silica)-alumina catalysts are shown higher activity and selectivity towards diacetin (di acetyl glycerol) and triacetins (tri acetyl glycerol) formation by catalytic acetylation of glycerol. Higher conversion (98 %) and good selectivity (51 %) is achieved.

Husk

Bimetallic strip

10.1007/s40090-016-0073-0

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Citations (15)

Polyaniline‐ZnO−NiO Nanocomposite Based Non‐enzymatic Electrochemical Sensor for Malathion Detection

Electroanalysis (2022)

Samuel Chufamo Jikamo Tesfaye Haile Habtemariam Tarekegn Heliso Dolla

Abstract An electrochemical sensor based on polyaniline‐ZnO−NiO (PANI‐ZnO−NiO) nanocomposite was developed for the non‐enzymatic detection of malathion. The structure, surface morphology, and optical properties of the as‐prepared nanocomposite were studied by XRD, FTIR, SEM, and UV‐Vis spectroscopy. The electrochemical behavior of the nanocomposite based sensor was first evaluated through cyclic voltammetry (CV). Under optimum conditions, differential pulse voltammetry (DPV) was further utilized for malathion detection, which proved the PANI‐ZnO−NiO/GCE electrode as an effective electrochemical sensor. The developed electrochemical sensor showed a low detection limit of 1.0×10 −8 M with a wider linear range of 10 to 70 nM for malathion.

Electrochemical gas sensor

Differential pulse voltammetry

Non-blocking I/O

10.1002/elan.202200317

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Mn substituted Mn_xZn_1−xCo₂O₄ oxides synthesized by co-precipitation; effect of doping on the structural, electronic and magnetic properties

RSC Advances (2018)

Tarekegn Heliso Dolla D.G. Billing C. J. Sheppard A. R. E. Prinsloo Emanuela Carleschi

Mn substituted Mn x Zn1-x Co2O4 (x = 0, 0.3, 0.5, 0.7, 1) oxides were synthesized by a facile co-precipitation method followed by calcination at 600 °C. The presence of manganese ions causes appreciable changes in the structural and magnetic properties of the Mn-substituted ZnCo2O4. The morphologies, structures, and electronic properties of Mn-Zn-Co oxide microspheres were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The X-ray diffraction and Fourier transform infrared spectroscopy results confirmed the formation of spinel Mn x Zn1-x Co2O4. It was shown that the Mn-Zn-Co oxide microspheres increase in size and become regular in shape with increasing Mn concentration with the crystal size lying in the range from 19.1 nm to 51.3 nm. Magnetization measurements were carried out using a vibrating sample magnetometer at room temperature and 10 K. The saturation magnetization is observed to increase with increasing Mn concentration from x = 0 to x = 1.

Coprecipitation

10.1039/c8ra08150f

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Citations (18)

Unveiling the Collaborative Strategy and Synergistic Effects of Pd/V₂O₅‐fAC towards Glycerol Electrooxidation

ChemCatChem (2023)

Thabo Matthews Makhaokane Paulina Chabalala Siyabonga Patrick Mbokazi Tarekegn Heliso Dolla Kudzai Mugadza

Abstract A series of Pd nanoparticles supported on V 2 O 5 immobilized on functionalized carbon, % Pd (1, 3, and 5) and % V 2 O 5 (10, 20, and 30), were prepared by sodium borohydride‐assisted microwave polyol synthesis for glycerol oxidation reaction (GlyOR) in an alkaline medium. Electrocatalysts loading, temperature, V 2 O 5 immobilization, and their synergistic effect on the electrocatalytic performance are systematically studied. The electrocatalysts′ morphology and electronic properties were investigated using X‐ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, Transmission electron microscopy, and X‐ray photoelectron spectroscopy. A significantly improved GlyOR is observed with increased V 2 O 5 content and Pd percentage. The 5 %Pd/30 %V 2 O 5 ‐fAC showed the highest mass activity of 2157.3 mA . mg Pd −1 , a more negative onset potential of 0.62 V RHE , versus the commercial equivalent, and possessed high stability and durability. The increase in electrocatalytic activity is attributed to the effective immobilization of V 2 O 5 on fAC efficient synergism between Pd and V 2 O 5 , strong metal support interaction (SMSI), and great exposure of the electroactive sites. The results herein contribute significantly to the understanding of the physicochemical and electrochemical effects of metal oxide immobilization, microwave irradiation, % Pd/% Metal oxide optimization, and SMSI on metal oxide‐carbon hybrid electrocatalysts for GlyOR, opening new avenues for fabricating high‐performance direct alkaline glycerol fuel cells.

Sodium borohydride

10.1002/cctc.202301044

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Citations (1)

Synthesis and characterization of deep eutectic solvent functionalized CNT/ZnCo2O4 nanostructure: Kinetics, isotherm and regenerative studies on Eosin Y adsorption

Journal of environmental chemical engineering (2018)

Isiaka A. Lawal Tarekegn Heliso Dolla K. Pruessner Patrick Ndungu

Deep eutectic solvent

Langmuir adsorption model

Eosin Y

10.1016/j.jece.2018.102877

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Citations (40)

Mesoporous Mn-substituted MnxZn1−xCo2O4 ternary spinel microspheres with enhanced electrochemical performance for supercapacitor applications

Scientific Reports (2024)

Tarekegn Heliso Dolla Isiaka A. Lawal Gizachew Wendimu Kifle Samuel Chufamo Jikamo Thabo Matthews

Abstract Extensive investigations have been carried out on spinel mixed transition metal oxide-based materials for high-performance electrochemical energy storage applications. In this study, mesoporous Mn-substituted Mn x Zn 1−x Co 2 O 4 (ZMC) ternary oxide microspheres (x = 0, 0.3, 0.5, 0.7, and 1) were fabricated as electrode materials for supercapacitors through a facile coprecipitation method. Electron microscopy analysis revealed the formation of microspheres comprising interconnected aggregates of nanoparticles. Furthermore, the substitution of Mn into ZnCo 2 O 4 significantly improved the surface area of the synthesized samples. The electrochemical test results demonstrate that the ZMC3 oxide microspheres with an optimal Mn substitution exhibited enhanced performance, displaying the largest specific capacitance of 589.9 F g −1 at 1 A g −1 . Additionally, the ZMC3 electrode maintained a capacitance retention of 92.1% after 1000 cycles and exhibited a significant rate capability at a current density of 10 A g −1 . This improved performance can be ascribed to the synergistic effects of multiple metals resulting from Mn substitution, along with an increase in the surface area, which tailors the redox behavior of ZnCo 2 O 4 (ZC) and facilitates charge transfer. These findings indicate that the incorporation of Mn into mixed transition metal oxides holds promise as an effective strategy for designing high-performance electrodes for energy storage applications.

Coprecipitation

Specific surface area

10.1038/s41598-024-58822-0

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Citations (6)

Carbon Encapsulated Ternary Mn−Ni−Co Oxide Nanoparticles as Electrode Materials for Energy Storage Applications

Electroanalysis (2020)

Tarekegn Heliso Dolla Isiaka A. Lawal D.G. Billing K. Pruessner Patrick Ndungu

Abstract Ternary transition metal oxides are promising advanced materials for use as electrode components in electrochemical energy storage systems. However, low electronic/ionic conductivity hinder practical applications. In this study, ternary Mn−Ni−Co oxide nanoparticles were encapsulated in carbon nanosheets, to improve the electrical conductivity and surface area. When tested as supercapacitor electrodes, the materials exhibited specific capacity of 91.2 mAh g −1 at a current density of 1 A g −1 in 2 M KOH. Moreover, after 3000 cycles the composite achieved a specific capacity of 74.6 mAh g −1 at a current density of 6 A g −1 and high capacitance retention of 96.4 %.

Carbon fibers

10.1002/elan.202060294

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Citations (12)

Advances in solid-state batteries fabrication strategies for their manufacture

Journal of Energy Storage (2024)

Tarekegn Heliso Dolla Samuel O. Ajayi Ludwe L. Sikeyi Mkhulu Mathe Nithyadharseni Palaniyandy

10.1016/j.est.2024.114737

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Citations (2)

Mn-Ni-Co-O Spinel Oxides towards Oxygen Reduction Reaction in Alkaline Medium: Mn0.5Ni0.5Co2O4/C Synergism and Cooperation

Catalysts (2021)

Thabo Matthews Tarekegn Heliso Dolla Sandile Surprise Gwebu Tebogo Abigail Mashola Lihle Tshepiso Dlamini

Mn-doped spinel oxides MnxNi1−xCo2O4 (x = 0, 0.3, 0.5, 0.7, and 1) were synthesized using the citric acid-assisted sol–gel method. The Mn0.5Ni0.5Co2O4 (x = 0.5) supported on carbon nanosheets, Mn0.5Ni0.5Co2O4/C, was also prepared using the same method employing NaCl and glucose as a template and carbon source, respectively, followed by pyrolysis under an inert atmosphere. The electrocatalytic oxygen reduction reaction (ORR) activity was performed in alkaline media. Cyclic voltammetry (CV) was used to investigate the oxygen reduction performance of MnxNi1−xCo2O4 (x = 0, 0.3, 0.5, 0.7, and 1), and Mn0.5Ni0.5Co2O4 was found to be the best-performing electrocatalyst. Upon supporting the Mn0.5Ni0.5Co2O4 on a carbon sheet, the electrocatalytic activity was significantly enhanced owing to its large surface area and the improved charge transfer brought about by the carbon support. Rotating disk electrode studies show that the ORR electrocatalytic activity of Mn0.5Ni0.5Co2O4/C proceeds via a four-electron pathway. Mn0.5Ni0.5Co2O4/C was found to possess E1/2(V) = 0.856, a current density of 5.54 mA cm−2, and a current loss of approximately 0.11% after 405 voltammetric scan cycles. This study suggests that the interesting electrocatalytic performance of multimetallic transition metal oxides can be further enhanced by supporting them on conductive carbon materials, which improve charge transfer and provide a more active surface area.

Carbon fibers

10.3390/catal11091059

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Citations (16)

Improving the electrocatalytic activity of Pd nanoparticles through electronic coupling interaction with a Ni₂P–MoS₂ hybrid support for ethanol electro-oxidation in an alkaline medium

Sustainable Energy & Fuels (2025)

Thabo Matthews Makhaokane Paulina Chabalala Siyabonga Patrick Mbokazi Memory Zikhali Tarekegn Heliso Dolla

Pd/Ni 2 P–MoS 2 hybrid shows improved electrocatalytic activity for ethanol electrooxidation. The interaction between Pd and the support enhances reaction kinetics and stability in alkaline environments, leading to better overall performance.

10.1039/d4se01223b

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