Detecting chronic autoimmune disorders (ADs) early reduces the risk of morbidity, disability, and mortality and offers the possibility of significant therapeutic action in a timely manner. Developing ...low-cost, reliable, and sensitive sensors for ADs can ensure the efficient utilization of healthcare resources at earlier stages. Here, we report on the development of an electrochemical biosensor for sensing CXCL10, a chemokine protein that serves as a biomarker for autoimmune diseases. A self-assembly strategy is used for the immobilization of biorecognition elements on a plastic chip electrode (PCE). A homemade PCE offers a versatile and cost-effective scaffold for sensing applications. Gold nanoparticles were electrochemically deposited on the electrode via the reduction of gold ions on the PCE galvanostatically. The CXCL10 antibody and recognition elements were immobilized on the gold-deposited PCE. The attachment of recognition molecules was confirmed by energy-dispersive scanning electron microscopy, atomic force microscopy, infrared spectroscopy, and electrochemical techniques. Electrochemical impedance spectroscopy (EIS) was used for the detection of CXCL10 within a concentration range spanning from pico- to micro-molar levels. The sensor exhibited remarkable linearity in both buffer and plasma solutions, with a limit of detection (LOD) of up to 0.72 pg mL −1 .
Electrocatalytic water splitting provides a sustainable method for storing intermittent energies, such as solar energy and wind, in the form of hydrogen fuel. However, the oxygen evolution reaction ...(OER), constituting the other half-cell reaction, is often considered the bottleneck in overall water splitting due to its slow kinetics. Therefore, it is crucial to develop efficient, cost-effective, and robust OER catalysts to enhance the water-splitting process. Transition-metal-based coordination polymers (CPs) serve as promising electrocatalysts due to their diverse chemical architectures paired with redox-active metal centers. Despite their potential, the rational use of CPs has faced obstacles including a lack of insights into their catalytic mechanisms, low conductivity, and morphology issues. Consequently, achieving success in this field requires the rational design of ligands and topological networks with the desired electronic structure. This study delves into the design and synthesis of three novel conjugated coordination polymers (CCPs) by leveraging the full conjugation of terpyridine-attached flexible tetraphenylethylene units as electron-rich linkers with various redox-active metal centers Co(II), Ni(II), and Zn(II). The self-assembly process is tuned for each CCP, resulting in two distinct morphologies: nanosheets and nanorings. The electrocatalytic OER performance efficiency is then correlated with factors such as the nanostructure morphology and redox-active metal centers in alkaline electrolytes. Notably, among the three morphologies studied, nanorings for each CCP exhibit a superior OER activity. Co(II)-integrated CCPs demonstrate a higher activity between the redox-active metal centers. Specifically, the Co(II) nanoring morphology displays exceptional catalytic activity for OER, with a lower overpotential of 347 mV at a current density of 10 mA cm–2 and small Tafel slopes of 115 mV dec–1. The long-term durability is demonstrated for at least 24 h at 1.57 V vs RHE during water splitting. This is presumably the first proof that links the importance of nanostructure morphologies to redox-active metal centers in improving the OER activity, and it may have implications for other transdisciplinary energy-related applications.
Green hydrogen has emerged as a promising clean energy carrier and renewable energy storage option. It has been promoted as a pivotal solution to the climate crisis and to lowering air pollution. A ...viable production of green hydrogen requires an efficient and durable non-precious metal electrocatalyst. In light of this, the current study describes the synthesis of an electrocatalyst consisting of Ni and N-doped graphitic carbon (Ni@NC) by a pyrolysis method under an argon atmosphere at different temperatures and the use of a cost-effective and scalable electrode platform for green hydrogen production. The electrocatalyst that was synthesized at 800 °C exhibits an overpotential of 400 mV
vs.
RHE at a current density of 10 mA cm
−2
, the Tafel slope of 110 mV decade
−1
, and good stability for the HER. The charge transfer resistance at the electrode-electrolyte interface is 10.8 Ω in the current study. The symbiotic effect of Ni carbon mixed with nitrogen shows excellent hydrogen evolution reaction (HER) activity. The morphology and structural properties of the electrocatalyst were well-characterized using XRD, FT-IR, Raman, FE-SEM, EDX, TEM, and XPS analysis. The Plastic Chip Electrode (PCE) enhanced the electrocatalytic activity and improved the durability issues, such as carbon corrosion in acidic conditions for the HER by the synergetic effect between the carbon electrode and a component of the catalyst.
Green hydrogen has emerged as a promising clean energy carrier and renewable energy storage option.
Synthesis and Characterization of Core-Shell Ni-nanoparticles with hetero-atom doping of S, N, O generated from mixed-ligand Ni-MOF and electrocatalytic application of these bifunctional materials ...for OER/HER has been investigated.
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•Synthesis of Core-Shell Ni@NCS nanomaterials by simple pyrolysis of Ni-MOF, thoroughly characterized by various analytical tools.•Ni@NCS-800 electrocatalyst showed excellent electrochemical activity and stability among all the calcined materials.•Ni@NCS-800 shows lower overpotential of 330 mV and 366 mV to reach 10 mAcm−2 current density in OER and HER, respectively.•ECSA, stability & Tafel slope supported the excellent activity of MOF-derived Core-Shell Ni@NCS nanomaterials.
Development of an affordable, stable, and efficient electrocatalyst using nonprecious material to generate green H2 and O2 is still a challenging research problem. This research demonstrates the development of an efficient bifunctional electrocatalyst for HER as well as OER. Self-sacrificial nickel-based MOF acted as a precursor in facile pyrolysis carried out at 600, 700, and 800 °C temperatures to yield three bifunctional electrocatalysts viz Ni@NCS-600, Ni@NCS-700, and Ni@NCS-800, respectively. A blend of metallic Ni-nanoparticles and heteroatoms (N, S, & O) doped graphitic matrix has shown a synergistic effect for efficient electrocatalysis. The facile transformation of Ni-MOF into core-shell structure imparts stability to metal electrocatalyst by preventing direct exposure to the electrolytes during water splitting. After systematic characterization by various analytical techniques, their electrocatalytic performances were evaluated for OER and HER in alkaline and acidic medium, respectively. Bifunctional electrocatalytic activity of Ni@NCS-800 was found to be highly efficient, and comparable to precious state-of-the-art catalysts (RuO2 and Pt/C). Ni@NCS-800 exhibits extremely low overpotential, which needs only 330 mV and 366 mV to reach 10 mAcm−2 current density in OER and HER, respectively. The Tafel slope has been derived from the EIS also, imparting the alternating current. Thereby, a superior electrokinetic activity of Ni@NCS-800 has been observed, due to the elimination of non-faradaic current, with a Tafel slope of 32 mV/dec. The stability was evaluated by potentiostatic and potentiodynamic techniques. Therefore, this study explores a suitable pathway for the fabrication of simple, nonprecious, stable, yet catalytically efficient material for HER and OER activity.
The synthesis of efficient hydrogen evolution reaction (HER) electrocatalysts is challenging for industrial-scale hydrogen generation by water splitting. Since their discovery in 2011, MXenes have ...been extensively investigated for their use in various energy applications as they possess sheet-like morphology that provides more active surface area and facilitates fast ion transfer. This work utilizes a facile hydrothermal treatment to fabricate palladium-modified MXene nanoflowers (nPdNFs). Chemical and morphological analysis of these synthesized nPdNFs shows that nPds have been successfully incorporated in MXene nanoflowers and act as an excellent support material for nPds. The effect of temperature and the thermal decomposition properties of the synthesized material were investigated by calcining it at different temperatures like 200, 300, and 400 °C in a flow of N2 gas. It is observed that nPdNFs-3 (calcined at 300 °C) exhibits maximum active catalytic sites for HER because its porous morphology supports rapid ion transportation. The electrochemical active surface area (ECSA) for all three materials was evaluated, among which nPdNFs-3 demonstrated the highest ECSA value, corroborating its HER activity and depicting a current density of 10 mA cm−2 at a low overpotential of 149 mV, with a Tafel slope of 96 mV dec–1 in 0.5 M H2SO4. The fabricated nanostructured material highlights ceaseless efforts and paves the way for developing MXenes and related materials, which can be employed in the energy conversion and storage sector.
Synthesis of NiO and CeO2 nanomaterials-based electrocatalysts and their characterizations. The fabricated electrode materials were used as working electrode for OER to investigate the stability and ...required overpotential for oxygen evolution in alkaline medium.
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•NiO and CeO2-based composites were developed by varying the concentration of NiO.•20-NiO@CeO2 appeared as an excellent OER electrocatalyst with good stability.•To achieve 50 mAcm−2 current density with 20-NiO@CeO2 for OER, 392 mV overpotential was required.•Excellent kinetics with 156 mV/dec Tafel slope was demonstrated by 20-NiO@CeO2.•ECSA, stability, and Rct support the excellent OER performance of 20-NiO@CeO2.
Electrochemical water electrolysis for the production of H2 and O2 is an extremely important and attractive technology that mainly depends on efficient and affordable electrocatalysts. However, the sluggish kinetics of OER is the main obstacle in water electrolysis. In this work, we have fabricated hybrid electrocatalysts based on CeO2 and NiO nanomaterials by varying the concentration of NiO to boost OER activity and stability. CeO2 and NiO nanomaterials were synthesized using (NH4)2 Ce(NO3)6 and Ni(NO3)2·6H2O as precursors, respectively. All the prepared electrocatalysts namely NiO, CeO2, 10-NiO@CeO2, 20-NiO@CeO2, 30-NiO@CeO2, and 40-NiO@CeO2, were well characterized by various analytical tools to evaluate their morphologies, phases, crystallinities, compositions and electrochemical activities. Among the series of fabricated electrocatalysts, 20-NiO@CeO2 appeared as an efficient electrocatalyst with a very low overpotential of 392 mV to reach 50 mAcm−2 current density. In addition, a lower value of the Tafel slope, as measured from the curve of linear sweep voltammetry (LSV), indicates better OER kinetics. Furthermore, the charge transfer resistance (Rct) and electrochemical active surface area (ECSA) were measured, which further supports the excellent OER performance of 20-NiO@CeO2. These findings pave the way toward the rational design of bimetallic electrode materials for excellent OER activity.
Spermine is considered an important biomarker for various malignancies. This article reports the development of two methods for measuring spermine at low concentrations. Fast Sulphon Black F (FSBF) ...is a cheap, water-soluble dye used to develop sensors to measure spermine in various biofluids via non-invasive pathways. Using the color change phenomenon, we have developed a smartphone-derived color chart to measure spermine by the naked eye using RGB and Lab values. To measure spermine at a further low concentration, we incorporated FSBF in a homemade and inexpensive copper-deposited plastic chip electrode (Cu-PCE), which can detect spermine at the sub-micromolar domain via impedimetry. HPLC-based validation of the colorimetric and electrochemical sensing platforms using real samples reveals a great prospect of low-cost methods for early diagnostics of malignancies. Direct loading of the FSBF on Cu-PCE eliminates a few additional steps, as described in the literature. Thus, offering portable and facile testing of spermine that would be useful in the day-to-day measurement of it in urine/plasma. We are not aware of using a receptor in two different methods for measuring spermine in biosamples. Furthermore, validation of the reported techniques involving biofluid is unprecedented in the literature.
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•Bimodal sensing of spermine in human biofluids at low concentrations.•Chromatic measurement of spermine using hydrophilic dye Fast Sulphon Black F.•Impedimetric sensing of spermine by a Cu-deposited plastic chip electrode.•Smartphone readout and impedimetric analysis of human urine samples.•HPLC-based validation of the developed sensors in aqueous and clinical samples.
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