Research Articles (Chemistry)

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

Browse

Now showing 1 - 20 of 390

Wood-derived single-atom catalysts via scalable in situ chloride etching strategy for zinc-air batteries
(Elsevier B.V., 2026) Iwuoha, Emmanuel; Huang, Yongfa; Li, Tingzhen
Carbon-supported nitrogen-coordinated single metal-site (M-N-C) catalysts are considered ideal platinum group metal (PGM)-free cathode catalysts for zinc-air batteries (ZABs) due to their high metal utilization efficiency, unique size-dependent quantum effects, and excellent catalytic activity. However, large-scale, sustainable preparation of M-N-C catalysts remains a significant challenge owing to the complex synthesis procedures and the difficulty in achieving an optimal coordination environment between metal atoms and the carbon matrix. In this study, we develop a large-scale preparation method for Fe-N-C catalysts, which directly utilizes lignocellulosic materials through in situ etching and carbonization, without the need for pickling. During the in situ etching process, chloride ions (Cl−) weaken the hydrogen bonds in lignocellulose, facilitating the dissolution of cellulose, hemicellulose, and lignin, thus creating abundant micropores. The Fe-N4 active site is successfully formed during the subsequent carbonization process. The resulting SA-FeN4/PC catalyst, benefiting from its porous structure and homogeneous dispersion of Fe-N4 sites, exhibits enhanced oxygen reduction and evolution reaction (ORR/OER) performance and superior stability. When used as the cathode in ZABs, SA-FeN4/PC demonstrates long-term stability, maintaining 520 h of operation at a current density of 5 mA/cm2. Furthermore, by varying the metal cation, we successfully prepare other metal-nitrogen-carbon catalysts (SA-MN4/PC, where M refers to Co, Ni, and Cu). This scalable synthesis strategy shows significant potential for the preparation of wood-based single-atom catalysts for high-temperature applications.
Catalyst-free upcycling of polycarbonate waste to phenol enabled by temperature–pressure-decoupled subcritical steam flow
(Elsevier Ltd, 2027) Ge, Zhitong; Luo, Zhicheng; Yu, Shitong
Polycarbonate (PC) is a widely used engineering plastic, yet its chemical recycling is hindered by poor phenol selectivity under conventional hydrothermal conditions. Here we report a catalyst-free temperature–pressure decoupling strategy that enables selective PC depolymerization in subcritical steam. By separating the roles of temperature and pressure, this approach creates a low-ionic-product steam-phase environment that suppresses proton-driven side reactions while maintaining sufficient reactivity for carbonate bond cleavage. Under optimized conditions (330 °C, water feed rate of 0.05 mL min−1, 4 h), the process achieves a phenol selectivity of 69.1%. Using bisphenol A (BPA) as a molecular probe, together with kinetic, thermodynamic and reaction-network analyses, we show that subcritical steam reprograms the hydrolysis pathway by suppressing alkylphenol-forming branches and favoring rapid conversion of 4-isopropenylphenol (IPP) to phenol and acetone. Kinetic fitting identifies carbonate bond cleavage as the rate-determining step in the overall depolymerization sequence. Extension to post-consumer PC products shows that the chemistry remains effective for real wastes, although morphology and additives can limit downstream conversion. Process-level assessment indicates promising practical potential, with an internal rate of return of 34.8% and a global warming potential as low as 187 kg CO2e per tonne of PC under renewable electricity. These results establish steam-phase reaction-environment engineering as an effective strategy for reprogramming selectivity in polymer hydrolysis and advancing low-carbon recycling of engineering plastics
Accumulation of metals and metalloids in marine invertebrates and macroalgae in False Bay (Cape Town, South Africa)
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Ojemaye, Cecilia. Y; Ameh, Alechine. E; Onwordi, Chionyedua Theresa
The concentrations of 18 metal(loid)s were measured in five marine invertebrate species (Oxystele tigrine and sinensis, Marthasterias glacialis, Cymbula oculus and granatina, Parechinus angulosus, and Mytilus galloprovincialis) and five macroalgae/seaweed species (Aeodes orbitosa, Gelidium pristoides, Caulerpa filiformis, Ulva sp., and Bifurcaria brassicac formis) collected from eight sites within the marine environment of False Bay, Cape Town, South Africa. To assess the potential human health hazards associated with consumption, samples were acid digestion and analysed using inductively coupled plasma optical emission spectrometry (ICP-OES). The analysed elements included trace metals (Fe, Mn, Zn) toxic metals (Pb, Cd, As), transition metals (Ta, Ti), alkali metals (Li), and metalloid (Se, As). Metal concentration varied widely among species and locations, with values ranging from Zn: not detected (nd)—3836.04 mg/kg dry weight (dw); As: nd—77.98 mg/kg dw; Pb: nd—301.15 mg/kg dw; Li: nd—97.28 mg/kg dw, indicating diverse metal accumulation patterns. Human health risk was evaluated using the target hazard quotient (THQ) and hazard index (HI). Arsenic consistently exceeded the THQ threshold of one across all sites, and all the HI values were greater than one for all edible species, suggesting potential non-carcinogenic health risks associated with the consumption, except for M. glacialis, which is not commonly consumed. The HI metrics demonstrate the adverse impacts of metal concentration in marine biota. The observed spatial and biological variability in metal accumulation highlights the limitations of relying solely on metal concentrations for assessing health risks, food safety or anthropogenic contamination, and therefore more frequent and comprehensive monitoring is recommended.
Design-guided synthesis of customizable carbonized electrodes for maximizing charge storage in carbon-based supercapacitors
(Elsevier Ltd, 2026) Jouanne, Cecile; Baker, Priscilla; Pham-Truong, Thuan-Nguyen
3D carbon foams, CarboHIPEs, were successfully developed as self-standing electrodes for supercapacitor applications through the sulfonation and pyrolysis of polymerized High Internal Phase Emulsions. The fabrication process was systematically optimized by investigating the influence of sulfonation duration and pyrolysis temperature on the structural, chemical, and electrochemical properties of the resulting materials. A prolonged sulfonation time of 24 h significantly enhanced char yield, while increasing the pyrolysis temperature promoted micropore development, leading to a high specific surface area of up to 579 m2 g−1 and apparent electrical conductivity of 1.3 ± 0.2 S cm−1. An optimal pyrolysis temperature of 800 °C provided the best balance between conductivity, hierarchical porosity, and heteroatom retention, resulting in superior electrochemical performance. The unique combination of interconnected macroporosity, microporous texture, and heteroatom functionalities enabled efficient ion transport and charge storage. Electrochemical characterization demonstrated the best performance in 1 M H2SO4, with stable specific and volumetric capacitances reaching 80 F g−1 and 50 F cm−3, respectively. Notably, self-standing nature of the electrode eliminates the need for binders and conductive additives while significantly reducing current collector size, highlighting a significant advantage over conventional powder-based carbon electrodes. Symmetric supercapacitor devices assembled from CarboHIPE electrodes delivered a cell capacitance of 6.4 F cm−3, together with a maximum energy density of 6.6 mWh cm−3 at a power density of 60.5 mW cm−3. The devices exhibited excellent long-term durability, retaining stable performance over 12,000 charge–discharge cycles. These results demonstrate that CarboHIPEs constitute a promising and scalable electrode platform, combining facile processing, binder-free architecture, robust cycling stability, and competitive electrochemical figures of merit for next-generation energy storage systems.
Transition-metal vs. rare-earth NaFePO4 hybrid nanocomposites: accelerating kinetics for emerging sodium energy storage devices
(Elsevier Ltd, 2026) Juqu, Thando; Ross, Natasha; Pokpas, Keagan
Emerging energy storage demands materials that are safe, cheap, and high-performing. While sodium-iron phosphate (NaFePO4/NFP) perfectly fits the bill for next-gen batteries, its commercial reality is stalled by a major bottleneck: poor conductivity and slow ion kinetics. We bypass this limitation by engineering nickel (Ni-NFP) and yttrium (Y-NFP) hybrid nanocomposites using a scalable sol-gel approach. By directly contrasting transition-metal and rare-earth composites, this study delivers a blueprint for tuning crystal structure and unlocking elite electrochemical performance. Comprehensive structural and morphological characterization, including XRD, Raman, FTIR, FESEM, and EDX, confirmed successful element incorporation into the host lattice. Morphologically, pristine NaFePO4 displayed highly aggregated particles with surface fractures (∼50.89 nm). In contrast, Ni-composite yielded crack-free, flake-like particles (∼ 71.49 nm) with minimized surface defects, while Y-composite promoted compact, densely packed grains (∼ 51.75 nm), signifying bolstered structural integrity. Crystallographic analysis confirmed that pristine NaFePO4 adopts the thermodynamically stable maricite framework (Pnma). Incorporation of Ni2+ induced significant lattice expansion (+3.86% unit-cell volume expansion) within the maricite host, whereas Y3+ doping resulted in a distorted maricite lattice with a 1.36% volume contraction. Electrochemical evaluations demonstrate that the unique chemistry of each element dictates redox activity, charge-transfer kinetics, and long-term cycling pathways. Electrochemically active Ni participates directly in electronic transport and redox behavior, boosting electronic conductivity to deliver improved sodium diffusion coefficient (6.23×10−9 cm2 s−1), enhanced dual-redox activity (Fe2+\Fe3+ and Ni2+\Ni3+), and a high initial voltametric capacity of 93.63 mAh g−1. Conversely, electrochemically inactive Y3+ primarily functions as a robust structural stabilizer. Although Y-NFP exhibited a lower initial diffusion coefficient (1.75×10−10 cm2 s−1), its structurally fortified, compact lattice provided exceptional resistance against degradation during extended operation.
Alpha Methylacyl-CoA Racemase (AMACR) biomarker-based chronocoulometric aptasensor for prostate cancer
(Elsevier B.V., 2026) Sanga, Nelia Abraham; Oranzie, Marlon; Isaacs, Beshara S.; January, Jaymi Leigh; Tovide, Oluwakemi; Pokpas, Keagan; Iwuoha, Emmanuel Iheanyichukwu
Prostate cancer (PCa) remains a major cause of cancer-related mortality in men, underscoring the need for rapid and reliable diagnostic strategies. Conventional detection of α-methylacyl-CoA racemase (AMACR) relies on enzyme-linked immunosorbent assay and reverse transcription PCR, which are limited by high cost, lengthy analysis time and operational complexity, while prostate-specific antigen lacks diagnostic specificity. Herein, we report a rapid electrochemical aptasensor based on mercaptosuccinic acid-capped tungsten telluride quantum dot (MSA-WTe3 QD) integrated with a 60-mer single-stranded DNA aptamer for AMACR detection. The platform achieves detection within 60 s, exhibiting a linear range of 1–200 pg.mL−1 and limits of detection of 0.05 pg.mL−1 in buffer and 0.12 pg.mL−1 in synthetic human serum, which fall well below reported AMACR levels in biological samples (44 μg.mL−1), enabling clinically relevant and early-stage detection. The aptasensor demonstrates high sensitivity, selectivity and stability, outperforming conventional assays in response time and analytical performance. These findings highlight the potential of the proposed sensing platform for rapid and early PCa diagnosis.
Stress-homogenized and solvation-regulated biomass hydrogel inducing Zn (101) epitaxial growth for ultra-stable anodes
(Elsevier B.V., 2026) Lang, Aoxue; Iwuoha, Emmanuel; Huang, Yongfa
Crystallographic orientation and interfacial integrity dictate the reversibility of aqueous zinc-ion batteries at high current densities. To mitigate unstable growth, weak interactions, and uneven stress on the (002) and (100) planes, mechanically confining deposition to the robust (101) facet is vital, as its strong adsorption and rapid charge transfer prevent dendrite-induced failure at high cumulative capacity. Herein, we designed a degradable, mechanically tough, and carboxyl-rich biomass hydrogel to induce sustained Zn (101) epitaxial growth. It is shown that abundant carboxyl groups reconstruct the Zn2+ solvation sheath, suppressing free water activity and selectively shielding reactive (002) and (100) facets via competitive occupation, thereby thermodynamically directing (101) nucleation. Simultaneously, the cross-linked cellulose network delivers high toughness and a high elastic modulus, dissipating interfacial stress to preserve structural integrity against volume fluctuations. This dual regulation lowers the desolvation barrier, homogenizes ion flux, and physically suppresses dendrites, enabling dense (101)-textured deposition. Consequently, symmetric cells achieve an exceptional cumulative capacity of 6000 mAh cm−2 at 5 mA cm−2/5 mAh cm−2, while Zn//Cu cells maintain 99.31% coulombic efficiency over 2000 cycles. This work establishes a precise mechano-chemical strategy for crystallographic regulation toward ultra-stable zinc anodes.
Unlocking concerted proton-electron transfer in cobalt oxyhydroxide for industrial-current biomass upgrading and integrated hydrogen production
(John Wiley and Sons Inc, 2026) Gan, Jianyun; Iwuoha, Emmanuel; Yang, Yunyi
Cobalt oxyhydroxide (CoOOH) is a promising catalyst for biomass electrooxidation, yet its reaction mechanism remains contentious regarding its competition with the oxygen evolution reaction (OER) at high overpotentials. Herein, we resolve this controversy by identifying a key intermediate that triggers a switch from the lattice oxygen mechanism (LOM) for OER to a concerted proton–electron transfer (CPET) mechanism for the glucose oxidation reaction (GOR). Operando spectroscopy and isotope-labeling experiments reveal that the electrochemically generated O–Co4+(O*)–O site preferentially extracts protons from glucose via CPET, which effectively suppresses O─O coupling and parasitic oxygen evolution. This mechanism enables CoOOH to achieve a high GOR current density of 100 mA cm−2 at only 1.23 V vs. RHE with a formate Faradaic efficiency of 97.0%. Moreover, the two-electrode flow electrolyzer integrating GOR with hydrogen evolution reaction achieves a current of 2.7 A (300 mA cm−2) at a low cell voltage of 1.70 V, co-producing formate and hydrogen with high Faradaic efficiencies (87.5% and 98.4%, respectively), and maintaining stable operation for over 100 h. This work not only clarifies the CPET-dominated mechanism in biomass electrooxidation but also proposes a scalable strategy for energy‑saving coproduction of valuable chemicals and green hydrogen
Compositional engineering of Lignocellulose via selective delignification toward closed-pore-rich hard carbon for high-plateau-capacity sodium storage
(American Chemical Society, 2026) Iwuoha, Emmanuel; Liao, Yunkang; Wang, Qi
Hard carbon derived from lignocellulosic biomass is a promising anode candidate for sodium-ion batteries due to its low cost and renewability. However, its practical application is limited by insufficient low-voltage plateau capacity, which is closely related to the closed-pore structure. Herein, we report a green and scalable compositional engineering strategy based on alkaline sulfite pretreatment, an industrially mature pulping process, to convert waste wood into closed-pore-rich hard carbon anodes. By selectively cleaving β-O-4 linkages in lignin, this pretreatment increases the relative cellulose content and fundamentally alters the carbonization pathway, yielding a highly disordered turbostratic structure. The optimized hard carbon (HHC-20) exhibits a doubled closed-pore volume (from 0.073 to 0.178 cm3 g–1) and an expanded interlayer spacing (0.385 nm). Consequently, HHC-20 delivers a high reversible capacity of 347 mAh g–1 at 20 mA g–1, with an outstanding low-voltage plateau capacity of 205 mAh g–1 and an initial Coulombic efficiency of 89.1%. In situ spectroscopic characterizations reveal a sequential sodium storage mechanism involving surface adsorption, interlayer intercalation, and pore filling. This work offers a sustainable and commercially viable pathway for designing high-performance hard carbon anodes for sodium-ion batteries. © 2026 American Chemical Society
Regulating local phosphoric acid environment via HDTMPA-modified catalyst layers for enhanced high-temperature proton exchange membrane fuel cells
(Elsevier B.V., 2026) Tian, Zihao; Khotseng, Lindiwe; Pasupathi, Sivakumar
Managing phosphoric acid (PA) distribution within the catalyst layers is a critical challenge for the development of high-performance high-temperature proton exchange membrane fuel cells (HT-PEMFCs). This work introduces a novel strategy using hexamethylenediamine tetra(methylenephosphonic acid) (HDTMPA) as a functional additive in the cathode to precisely regulate the local PA environment. HDTMPA performs a dual function: its strong hydrogen-bonding interactions with PA effectively anchor the acid, which prevents the excessive flooding and poisoning of Pt catalyst sites, while its electron-rich nitrogen atoms help establish a robust proton-conduction network. Consequently, a membrane electrode assembly (MEA) with an HDTMPA-modified cathode (0.5 mgPt cm−2) achieves a peak power density of 715 mW cm−2 at 150 °C, a 42% enhancement over the unmodified baseline (503 mW cm−2). Furthermore, the modified MEA demonstrates exceptional durability, exhibiting only a 5.0% performance decay after an accelerated durability test of 10,000 cycles, compared to a 17.5% decay for the control. In-situ electrochemical analysis confirms the enhanced kinetics, validating this molecular design approach as a new avenue for developing highly stable and efficient HT-PEMFCs.
Thiol-mediated electrochemical sensor for the breast cancer biomarker CA 15-3
(Frontiers Media SA, 2026) Ghaffari, Nastaran; Baker, Priscilla
Cancer antigen 15-3 (CA 15-3), a circulating fragment of the MUC1 glycoprotein, is widely used for monitoring breast cancer progression. In this study, we report a label-free, receptor-free electrochemical detection strategy based on adsorption-mediated modulation of gold surface oxidation. Pencil graphite electrodes (PGEs) were modified with electrochemically deposited gold nanoparticles (AuNPs) using a reproducible multi-electrode fabrication system. The nanostructured AuNP surface exhibited enhanced electroactive area and improved electron-transfer properties, as confirmed by ferri/ferrocyanide characterization. Analytical detection was performed in phosphate-buffered saline by monitoring the intrinsic gold oxidation peak. Following incubation with CA 15-3, a concentration-dependent decrease in the gold oxidation current was observed, attributed to adsorption-induced surface passivation of electrochemically active gold sites. The platform demonstrated a linear response across the tested concentration range with a calculated limit of detection of 1.2 × 10−4 U/mL. Measurements in spiked plasma samples confirmed the feasibility of detecting CA 15-3 in complex matrices under controlled conditions. This work establishes a chemically driven, adsorption-based electrochemical sensing strategy that exploits gold surface chemistry for label-free biomarker detection.
Bioactive 13,28-oxidooleanane-type saponins from Measa kamerunensis Merk
(Elsevier Ltd, 2026) Tchinda, Alex Tedonkeu; Tchegnitegni, Billy Toussie; Küçükaydın, Selçuk; Taş Küçükaydın, Meltem; Antunes, Edith; Beukes, Denzil; Tene, Mathieu; Duru, Mehmet Emin
Four previously undescribed 13β,28-oxidooleanane-type triterpenoid saponins, maekamerunosides A–D (1–4), together with one new triterpenoid aglycone, maekamerunogenin (6), and the known saponin maesargentoside IV (5), were isolated from the stem bark of Maesa kamerunensis. Their structures were elucidated by extensive spectroscopic analyses (1D and 2D NMR, HR-ESI-MS) and chemical methods, including acid hydrolysis and GC–MS analysis of sugar moieties. The isolated saponins share a common oleanane-type aglycone featuring a rare 13β,28-epoxy bridge and are characterized by complex oligosaccharide chains containing glucuronic acid, galactose, and rhamnose units. Biological evaluation of the MeOH extract, n-BuOH fraction, and isolated compounds (1–5) revealed moderate to significant bioactivities. Compound 4 exhibited the highest antioxidant activity with IC50 values of 95.19 ± 1.15, 135.74 ± 0.80, and 117.04 ± 0.98 μM in β-carotene–linoleic acid, DPPH•, and ABTS+• assays, respectively. Compound 5 showed notable butyrylcholinesterase inhibition (IC50 = 93.4 ± 0.74± 0.74 μM) and the highest inhibitory effects against α-glucosidase (31.29 ± 0.85%) and α-amylase (27.72 ± 0.77 ± 0.77%) at 200 μg/mL. Additionally, compound 5 demonstrated the strongest urease inhibition (IC50 = 15.90 ± 0.52 μM), while no significant tyrosinase inhibition was observed. These findings suggest that M. kamerunensis is a valuable source of structurally diverse triterpenoid saponins and that synergistic effect in the crude extract may contribute to its enhanced bioactivity.
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.

Browse

Recent Submissions