Search Results (144)

To address the challenge of treating refractory organic dyes in textile wastewater, this study synthesized a novel copper-based composite material (designated MEL-Cu-6HNA) via a supramolecular self-assembly–pyrolysis pathway. Its core component consists of CuO/Cu₂O(SO₄), which was applied to efficiently degrade the Reactive Red 3BS dye within a sodium bicarbonate-activated hydrogen peroxide (BAP) system. This material was applied to degrade the Reactive Red 3BS dye using a sodium bicarbonate-activated hydrogen peroxide system. The morphology, crystal structure, and surface chemistry of the material were systematically characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Electron paramagnetic resonance (EPR) was employed to identify reactive species generated during the reaction. The effects of dye concentration, H₂O₂ concentration, MEL-Cu-6HNA dosage, and coexisting substances in water on degradation efficiency were systematically investigated, with active species identified via EPR. This study marks the first application of the supramolecular self-assembled CuO/Cu₂O(SO₄)₂ composite material MEL-Cu-6HNA, prepared via pyrolysis, in a sodium bicarbonate-activated hydrogen peroxide system. It achieved rapid and efficient decolorization of the recalcitrant Reactive Red 3BS dye. The three-dimensional sulfate framework and dual Cu²⁺ sites of the material significantly enhanced the degradation efficiency. MEL-Cu-6HNA achieved rapid and efficient decolorization of the recalcitrant Reactive Red 3BS in a sodium bicarbonate-activated hydrogen peroxide system. The material’s three-dimensional sulfate framework and dual Cu²⁺ sites significantly enhanced interfacial electron transfer and Cu²⁺/Cu⁺ cycling activation capacity. ·OH served as the primary reactive oxygen species (ROS), with SO₄²⁻, ¹O₂, and ·O₂⁻ contributing to sustained radical generation. This system achieved 95% decolorization within 30 min, demonstrating outstanding green treatment potential and providing a reliable theoretical basis and practical pathway for efficient, low-energy treatment of dyeing wastewater. Full article

In this study, a ternary Ni/Mg/g-C₃N₄ composite was synthesized via a controlled precipitation–calcination route and evaluated for its visible-light-assisted degradation of methylene blue (MB). The structural, morphological, and optical characteristics of the composites were systematically investigated using XRD, FT-IR, FESEM, BET, and UV–Vis analyses. The results confirmed the successful construction of Ni/Mg/g-C₃N₄ heterojunctions with strong interfacial coupling and enhanced surface porosity. Among all samples, the Ni/Mg/CN20 composite exhibited the highest activity, achieving 66% MB degradation within 180 min under visible light. This superior performance was attributed to synergistic effects arising from efficient interfacial charge transfer, broadened light absorption, and abundant active sites. The composite also displayed excellent thermal stability. This work demonstrates that the rational control of g-C₃N₄ loading plays a decisive role in tuning the physicochemical and catalytic properties of Ni/Mg/g-C₃N₄ composites. The findings provide new insights into the design of cost-effective, thermally stable, and high-performance photocatalysts for visible-light-driven wastewater treatment. Full article

Flexible biosensors offer rapid and low-cost diagnostics but are often limited by the mechanical and electrochemical instability of polymer-based designs in biological media. Here, we introduce a metallic flexible microcrack transducer that exploits the intrinsic deformability of superelastic nickel–titanium (NiTi) for label-free impedimetric detection. Mechanical bending of NiTi wires spontaneously generates martensitic-phase microcracks whose metal–gap–metal geometry forms the active transduction sites, where functional interfacial layers and captured analytes modulate the local dielectric environment and govern the impedance response. Our approach imparts a novel dielectric character to the alloy, enabling its unexplored application in the megahertz (MHz) frequency domain (0.01–10 MHz) where native NiTi is merely conductive. Functionalization with Escherichia coli (E. coli)-specific antibodies renders these microdomains biologically active. This effectively transforms the mechanically induced microcracks into tunable impedance elements driven by analyte binding. The γ-bent NiTi sensors achieved stable and quantitative detection of E. coli ATCC 25922 in sterile human urine, with a detection limit of 64 colony forming units (CFU) mL⁻¹ within 45 min, without redox mediators, external labels, or amplification steps. This work pioneers the use of martensitic microcrack networks, mimicking self-healing behavior in a superelastic alloy as functional transduction elements, defining a new class of metallic flexible biosensors that integrate mechanical robustness, analytical reliability, and scalability for point-of-care biosensing. Full article

The electrochemical water splitting process represents a promising and sustainable route for generating high-purity hydrogen with minimal environmental impact. The development of efficient and economically viable electrocatalysts is crucial for enhancing the kinetics of the oxygen evolution reaction (OER), which is a major bottleneck in overall water splitting. In this study, a Co₃V₂O₈/PEG-CTAB electrocatalyst was synthesized and systematically evaluated for its OER activity in alkaline conditions. The nanosheet-like architecture of the PEG-CTAB-assisted Co₃V₂O₈ electrocatalyst facilitates effective interfacial contact, thereby improving charge transport and catalytic accessibility. Among the examined compositions, the Co₃V₂O₈/PEG-CTAB catalyst exhibited superior OER performance, requiring a low overpotential of 298 mV to deliver a current density of 10 mA cm⁻² and displaying a Tafel slope of 90 mV dec⁻¹ in 1 M KOH. Furthermore, the catalyst demonstrated outstanding durability, retaining its electrocatalytic activity after 5000 consecutive CV cycles and prolonged chronopotentiometric testing. The Co₃V₂O₈/PEG-CTAB || Pt-C asymmetric cell required a cell voltage of 1.83 V to reach the threshold current density, confirming its ability to efficiently sustain overall water splitting under alkaline conditions. The enhanced performance is attributed to the synergistic effect of the electrocatalyst, which promotes active site exposure and structural stability. These findings highlight the potential of the Co₃V₂O₈/PEG-CTAB system as a cost-effective and robust electrocatalyst for practical water oxidation applications. Full article

The intrinsic limitations of Ti₃C₂T_x electrodes, specifically low interfacial charge-transfer efficiency and structural degradation in strongly acidic environments, hinder their performance in high-rate aqueous supercapacitors. Herein, we report a synergistic strategy combining nitrogen plasma surface engineering with a redox-active ascorbic acid electrolyte to optimize the electrode/electrolyte interfacial kinetics. By systematic investigation, the Ti₃C₂T_x supercapacitor obtained by a 10-min plasma duration (N10P-AA) achieved the optimal balance between activating surface sites and preserving the conductive Ti–C framework integrity. The ascorbic acid electrolyte broadened the potential window to approximately 0.7 V, and N10P-AA exhibited the lowest charge-transfer impedance and superior rate capability, retaining a relatively high Coulombic efficiency (>72%) even at a high scan rate of 10,000 mV·s⁻¹. The EIS results and kinetics analysis (b values) confirmed that the moderate plasma activation effectively promoted more surface-dominated charge storage kinetics and mitigated diffusion limitation, consistent with reduced charge-transfer resistance and a smaller Warburg slope. The XPS results revealed that the 10-min treatment suppressed detrimental oxidation during cyclings and facilitated the formation of electrochemically favorable hydroxylated surface functional groups. This work demonstrates a feasible surface electrolyte co-engineering strategy for modulating the interfacial behavior of MXene, which is of great significance for future high-efficiency aqueous electrochemical energy storage and potential biosensing applications. Full article

To investigate the performance of horizontally reinforced composite foundations in resisting surface rupture of normal faults, this study designed and conducted a series of physical model tests. A systematic comparative analysis was performed on the fracture resistance of sites with three-layer sand, five-layer sand, and three-layer clay geogrid horizontally reinforced composite foundations under 70° normal fault dislocation. The results indicate that significant changes in earth pressure serve as a precursor indicator of fault rupture, and their evolution process reveals the internal energy accumulation and release mechanism. Increasing the number of geogrid layers significantly enhances the lateral confinement of the foundation, resulting in a narrower macro-rupture zone located farther from the structure in sand sites, and promotes the formation of a step-fault scarp deformation mode at the surface, which is more conducive to structural safety. Under identical reinforcement conditions, the clay site exhibited comprehensively superior fracture resistance compared to the sand site due to the soil cohesion and stronger interfacial interaction with the geogrids, manifested as more significant deviation of the rupture path, and lower microseismic accelerations and structural strains transmitted to the building. Comprehensive analysis confirms that employing geogrid-reinforced composite foundations can effectively guide the surface rupture path and improve the deformation pattern, representing an effective engineering measure for mitigating disaster risk for buildings spanning active faults. Full article

Platinum is known as the most efficient catalyst for oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). However, Pt catalysts still encounter high loading demands, poor atom utilization, and uncontrolled nanoparticle aggregation, which severely restrict their practical use. To address these issues, we designed a Pt-W_1.33C hybrid catalyst with strong interfacial coupling between Pt nanoparticles and the vacancy-rich i-MXene, W_1.33C matrix. This robust Pt-W_1.33C interaction effectively restricts Pt overgrowth, producing uniformly dispersed nanoparticles with an average physical size of 3.1 nm. The results show that the modulated electronic structure facilitates electron transfer from W_1.33C to neighboring Pt sites, which reduces the energy barriers of chemical reactions and enhances the intrinsic electrochemical catalytic activity of the hybridized catalysts. As a result, the Pt-W_1.33C catalyst with low Pt loading achieves an ORR overpotential of 320 mV at 0.1 mA cm⁻², an HER overpotential of 36 mV at 10 mA cm⁻², and Tafel slopes of 66 and 27.8 mV dec⁻¹ for ORR and HER, respectively. The enhanced ORR and HER performance of Pt-W_1.33C can be attributed to the synergistic interplay between Pt and W_1.33C, including the disordered stacking of W_1.33C, high conductivity of W_1.33C, high catalytic activity of Pt, and strong Pt-W_1.33C interfacial coupling, which, together, optimize electronic interaction and active-site accessibility in the hybrid catalyst. Full article

A rapid solvent-free microwave-assisted strategy was developed to fabricate Pt- and Ni-modified Co(OH)₂ catalysts for alkaline hydrogen evolution. Among them, Ni-Pt@Co(OH)₂, prepared via sequential Ni-first then Pt loading, exhibited the best performance. Structural analyses confirmed uniform Pt dispersion with dominant Pt(111) facets, while ICP-MS showed reduced Pt usage compared to Pt@Co(OH)₂. Electrochemical measurements in 1.0 M KOH revealed an overpotential of 71 mV at 10 mA·cm⁻², comparable to Pt/C, and a mass activity 4–6.5 times higher across 25–75 mV. EIS demonstrated lower charge-transfer resistance, and stability tests showed negligible degradation after 3000 CV cycles and 11 h continuous operation. The outstanding performance arises from enhanced Pt utilization, abundant conductive sites, and strong Ni-Pt interfacial synergy, highlighting Ni-Pt@Co(OH)₂ as a promising catalyst for efficient alkaline HER with reduced Pt consumption. Full article

This study presents a dual surfactant-assisted hydrothermal approach for the synthesis of Co₃V₂O₈ (CoVO) nanostructures and their surfactant-modified derivatives, PVP-assisted Co₃V₂O₈ (P-CoVO) and PVP–SDS co-assisted Co₃V₂O₈ (P/S-CoVO), which were directly grown on nickel foam. The use of PVP and SDS enabled controlled nucleation and growth, yielding a hierarchical nanoflower-like morphology in P/S-CoVO with increased porosity, a higher surface area, and uniform structural features. Comprehensive physicochemical characterization confirmed that surfactant incorporation effectively modulated particle size, dispersion, and active-site availability. Electrochemical measurements demonstrated that P/S-CoVO exhibited superior performance, with the largest CV area, low equivalent series resistance (0.52 Ω), and a maximum areal capacitance of 13.71 F cm⁻² at 8 mA cm⁻², attributable to rapid redox kinetics and efficient ion transport. The electrode also showed excellent cycling stability, retaining approximately 83.7% of its initial capacitance after 12,000 charge–discharge cycles, indicating robust structural integrity and interfacial stability. Additionally, an asymmetric supercapacitor device (P/S-CoVO//AC) delivered a high energy density of 0.082 mWh cm⁻², a power density of 1.25 mW cm⁻², and stable operation within a 1.5 V potential window. These results demonstrate that cooperative surfactant engineering provides an effective and scalable strategy to enhance the morphology, electrochemical kinetics, and durability of Co₃V₂O₈-based electrodes for next-generation high-performance supercapacitors. Full article

The pervasive discharge of synthetic dyes into aquatic ecosystems poses a significant threat due to their chemical stability, low biodegradability, and carcinogenicity. Conventional dye remediation methods—such as biological treatments, coagulation, and adsorption—have demonstrated limited efficiency and poor reusability, particularly against resilient azo dyes. Cerium oxide (CeO₂) nanoparticles have gained traction as photocatalysts owing to their redox-active surfaces and oxygen storage capabilities; however, issues like particle agglomeration and rapid charge recombination restrict their catalytic performance. To address these challenges, this study presents the novel synthesis of a graphene oxide–cerium oxide (GO-CeO₂) nanocomposite via a facile in situ hydrothermal approach, using graphite from lead pencils as a sustainable precursor. The composite was structurally characterized using UV–visible spectroscopy, XRD, FTIR, and TEM. The GO matrix not only facilitates uniform dispersion of CeO₂ nanoparticles but also enhances interfacial electron mobility and active site availability. The nanocomposite demonstrated exceptional photocatalytic degradation efficiencies for methyl orange (94%), methyl red (98%), congo red (96%), and 4-nitrophenol (85.6%) under sunlight irradiation, with first-order rate constants significantly exceeding those of pure CeO₂. Notably, GO–CeO₂ retained strong catalytic activity over four degradation cycles, confirming its recyclability and structural stability. Total organic carbon (TOC) analysis revealed 79% mineralization of methyl orange, outperforming CeO₂ (45%), indicating near-complete conversion into benign byproducts. This work contributes a scalable, low-cost, and highly active heterogeneous photocatalyst for wastewater treatment, combining green synthesis principles with improved photodegradation kinetics. Its modular architecture and reusability make it a promising candidate for future environmental remediation technologies and integrated photocatalytic systems. Full article

To tackle the intrinsic limitations of fast charge recombination and sluggish reaction kinetics in carbon nitride (C₃N₄) for photoelectrocatalytic (PEC) water reduction reaction, we constructed a NiS/C₃N₄ heterojunction photoelectrode via a sequential approach combining chemical vapor deposition and hydrothermal treatment. Compared with pristine C₃N₄, the introduction of NiS significantly reduced interfacial charge transfer resistance and effectively suppressed the photogenerated carrier recombination. Among all compositions investigated, the NiS-0.2 photoelectrode demonstrated a maximum photocurrent density of −13.44 mA cm⁻² at −0.8 V vs. RHE, representing a more than 6.7-fold enhancement in comparison to bare C₃N₄ (−2.00 mA cm⁻²). This remarkable improvement is attributed to the construction of an efficient type-II heterojunction between C₃N₄ and NiS. Under the driving force of the internal electric field at the interface, photoinduced electrons migrate from the conduction band of C₃N₄ to NiS, whereas holes move from the valence band of NiS to C₃N₄. This spatial separation mechanism, coupled with the role of NiS as an efficient active site for the water reduction reaction, synergistically enhances the overall PEC performance. This work offers a rational and feasible approach for designing efficient, stable, and cost-effective C₃N₄-based photoelectrodes. Full article

Developing cost-effective and durable electrocatalysts with high hydrogen evolution efficiency remains a critical challenge for sustainable energy conversion. Herein, spinel-type Co₂CuO₄ and Co₃O₄ nanosheet electrodes were fabricated directly on Ni foam via a simple electrodeposition route and evaluated for the alkaline hydrogen evolution reaction (HER) in 1.0 M KOH. Structural and surface analyses confirmed the formation of phase-pure, porous, and highly interconnected nanosheet architectures, where the substitution of Cu²⁺ into the Co₃O₄ lattice induced charge-redistribution and optimized the electronic configuration. The Co₂CuO₄ catalyst exhibited superior activity, requiring an overpotential of 127 mV to achieve 10 mA cm⁻² with a corresponding Tafel slope of 61 mV dec⁻¹, outperforming the Co₃O₄ catalyst (176 mV and 95 mV dec⁻¹). This enhancement arises from improved intrinsic kinetics, higher turnover frequency, and reduced charge-transfer resistance, reflecting an increased density of active sites and enhanced interfacial conductivity. Furthermore, the Co₂CuO₄ catalyst maintained excellent stability for 100 h at both 10 and 500 mA cm⁻², attributed to its strong adhesion and open nanosheet framework, which facilitates efficient gas release and electrolyte diffusion. These findings establish Co₂CuO₄ as a promising and durable HER electrocatalyst for alkaline water electrolysis. Full article

Electrocatalytic water splitting offers a promising route to sustainable H₂, but the oxygen evolution reaction (OER) in alkaline media remains the principal bottleneck for activity and durability. This review focuses on alkaline OER and integrates mechanism, kinetics, materials design, and cell-level considerations. Reaction mechanisms are outlined, including the adsorbate evolution mechanism (AEM) and the lattice oxygen mediated mechanism (LOM), together with universal scaling constraints and operando reconstruction of precatalysts into active oxyhydroxides. Strategies for electronic tuning, defect creation, and heterointerface design are linked to measurable kinetics, including iR-corrected overpotential, Tafel slope, charge transfer resistance, and electrochemically active surface area (ECSA). Representative catalyst families are critically evaluated, covering Ir and Ru oxides, Ni-, Fe-, and Co-based compounds, carbon-based materials, and heterostructure systems. Electrolyte engineering is discussed, including control of Fe impurities and cation and anion effects, and gas management at current densities of 100–500 mA·cm⁻² and higher. Finally, we outline challenges and directions that include operando discrimination between mechanisms and possible crossover between AEM and LOM, strategies to relax scaling relations using dual sites and interfacial water control, and constant potential modeling with explicit solvation and electric fields to enable efficient, scalable alkaline electrolyzers. Full article

The development of durable and efficient catalysts capable of driving both hydrogen and oxygen evolution reactions is essential for advancing sustainable hydrogen production through overall water electrolysis. In this study, we developed a corrosion-mediated approach, where Ni ions originate from the self-corrosion of the nickel foam (NF) substrate, to construct Pt-modified NiFe layered double hydroxide (Pt-NiFeO_xH_y@NiFe-LDH) under ambient conditions. The obtained catalyst exhibits a hierarchical architecture with abundant defect sites, which favor the uniform distribution of Pt clusters and optimized electronic configuration. The Pt-NiFeO_xH_y@NiFe-LDH catalyst, constructed through the interaction between Pt sites and defective NiFe layered double hydroxide (NiFe-LDH), demonstrates remarkable hydrogen evolution reaction (HER) activity, delivering an overpotential as low as 29 mV at a current density of 10 mA·cm⁻² and exhibiting a small tafel slope of 34.23 mV·dec⁻¹ in 1 M KOH, together with excellent oxygen evolution reaction (OER) performance, requiring only 252 mV to reach 100 mA·cm⁻². Moreover, the catalyst demonstrates outstanding activity and durability in alkaline seawater, maintaining stable operation over long-term tests. The Pt-NiFeO_xH_y@NiFe-LDH electrode, when integrated into a two-electrode system, demonstrates operating voltages as low as 1.42 and 1.51 V for current densities of 10 and 100 mA·cm⁻², respectively, and retains outstanding stability under concentrated alkaline conditions (6 M KOH, 70 °C). Overall, this work establishes a scalable and economically viable pathway toward high-efficiency bifunctional electrocatalysts and deepens the understanding of Pt-LDH interfacial synergy in promoting water-splitting catalysis. Full article

Heavy metal ions (HMIs) threaten ecosystems and human health due to their carcinogenicity, bioaccumulativity, and persistence, demanding highly sensitive, low-cost real-time detection. Electrochemical sensing technology has gained significant attention owing to its rapid response, high sensitivity, and low cost. Molybdenum disulfide (MoS₂), with its layered structure, tunable bandgap, and abundant edge active sites, demonstrates significant potential in the electrochemical detection of heavy metals. This review systematically summarizes the crystal structure characteristics of MoS₂, various preparation strategies, and their mechanisms for regulating electrochemical sensing performance. It particularly explores the cooperative effects of MoS₂ composites with other materials, which effectively enhance the sensitivity, selectivity, and detection limits of electrochemical sensors. Although MoS₂-based materials have made significant progress in theoretical and applied research, practical challenges remain, including fabrication process optimization, interference from complex-matrix ions, slow trace-metal enrichment kinetics, and stability issues in flexible devices. Future work should focus on developing efficient, low-cost synthesis methods, enhancing interference resistance through microfluidic and biomimetic recognition technologies, optimizing composite designs, resolving interfacial reaction dynamics via in situ characterization, and establishing structure–property relationship models using machine learning, ultimately promoting practical applications in environmental monitoring, food safety, and biomedical fields. Full article