Research Articles (Chemistry)

Permanent URI for this collectionhttps://hdl.handle.net/10566/387

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Synthesis and characterization of cathode catalysts for use in direct methanol fuel cells
(University of the Western Cape, 2010) Piet, Marvin
In this work a modified pol yo I method was developed to synthesize in-house catalysts. The method was modified for maximum delivery of product and proved to be quick and efficient as well as cost effective. The series of IH catalysts were characterized using techniques such as UV -vis and FT -IR spectroscopy, TEM, XRD, ICP and CV. The polyol method developed effectively reduced and deposited Pt nanoparticles onto different carbon supports. Functionalization of some of the supports was also successfully carried out through acid oxidative treatment which introduced carboxylic acid and hydroxyl groups onto the surface of the supporting material, which was supported by FT-IR which demonstrated that there was a relative increase in absorbance of functionalities viz., carboxylic acid (l270 em") and hydroxyl groups on the surface of the acid treated MWCNT's-F compared to the untreated MWCNT's. Addition of a sedimentation promoter proved to increase the amount of metal deposition on the support thereby improving the loading dramatically. It was also found that addition of a specific amount of water in the polyol method allowed one to control the particle growth during the deposition phase on the various carbon supports investigated namely; XC-72 carbon, MWCNT's and MWCNT's-F. The in-house catalysts synthesized namely; PtJC-IH, PtJMWCNT's-IH and PtJMWCNT's-F-IH all displayed narrow particle size distributions with average mean particle sizes of 2-5 nm, 2-6 nm and 3-6 nm respectively which was in good agreement with particle size measurements obtained from XRD using the Scherrer formula. All measured CV's obtained for the series of IH catalysts prepared by this protocol were comparable with the commercial catalyst. The IH catalysts displayed the characteristic XRD peaks associated with Pt on carbon supports in acidic media. The ORR measurements for PtJMWCNT's-F-iH (functionalised) proved to be slightly superior (0.058 Azcm") compared to that of the commercial catalyst (0.047 Alcm2) at a potential of O.3V.
Antimony-decorated reduced graphene oxide in zinc oxide buffer layer for thin-film solar cells
(Elsevier, 2026) Ramoroka Morongwa E.; Nwambaekwe Kelechi C.; Sitole Soyama
Recently, nanoparticle–graphene oxide composites have emerged as promising materials for optoelectronic applications. In this study, a graphene oxide (GO) composite anchored with Sb nanoparticles (Sb NPs) was synthesized via a microwave-assisted method. Comprehensive characterization was conducted to compare the structural, optical, thermal, and electrochemical properties of Sb-rGO with those of pristine GO and Sb NPs. Subsequently, GO, Sb NPs, and Sb-rGO were incorporated into a ZnO electron transport layer (ETL) in Cu2ZnSnS4 (CZTS) kesterite solar cells. Incorporation of Sb-rGO yielded a power conversion efficiency (PCE) of 4.24%, surpassing the efficiencies achieved with GO (3.85%) and Sb NPs (3.94%), primarily due to enhanced electron extraction from the absorber. Electrochemical impedance spectroscopy and dark current–voltage analysis confirmed that the performance enhancement arises from reduced charge-carrier recombination and improved charge collection. The ZnO:GO, ZnO:Sb NPs, and ZnO:Sb-rGO layers exhibited optical transmittance above 85%, and the corresponding devices retained more than 79% of their initial PCE after 20 days of storage. These results show the beneficial role of Sb-rGO in improving both the efficiency and stability of CZTS-based kesterite solar cells.
Unravelling redox driven electron transfer mechanisms within polythionine modified sensors, in the context of cortisol detection in vitro.
(Elsevier, 2026) Wilson Lindsay R.; Arendse Christopher J.; Baker Priscilla G.L.
Polythionine (PTH), a heterocyclic thiazine based conducting polymer known for its excellent redox activity, electrocatalytic properties, and biocompatibility. This study investigates the electrochemical behaviour of PTH on screen-printed carbon electrodes (SPCEs). Cyclic voltammetry, electrochemical impedance spectroscopy and spectroelectrochemistry were employed to characterize and assess electronic and redox processes. Polythionine modified SPCE exhibited pH dependent redox and capacitive behaviour according to spectroelectrochemistry and impedimetric phase angle maxima measurements as a function of applied voltage, with the lowest measured in acidic medium. Absorbance spectra are blue shifted for PTH bound SPCE in comparison to TH monomer. The difference in oxidation states allows PTH to be tunable for (bio)-chemical analysis, particularly useful for detection of critical hormones. Here, the platform was used to show usefulness for the electrochemical detection of cortisol, the stress hormone The sensing was done and achieved as a novel approach using polythionine modified SPCE. The assay exhibited a LOD of 45 μM, LOQ of 135 μM, dynamic linear range of 456 μM to 952 μM and sensitivity of 0.045 μA/μM. Though the polymer based chemical sensor performance metrics are not suitable for low cortisol concentrations, the assay remains a critical step towards proof-of-concept sensor systems for measuring critical biologically relevant small organic molecules in the micro molar range in vitro.
TFA generation and deposition over Europe may currently see a greater influence from hfo-1234yf than hfc-134a
(American Chemical Society, 2026) Holland, Rayne; Adam, Ben; Shallcross, Dudley Edmund
Concerns around the prevalence of trifluoroacetic acid (TFA, CF3COOH) in the environment have been ongoing for more than 20 years. One source of TFA to the environment is via the atmospheric degradation of fluorinated gases (F-gases) to TFA and its subsequent deposition. During the past decade, controls on one major class of F-gases, hydrofluorocarbons (HFCs), have resulted in an increase in the production and use of hydrofluoroolefins (HFOs). Here, a tropospheric chemical transport model, STOCHEM-CRI, is used to compare the amount of TFA generated by the breakdown of an abundant HFC, HFC-134a (1,1,1,2-tetrafluoroethane, CF3CH2F), and its typical replacement, HFO-1234yf (2,3,3,3-tetrafluoropropene, CH2═CFCF3). Using derived global emission estimates for 2023, we predict that HFO-1234yf is already dominating atmospheric generation and deposition of TFA over Europe when compared with HFC-134a. This is despite the fact that the derived global emissions of HFC-134a are 22 times higher than those of HFO-1234yf. Globally, our simulations show that TFA production from HFO-1234yf is already equivalent to 26–75% of the TFA production from HFC-134a. As the transition away from HFCs progresses, it is likely that HFO-1234yf will continue to increase in its global contribution to TFA generation and resultant environmental contamination
Tfa generation and deposition over Europe may currently see a greater influence from hfo-1234yf than hfc-134a
(American Chemical Society, 2026) Shallcross, Dudley E.; Holland, Rayne; Adam, Ben
Concerns around the prevalence of trifluoroacetic acid (TFA, CF3COOH) in the environment have been ongoing for more than 20 years. One source of TFA to the environment is via the atmospheric degradation of fluorinated gases (F-gases) to TFA and its subsequent deposition. During the past decade, controls on one major class of F-gases, hydrofluorocarbons (HFCs), have resulted in an increase in the production and use of hydrofluoroolefins (HFOs). Here, a tropospheric chemical transport model, STOCHEM-CRI, is used to compare the amount of TFA generated by the breakdown of an abundant HFC, HFC-134a (1,1,1,2-tetrafluoroethane, CF3CH2F), and its typical replacement, HFO-1234yf (2,3,3,3-tetrafluoropropene, CH2═CFCF3). Using derived global emission estimates for 2023, we predict that HFO-1234yf is already dominating atmospheric generation and deposition of TFA over Europe when compared with HFC-134a. This is despite the fact that the derived global emissions of HFC-134a are 22 times higher than those of HFO-1234yf. Globally, our simulations show that TFA production from HFO-1234yf is already equivalent to 26–75% of the TFA production from HFC-134a. As the transition away from HFCs progresses, it is likely that HFO-1234yf will continue to increase in its global contribution to TFA generation and resultant environmental contamination.
Enabling plateau-dominated sodium storage in dual-doped hard carbon via industrial-scale engineering
(John Wiley and Sons Inc, 2026) Wang, Qi; Iwuoha, Emmanuel; Li, Tingzhen
Hard carbon (HC) has emerged as a key anode for sodium-ion batteries (SIBs) due to its unique microcrystalline graphite regions and nanocavity structures. However, its relatively low plateau reversible capacity limits the energy density of SIBs. While conventional heteroatom doping can improve capacity, it often leads to low initial coulombic efficiency (ICE) and shifts the high capacity to the slope region. To overcome this, we develop a novel industrial-level heteroatom dual-doped strategy. By optimizing the dual-doped structure, we significantly enhance the Na+ ions adsorption and migration in the plateau region, leading to high reversible capacity (394 mAh/g) and high ICE (89%). We further reveal a coupled sodium storage mechanism during plateau sodiation. This mechanism involves both pore filling and interlayer embedding. The coexistence of these two processes explains the improved plateau capacity. The kilogram-scale HC shows stable performance over a wide temperature range in cylindrical full cells. Life cycle assessment shows a lower environmental impact than conventional graphite. Techno-economic analysis confirms competitive cost and good economic potential. This work provides a practical route toward high-energy, sustainable, and cost-effective SIBs for wide-temperature applications.
Design development of bimetallic clusters onto copper-benzimidazole metal–organic frameworks and their derived materials as electrocatalysts for water electrolysis and hydrogen fuel cell applications
(American Chemical Society, 2026) Ramohlola, Kabelo E.; Monama, Gobeng R.; Mothlathlo, Terrence
The development of efficient and cost-effective electrocatalysts is essential for advancing clean hydrogen energy technologies. In this study, a copper-based zeolitic imidazolate framework (CuZIF) was synthesized and further modified with platinum (Pt) and ruthenium (Ru) via electroless plating to obtain PtRu@CuZIF, followed by pyrolysis to form PtRu@Cu–N/C. Comprehensive characterization was confirmed using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction spectroscopy (XRD), Brunauer–Emmett–Teller (BET) analysis, and scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) analysis. Electrochemical evaluations in 0.1 M KOH demonstrated that the PtRu@CuZIF electrocatalyst achieved superior hydrogen evolution reaction (HER) performance, with a low overpotential of 284 mV at 10 mA cm–2, a Tafel slope of 119 mV dec–1, and a high turnover frequency of 7.08 × 10–4 s–1, following a Volmer–Heyrovsky mechanism. Although CuZIF showed the highest conductivity and electrochemical surface area, its HER performance was hindered by dispersion of PtRu particles. The PtRu@Cu–N/C electrocatalyst showed the highest stability and power output, achieving an energy density of 165.78 Wh kg–1 and a power density of 497.33 W kg–1. These findings highlight the potential of bimetallic MOF-derived materials for integrated water electrolysis and hydrogen fuel cell applications.
A novel Dinuclear rhenium(I) Tricarbonyl complex as a potential anticancer agent: synthesis, structural characterisation, in vitro evaluation, density functional theory, and molecular docking binding modes
(Elsevier Inc., 2026) Alexander, Orbett T.; Ramoba, Lesetja V.; Direm, Amani
Rhenium tricarbonyl complexes in their monometallic forms have been extensively studied, mainly for their potent inhibitory activity against cancer cells. However, far fewer dinuclear complexes have been investigated for similar applications. In this study, we report the synthesis, crystal structure, DFT analysis, in vitro biological screening, and in silico molecular docking of the complex NEt4[{Re(CO)3}2-μ-(OCH3)2-μ-(3,5-Me2py)], C1 (where OCH3 = methoxy; 3,5-Me2py = 3,5-dimethyl-1H-pyrazolate). This dinuclear complex, C1, was characterised spectroscopically by FT-IR, 1H and 13C NMR, UV–Vis, as well as single-crystal X-ray diffraction. Preliminary in vitro screening at a single dose of 10 μM in DMSO revealed excellent cytotoxicity of C1 against cervical (HeLa and CaSki), pancreatic (PANC-1 and CFPAC-1), and breast (MCF-7) cancer cell lines. It was further evaluated for its half-maximal inhibitory concentration (IC50) which was determined as 1.59 ± 0.34 (SI = 6.39), 1.06 ± 0.35 (SI = 9.59), 0.74 ± 0.22 (SI = 13.73), 3.58 ± 0.10 (SI = 2.83) and 2.24 ± 0.45 (SI = 4.54) μM against HeLa, CaSki, CFPAC-1, PANC-1 and MCF-7, respectively, while the IC50 against MRC-5 (non-cancerous human fibroblast cells) was 10.16 ± 0.8 μM. The DFT calculations indicated that C1 is both reactive and conductive, with an energy gap (EHOMO-ELUMO) of 4.11 eV. Additionally, C1 was docked against tubulin to illustrate its potential binding modes to the target tubulin, and the in silico molecular docking results revealed binding affinities ranging from −5.43 to −4.37 kcal/mol.
The potential of hydrothermally synthesized MoO3 and Cr doped MoO3 nanoparticles for electrochemical energy storage applications
(Elsevier B.V., 2026) Iwuoha, Emmanuel Iheanyichukwu; Ogirima, Ibrahim Yakubu; Geremu, Tadele
Molybdenum trioxide (MoO3) based electrode materials have generated interest for electrochemical energy storage application due to their exceptional optical and chemical properties. However, MoO3 suffers from some drawbacks such as weak electrical conductivity and instability which have necessitated new and innovative approaches to overcome these challenges. In this work, we doped MoO3 with chromium (Cr) with the aim of enhancing its conductivity and further studied the effect of hydrothermal treatment time on its physicochemical and electrochemical properties. The x-ray diffraction results indicate that the materials exhibited an orthorhombic crystal structure. The electrochemical results show that the Cr doped MoO3 obtained after 12 h of hydrothermal treatment (Cr@MoO3-12h) gave the highest specific capacitance of 465 Fg−1, much higher than the other chromium doped MoO3 and the undoped MoO3 nanoparticles at all the hydrothermal treatment times considered. The Cr@MoO3-12h electrode also showed the highest stability retaining almost 89% of its initial specific capacitance over charge-discharge cycles 5000 cycles at 1 A g−1. This suggests that chromium doping and maximizing the hydrothermal treatment duration improved the electrochemical performance of the molybdenum trioxide nanoparticles.
Label-free novel platform for electrochemical detection of E. coli in tap water
(Elsevier B.V, 2026) Shahzad, Suniya; Iftikhar, Faiza Jan; Khan, Asad Ullah; Ullah, Riaz; Iwuoha, Emmanuel; Shah, Afza; Khan, Raees; Saqib, Ahmad Nauman Shah
Waterborne infections such as hepatitis, diarrhea, encephalitis etc., are caused by viruses and remain the main cause of fatality worldwide. Diarrhea alone has led to 2.2 million deaths per year worldwide. These viruses are mostly transferred by fecal-oral passage, causing waterborne diseases. The World Health Organization (WHO) estimates that waterborne pathogens contribute to 4% of the diseases worldwide which highlights a critical need to search for efficient methods to detect these pathogens in a robust and rapid manner. Thus, by employing a sensitive platform that can improve the limit of detection (LOD) by manifolds, the aim is to detect the virus timely and thus reduce disease prevalence. Here Zeolite imidazolate framework (ZIF) a type of MOFs with bimetallic transition elements, has been used to improve electrocatalytic performance and ability to detect pathogens without the need of using labels such as enzymes, fluorescent tags etc. We report an ultrasensitive electrochemical sensor based on NiCoZIF/CNTs to detect low concentrations of E.Coli in tap water where the LOD is reported as 0.37 CFU/mL. The sensing platform has also been morphologically and electrochemically studied. This sensor has clear practical applications such as public health, water quality monitoring and food safety.
Field-based assessment of selected pharmaceuticals, pesticides and sediment metals using macrofauna and nematode communities in False Bay, South Africa
(Elsevier Ltd, 2026) Mazeka, Buyani; Tshingana-Bali, Bomikazi; Murgatroyd, Olivia; Moser, Justin; Ojemaye, Cecilia Y.; Petrik, Leslie F; Karenyi, Natasha
False Bay supports high biodiversity but is increasingly subjected to anthropogenic pressures, including urbanisation and harbour activities. This study aimed to (1) quantify selected pharmaceuticals (e.g., acetaminophen, carbamazepine, diclofenac), herbicides (atrazine and metolachlor) and metals (Cu, Fe, Mn, Pb and Zn), (2) examine their spatial distribution, and (3) assess their potential effects on benthic assemblages. Sampling was conducted between 18 April and 14 June 2021 across 19 stations. Pharmaceuticals and herbicides were widely detected in seawater (LDL – 1.1 ng/L) and sediments (LDL – 54.6 ng/g), with higher concentrations in sediments, indicating their role as long-term contaminant reservoirs. Spatial patterns revealed localised enrichment near wastewater discharge zones and urbanised areas. Metal concentrations (1.6–7732 μg/g) were similarly elevated in anthropogenically influenced areas. However, risk quotient (RQ) remained <0.1 and metal concentrations were below ERL thresholds, suggesting a low potential of acute biological effects. Benthic assemblages were diverse and typical of coastal sandy environments, with no significant relationships detected between contaminant concentrations and community metrics. Nematode indices (MI and ITD) indicated good to high ecological quality. The single sampling design and family-level taxonomic resolution may have limited the detection of sub-lethal, chronic or species-specific responses. While contaminants are widespread and accumulate in sediments, their current concentrations are unlikely to cause acute ecological impacts benthos. However, chronic effects and the presence of unmonitored contaminants cannot be excluded. Long-term monitoring and higher taxonomic resolution are recommended to better understand and access cumulative ecological risks.
Towards regulatory readiness: evaluating frameworks for microplastic health risk assessment
(Springer Nature, 2026) Christopher, Emily A.; Bouwmeester, Hans; Christopher, Emily A.; Coffin, Scott; Haase, Andrea; Lane, Taylor; Legler, Juliette
Micro- and nanoplastic particles (MNPs) have emerged as pollutants of high public concern. Assessing and managing the risks of these particles remains challenging for several reasons. A long-term goal is to establish a comprehensive risk-governance framework that includes risk framing, scientifically sound risk assessment that accounts for human and environmental safety, evaluation, and risk management/decision making. A realistic short-term goal is to develop a comprehensive human health risk assessment framework (RAF). Very recently, RAFs for evaluating the human-health risks of MNPs have become available; however, comparative analyses of these frameworks are lacking. Here, we discuss six established frameworks to assess their technological and regulatory readiness. We begin by proposing nine technical criteria that a risk-assessment framework should meet to inform policy and action. These include the degree of quantifiability of outputs; the provision for systematic evaluation of the quality of input data; the consistency between exposure and effect data with respect to underlying mechanisms; the extent to which the complexity and diversity of environmentally realistic microplastics are addressed; readiness for integration into existing regulatory approaches; and the extent of real-world implementation to date. We discuss the specific strengths of each framework and recommend combining them into a single overarching framework that integrates these strengths.
Meroterpenoids and fucoxanthin from the brown seaweed sargassum incisifolium: solid lipid nanoparticle delivery, physicochemical characterization, and antimicrobial activity
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Witness, Sibiya; Samsodien, Mogammad L.; Vreulink, Jo-Marie; Le Roes-Hill, Marilize; Bolton, John J.; Beukes, Denzil R.; Antunes, Edith
Marine macroalgae are a rich source of bioactive natural products, although the application of many lipophilic compounds is limited by poor aqueous solubility and instability. This study investigated metabolites isolated from the South African brown seaweed Sargassum incisifolium and evaluated a solid lipid nanoparticle (SLN) system to improve their physicochemical properties and enable bioactivity studies. Five metabolites, including one previously unreported derivative and four known metabolites (including fucoxanthin), were isolated and characterized using standard chromatographic and spectroscopic techniques. SLNs composed of stearic acid and Poloxamer 188 were prepared via hot homogenization and characterized using dynamic light scattering, scanning electron microscopy, thermogravimetric analysis, and NMR, which confirmed the efficient encapsulation of the lipophilic compounds. Antimicrobial activity against clinically relevant bacterial and fungal pathogens was evaluated using a resazurin-based microdilution assay, with results expressed as percentage growth relative to untreated controls. The pure compounds exhibited moderate, concentration-dependent activity, while the SLN formulations improved dispersibility, and in several cases, reduced % growth or produced more consistent responses, particularly against Gram-positive bacteria and Candida auris. Although activity remained lower than that of conventional antimicrobials, these findings demonstrate that SLN-based delivery enables functional evaluation of hydrophobic marine metabolites and supports further development of Sargassum-derived natural products.
Synthesis of BEA zeolite from coal fly ash nano-silica extract: application in CO2 adsorption
(Elsevier B.V., 2026) Ameh, Alechine; Mukaba, Jean-Luc; Pokpas, Keagan; Petrik, Leslie
This study demonstrates a circular economy approach to carbon dioxide sorption by re-purposing coal fly ash (CFA) into BEA zeolite using CFA-derived nano-silica and aluminum precursors via hydrothermal synthesis. The XRD patterns, with characteristic peaks at 15° and 37° 2θ, and SEM images both confirmed the complete transformation of the spherical-shaped CFA particles into amorphous nano-silica materials with particle sizes less than 100 nm. The absence of amorphous phases and the formation of high-intensity peaks at 7.8° and 22.8° 2θ further indicated the production of a highly crystalline BEA zeolite, obtained after hydrothermal synthesis durations between 10 and 72 h. The conversion of amorphous nano-silica into BEA zeolites significantly enhanced the surface area from 54 m2/g to 547 m2/g. The as-synthesized BEA zeolites exhibit a spheroidal shape with crystal dimensions ranging from 190 to 450 nm, solely controlled by the molar ratio of H2O/Si during hydrothermal synthesis. CO2 sorption capacity upon the transformation of nano-silica into BEA zeolites rose from 0.91 to 3.24 mmol/g for low-temperature evaluation (≈0 °C, 1.2 bar). The BEA zeolite adsorbent retained structural integrity with only ∼9% performance loss after ten adsorption–desorption cycles. These outcomes highlight CFA-derived BEA zeolite as a robust, scalable, and resource-efficient adsorbent for CO2 capture.
Silica derived from rice husk waste as anode material for lithium-ion battery: a comprehensive study
(Elsevier B.V., 2026) Iwuoha, Emmanuel Iheanyichukwu; Nzereogu, Paul; Omah, Augustine Dinobi
This research investigates the synthesis and characterization of silica extracted from rice husks sourced from Adani in Enugu State, Nigeria, and its application in lithium-ion batteries. In this work, two methodologies for extracting SiO2 from rice husk were explored: rice husk pre-treatment process (acid leaching) and rice husk post-treatment process (alkaline digestion). The rice husks underwent acid leaching with 10 % HCl, followed by calcination at temperatures ranging from 500°C to 800°C. The sample post-treatment involved alkaline digestion using a 1 N sodium hydroxide solution. Results from structural analysis showed a progressive increase in purity and amorphous properties of silica up to a calcination temperature of 700°C. At 800°C, crystalline forms of silica, such as cristobalite and tridymite, were observed. The post-treated samples, especially those calcined at 700°C (PT700), exhibited comparative higher purity. Electrochemical studies were carried out using Cyclic Voltammetry (CV), Galvanostatic Charge/Discharge (GCD) and Electrochemical Impedance Spectroscopy (EIS), and the results show that the post treated rice husk that was calcined at 700 °C (PT700) had the highest specific capacity of 913 mAh g⁻¹ at a current density of 100 mA g−1 and retained ∼89 % of this capacity after 1000 charge-discharge cycles. The energy density of the PT700 sample was 302 Wh kg⁻¹, demonstrating its potential as a viable alternative to graphite in lithium-ion battery applications. The study concludes that silica extracted from rice husks is a sustainable and efficient material for use in energy storage devices, offering significant advantages in terms of reactivity, surface area, and electrochemical performance.
Green synthesis and application of biochar derived from alien vegetation wood for proton exchange membrane fuel cells
(John Wiley and Sons Inc, 2025) Sobekwa, Alunge Gift
Invasive alien vegetation brought about by various human activities has grown to be a significant threat to the ecosystem and its diversity; therefore, control strategies to combat this threat are being explored. This review aims to investigate the prospect of using biochar specifically from alien vegetation as a support material for the proton exchange membrane (PEM) fuel cell electrocatalyst, highlighting the need to move to green energy and invest in Eco conservation. The use of biochar derived from alien vegetation as carbon support for the platinum (Pt) electrocatalyst for PEM fuel cells is an interesting field that is slowly gaining momentum. Biochar has the potential to be used as a carbon support due to its high specific surface, area, and intrinsic property needed for an electrocatalyst support. The current widely used electrocatalyst, which is Pt supported on carbon black, has shown to suffer from corrosion which weakens the bond between the support and the Pt nanoparticles, leading to instability and resistance; therefore, alternative supports are needed also to decrease the Pt loading as it is expensive. The focus of this review is on the benefits and prospects of these cheap green resources in increasing efforts to conserve the environment.
Development of an efficient supercapacitor using hydrothermally synthesized nickel sulfide
(Springer, 2025) Sindhu, Sarita
The current research explores the hydrothermal synthesis of nickel sulfide over a temperature range of 120–180°C, with advanced characterization used to assess features influencing its electrochemical behavior in supercapacitor applications. The temperature variation in the synthesis process results in a pure β-NiS phase at lower temperatures, while at higher temperatures, up to 180°C, mixed phases were confirmed by XRD, with FTIR revealing the characteristic vibrational modes of nickel sulfide. FE-SEM micrographs show a morphological transition from nanoflakes to microflowers to agglomerated flakes, influencing the specific surface area (10.45 m2g⁻1), for the sample synthesized at 140 °C, as determined by BET analysis. The electrochemical analysis of the fabricated electrodes was conducted in different electrolytes, revealing that NiS synthesized at 140°C achieves the highest capacitance of 294 Fg⁻1 at 1 A g⁻1 in KOH, establishing it as a promising candidate for supercapacitor applications.
Electrochemical performance of ZnCo2O4: versatility in applications
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Sitole, Soyama; Ross, Natasha; Bilibana, Mawethu Pascoe
Zinc cobaltite (ZnCo2O4) is a ternary metal oxide found in spinel with promising properties for various applications. Optimizing its catalytic activity requires an understanding of its electrochemical behavior. The electrochemical properties of ZnCo2O4 have significantly improved due to recent developments in nanostructuring, doping, surface modification, hybridization, structural engineering, and electrochemical activation. These improvements have inspired and motivated researchers by presenting the latest developments in the field. The spinel structure, coupled with the redox properties of cobalt ions, semiconducting characteristics, and electrocatalytic potential, positions ZnCo2O4 as a versatile material for several electrochemical energy storage and conversion systems. This review explores these advancements; the notable properties of ZnCo2O4; and its applications in sensors, batteries, photovoltaics, and supercapacitors.
Green synthesis of crystalline silicon nanoparticles (SiNPs) via magnesiothermic reduction of mesoporous silica extracted from sugarcane bagasse ash (SCBA)
(Elsevier Ltd, 2026) September, Lyle; Seroka, Ntalane; Khotseng, Lindiwe
In this study, crystalline silicon nanoparticles (SiNPs) were successfully produced utilising a low-temperature magnesiothermic reduction method of mesoporous silica nanoparticles (SiO2NPs). Silicon nanoparticles (SiNPs) have gained attention in recent years due to their range of applications and specific properties. However, producing high-purity SiNPs necessitates high-energy production, such as carbothermic reduction at >2000 °C, in addition to the significant pollutants and CO2 emissions generated throughout the process. Thus, there has been an increase in research on extracting SiNPs from various agricultural wastes as a cost-effective source. This study investigates the extraction of SiO2NPs using sol-gel synthesis from sugarcane bagasse ash (SCBA) and resulted in a purity of 94.8% utilising XRF. After magnesiothermic reduction of SiO2NPs at 650 °C, XRD and Raman confirmed the resulting crystalline SiNPs. Furthermore, SEM and TEM were used to investigate the morphology along with BET to determine specific surface area, pore volume, and pore diameter, which resulted in 57.85 m2/g, 0.18 cm3/g, and 12.4 nm, respectively, for the produced SiNPs. Additionally, this study includes the use of a green-sustainable synthesis method to decrease energy usage and attempts to replace toxic counterparts with reagents such as the use of L-cysteine hydrochloride monohydrate and citric acid, while obtaining high-purity SiNPs. SiNPs have a variety of possible applications in new advancements, including energy production like solar photovoltaic cells and energy storage devices, which contribute towards the UN's sustainable development goals (SDG), particularly SDG 7 (Affordable and clean energy) and SDG 13 (Climate Action), as this study exhibits sustainability and increases the potential to reduce biomass waste production.
Adsorption removal of methyl violet dye by α-fe2o3 and aminated α-fe2o3 metal oxide composites synthesized via solvothermal process
(Elsevier Ltd, 2026) Mouele, Emile Salomon Massima; Asemahle, Tupha; Petrik, Leslie F.; Bladergroen, Bernard; Okoh, Anthony Ifeanyi; Okoh, Omobola O.
The discharge of persistent artificial dyes, like the cationic methyl violet (MV) dye from textile industrial sewages, requires the development of efficient, cost-effective, and recyclable adsorbents. This work reports on the synthesis of hematite (α-Fe2O3) and amino-modified α-Fe2O3 via the solvothermal method. The effects of surface amination on the nanomaterials' physicochemical attributes were probed by the adsorption of MV wastewater. Successful amine functionalization was confirmed using FTIR and elemental analyses. SEM analysis revealed porous spherical morphologies with an enhanced surface texture following amination. XRD and TGA confirmed the structural stability and thermal resilience of the nanomaterials. Zeta potential showed that the aminated α-Fe2O3 carried a negative surface charge above pH 3, favoring the cationic dye adsorption. The aminated material exhibited a maximum MV adsorption capacity of 10.21 mg/g with equilibrium data conforming to the Langmuir isotherm (R2 = 0.978) as compared to the Freundlich (R2 = 0.662) and Temkin (R2 = 0.634) isotherms, while kinetics data fitted the pseudo-second-order model (R2 = 0.966). The regeneration of aminated α-Fe2O3 sorbent with 0.4 M HCl favoured reclaim for four successive cycles with a slight decrease in efficiency of about 19%. The study demonstrates that the solvothermally produced α-Fe2O3 is a promising low-cost adsorbent for the removal of organic dyes in wastewater treatment applications.

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