Research Articles (Chemistry)

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Controlling the optoelectronics of poly(3-hexylthiophene-2,5-diyl) dendritic star copolymers on a polypropylenimine core as donor materials for organic solar cells
(American Chemical Society, 2026) Ramoroka, Morongwa Emmanuel; Cox, Meleskow; Feleni, Gwibakazi Abena; Mabuza, Luyanda S.; Isaacs, Beshara Sandra; Mohamed, Rhiyaad; Xia, Ruidong; Peng, Xinwen; Iwuoha, Emmanuel Iheanyichukwu
The development of novel copolymers as donor materials for organic solar cells and optimization of their properties are particularly interesting, but remain challenging. This research report presents the first study on the effect of copolymerization time on the synthesis of the copolymer poly(propyleneimine) tetra(N-methyl-2-pyrrolylmethylene amine)-co-poly(3-hexylthiophene-2,5-diyl) (P3HT-PP) using the chemical oxidative polymerization method. Through thorough experiments and copolymer characterization, a preferred copolymerization time is proposed, ensuring that the properties of the synthesized copolymers are significantly improved. The structural, optical, morphological, thermal, and rheological properties of synthesized copolymers at different copolymerization times (24, 48, and 72 h) were investigated by using nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, thermal gravimetric analysis, Raman spectroscopy, small-angle X-ray scattering, rheometry, X-ray diffraction, ultraviolet–visible spectroscopy, and photoluminescence spectroscopy. Additionally, the effects of copolymerization time on the LUMO/HOMO energy levels and charge-transfer processes were examined by using cyclic voltammetry and electrochemical impedance spectroscopy, respectively. It was revealed that the copolymer synthesized for 24 h (P3HT-PP24) has the best properties suitable for organic solar cell applications as a donor material as compared to copolymers synthesized for 48 h (P3HT-PP48) and 72 h (P3HT-PP72). The P3HT-PP24-based organic solar cell exhibited the best photovoltaic performance due to reduced photogenerated charge recombination and more efficient exciton separation. © 2026 The Authors. Published by American Chemical Society.
Adsorption of rees from aqueous solutions using modified polystyrene- di (2-ethylhexyl) phosphoric acid electrospun nanofibers
(Elsevier B.V., 2026) Mukaba Jean-Luc; Massima Mouele, Emile Salomon; Ameh, Alechine Emmanuel; Eze, Chucks Paul; Petrik, Leslie Felicia; 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+).
A self-powered triboelectric nanogenerator for energy collection based on polydimethylsiloxane/dopamine/Ag nanowires porous materials formed by manganese carbonate
(Elsevier B.V, 2025) Guan, Yanfang; Yang, Wei; Yang, Lin; Wang, Han; Xi, Zhengyang; Kang, Yuliang; Zhao, Zaoran; Zhu, Changwei; Petrik, Leslie Felicia; Shen, Minggang; Wan, Zhenshuai; Yue, Longwang; Li, Peng
Triboelectric nanogenerators (TENG) possess significant potential and offer a wide range of applications to harness low frequency micro energy from the environment. However, TENG faces challenges related to the weak tightness of bipolar materials, low charge density, and so on. In this paper, we present a novel TENG, utilizing a 0.1 mm thick nylon film as the positive electrode material and a porous material composed of PDMS/MnCO3 modified by dopamine (PDA) and Ag NWs as the negative electrode material. The sacrificial material, MnCO3, was employed to create dense internal pores within the substrate material, PDMS, resulting in a highly porous PDMS (PPDMS) substrate. The triboelectric layer of TENG resembles a sponge with 20–40 μm pores, filling the PPDMS with high dielectric constant silver nanowires (Ag NWs) effectively enhances surface charge on the triboelectric material, leading to improved output performance. The modified TENG, based on PDMS/PDA/Ag NWs (PPA) achieves an 80 V open circuit voltage, 70.4 mW/m2 effective output power density, and sustains 10,000 contact separations without damage. Finally, energy collection devices for ocean-ball and human walking scenarios with the PPA/nylon-based TENG are designed and fabricated. The PPA/nylon-based TENG exhibits promising potential for collecting, converting, and storing clean energy.
Effects of morphological and physicochemical surface properties of track-etched membranes made from polyethylene terephthalate, polycarbonate and polyethylene naphthalate on protein adsorption
(Elsevier B.V, 2026) Serpionov, Genrikh V.; Molokanova, Ludmila G; Nikolskaya, Daria V; Drozhzhin, Nikita A; Vinogradov, Iliya I; Rossouw, Arnoux; Andreev, Evgeny V; Orelovich, Oleg L; Petrik, Leslie F; Nechaev, Alexander N
This study presents a comparative analysis of bovine serum albumin (BSA), hemoglobin, and lysozyme adsorption on track-etched membranes (TMs) based on polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polycarbonate (PC) with similar structural parameters. The specific surface area was 1.7, 1.9, and 1.3 m²·g⁻¹ for PEN, PET, and PC TMs, respectively. PEN and PET TMs were rougher (Sq ≈ 6.2–9.4 nm) and hydrophilic (contact angle ≈55°), whereas PC TMs were smoother (Sq ' 2.8 nm) and moderately hydrophobic (contact angle '80°). All membranes were negatively charged (zeta potential: –14.9 to –23.6 mV). No measurable BSA adsorption was observed using the spectrophotometric method. Hemoglobin adsorption followed PEN ' PET ' PC, with capacities of 7.9, 6.4, and 3.4 mg·g⁻¹ , respectively, all fitted by the Langmuir isotherm. Lysozyme adsorption was substantially higher on PEN (9.9 mg·g⁻¹) and PET (9.3 mg·g⁻¹) than on PC (2.3 mg·g⁻¹). Adsorption on PEN was best described by the Jovanović model, on PET by the Temkin isotherm, and on PC by the Langmuir model, indicating different adsorption behaviours. The novelty of this work lies in the multimethodological and multimodel approach that identifies surface roughness, protein molecular size and electrostatic interactions as key factors governing protein adsorption on TMs. Protein adsorption on PEN-based TMs is reported for the first time. This study shows that protein adsorption on TMs is relevant not only to fouling in filtration but also to biosensing and cell culture, providing a basis for rational selection of TM materials for biomedical and separation applications.
Macrophages bend long fibres with flexural rigidity lower than 3 mN·nm2 to avoid frustrated phagocytosis
(BioMed Central Ltd, 2026) Brossell, Dirk; Meyer-Plath, Asmus; Gräb, Oliver; Heunisch, Elisabeth; Kämpf, Kerstin; Haase, Andrea; Wiemann, Martin
Background: It is an established toxicological principle that the inhalation pathogenicity of respirable and biodurable fibres is caused by excessive fibre length as alveolar macrophages fail to uptake and remove such fibres. However, studies on carbon nanotubes showed that this principle needs revision, as thin, flexible variants showed reduced fibre-specific toxicity. One potential explanation is that the low flexural rigidity of thin fibres enables macrophages to bend and internalize even those that are long relative to the cell size. To evaluate this proposed “rigidity hypothesis,” the mechanisms governing the uptake of flexible long fibres that determine a critical threshold value for flexural rigidity require clarification. Methods: We exposed NR8383 rat alveolar macrophages to three silver nanowire variants differing in diameter and length. Time-lapse microscopy captured fibre uptake processes. Successful internalization of long fibres was found to require fibre bending during uptake. A mechanical model was developed by combining established cytoskeletal biophysics with the observed fibre deformation dynamics. As flexural rigidity describes fibre behaviour under load, our model estimated rigidity by reproducing the observed bent fibre shape. By defining limit cases for physically ‘weak’ and ‘strong’ NR8383 macrophages, i.e., assuming upper bounds on the forces generated by their cytoskeletal nanomachinery, our model enabled us to derive a range for the critical fibre rigidity threshold. Results and conclusion: A macrophage was observed bending an exceptionally long fibre (~ 140 μm) first into an arc and then a spiral for full internalization, initiated by a pseudopod extending along the fibre and buckling the internalized segment. Our model can reproduce such behaviour. It yielded a flexural rigidity of 20 mN·nm² for this fibre. Predicted critical rigidity limits for fibres that just fit into NR8383 macrophages range from 3 to 62 mN·nm².
Dual-facet modulation involving surface carboxyl functionalization and interlayer regulation by CQDs in g-C3N4 for enhanced xylose photooxidation
(Elsevier B.V., 2026) Iwuoha, Emmanuel
Photocatalytic oxidation of biomass-derived xylose to xylonic acid provides a sustainable route for producing high-value sugar acids under mild conditions. However, its practical application is often limited by poor selectivity caused by uncontrolled radical reactions promoting Csingle bondC bond cleavage and deep oxidation. Herein, we propose that bamboo-derived carbon precursors are employed to construct an in-plane heterojunction between conjugated carbon domains and graphitic carbon nitride (g-C3N4), in which bamboo-derived carbon quantum dots (CQDs) act as electron bridges to facilitate interlayer charge transport and thereby enhance surface-directed electron migration. This effect is evidenced by enhanced photocurrent responses, reduced charge-transfer resistance, prolonged carrier lifetimes, and increased electron delocalization. Meanwhile, carbonyl groups on the CQD surface promote the adsorption and activation of xylose at the reaction interface through an electron-withdrawing effect. Mechanistic investigations further identify superoxide (·O2−) and singlet oxygen (1O2) as the dominant reactive oxygen species responsible for selective xylose oxidation. Consequently, the optimized catalyst achieves an 84.4% yield of xylonic acid under visible-light irradiation with excellent stability. This work establishes reaction-demand-oriented charge-transport engineering as a key design principle for the selective photocatalytic upgrading of biomass-derived sugars.
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.
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.
Single-atom-anchored hierarchically nanopores hard carbon toward high-performance sodium storage
(Elsevier B.V., 2026) Iwuoha, Emmanuel; Wang, Qi; 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.
The crystal structure of fac-tricarbonyl(1,10-phenanthroline-κ2N,N′)-(azido- κ1N)rhenium(I),C15H8N5O3Re
(Walter de Gruyter GmbH, 2025) Ledibane, Mmabatho L; Alexander, Orbett T
C15H8N5O3Re, monoclinic, C2/c (no. 15), a = 18.7508(8) Å, b = 12.2267(6) Å, c = 15.8442(11) Å, β = 123.6160(10)°, V = 3025.0(3) Å3, Z = 8, Rgt(F) = 0.0377, wRref(F2) = 0.0902, T = 292 K.
Engineering titanium dioxide-reduced graphene oxide nanocomposite for electrooxidation of nitrite as a surrogate for electrochemical sensing of NO2
(Elsevier Ltd., 2026) Leve, Zandile D; Januarie, Kaylin; January, Jaymi Leigh; Oranzie, Marlon; Sanga, Nelia A; Uhuo, Onyinye; Ross, Natasha; Pokpas, Keagan; Iwuoha, Emmanuel
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.
Lanthanide-mediated spectral conversion and electrochemical charge dynamics in gadolinium oxyselenide for high-performance solar cells
(American Chemical Society, 2025) Nwambaekwe, Kelechi Chiemezie; Tshobeni, Ziyanda Zamaswazi; Cox, Meleskow; Xia, Ruidong; Admassie, Shimelis; Zhong, Linxin; Peng, Xinwen; Iwuoha, Emmanuel Iheanyichukwu
To improve visible-light absorption and charge transport in wide-band-gap oxide-based solar absorbers, photovoltaic (PV) devices were developed using terbium (Tb)- and europium (Eu)-doped gadolinium oxyselenide (GOSe) as the photoactive material. GOSe was selected for its thermal stability, optoelectronic tunability, and capacity to accommodate lanthanide dopants that introduce energy levels favorable for photon conversion and defect passivation. The nanophosphors were synthesized using a microwave-assisted solvothermal method to ensure controlled morphology and crystallinity. Structural analysis confirmed hexagonal Gd2O2Se phase formation, with dopant-induced modifications in unit cell parameters and bond lengths. Eu doping resulted in denser atomic packing and shorter bond lengths, while Tb doping introduced lattice strain, both influencing optical and charge-transport behavior. Optical characterization showed significant band-gap reduction from 3.8 eV in GOSe to 3.1 eV (GOSeT) and 2.8 eV (GOSeE), expanding absorption into the visible region. Photoluminescence confirmed characteristic 4f emissions at 543 nm (Tb) and 615 nm (Eu), indicating successful energy transfer and validating activation of Tb3+and Eu3+transitions. Electrochemical impedance spectroscopy and voltammetry analyses revealed improved electron mobility, reduced charge-transfer resistance (GOSeE: 0.60 kΩ), and enhanced surface kinetics. The doped nanophosphors were incorporated into thin-film solar cells with the architecture Ag/GOSe:Ln/CdS/ZnO/Al:ZnO/ITO. GOSeE-based devices achieved a power conversion efficiency of 3.22%, with a short-circuit current of 8.20 mA cm–2and an open-circuit voltage of 1.20 V, outperforming both GOSeT (1.40%) and undoped GOSe (0.12%). Energy-band analyses of the device layers showed favorable band alignment in doped samples, supporting efficient charge separation. 24-h stability tests under AM 1.5G conditions revealed that GOSeE had better device performance retention, indicating reduced recombination and better structural stability. This study confirm that RE-metal doping is an effective strategy to tune optical and electronic properties of GOSe for use in high-efficiency thin-film PV devices. © 2025 The Authors. Published by American Chemical Society.
Plasma-enabled electrocatalytic reduction of nitrogen oxides to ammonia over Cu-N-P catalysts
(ACS Catalysis, 2026) Man, Chenxi; Xie, Bingtao; Li, Lun; Xu, Xinyu; Zhang, Shuai; Huang, Bangdou; Dou, Liguang; Xi, Dengke; Pei, Xuekai; Petrik, Leslie; Zhang, Cheng; Shao, Tao
The electrocatalytic reduction of nitrogen oxides (NOx) to ammonia represents a promising alternative to direct N2 reduction but is often limited by low reaction rates, poor selectivity, and severe competition from hydrogen evolution under dilute feed conditions. Here, we report a plasma-enabled electrocatalytic strategy for efficient NOx-to-NH3 conversion using an electronically engineered Cu-N-P catalyst. A rotating gliding arc plasma converts air into reactive NOx species, providing a continuous and controllable feed for downstream electrochemical reduction. The Cu-N-P catalyst achieves an ammonia production rate of 2.36 mmol h−1 cm−2 with nearly 100% Faradaic efficiency at −0.575 V versus RHE and maintains stable operation for over 125 h under plasma-derived NOx conditions. Compared with unmodified Cu, the N, P co-doped catalyst promotes selective NOx adsorption and accelerates the hydrogenation of key intermediates while suppressing parasitic hydrogen evolution. Spectroscopic characterizations and theoretical analysis reveal that electronic structure modulation facilitates efficient NOx utilization and favorable hydrogenation kinetics. This work establishes an effective catalytic pathway for NOx-to-ammonia conversion under plasma-assisted conditions, providing insights into catalyst design for coupled plasma-electrochemical nitrogen conversion systems.
Delamination of aluminium current collectors from spent lithium-ion battery cathodes using room-temperature organic acid-assisted ultrasonication
(MDPI, 2026) Tawonezvi, Tendai; Sinto, Anele; Qhina, Mihle N; Zide, Dorcas; Mlotha, Emihle; Bladergroen, Bernard J
The strong adhesion between cathode materials and aluminium (Al) foil substrates presents a significant challenge in the recycling of spent lithium-ion batteries (LiBs). Conventionally, high temperatures and high concentrations of costly organic solvents such as N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) are used to enhance ultrasonication-based delamination. In this study, a novel, eco-efficient approach was demonstrated for delaminating cathode materials from Al foil using a low-concentration organic citric-acid-assisted low-power ultrasonic treatment coupled with a gentle, low-power-per-volume mechanical mixing system at room temperature. The separation mechanism was attributed to the structure disruption, possibly swelling, of the polyvinylidene fluoride (PVDF) binder using low-concentration citric acid and the cavitation effects induced by ultrasound. Key parameters influencing the delamination efficiency included the solvent type, temperature, ultrasonic power, and treatment duration. Under optimised conditions, citric acid was used as the sonication reagent, with a process temperature of 20 °C, 60 W ultrasonic power, and 80 min of ultrasonication; a delamination efficiency of approximately 92% was achieved. The recovered cathode materials exhibited low agglomeration, favouring subsequent leaching processes. This work proposes an environmentally friendly and effective method for cathode and Al foil recovery from spent LiBs, integrating manual dismantling, ultrasonic treatment, and material separation.
Green synthesis of copper nanoparticles from onion peel for wastewater bacteria detection and methyl orange degradation
(John Wiley and Sons Ltd, 2026) Nqunqa, Sphamandla; Feleni, Usisipho; Mulaudzi, Takalani; Mini, Sixolile; Hitzeroth, Arina C; Ngece-Ajayi, Rachel F
Wastewater from industrial and domestic sources is frequently contaminated with pathogenic bacteria, such as coliforms, posing a significant threat to human and environmental health. Conventional methods for synthesising metal nanoparticles are often hazardous and energy-intensive, highlighting the need for sustainable alternatives. Green synthesis using plant-derived biomolecules offers an eco-friendly and cost-effective route, yet systematic studies exploring Allium cepa L. (onion) peel extract (OPE) for multifunctional copper nanoparticle (CuNP) synthesis remain limited. In this study, OPE was employed as a natural reducing and stabilising agent to synthesise CuNPs via a sand-bath-mediated method. The reaction parameters (pH, temperature and time) were optimised to achieve stable nanoparticles, with characterisation by UV–Vis spectroscopy, FT-IR, HRTEM, DLS and XRD confirming spherical, crystalline OPE-CuNPs with an average size of ∼3–21 nm. The biosynthesised OPE-CuNPs exhibited effective antibacterial activity against Klebsiella pneumoniae, obtaining a minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of 12.5 μg/mL, values lower than several previously reported plant-mediated CuNPs. At concentrations of 50 and 100 μg/mL, inhibition zones of 12.5 ± 0.3 mm and 25.5 ± 0.3 mm were recorded, demonstrating concentration-dependent activity. Ciprofloxacin was used as a positive control and OPE as a negative control, confirming that the antibacterial activity originated from the OPE-CuNPs. In addition, the OPE-CuNPs showed excellent photocatalytic activity, with 96% degradation efficiency for methyl orange under sunlight within 25 min, which surpasses several green-synthesised CuNP studies reported in the literature. These findings suggest that onion peel, a readily available biowaste, can be effectively valorised for the sustainable synthesis of OPE-CuNPs with dual antibacterial and photocatalytic applications, offering a promising strategy for wastewater remediation and environmental protection.
Fabrication and characterisation of Ni/Ti/Ni/Ti multilayer thin film systems for hydrogen storage applications
(John Wiley and Sons Inc, 2025) Nemukula, Enos; Rampai, Mojesi Monica; Mashiloane, Kamogelo Joseph; Peng, Zhuo; Mtshali, Christopher Bongani; Nemangwele, Fhulufhelo
This study explores the fabrication and characterisation of Ni/Ti/Ni/Ti multilayers for hydrogen storage. The thin films were fabricated using the e-beam under high vacuum pressure to allow for precise control over the film thickness. Rutherford backscattering spectrometry was used to study the elemental composition of the film stacks, and elastic recoil detection analysis was used for hydrogen profiling. X-ray diffraction (XRD) and atomic force microscopy were used for structural and morphological analysis of the samples. The results revealed that the nickel layer was pure and contained no impurities. The hydrogen absorption was found to be temperature-sensitive, with maximum absorption at 200 (Formula presented.) C with a total hydrogen content of 46.42 at.%. XRD confirmed the formation of titanium hydride (TiH (Formula presented.)), at higher temperatures and the titanium peaks becoming more prominent at 500 (Formula presented.) C. Surface roughness analysis revealed a correlation between the roughness of the samples and hydrogen absorption; the highest roughness was recorded at 200 (Formula presented.) C. The nickel layer acted as a catalyst, enhancing hydrogen dissociation and minimising the negative impacts of oxides. These findings demonstrate the potential for the use of Ni/Ti/Ni/Ti for efficient hydrogen storage, with the optimal temperature being 200 (Formula presented.) C.
Synthesis of sodium dithionite through in-situ electrochemical method at the cathode in a gap-flow bipolar membrane electrolysis cell
(Materials China, 2026-04) Vladimir Linkov; Shan Ji; Fangfang Liu
Global demand for sodium dithionite (Na2S2O4, TDS) has been steadily rising, as it is an effective flame retardant, bactericide, and bleaching agent. However, conventional manufacturing methods often involve high operational costs, excessive use of reducing agents, and significant environmental pollution, which hinder sustainable industrial production. To address these issues, this study focused on the design of efficient electrochemical reactor, optimizing reaction parameters, investigating the electrochemical reaction mechanisms, and developing high-performance carbon-based electrocatalysts. A micro-gap-flow electrochemical reaction system for the electrosynthesis of TDS was successfully developed. This system integrates traditional chemical synthesis with electrochemical reduction, enabling the efficient creation of TDS in an aqueous sodium bisulfite solution. The current efficiency of this electrical synthesis process was notably improved, increasing from 85% to over 90%. Furthermore, the energy consumption for TDS production was 0.81 kW·h·kg−1 when using the Cu/NC electrode. The processes and pathways of TDS electrochemical synthesis were explored using electrochemical tests and theoretical calculations.
Monosaccharide oxidation powered hybrid zinc-air battery with ultrahigh energy efficiency
(Elsevier B.V., 2026-05) Emmanuel Iwuoha; Jianyun Gan; Guanwu Lian
Rechargeable zinc-air batteries (ZABs) are promising for sustainable energy storage yet remain constrained by the high charging voltages and low energy efficiencies (∼60 %). Herein, we report a hybrid ZAB system (h-ZAB) that replaces the energy-intensive oxygen evolution reaction (OER) with the monosaccharide oxidation reaction (MOR) during charging, enabled by a high-performance nitrogen-doped carbon nanotube (NCNT)-encapsulated NiCo alloy bifunctional catalyst. This catalyst exhibits remarkable bifunctional performance, achieving a MOR potential of 1.29 V (vs. RHE) at 100 mA cm−2 and an oxygen reduction reaction (ORR) half-wave potential of 0.85 V (vs. RHE). Combined experimental and theoretical studies reveal that the built-in electric field at the interface of NiCo and NCNT induces charge redistribution, which optimizes intermediates adsorption and reduces reaction energy barriers, thereby boosting electrocatalytic kinetics. The h-ZAB delivers a low charge-discharge voltage gap of 0.32 V with 82.6 % round-trip efficiency at 10 mA cm−2, simultaneously producing value-added formate. Notably, the system maintains stable operation for 200 h at 40 mA cm−2 with a voltage gap below 0.58 V. This work provides a sustainable strategy integrating energy storage with biomass valorization, offering new insights into renewable energy-electrochemical systems.
Reconstructed wood carbon aerogel with single-atom sites for flexible Zn–air batteries
(American Chemical Society, 2025) Iwuoha Emmanuel; Chen, Zehong; Zhong, Linxin
Single-atom catalysts (SACs) have become vital air cathodes for metal−air batteries, but fabricating monolithic SACs with high catalytic activity and mechanical strength is currently lacking. Herein, an all-natural wood carbon aerogel with single-atom sites is reconstructed via modulating the multi-interactions within lignocellulosic components. Cellulose nanofiber (CNF) constitutes an oriented scaffold via physical interweaving and strong electrostatic repulsion, while lignosulfonate, acting as a multifunctional bioligand, coordinates with metal ions and forms hydrogen bonds with CNF to prevent the agglomeration of adjacent metal atoms. The resulting carbon aerogel features a biomimetic channel-ordered microstructure with M−N4 active sites (M = Cu, Fe, and Co), leading to outstanding mechanical elasticity and oxygen reduction and evolution activities with a half-wave potential of 0.881 V. Therefore, the SA-Cu@NCA-based aqueous Zn−air battery (ZAB) exhibits a high specific capacity of 779.3 mA h g−1 and long-term stability, while the flexible ZAB with SA-Cu@NCA as an integrated cathode delivers a high specific capacity and impressive operating stability even under harsh structural deformations. This study presents a viable approach for the sustainable production of flexible SACs for wearable and portable electronics.
Photochemical ozone production along flight trajectories in the upper troposphere and lower stratosphere and route optimisation
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Shallcross, Dudley Edmund; Foster, Allan; Derwent, Richard
Aviation is widely recognised to have global-scale climate impacts through the formation of ozone (O3) in the upper troposphere and lower stratosphere (UTLS), driven by emissions of nitrogen oxides (NOX). Ozone is known to be one of the most potent greenhouse gases formed from the interaction of aircraft emission plumes with atmospheric species. This paper follows up on previous research, where a Photochemical Trajectory Model was shown to be a robust measure of ozone formation along flight trajectories post-flight. We use a combination of a global Lagrangian chemistry-transport model and a box model to quantify the impacts of aircraft NOX on UTLS ozone over a five-day timescale. This work expands on the spatial and temporal range, as well as the chemical accuracy reported previously, with a greater range of NOX chemistry relevant chemical species. Based on these models, route optimisation has been investigated, through the use of network theory and algorithms. This is to show the potential inclusion of an understanding of climate-sensitive regions of the atmosphere on route planning can have on aviation’s impact on Earth’s Thermal Radiation balance with existing resources and technology. Optimised flight trajectories indicated reductions in O3 formation per unit NOX are in the range 1–40% depending on the spatial aspect of the flight. Temporally, local winter times and equatorial regions are generally found to have the most significant O3 formation per unit NOX; moreover, hotspots were found over the Pacific and Indian Ocean.

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