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One and done, or a bundle and stumble? an exploration of assessment methods in undergraduate science curricula

- Edwards, Shelley

Authors: Edwards, Shelley
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/461539 , vital:76211 , xlink:href="https://doi.org/10.2478/atd-2022-0023"
Description: Assessment, historically, has been done in a summative manner in post-secondary education (HE). Whilst useful for the purposes of grading and assessment of competency, there is also increasing pressure from post-secondary education institutions to meet certain standards in terms of education quality and graduate numbers, putting pressure on teachers to produce evidence of students’ level of understanding and thus putting a greater emphasis on the use of summative assessments. The formative assessment approach for student learning is preferable in some fields, but how useful is this format for the science subjects?
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Date Issued: 2022

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Photo-and thermoresponsive N-salicylideneaniline derivatives: solid-state studies and structural aspects

- Hulushe, Siyabonga T, Malan, Frederick P, Hosten, Eric C, Lobb, Kevin A, Khanye, Setshaba D, Watkins, Gareth M

Authors: Hulushe, Siyabonga T , Malan, Frederick P , Hosten, Eric C , Lobb, Kevin A , Khanye, Setshaba D , Watkins, Gareth M
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/451137 , vital:75021 , xlink:href="https://pubs.rsc.org/en/content/articlehtml/2022/nj/d1nj03056f"
Description: N-Salicylideneaniline (SA) and its derivatives are known to possess chromism upon exposure to external stimuli. Herein, we present mechanochemical synthesis of a series of photo-and thermoresponsive SAderivatives and report on solid-state stabilisation of their tautomeric forms either by change in temperature or by photoirradiation. The influence of UV light on proton transfer between the enol-imine (EI) and keto-amine (KA) forms was investigated at l1 = 254 and l2 = 365 nm. Differential scanning calorimetry (DSC) measurements provided extra information on the thermodynamic relationship between the prototropic tautomers, and their exposition to liquid nitrogen, combined with variable temperature single-crystal X-ray diffraction (VT-SCXRD) and spectroscopic data, ascertained structural reasons for the intrinsic thermo-optical properties of the compounds. A series of structural determinations between 150 and 300 K further shed light on the thermomechanical behaviour exhibited by the thermoresponsive compounds. By virtue of calorimetry we were able to demonstrate proton transfer via the intramolecular ON hydrogen bond over the temperature range 193–453 K. This present work demonstrates the importance of applying complementary analytical techniques and appropriate approaches for understanding the switching behaviour between the EI and KA forms. Furthermore, the assertion that it is predominantly the planarity (j o 251) that determines thermochromaticity is questioned.
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Date Issued: 2022

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Photodegradation of ibuprofen using 5-10-15-20-tetrakis (4-bromophenyl) porphyrin conjugated to graphene quantum dots

- Magaela, N Bridged, Ndlovu, Knowledge S, Tshangana, Charmaine S, Muleia, Adoph A, Mamba, Bhekie B, Nyokong, Tebello, Managa, Muthumuni

Authors: Magaela, N Bridged , Ndlovu, Knowledge S , Tshangana, Charmaine S , Muleia, Adoph A , Mamba, Bhekie B , Nyokong, Tebello , Managa, Muthumuni
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/304819 , vital:58493 , xlink:href="https://doi.org/10.1016/j.optmat.2022.113147"
Description: Ibuprofen (IBU) is a common anti-inflammatory drug that is consumed by many individuals in the world. As such, analytical studies have detected high concentrations of the drug in many waterbodies, which poses a risk of harmful effects on the environment and public health. The hydroxyl radical technologies, a collective of techniques also known as advanced oxidation processes (AOPs), can be utilized to degrade this emerging pollutant. In this study, the photodegradation of ibuprofen using 5,10,15,20-tetrakis(4-bromophenyl) porphyrin conjugated to graphene quantum dots was investigated using a custom-built photoreactor. Three different concentrations of IBU (200, 300 and 500 μM) were utilized as initial concentrations. The pH of the IBU was varied between acidic (pH 3.0), natural (pH 5.0) and alkaline (pH 9.0) to note the effect on IBU degradation as a function of time. The Highest ФΔ was obtained for InTBrP- GDQs (ФΔ = 0.80), followed by InTBrP (ФΔ = 0.74). The photodegradation efficiency of the TBrP-GQDs and InTBrP-GQDs were determined to be 43.2 and 76.1% respectively.
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Date Issued: 2022

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Photodegradation of tetracycline by asymmetrical zinc (II) phthalocyanines conjugated to cobalt tungstate nanoparticles

- Mgidlana, Sithi, Sen, Pinar, Nyokong, Tebello

Authors: Mgidlana, Sithi , Sen, Pinar , Nyokong, Tebello
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/300233 , vital:57908 , xlink:href="https://doi.org/10.1016/j.molstruc.2022.132938"
Description: This work focused on syntheses of novel asymmetrically tetra substituted Zn phthalocyanines (ZnPc) each containing a single carboxyl group, with the other substituents bearing alkynyl (complex 1) and fluorine containing groups (complexes 2 and 3). The complexes were conjugated to cobalt tungstate nanoparticles and employed as efficient photocatalysts for degradation of tetracycline in water. ZnPc complexes and their conjugates showed good photophysical and photochemical properties behaviour with complex 1 giving higher triplet and singlet oxygen quantum yields compared to 2 and 3. Complex 1 showed higher activity towards the photodegradation of tetracycline compared to complexes 2 and 3, with higher kobs and initial rates for the former. The photocatalysis obeyed the Langmuir-Hinshelwood kinetic model.
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Date Issued: 2022

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Photodynamic activity of novel cationic porphyrins conjugated to graphene quantum dots against Staphylococcus aureus

- Magaela, N Bridged, Makola, Lekgowa C, Managa, Muthumuni, Nyokong, Tebello

Authors: Magaela, N Bridged , Makola, Lekgowa C , Managa, Muthumuni , Nyokong, Tebello
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/295797 , vital:57379 , xlink:href="https://doi.org/10.1142/S1088424622500316"
Description: Novel 5-(pyridyl)-10-15-20-tris(4-bromophenyl) porphyrin (complex 1), indium metal derivative (complex 2), and quaternized derivative (complex 3) were synthesized and conjugated to graphene quantum dots (GQDs). The conjugation of the porphyrins to GQDs was through ππ-ππ stacking. Herein, the ππ-ππ stacking approach was used to avoid covalent conjugation which might compromise the intrinsic chemical and physical properties. The photodynamic activities of the proposed nanomaterials were assessed towards Staphylococcus aureus cell obliteration. The photophysical properties of the prepared complexes were also studied prior to the application. Moreover, a decrease in fluorescence lifetimes was observed upon metalation of complex 1. As anticipated, singlet oxygen quantum yield (ΦΔ)ΦΔ) increased notably upon heavy metal (indium) insertion and upon composite formation. Antimicrobial photodynamic therapy comparative studies were done on quaternized and unquaternized indium porphyrins conjugated to GQDs. Complex 3-GQDs exhibited the highest antibacterial activities compared to other complexes, and this was attributed to the high ΦΔΦΔ which plays an imperative role in photodynamic therapy applications.
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Date Issued: 2022

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Photodynamic therapy activity of 5, 10, 15-tris (5-bromo-2-thienyl), 20 (phenylcarboxy) porphyrin conjugated to graphene quantum dot against MCF-7 breast cancer cells

- Makola, Lekgowa Collen, Nwahahra, Nnamdi, Managa, Muthumuni, Nyokong, Tebello

Authors: Makola, Lekgowa Collen , Nwahahra, Nnamdi , Managa, Muthumuni , Nyokong, Tebello
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/300244 , vital:57909 , xlink:href="https://doi.org/10.1080/00958972.2022.2087515"
Description: A novel 5,10,15-tris(5-bromo-2-thienyl),20(phenylcarboxy)porphyrin and its gallium derivative have been synthesized and fully characterized by various spectroscopic techniques and their respective photophysical and photochemical properties, such as the singlet oxygen quantum yield (ΦΔ), fluorescence quantum yield (ΦF) and triplet lifetime (τT) were determined. The complexes were conjugated to PEI_GQDs resulting is stable conjugates, owing to strong π–π stacking interaction between the PEI_GQDs and the porphyrins. PDT studies were carried out on these nanoconjugates and results obtained indicated they are suitable candidates for further in-depth PDT studies.
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Date Issued: 2022

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Photodynamic therapy characteristics of phthalocyanines in the presence of boron doped detonation nanodiamonds

- Matshitse, Refilwe, Nwaji, Njemuwa, Managa, Muthimuni, Chen, Zhi-Long, Nyokong, Tebello

Authors: Matshitse, Refilwe , Nwaji, Njemuwa , Managa, Muthimuni , Chen, Zhi-Long , Nyokong, Tebello
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/229921 , vital:49723 , xlink:href="https://doi.org/10.1016/j.pdpdt.2021.102705"
Description: The synthesis, photophysicochemical and photodynamic therapy (PDT) activities of benzothiazole substituted zinc phthalocyanine (Pc): 1 (asymmetrically substituted and composed of no charges), 2 (asymmetrically substituted and composed of three positive charges), and 3 (symmetrically substituted and composed of four positive charges), are presented. The triplet and singlet oxygen quantum yields were highest for complex 2 showing the importance of asymmetry and charge. The complexes are covalently and non-covalently linked to B doped detonation nanodiamonds (B@DNDs) to yield nanohybrids (B@DNDs-1, B@DNDs-2, B@DNDs-3). The presence of B@DNDs, asymmetry and positive charge resulted in improved PDT with the lowest cell viability being observed for B@DNDs-2 at 5%. The cell viability ranged from 5% to 7% for the nanohybrids compared to 19–26% for Pcs alone.
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Date Issued: 2022

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Phthalocyanine based fabricated exfoliated graphite photoanode for electrodegradation of 4-acetamidophenol under visible light irradiation

- Mpeta, Lekhetho S, Nyokong, Tebello

Authors: Mpeta, Lekhetho S , Nyokong, Tebello
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/295809 , vital:57380 , xlink:href="https://doi.org/10.1016/j.jphotochem.2022.114115"
Description: In this study exfoliated graphite (EG) was prepared from natural graphite flakes and incorporated with zinc phthalocyanine for fabrication of photoanode. The electron transfer capabilities of fabricated photoanode were examined by using cyclic voltammetry, electrochemical impedance spectroscopy and scanning electrochemical microscopy. Electrophotocatalytic degradation of 4-acetamidophenol in 0.1 M Na2SO4 electrolyte was performed. The photoanode with zinc phthalocyanine (EG-ZnPc) displayed better degradation compared to when only exfoliated graphite was used (EG). Furthermore, electrophotocatalytic degradation gave better performance (removal efficiency of 47.76%) than when individual electrochemical degradation and photodegradation techniques were used.
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Date Issued: 2022

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Plagiarism and the commodification of knowledge

- McKenna, Sioux

Authors: McKenna, Sioux
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/426967 , vital:72404 , xlink:href="https://doi.org/10.1007/s10734-022-00926-5"
Description: Universities have put in place various policies and punishments to manage plagiarism and it is an issue of signifcant interest. This article looks at how plagiarism is discussed in the 55 Higher Education articles between 1982 and June 2022 that make some reference to the term. Many of the articles focused on a police-catch-punish approach and imbued a strong moral charge to the issue. In contrast to such articles were those that presented citation as a complex academic practice that needs to be engaged with educationally. Our understandings of and responses to plagiarism emerge from a number of causal mechanisms but I argue that a key mechanism is the commodifcation of knowledge. Where knowledge is a product to be packaged, bought, and sold, then ownership and attribution become more important than engagement and personal meaning making. Instead of our obsession with a police-catch-punish approach to plagiarism, at a more micro-level, we should be inducting students into the many roles citations serve, and at a macro-level, we should be engaging in considerations of the purposes of a higher education and how we might better enable students to enjoy a transformative relationship to knowledge.
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Date Issued: 2022

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Planetary Urgency, Researcher Reflexivity and ESE Research: Questions Arising from an Initial Exploration of Goethean-inspired Phenomenology

- Olvitt, Lausanne L

Authors: Olvitt, Lausanne L
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , book chapter
Identifier: http://hdl.handle.net/10962/437541 , vital:73392 , ISBN
Description: Many of the theoretical and methodological frameworks that are currently influential in Environment and Sustainability Education (ESE) research in South Africa foreground interventionist research, activism, causal explanation, critique, social-ecological transformation and decoloniality. These frameworks guide ESE researchers to design, implement and report on research in particular ways, hence influencing how social-ecological phenomena, learning and social change are understood and enacted. In this essay, I present some exploratory perspectives on the relevance and potential contribution of phenomenological approaches to ESE research, especially Goethean inspired observation.
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Date Issued: 2022

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Plant disease detection using deep learning on natural environment images

- De Silva, Malitha, Brown, Dane L

Authors: De Silva, Malitha , Brown, Dane L
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/465212 , vital:76583 , xlink:href="https://ieeexplore.ieee.org/abstract/document/9855925"
Description: Improving agriculture is one of the major concerns today, as it helps reduce global hunger. In past years, many technological advancements have been introduced to enhance harvest quality and quantity by controlling and preventing weeds, pests, and diseases. Several studies have focused on identifying diseases in plants, as it helps to make decisions on spraying fungicides and fertilizers. State-of-the-art systems typically combine image processing and deep learning methods to identify conditions with visible symptoms. However, they use already available data sets or images taken in controlled environments. This study was conducted on two data sets of ten plants collected in a natural environment. The first dataset contained RGB Visible images, while the second contained Near-Infrared (NIR) images of healthy and diseased leaves. The visible image dataset showed higher training and validation accuracies than the NIR image dataset with ResNet, Inception, VGG and MobileNet architectures. For the visible image and NIR dataset, ResNet-50V2 outperformed other models with validation accuracies of 98.35% and 94.01%, respectively.
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Date Issued: 2022

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Plant disease detection using multispectral imaging

- De Silva, Malitha, Brown, Dane L

Authors: De Silva, Malitha , Brown, Dane L
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/463439 , vital:76409 , xlink:href="https://link.springer.com/chapter/10.1007/978-3-031-35641-4_24"
Description: People worldwide are undergoing many challenges, including food scarcity. Many pieces of research are now focused on improving agriculture to increase the harvest and reduce the cost. Identifying plant diseases and pests in the early stages helps to enhance the yield and reduce costs. However, most plant disease identification research with computer vision has been done with images taken in controlled environments on publically available data sets. Near-Infrared (NIR) imaging is a favourable approach for identifying plant diseases. Therefore, this study collected NIR images of healthy and diseased leaves in the natural environment. The dataset is tested with eight Convolutional Neural Network (CNN) models with different train-test splits ranging from 10:90 to 90:10. The evaluated models attained their highest training and test accuracies from the 70:30 split onwards. Xception outperformed all the other models in all train-test splits and achieved 100% accuracy, precision and recall in the 80:20 train-test split.
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Date Issued: 2022

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Postgraduate education in a globalised world

- Boughey, Chrissie

Authors: Boughey, Chrissie
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , book chapter
Identifier: http://hdl.handle.net/10962/434469 , vital:73066 , ISBN 9781991201225 , https://www.google.co.za/books/edition/The_Global_Scholar/KvQ3EAAAQBAJ?hl=enandgbpv=0
Description: Interest in postgraduate education and the supervision of postgraduate research has developed in recent years, largely as a result of the impact of the so-called ‘knowledge economy’. South Africa’s National Plan 20301 draws on globalised discourses in holding that increases in the number of graduates, particularly at doctoral level, will contribute to economic prosperity because of the potential of postgraduate education to contribute to the processes of reinvention that drive the economic system itself. Even a brief glance at the mission and vision statements of a small sample of universities shows how this idea has been taken up within the higher education sector. In the context of high levels of unemployment, the idea that a postgraduate degree can lead to better work prospects also means that students who might never have considered doing a postgraduate degree previously, have now come forward to study at this level. All this then means that academics are being called upon to take on heavier supervision loads with a diverse array of students.
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Date Issued: 2022

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Preparation, characterization, and in vitro evaluation of polymer-based wound dressings for the management of chronic wounds

- Alven, Sibusiso

Authors: Alven, Sibusiso
Date: 2022
Subjects: Toxicity testing -- In vitro , Wound healing , Chronic diseases
Language: English
Type: Doctoral theses , text
Identifier: http://hdl.handle.net/10353/27992 , vital:71414
Description: Microbial infections are responsible for the retarded recovery process of chronic wounds. Polymer-based scaffolds possess features suitable for the treatment of chronic injuries. However, these scaffolds are commonly encapsulated with therapeutic agents to enhance their biological activities, including antibacterial efficacy. In this research, two types of polymer-based scaffolds were formulated and evaluated as effective formulations for the treatment of chronic wounds: sponges and topical gels. Sponges were formulated from cross-linking of gelatin and PEG. Ag nanoparticles and metronidazole were incorporated into the sponges to improve their antibacterial activity. Topical gels were loaded with essential oils and Ag nanoparticles and prepared from CMC and poloxamer. The prepared sponges and topical gels were evaluated using various analysis and characterization techniques. SEM/EDX, FTIR, and TGA were employed to characterize gelatin/PEG hybrid sponges followed by porosity, in vitro biodegradability, cytotoxicity, and antibacterial studies. FTIR, SEM/EDX, and TGA confirmed their physicochemical properties and successful fabrication of sponges loaded with metronidazole and Ag nanoparticles. The sponges were biodegradable, indicating their capability to induce skin regeneration. The drug release studies showed a rapid release of metronidazole 28.32-71.97 percent from the sponges over the first hour, followed by a sustained drug release. The Ag nanoparticles were released in a sustained manner, suggesting that these sponges can rapidly destroy bacteria and inhibit persisting bacterial infections as well as protect the lesion bed from further bacteria infections. The in vitro antibacterial studies of sponges displayed superior antibacterial activity against most of the Gram-negative and Gram-positive bacteria strains commonly found in chronic wound infections with a MIC value of 15.625 μg/mL. In vitro cytotoxicity experiments revealed excellent biocompatibility with a percent cell viability of more than 70 percent. The in vitro wound scratch healing assay exhibited that the sponges encapsulated with only metronidazole promoted high cell migration than the dual drug-loaded sponges and untreated cells, suggesting its potential to quicken the wound healing process. CMC/Poloxamer topical gels were also characterized by FTIR, followed by pH, viscosity, spreadability, cytotoxicity, and antibacterial studies. FTIR showed successful preparation of CMC/Poloxamer topical gels loaded with essential oils and Ag nanoparticles. The topical gels exhibited pH in the range of 5.20-6.68, spreadability between 5.4 and 5.9 cm, and viscosity ranged from 216 to 1200 cP at 50 rpm and 210–858 cP at 100 rpm. The in vitro drug release studies demonstrated that Ag nanoparticles were released from the topical gels in a sustained manner. Most formulated topical gels demonstrated superior antimicrobial efficacy against Gram-positive and Gram-negative bacteria strains than the blank gel and controls. The cytotoxicity analysis displayed more than 90.83 percent cell viability for the topical gels, revealing excellent biocompatibility. The outcomes revealed that the topical gels enriched with essential oils lavender and tea tree and Ag nanoparticles and sponges incorporated with metronidazole and Ag nanoparticles are potential wound dressing scaffolds that can be employed for the treatment of chronic infected injuries. The in vitro wound healing experiments showed that the HaCaT cells cultured with gels co-enriched with lavender oil and Ag nanoparticles possessed a higher rate of closure in comparison to the untreated cells for 96 hours. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
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Date Issued: 2022

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Principles of Computer Architecture

- Machanick, Philip

Authors: Machanick, Philip
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/439184 , vital:73553 , https://homes.cs.ru.ac.za/philip/Courses/CSHonsArch/HonsArchNotes2022.pdf
Description: Last week, Control Data ... announced the 6600 system. I understand that in the laboratory developing the system there are only 34 people including the janitor. Of these, 14 are engineers and 4 are programmers... Contrasting this modest effort with our vast development activities, I fail to understand why we have lost our industry leadership position by letting someone else offer the world’s most powerful computer – Thomas Watson Jr., IBM CEO, August 1963 It seems like Mr. Watson has answered his own question – Seymour Cray
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Date Issued: 2022

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Promotion of Catalytic Oxygen Reduction Reactions

- Wei, Yuqin, Zhao, Long, Yuan, Rui, Xue, Zhaoli, Mack, John, Chivumba, Choonzo, Nyokong, Tebello, Zhang, Jianming

Authors: Wei, Yuqin , Zhao, Long , Yuan, Rui , Xue, Zhaoli , Mack, John , Chivumba, Choonzo , Nyokong, Tebello , Zhang, Jianming
Date: 2022
Subjects: To be catalogued
Language: English
Type: text , article
Identifier: http://hdl.handle.net/10962/300347 , vital:57919 , xlink:href="https://doi.org/10.1021/acs.inorgchem.2c01591"
Description: Three ABAB-type cobalt meso-tetraarylporphyrins with fluorine (F-CoPor), acetic acid (AC-CoPor), and cyanoacetic acid (CN-CoPor) groups at the para-positions of phenyl rings at the 10,20-positions are synthesized and evaluated as catalysts for oxygen reduction reactions (ORRs). In density functional theory calculations, the frontier molecular orbitals of these complexes were found to be stabilized relative to model complexes with electron-withdrawing atoms or moieties on the meso-aryl rings. Electrochemical measurements suggest that electrodes with CN-CoPor (CN-CoPor/C) exhibit the most positive ORR potential values and the highest limiting current density in both acidic and alkali electrolytes, while the F-CoPor/C electrocatalyst exhibits extremely low ORR performance. The electron transfer numbers for the electrocatalysts are more than 3.0, indicating that a mixture of 2- and 4-electron transfer pathways occurs. The results demonstrate that coupling the hydrogen bonding properties and electron-withdrawing abilities through rational design of the substituent at the meso-position is an efficient way to modify the ORR performance.
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Date Issued: 2022

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