Research Articles (Chemistry)

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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.
Non‐thermal plasma‐activated ammonia decomposition for hydrogen production: tuning CeO2 catalyst nanomorphology to enhance performance
(Wiley, 2026) Wu, Xuan; Xu, Shaojun; Bladergroen, Bernard Jan; Xiang, Nianwen; Bladergroen, Bernard Jan; Xiang, Nianwen; Zhang, Cheng; Shao, Tao; Chen, Weijiang; Ding, Lijian
Non‐thermal plasma coupled with catalysts offers a promising route to improve ammonia‐to‐hydrogen conversion efficiency.This study integrates plasma discharge with morphology‐controlled CeO2 nanocrystals (fiber, cuboids‐S, cuboids‐L, nano‐rod,and pyramid) to enhance ammonia decomposition. Among them, CeO2 fiber achieves outstanding ammonia conversionexceeding 99.9% (SIE = 19.8 kJ L−1) without metal additives or external heating, while also demonstrating remarkable long‐term stability. Through combined microscopic, electrical, and Mass Spectrometry‐based transient analysis, it is revealed that thefibrous CeO2 structure increases the surface Ce3+ and oxygen vacancy concentration and provides balanced NH3 adsorption,boosting catalytic activity. Additionally, its favorable dielectric properties enhance plasma discharge and plasma−catalystinteractions. These results demonstrate that tuning catalyst nanostructure is an effective alternative to noble metal doping forefficient plasma‐driven catalysis.
Characterization of ornithobacterium hominis colonization dynamics and interaction with the nasopharyngeal microbiome in a South African birth cohort
(Microbiology Society, 2026) De Allende, Celine C.; Salter, Susannah J.; Brigg, Siobhan Ernan; Boardman, Micaela; Claassen-Weitz, Shantelle; Mwaikono, Kilaza Samson; Workman, Lesley J.; Zar, Heather J.; Nicol, Mark P.; Parkhill, Julian; Dube, Felix S.
Ornithobacterium hominis is a recently described Gram-negative bacterium that colonizes the human nasopharynx and may be associated with poor upper respiratory tract health. Here, we describe the isolation of O. hominis from samples collected from a South African birth cohort, creating the first archive of cultured strains of the species from Africa. Sequenced genomes from this archive reveal that South African O. hominis is more similar to Australian strains than those from Southeast Asia and that it may share genes with other members of the microbiome that are relevant for virulence, colonization and antibiotic resistance. Leveraging existing microbiome data from the cohort, O. hominis was found to be closely associated with bacterial co-colonizers that are rare in non-carrier individuals, including Suttonella, Rappaport, Helcococcus, Lwoffella, Moraxella and Gracilibacteria. Their collective acquisition has a significant impact on the diversity of nasopharyngeal communities that contain O. hominis. Individuals who have not yet acquired O. hominis have a higher abundance of Lwoffella lincolnii than individuals who never acquire O. hominis, suggesting that this could be a precursor state for successful colonization.
Investigation of Pd-Ti multilayer thin films for hydrogen storage applications
(Elsevier B.V, 2026) Rampai, Mojesi Monica; Nemukula, Enos; Mashiloane, Kamogelo Joseph
This study investigates the hydrogen storage properties of Pd/Ti/Pd/Ti multilayer thin films fabricated using an electron-beam evaporator. Rutherford backscattering spectrometry (RBS) was used for elemental composition and thickness analysis. The hydrogen profiling was performed using elastic recoil detection analysis (ERDA). The structural and morphological characterisations were performed using X-ray diffraction (XRD) and atomic force microscopy (AFM). The results revealed that the Pd layers were pure and free of any contamination, whereas the Ti layers were contaminated with oxygen, up to 63 at.%. Hydrogen absorption peaked at 200°C with a total concentration of 51.3 at.%.∼ 1.9 wt.%., but declined at higher temperatures. XRD confirmed the formation of TiH2 at elevated temperatures, while AFM showed a correlation between surface roughness and the hydrogen absorption
Adsorption of rees from aqueous solutions using modified polystyrene- di (2-ethylhexyl) phosphoric acid electrospun nanofibers
(Elsevier B.V., 2026) Mukaba, Jean-Luc; Mouele, Emile Salomon Massima; Ameh, Alechine Emmanuel; Eze, Chucks Paul; Petrik, Leslie; Tshentu, Zenixole R.
The recovery and separation of rare earth elements (REEs) is an emerging area of the current research due to their applications in modern technology and because both accessible and cost-effective approaches are required. In this study, polystyrene (PS) grafted with di(2-ethylhexyl) phosphoric acid (D2EHPA) ligand was fabricated via the electrospinning technique. The electrospun PS/DEHPA nanofiber mats were characterised using various techniques such as HR-SEM, TGA, FTIR, XRD, BET and ICP-OES. The fabricated electrospun nanofiber materials were then used for the recovery of Nd and Sm metal ions from the aqueous solutions. The supreme sorption uptake of Nd3+ and Sm3+was ˃ 100 mg/g at pH 4.0, reached at an equilibrium time of 70 min with the modified PS/DEHPA nanofiber mats. The recovery of Nd3+ and Sm3+was best described by the Langmuir isotherm and followed a pseudo second-order kinetic model. Thermodynamic data, ΔG°, Δ H° and ΔS° suggest that Nd3+ sorption onto PS/DEHPA was spontaneous and endothermic. The coordination of PS with the D2EHPA ligand occurred via hydrogen bonding while the binding of PS/DEHPA to the metal ion was likely bonded by ionic, covalent or electrostatic interactions. The reusability investigation indicates that the synthesized PS/DEHPA nanofiber mats can withstand up to four successive cycles, and the adsorption and desorption performances were over 60 %. Nd3+ sorption in the presence of interfering Ni2+ and Co2+ metals was 96.82 mg g−1(0.671 mmol g−1), closer to 101.46 mg g−1(0.703 mmolg−1) obtained in a single metal ion solution suggesting a good selectivity of PS/DEHPA fibres towards REEs (Nd3+).
Single-atom-anchored hierarchically nanopores hard carbon toward high-performance sodium storage
(Elsevier B.V., 2026) Iwuoha, Emmanuel; Wang, Q; Zou, Ren
Hard carbon anodes for sodium-ion batteries (SIBs) face a critical challenge in simultaneously achieving high capacity and rapid reaction kinetics, particularly in the low-voltage plateau region, due to the ambiguous storage mechanism and sluggish ion transport. Herein, we demonstrate a one-step metal salt-catalyzed strategy that enables the concurrent construction of hierarchical nanopores and the immobilization of single-atom Zn-N4 sites within hard carbon derived from lignosulfonate biomass. The resulting material achieves a remarkable reversible capacity of 354 mAh/g at 0.02 A/g and outstanding rate capability (238 mAh/g at 3.0 A/g). In situ X-ray diffraction (XRD) and Raman spectroscopy (Raman) spectroscopy elucidate a cooperative layer-insertion/nanopore-filling mechanism governing sodium storage in the plateau region. Furthermore, theoretical simulations reveal that Zn-N4 sites do not dominate the Na-storage behavior alone, but cooperate with the hierarchical pore structure by optimizing the local sodium ions (Na+) adsorption strength and facilitating ion transport. Compared with pure carbon nanopores, Zn-N4 modified nanopores show moderated Na+ binding over the whole pore-size range, indicating a more balanced interaction between Na+ and the carbon framework. This work highlights the advantages of integrating an ordered hard carbon framework with single-atom sites and provides new insights into high-performance sodium storage. The synergistic combination of hierarchical nanopores with single-atom sodium-affinity sites offer a general design paradigm for next-generation sodium-ion battery anodes.
Potential use of metal organic framework composites by recycling 4-nitrophenol in wastewater for electrocatalytic hydrogen production: A waste-to-profit approach
(Elsevier Ltd, 2026) Iwuoha, Emmanuel I.; Maake, Tumisang J.; Ramohlola, Kabelo E.
Development of efficient and sustainable hydrogen evolution reaction (HER) electrocatalyst is crucial for advancing green hydrogen technology. Herein, a waste-to-profit strategy is proposed wherein metal–organic frameworks (Cu-BTC and Cu-BDC) are employed for the removal of 4-nitrophenol (4NP) from wastewater and use the resultant adsorbent–adsorbate composites (Cu-BTC4NP and Cu-BDC4NP) for HER. MOFs were synthesised hydrothermally, and their effective adsorption of 4NP was confirmed through equilibrium and kinetic studies, revealing high adsorption capacities exceeding 500 mg g−1. Linear sweep voltammetry (LSV) revealed that Cu-BDC required low overpotential of 133.99 mV to reach a current density of 10 mA cm−2 compared to the 4NP-loaded composites which exhibited higher overpotentials of 175.54 mV (Cu-BTC4NP) and 203.88 Mv (Cu-BDC4NP). This decline suggests that 4NP adsorption modifies the electronic environment of Cu active sites and may induce framework instability in aqueous media, where hydrolysis of metal–carboxylate bonds is a concern.
Engineering titanium dioxide-reduced graphene oxide nanocomposite for electrooxidation of nitrite as a surrogate for electrochemical sensing of NO2
(Elsevier Ltd, 2026) Leve, Zandile Dennis; Januarie, Kaylin Cleo; January, Jaymi Leigh; Oranzie, Marlon; Sanga, Nelia Abraham; Uhuo, Onyinyechi Vivian; Ross, Natasha; Pokpas, Keagan; Iwuoha, Emmanuel Iheanyichukwu
Nitrogen dioxide (NO2) is a reddish-brown irritating gas characterised by sharp and biting odour. Its detection is imperative as it is harmful to the respiratory system and contributes to the acid rain formation. Aqueous NO2 gas is converted into nitrite (NO2−) ion in solution, which is considered an environmental pollutant with consequential health effects. Oxidation of NO2− has been reported to provide provisional insights for that of NO2 gas in electrolyte. However, detection of NO2− at electrode surface is encountered by difficulty due to high overpotentials. This study presents electrochemical behaviour of a titanium dioxide/reduced graphene oxide-palladium/silver nanocomposite-modified screen-printed carbon electrode (TiO2/rGO-PdAg/SPCE) for the detection of NO2− as a surrogate for NO2 oxidation mechanism in aqueous NaClO4 as electrolyte. Comparative analysis demonstrated superior performance of TiO2/rGO-PdAg/SPCE over bare, TiO2, and TiO2/rGO modified SPCEs due to the synergistic effect of its components. The sensor exhibited a broad detection range of 0.1 – 10 mM and a linear response at 0.1 – 1.4 mM with a limit of detection (LOD) = 1.07 µM NO2− and a sensitivity of 44.38 µA/mM. Simultaneous detection of NO2−and S2O32−demonstrated that the oxidation peak of the former was favoured while the latter was not observed in the investigated potential range. However, adsorption of S2O32− exhibited interference with a decrease in sensitivity to 24.15 µA/mM, which limits the selectivity of the sensor for oxidation of NO2−. Reproducibility exhibited an RSD of 4.18 % at five different electrodes, and stability tests with 74.02 % of peak current retained from initial response for a 12-day period. The recovery of NO2 gas in aqueous medium was studied using calibration curve of NO2−, with average of the triplicate experiments corresponding to 0.4 mM NO2−. These observations present TiO2/rGO-PdAg/SPCE sensor as a potential for reproducible, sensitive, and selective detection of NO2 in environmental monitoring.
Sustained release and efficacy of Kn2-7-loaded chitosan nanoparticles under low pH conditions
(Nature Research, 2026) Phathekile, Bonke; Sibuyi, Nicole Remaliah Samantha; Meyer, Samantha; Madiehe, Madimabe Abram; Okuthe, Emily Grace; Onani, Martin Opiyo; Meyer, Mervin E.
Delivery of antimicrobial peptides to low-pH sites is a significant challenge, and results in reduced treatment efficacy for vaginal infections. Chitosan nanoparticles (CNPs) could be ideal vehicles for drugs to acidic pH environments and sustain their therapeutic effects. CNPs were synthesized using the ionic gelation technique and loaded with Kn2-7 peptide. The CNPs were characterized by dynamic light scattering, Fourier transform infrared spectroscopy, high-resolution transmission and scanning electron microscopes. The stability and antibacterial effects of Kn2-7-loaded CNPs were evaluated at low and normal pH levels. The CNPs had a size distribution of 327–416 nm and a zeta potential of 9.61–23.9 mV. The size distribution (340.2–753.7 nm) and Zeta potential (15.9–67.7 mV) of CNPs changed after loading Kn2-7. The CNPs loading capacity and Kn2-7 entrapment efficiency were 35.6% and 78.3%, respectively. The Kn2-7-CNPs were not stable at low-pH and released Kn2-7 instantly; however, stabilization of Kn2-7-CNPs with poly (acrylic acid) (PAA) and tripolyphosphate (TPP) increased their stability and sustained Kn2-7 release at acidic pH. The Kn2-7-CNPs_1 mg/mL TPP-PAA inhibited the growth of Staphylococcus aureus at pH 3.8 better than the Kn2-7 alone. Therefore, the Kn2-7-CNPs_1mg/mL TPP-PAA could serve as a promising candidate for protecting and delivering drugs in low-pH environments.
POM-activated gCN intermediate as a new composite precursor for organic–inorganic materials: introducing a new composite as a starting material toward graphitic carbon nitride-based photocatalysts
(Springer, 2026) Tchegnitegni, Billy Toussie; Djoko, Simon; Schwarze, Michael
Polyoxometalate (POM)-modified graphitic carbon nitride (gCN) has emerged as a promising candidate for heterogeneous catalytic reactions. The introduction of POM-modified graphitic carbon nitride as a novel ligand/binder composite represents a significant stride in material science, particularly in synthesizing organic–inorganic hybrid materials. When combined with phosphomolybdic acid (PMA), gCN can form an activated composite intermediate (gCN/PMA) exhibiting multifunctional properties suitable for various applications in materials science and catalysis. This study advocates for a gCN/PMA composite as a fresh starting reagent for chemical synthetic routes, leading to the creation of structured materials. This groundbreaking composite material utilizes the special properties of POMs and gCN, creating a versatile platform for the formation of derived metal semiconductor materials. Chemical synthetic routes, including the gCN/PMA composite, have been proposed for fabricating 2D and 3D porous doped gCN and nanoparticle@MOF hybrid materials. By harnessing the complementary properties of PMA and gCN, this composite material offers enhanced functionality and performance compared to its individual components. The potential for continued research and development in this area is immense, with the promise of significant and promising breakthroughs that will further solidify the role of these composites in advancing modern technology and sustainable solutions. This work opens up a world of possibilities for designing advanced materials with tailored properties for various applications, including photocatalysis, energy storage, and environmental remediation.
Diethylene triamine penta (methylene phosphonic acid) functionalized magnetic nanosilica for adsorptive removal of heavy metals (Pb2+ and Ni2+) from aqueous solution
(Elsevier, 2025) Donga Cabangani; Ajay Kumar Mishra; Shivani Bhardwaj Mishra
Magnetic nanosilica nanoparticles are used for the remediation of wastewater. In this study, a robust nanoadsorbent material was fabricated by functionalising magnetic nanosilica with diethylene tria magnetic nano-adsorbent material was characterised by various techniques such as FT-IR, XRD, SAXS, FESEM coupled with Thermo Scientific Ultra dry EDS detector, TEM, VSM, BET and Zeta potential measurements. VSM analysis showed enhanced magnetic separation ability for Fe3O4@SiO2-DTPMP as was shown by a saturation magnetisation of 24 emug􀀀 1, while EDS analysis gave spectra showing high purity of the synthesised nanocomposite. Batch adsorption experiments on the effects of pH, initial metal ion concentration, adsorbent dose, temperature, and contact time were conducted on the removal of metal ions from aqueous solution. The asprepared Fe3O4@SiO2-DTPMP nano-adsorbent was easily separated from aqueous solution using an external permanent magnet. The adsorption isotherm models follow the Langmuir model and pseudo-second-order kinetics. From the results of this study, Fe3O4@SiO2-DTPMP showed enhanced adsorption performance for the Pb2+ and Ni2+ after 60 min and 30 min, respectively. Metal ions removal reached 92 % for Pb2+ at pH 6 and 54 % for Ni2+ at pH 5, with Qemax of 13.28 and 8.56 mg g􀀀 1, respectively. The Fe3O4@SiO2-DTPMP nano-adsorbents were regenerated and reused without the leaching of core mineral contents for at least 5 cycles. Therefore, the results of the study showed the Fe3O4@SiO2-DTPMP nano-adsorbent as a promising adsorbent material for water/wastewater treatment.
Investigation of organic hydrotrioxide (ROOOH) formation from RO2 + OH reactions and their atmospheric impact using a chemical transport model, STOCHEM-CRI†
(Royal Society of Chemistry, 2025) Shallcross Dudley; Khan, M. Anwar H.; Holland Rayne
Incorporating the reactions of fifty peroxy radicals (RO2) with the hydroxyl radical (OH) into the global chemistry transport model, STOCHEM-CRI, affected the composition of the troposphere by changing the global burdens of NOx (−2.7 Gg, −0.5%), O3 (−2.3 Tg, −0.7%), CO (−3.2 Tg, −0.8%), HOx (+2.1 Gg, +7.7%), H2O2 (+0.5 Tg, +18.3%), RO2 (−8.0 Gg, −18.2%), RONO2 (−19.4 Gg, −4.7%), PAN (−0.1 Tg, −3.4%) HNO3 (−7.4 Gg, −1.3%) and ROOH (−96.9 Gg, −3.8%). The RO2 + OH addition reactions have a significant impact on HO2 mixing ratios in tropical regions with up to a 25% increase, resulting in increasing H2O2 mixing ratios by up to 50% over oceans. Globally, a significant amount of organic hydrotrioxides (ROOOH) (86.1 Tg per year) are produced from these reactions with CH3OOOH (67.5 Tg per year, 78%), isoprene-derived ROOOH (5.5 Tg per year, 6%) and monoterpene-derived ROOOH (4.2 Tg per year, 5%) being the most significant contributors. The tropospheric global burden of CH3OOOH is found to be 0.48 Gg. The highest mixing ratios of ROOOH, of up to 0.35 ppt, are found primarily in the oceans near the tropical land areas. The RO2 + OH reactions have a small, but noticeable, contribution to OH reactivity (∼5%) over tropical oceans. Additionally, these reactions have a significant impact on RO2 reactivity over tropical oceans where losses of the CH3O2 radical, isoprene derived peroxy radical (ISOPO2) and monoterpene derived peroxy radical (MONOTERPO2) by OH can contribute up to 25%, 15% and 50% to the total RO2 loss, respectively. The changes in RO2 reactivity influence the global abundances of organic alcohols (ROH) which are important species due to their crucial impact on air quality. The ROOOH generate secondary organic aerosol (SOA) of up to 0.05 mg m−3 which affects the Earth's radiation budget because of enhancing modelled organic aerosol by up to 5% and 2000% on land surfaces and the remote tropical oceans, respectively.
Nanostructured activated biomass carbon-cu2znsns4 kesterite material for high-performance supercapacitor
(John Wiley and Sons Ltd, 2025) Feleni, Gwibakazi Abena; Ndipingwi, Miranda Mengwi; Nwambaekwe, Kelechi Chiemezie; Mabuza, Luyanda Smile; Isaacs, Beshara Sandra; Iwuoha, Emmanuel Iheanyichukwu
This work introduces a novel Cu 2ZnSnS 4 (copper zinc tin sulﬁde [CZTS]) kesterite/coconut shell-derived biomass activated carbon(AC) nanocomposite material (CZTS 0.5:AC 0.5 ) for supercapacitor application. CZTS was prepared by microwave-assisted synthesisand combined with AC to produce CZTS0.5 :AC0.5 through mechanical milling and low-temperature annealing at 350°C. X-raydiffraction (XRD) and Raman spectroscopic analyses of CZTS0.5 :AC 0.5 nanocomposite revealed the formation of a multiphasesystem consisting of residual CZTS and secondary sulﬁdes (zinc sulﬁde [ZnS], CuS, and SnS), which are embedded within a highlyconductive amorphous carbon matrix. High-resolution transmission electron microscopy (HRTEM) results indicate a reduction ofthe particle size from 55.7 nm (for CZTS) to 21.7 nm (for CZTS 0.5 :AC0.5 ) due to annealing. The nanostructurization of CZTS0.5 :AC0.5 created abundant electroactive sites that made the material an efﬁcient charge storage system. Galvanostatic studies of AC//CZTS 0.5 :AC 0.5 in a three-electrode conﬁguration produced a speciﬁc capacitance (Csp ) of 458.2 Fg−1 at 1 Ag−1 . Two-electrode AC//CZTS0.5 :AC 0.5 asymmetric supercapacitor device had a maximum energy density of 12.8 Wh kg−1 and a maximum power densityof 890.5 W kg−1 . The supercapacitor device exhibited excellent stability with a coulombic efﬁciency retention of 99.99% and acapacitance retention of 81.4% after 10,000 cycles. The results portray CZTS 0.5 :AC 0.5 nanocomposite material as a promising,sustainable electrode material for next-generation supercapacitors.
Atmospheric oxidation of hydrofluoroolefins and hydrochlorofluoroolefins by ozone produces HFC-23, PFC-14, and CFC-13
(American Chemical Society, 2025) Garavagno, Maria de los Angeles; Wenger, Angelina; Holland, Rayne E.T.; Fena, Benjamin R.; Goldstein, Sanford D.; Hicks, Dana E.; Liu, Fuxuan; Madell, Joseph B.; Solomon, Sarah J.; McGillen, Max R.; Khan, M Anwar H; Shallcross, Dudley E.; Stanley, Kieran M.; Orr-Ewing, Andrew J.
Hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs) are fluorinated compounds developed to replace refrigerant and propellant gases known to be ozone-depleting substances and/or potent greenhouse gases (GHGs). Their short atmospheric lifetimes result in low direct global warming potentials, but the environmental impacts of their degradation products remain poorly understood. We show that gas-phase ozonolysis of four HFOs produces the long-lived GHGs trifluoromethane (HFC-23) or carbon tetrafluoride (PFC-14), while HCFO-1233xf produces the ozone-depleting chlorotrifluoromethane (CFC-13). At 298 K and 1 bar, the HFC-23 yield is + (7.9 0.2)% 0.4 from HFO-1234ze(E) ozonolysis, and the PFC-14 yield is + (1.04 0.05)% 0.07 from HFO-1225ye(E), + (1.02 0.05)% 0.05 from HFO-1225ye(Z), and + (0.12 0.01)% 0.04 from HFO-1234yf, while HCFO-1233xf ozonolysis produces CFC-13 in + (0.034 0.006)% 0.009 yield. Global model integrations quantify the atmospheric impacts of these breakdown products. Mechanistic computational studies link the HFO and HCFO molecular structures to the formation of these persistent species, identifying structural features that favor their production. These results highlight the importance of considering not only the direct environmental influence of replacement compounds but also the consequences of their atmospheric degradation. The new insights that emerge will guide efforts to design compounds with lower long-term environmental impacts.
Advancing functionalized track-etched membranes: composite and hybrid materials through the JINR–South Africa partnership
(E.A. Buketov Karaganda University Publish house, 2025) Rossouw, Arnoux; Petrik, Leslie Felicia; Nechaev, Alexander Nikolaevich; Apel, Pavel Yurievich
Track-etched polymer membranes (TeMs) are precision porous materials widely applied in water purification, sensing, and catalysis. However, their practical use is limited by hydrophobicity, fouling, and lack of functional activity. The purpose of this review is to synthesize the outcomes of the long-standing collaboration between South African institutions and the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research in Dubna, Russia (FLNR, JINR), highlighting their contribution to overcoming these chal-lenges. The objective is to present a focused survey of advances in TeMs functionalization, contextualized within global progress, and to assess their implications for applied membrane science. The methodology involved a structured literature survey (2007–2025) across Scopus, Web of Science, and Google Scholar, combined with critical evaluation of collaborative outputs. Emphasis was placed on peer-reviewed studies of metal sputtering, chemical grafting, and electrospun nanofiber composites. Results indicate that these approaches improve TeMs performance by enhancing hydrophilicity, mechanical stability, and catalytic or sensing func-tionality. Case studies include Ti/TiO2 coatings for self-cleaning membranes, silver/gold nanoparticle-modified TeMs for surface-enhanced Raman spectroscopy, and nanofiber/TeMs hybrids for pollutant adsorp-tion. In conclusion, the JINR — South Africa partnership demonstrates how targeted international collaboration can deliver impactful technologies. Future research should prioritize stimuli-responsive “smart” mem-branes, MOF-integrated hybrids, and roll-to-roll scale-up for industrial deployment.
Smart Worksheets to probe and support scientific numeracy proficiency of first-year chemistry students
(Academy of Science of South Africa, 2025) Sewry, Joyce; Coyte, Emily; Williams, Leanne; Barker, Aidan; Suryawanshi, Shubham; Shallcross, Dudley E; Davies-Coleman, Michael T
The transition to university-level chemistry often reveals numeracy skills gaps that can hinder student confidence and academic success. Online learning tools can help characterise and address these gaps. This study introduces a Scientific Numeracy Smart Worksheet (SNSW) resource to characterise and address the numeracy-based strengths and weaknesses of a large cohort of first-year chemistry students at a South African university. We also investigated student usage and perceptions of this educational resource. The SNSW integrates core mathematical concepts with subject-specific contexts, features high levels of feedback, value randomisation, and an auto-solve feature for struggling students. It was offered as formative support for chemistry students near the start of their university journey. Usage and performance analytics from consenting students were used to study overall and section-level SNSW performance, while an anonymous questionnaire explored student perceptions. Students performed well at ‘Displaying numbers’ (85%) and ‘Rearranging and solving equations’ (84%). The lowest scoring sections were ‘Graphs’ (64%) and ‘Averages and spread of data’ (72%). ‘Scientific units’ showed the highest auto-solve percentage. Students who repeated the SNSW scored significantly higher and used the auto-solve feature significantly less on the second attempt (both p < 0.001) and scored higher in quantitative components of their end-of-module assessment, but not significantly so (p = 0.082). The questionnaire indicated high student rating for the SNSW (8.2/10), with most students finding it helpful and at the appropriate level. Providing supportive and diagnostic resources can help students develop numeracy skills and identify areas for personal improvement. Instantaneous data, generated from each student engagement with SNSW, can assist staff to develop educational strategies to target specific transitional skill deficiencies. Significance: Learners at secondary schools and university students alike struggle with basic numeracy concepts, such as ratios and proportions, graphs and SI units. First year chemistry curricula are full, with little time spent on revising content from school. The SNSW is a means of solving this problem. Students work through the worksheets at their own pace and receive immediate feedback. This research highlights both the gaps in students’ numeracy skills, and a corrective intervention by first-year chemistry lecturers.
Enhanced activity and durability of high-temperature proton exchange membrane fuel cells enabled by ionic liquid-modified Pt-Ni nanochains
(Elsevier Ltd, 2025) Liu, Qingqing; Liu, Huiyuan; Zhang, Weiqi; Xu, Qian; Khotseng, Lindiwe; Pasupathi, Sivakumar; Su, Huaneng
The performance of high-temperature proton exchange membrane fuel cells (HT-PEMFCs) is severely limited by the poisoning effect and low oxygen solubility of the phosphoric acid (PA) electrolyte. To address this, we report an innovative catalyst architecture consisting of one-dimensional hollow PtNi nanochains coated with a functional ionic liquid (IL), termed PtNi@IL/C. This design creates a multifunctional interface that demonstrates exceptional PA tolerance, achieving an oxygen reduction reaction (ORR) half-wave potential of 0.840 V in a PA-containing electrolyte, which is 90 mV higher than commercial Pt/C.
Derivatives of pyrazole-based compounds as prospective cancer agents
(American Chemical Society, 2025) Ramoba, Lesetja V; Nzondomyo, Wakopo J; Serala, Karabo; Macharia, Lucy W; Biswas, Supratim; Prince, Sharon; Malan, Frederick P; Alexander, Orbett T; Manicum, Amanda-Lee E
Five pyrazole-based compounds, 3,5-dimethyl-1H-pyrazole, L1; 3,5-diphenyl-1H-pyrazole, L2; 3-(trifluoromethyl)-5-phenyl-1H-pyrazole, L3; 3- (trifluoromethyl)-5-methyl-1H-pyrazole, L4; and 3,5-ditert-butyl-1H-pyrazole, L5 were synthesized from a typical condensation reaction of β-diketone derivatives with hydrazine hydrate reagent and characterized using various spectroscopic techniques such as FT-IR, UV−vis, 1H and 13C NMR, and LC−MS spectroscopy. L1 was further analyzed by single-crystal X-ray diffraction, and the N1−N1′ bond distance was found to be 1.361(3) Å and correlated well with other pyrazole-based compounds. The short-term cytotoxicity of 10 μM pyrazole compounds (L1−L5) was evaluated against pancreatic (CFPAC-1 and PANC-1), breast (MDA-MB-231 and MCF-7), and cervical (CaSki and HeLa) cancer cell lines using the MTT cell viability assay. Cisplatin and gemcitabine were included as positive control drugs followed by the determination of the half-maximal effective concentrations of prospective compounds. L2 and L3, respectively, displayed moderate cytotoxicity against CFPAC-1 (61.7 ± 4.9 μM) and MCF-7 (81.48 ± 0.89 μM) cell lines.
Advances on electrochemiluminescent biosensors for TB biomarkers
(American Chemical Society, 2025) Cox, Meleskow; January, Jaymi; Mokwebo, Kefilwe Vanessa; Yussuf, Sodiq T; Sanga, Nelia Abraham; Leve, Zandile Dennis; Douman, Samantha Fiona; Iwuoha, Emmanuel Iheanyichukwu
Tuberculosis (TB) is a highly contagious bacterial infection that remains a leading cause of death and persistent threat to global health. The spread of TB is exacerbated by the major limitations of conventional diagnostic approaches, such as complex technicalities, high cost, and low sensitivity. To address these challenges, recent research has focused on using electrochemiluminescence (ECL) as an alternative detection strategy coupled to biosensors. ECL biosensors leverage electrochemically generated chemiluminescence, converting electrical energy to light, as a novel transduction mechanism for TB biosensors. This unique approach offers several advantages, namely, wide linear dynamic ranges, improved device sensitivities, and prompt response times for sensitive early detection. This Review offers a comprehensive overview of advancements in ECL biosensor configurations, including detection and amplification strategies, substrates, and the development of luminophores and coreactants tailored for TB biomarker detection. The focus is on ECL biosensor designs, including biorecognition elements like immunosensors, DNA sensors, and aptasensors, along with various immobilization strategies tailored to target specific TB biomarkers. A comprehensive discussion spans biomarker detection trends over the past decade, clinical relevance, sensitivity thresholds, and detection limits. Furthermore, widely recognized TB biomarkers commonly detected in commercial diagnostic tests are discussed alongside novel markers that, while not exclusive to TB, have demonstrated clinical importance. This Review aims to highlight the potential of ECL-based biosensors as an effective means to advance an early, reliable, and accessible TB detection approach.

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