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MXenes are emerging rapidly as promising electrode materials for energy storage due to their high electronic conductivity and rich surface chemistry, but their potassium storage performance is unsatisfactory because of the large size of K+ and irreversible interfacial reaction. Here, a developed 3D foam‐like MXene scaffold (3D‐FMS) is constructed via an electrostatic neutralization of Ti3C2Tx with positive‐charged melamine followed with calcination, which offers massive surface‐active sites and facilitates fast K+ transfer for boosting the potassium‐ion storage capacity and dynamics. In addition, using KFSI‐based electrolyte, the formation of a robust solid electrolyte interface layer with more inorganic components on MXene anode is revealed for enhancing the Coulombic efficiency. Consequently, the 3D‐FMS with KFSI‐based electrolyte delivers enhanced potassium‐ion storage performance in terms of capacity (161.4 mAh g−1 at 30 mA g−1), rate capability (70 mAh g−1 at 2 A g−1), and cycling stability (80.5 mAh g−1 at 1 A g−1 after 2000 cycles). Moreover, the assembled 3D‐FMS//activated carbon potassium‐ion hybrid supercapacitor delivers a high energy density of 57 Wh kg−1 at a power density of 290 W kg−1. These excellent performances demonstrate the great superiority of 3D‐FMS in KFSI‐based electrolyte and may accelerate the development of MXene‐based materials for potassium storage systems. [ABSTRACT FROM AUTHOR]

Owing to unique physical and optical properties, fluorescent carbon dots (C-dots) are used in various biomedical applications. In this study, C-dots have been integrated as sensing agent on paper surface for colorimetric determination of clinically important analytes. Polyacrylamidebased C-dots coated C-dips showed visible color change from white to brown for iron (Fe2+, Fe3+) sample. Moreover, iron and copper (Cu2+) samples showed significant quenching of C-dots under UV. Images captured with/without UV were analyzed to study the relationship between different iron and copper concentrations and colorimetric intensity values. Color intensity and fluorescence showed a linear relationship with concentrations of iron and copper (Range: 1×10-4 to 1×10-2 M, Linearity: R² = 0.94). LOD from the paper sensor showed a sensitivity of 3.89×10-5 μM, 4.65×10-5 μM and 6.7×10-5 μM for Fe3+, Fe2+ and Cu2+ respectively, reflecting its reliability as low-cost sensing solution to analyze clinically relevant analytes as reported in current study. [ABSTRACT FROM AUTHOR]

MXenes-Ti3C2Tx, based on their versatile surface characteristics, has rapidly advanced as an interactive substrate to develop electrochemical sensors for clinical applications. Herein, Ni embedded Ti3C2Tx (MX−Ni) composites were prepared using a self-assembly approach where Ti3C2Tx sheets served as an interactive conductive substrate as well as a protective layer to nickel nanoparticles (Ni NPs), preventing their surface oxidation and aggregation. The composite displayed a cluster-like morphology with an intimate interfacial arrangement between Ni, Ti3C2Tx and Ti3C2Tx-derived TiO2. The configuration of MX−Ni into an electrochemical sensor realized a robust cathodic reduction current against methylmalonic acid (MMA), a biomarker to vitamin B12 deficiency. The synergism of Ni NPs strong redox characteristics with conductive Ti3C2Tx enabled sensitive signal output in wide detection ranges of 0.001 to 0.003 µM and 0.0035 to 0.017 µM and a detection sensitivity down to 0.12 pM of MMA. Importantly, the sensor demonstrated high signal reproducibility and excellent operational capabilities for MMA in a complex biological matrix such as human urine samples. [ABSTRACT FROM AUTHOR]

This study presents the synthesis of CeO2-TiO2 nanocomposite and its potential application for the visible light-driven photocatalytic degradation of model crystal violet dye as well as real industrial waste water. The ceria-titania (CeO2-TiO2) nanocomposite material was synthesised using facile hydrothermal route without the assistance of any template molecule. As-prepared composite was characterised by SEM, TEM, HRTEM, XRD, XPS for surface features, morphological and crystalline characters. The formed nanostructures were determined to possess crystal-like geometrical shape and average size less than 100 nm. The as-synthesised nanocomposite was further investigated for their heterogeneous photocatalytic potential against the oxidative degradation of CV dye taken as model pollutant. The photo-catalytic performance of the as-synthesised material was evaluated both under ultra-violet as well as visible light. Best photocatalytic performance was achieved under visible light with complete degradation (100%) exhibited within 60 min of irradiation time. The kinetics of the photocatalytic process were also considered and the reaction rate constant for CeO2-TiO2 nanocomposite was determined to be 0.0125 and 0.0662 min−1 for ultra-violet and visible region, respectively. In addition, the as-synthesised nanocomposite demonstrated promising results when considered for the photo-catalytic degradation of coloured industrial waste water collected from local textile industry situated in Faisalabad region of Pakistan. Enhanced photo-catalytic performance of CeO2-TiO2 nanocomposite was proposed owing to heterostructure formation leading to reduced electron-hole recombination. [ABSTRACT FROM AUTHOR]

The study describes the application of oxidation resistant copper nanostructures as an efficient heterogeneous catalyst for the treatment of organic dye containing waste waters. Copper nanostructures were synthesized in an aqueous environment using modified surfactant assisted chemical reduction route. The synthesized nanostructures have been characterized by UV-Vis, Fourier transform infrared spectroscopy FTIR spectroscopy, Atomic force microscopy (AFM), Scanning Electron Microscopy (SEM), and X-ray diffractometry (XRD). These surfactant capped Cu nanostructures have been used as a heterogeneous catalyst for the comparative reductive degradation of methyl orange (MO) in the presence of sodium borohydride (NaBH4) used as a potential reductant. Copper nanoparticles (Cu NPs) were found to be more efficient compared to copper nanorods (Cu NRds) with the degradation reaction obeying pseudofirst order reaction kinetics. Shape dependent catalytic efficiency was further evaluated from activation energy (EA) of reductive degradation reaction. The more efficient Cu NPs were further employed for reductive degradation of real waste water samples containing dyes collected from the drain of different local textile industries situated in Hyderabad region, Pakistan. [ABSTRACT FROM AUTHOR]

The aim of this study was to reduce the highly toxic hexavalent chromium Cr(VI) into less toxic chromium Cr(III) species by using nickel nanoparticles (Ni NPs) as catalysts in order to provide safety to the aqueous environment. In the first phase Ni NPs were synthesized in ethylene glycol and capped with 1-cysteine by a modified microwave irradiation method using NaOH as the accelerator. The formed Ni NPs were characterized by various techniques such as UV-Visible spectroscopy, Fourier Transform Infra-red (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). In the second phase the formed Ni NPs were immobilized on glass surfaces and employed as catalyst for the reduction of Cr(VI) ions. According to observations, 99% reduction of Cr(VI) ions was achieved in the presence of 0.5 mg of Ni NPs catalyst in just five minutes as compared to nickel powder that showed only 16% reduction in 15 minutes. The study has a great impact on the aqueous pollution control of Cr(VI) especially caused by the discharge of waste water from several industries utilizing Cr(VI) containing salt as one of the essential gradients. [ABSTRACT FROM AUTHOR]

Procalcitonin (PCT) protein has recently been identified as a clinical marker for bacterial infections based on its better sepsis sensitivity. Thus, an increased level of PCT could be linked with disease diagnosis and therapeutics. In this study, we describe the construction of the photoelectrochemical (PEC) PCT immunosensing platform based on it situ grown photo-active CuWO4 nanospheres over reduced graphene oxide layers (CuWO4@rGO). The in situ growth strategy enabled the formation of small nanospheres (diameter of 200 nm), primarily composed of tiny self-assembled CuWO4 nanoparticles (2–5 nm). The synergic coupling of CuWO4 with rGO layers constructed an excellent photo-active heterojunction for photoelectrochemical (PEC) sensing. The platform was then considered for electrocatalytic (EC) mechanism-based detection of PCT, where inhibition of the photocatalytic oxidation signal of ascorbic acid (AA), subsequent to the antibody–antigen interaction, was recorded as the primary signal response. This inhibition detection approach enabled sensitive detection of PCT in a concentration range of 10 pg·mL−1 to 50 ng.mL−1 with signal sensitivity achievable up to 0.15 pg·mL−1. The proposed PEC hybrid (CuWO4@rGO) could further be engineered to detect other clinically important species. [ABSTRACT FROM AUTHOR]

Bismuth-based materials are regarded as promising anode materials for potassium ion batteries (PIBs) due to their high theoretical capacity and low working potential. However, the large volume expansion and sluggish kinetics during cycling are major limitations to their practical application. Herein, a unique Bi/Bi 2 O 3 -C heterostructure was designed through a simple Bi-metal-organic framework (MOF) modulation-pyrolysis process. X-ray photoelectron spectroscopy, transmission electron microscopy, and X-ray diffraction revealed that the Bi and Bi 2 O 3 can form hetero-particles, which were uniformly embedded in a plate-like carbon skeleton, constructing a Bi/Bi 2 O 3 -C heterostructure. The carbon skeleton and the formation of numerous hetero-interfaces between Bi, Bi 2 O 3 , and carbon can effectively promote the interfacial charge transfer, shorten the K + diffusion pathway, and alleviate the volume expansion of Bi/Bi 2 O 3 during potassiation. Consequently, the Bi/Bi 2 O 3 -C heterostructure exhibited a high reversible capacity of 426.0 mAh g -1 at 50 mA g -1 , excellent cycle performance of 251.8 mAh g -1 after 350 cycles with a capacity retention of 76.6 %, and superior rate capability of 82.7 mAh g -1 at 1 A g -1 , demonstrating its promising potential for the application of PIBs anode., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Interfacial charge-carrier recombination is a bottle-neck issue restricting photoelectrochemical biosensors advancement in the wearable clinical electronics. In this study, we propose a simple approach to construct a highly efficient photoactive heterojunction capable of functioning as an active substrate in PEC biosensing of CD44 proteins. Taking the advantage of high photocatalytic activity of BiVO 4 , and biocompatible yet conductive 2D-Ti 3 C 2 T x nanosheets, a workable heterojunction was constructed between in-situ formed TiO 2 from the partially oxidized Ti 3 C 2 T x and lysine functionalized BiVO 4 (TiO 2 /MX-BiVO 4 ). The interfacial arrangement was ideal for promoting fast charge transfer from photo-excited BiVO 4 and TiO 2 to Ti 3 C 2 T x , constructing an energy level-cascade that permits minimal charge-carrier recombination besides robust photocatalytic redox activity. The PEC biosensor relies on the ligand-protein interaction, where hyaluronic acid was directly immobilized over TiO 2 /MX-BiVO 4 based on the interactions between carboxyl of lysine and amino moieties of hyaluronic acid. The PEC biosensor response depends on the inhibition in the measured photo-oxidation current of mediator species, i.e., ascorbic acid after the addition of CD44 proteins. The superior photo-activity, and robust heterojunction arrangement, produced a sensitive signal capable of recognizing CD44 in the wide concentration window of 2.2 × 10 -4  ng mL -1 to 3.2 ng mL -1 with a low-detection limit of 1.4 × 10 -2  pg mL -1 . The strong interaction between lysine functionalized BiVO 4 and hyaluronic acid enabled biosensor to exhibit robust antifouling characteristics towards similar proteins such as PSA and NSE. The quantification of CD44 protein from real-blood serum samples further confirmed the biosensor's reliability for clinical application., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Procalcitonin (PCT) protein has recently been identified as a clinical marker for bacterial infections based on its better sepsis sensitivity. Thus, an increased level of PCT could be linked with disease diagnosis and therapeutics. In this study, we describe the construction of the photoelectrochemical (PEC) PCT immunosensing platform based on it situ grown photo-active CuWO 4 nanospheres over reduced graphene oxide layers (CuWO 4 @rGO). The in situ growth strategy enabled the formation of small nanospheres (diameter of 200 nm), primarily composed of tiny self-assembled CuWO 4 nanoparticles (2-5 nm). The synergic coupling of CuWO 4 with rGO layers constructed an excellent photo-active heterojunction for photoelectrochemical (PEC) sensing. The platform was then considered for electrocatalytic (EC) mechanism-based detection of PCT, where inhibition of the photocatalytic oxidation signal of ascorbic acid (AA), subsequent to the antibody-antigen interaction, was recorded as the primary signal response. This inhibition detection approach enabled sensitive detection of PCT in a concentration range of 10 pg·mL -1 to 50 ng.mL -1 with signal sensitivity achievable up to 0.15 pg·mL -1 . The proposed PEC hybrid (CuWO 4 @rGO) could further be engineered to detect other clinically important species.

This study describes the construction of highly-sensitive photo-electrochemical (PEC) immunosensor for the detection of neuron-specific enolase (NSE). The biosensing platform is comprised of photo-active NiWO 4 nanostructures, in-situ-grown over a conductive substrate (indium tin oxide) using a low-temperature template-based co-precipitation approach. The discussed approach enables the formation of discrete, yet morphologically-analogous, nanostructures with complete coverage (pinhole-free) of the electrode surface. The in-situ-grown nanostructure possess dense population with sharp saw-blade like morphological features that can support substantial immobilisation of anti-NSE agent. The constructed platform demonstrated excellent photo-catalytic activity towards uric acid (UA) which served as the base for the Electrochemical -mechanism (EC) based PEC inhibition sensing. The detection of NSE, relied on its obstruction in analytical signal observed for the photo-oxidation of UA after binding to the electrode surface via protein-antibody interaction. The constructed PEC immunosensor exhibits signal sensitivity up to 0.12 ng mL -1 of NSE with excellent signal reproducibility and electrode replicability. Moreover, the constructed platform was successfully used for NSE determination in human serum samples., (Copyright © 2019 Elsevier B.V. All rights reserved.)