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•MAX filament promise advances in sustainable energy applications.•3D printing offers new potential for MXene synthesis.•Novel method bypasses need for toxic HF in MXene production.
...Two-dimensional (2D) MXenes are promising materials for a variety of sustainable energy-related applications such as photoelectrochemical water splitting and energy storage devices. Among the MXene family, the Ti3C2Tx is mostly prepared by selective etching of Al from the Ti3AlC2 MAX phase using hydrofluoric acid (HF) or in-situ produced HF as an etchant. However, the severe toxicity, handling of HF acid as well as the oxidation and degradation of freshly synthesized MXenes when stored as aqueous suspensions obstruct the large-scale production of MXenes. 3D printing is an innovative and versatile technology utilized for a plethora of applications in the field of energy applications. Thus, integration of 3D printing technology with the synthesis procedure of MXene will provide a new outlook for large-scale production and the long-storing capability of MXene. Herein, we fabricated a novel MAX (Ti3AlC2)/polylactic acid (PLA) filament for fused deposition modeling (FDM) 3D printing followed by etching of the 3D-printed MAX/PLA electrode into 3DP-etched-MAX employing chronoamperometry technique consecutively in 9 M HCl and 4 M NaOH as electrolytes. The 3D printed electrochemically etched MAX (3DP-etched-MAX) electrode shows promising behaviour for the photoelectrochemical hydrogen evolution reaction (HER) and capacitive performance. In general, this work demonstrates a path of production of large-scale manufacturing of MAX/PLA filament and 3DP-etched-MAX electrodes without using toxic HF for energy conversion and energy storage applications. This work paves the way to fabricate other novel MAX filaments and electrodes for several applications beyond energy conversion and storage.
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•Selective fluorimetric chemosesning of Cu2+ by probe 1.•Probe 2 demonstrated selectivity in detection of Al3+ ion through fluorimetry.•Nanomolar limit of detection in case of both ...ions.•Application of probe 1 in logic gate construction for detection of Cu2+.
Schiff base probes (1 and 2) made from o-phenylenediamine and o-aminophenol were appeared as highly selective fluorimetric chemosensor of Cu2+ and Al3+ ions respectively. Strong fluorescence emission of probe 1 at 415 nm (excitation at 350 nm) was instantly turned off on addition of Cu2+. Very weak fluorescence of probe 2 at 506 nm (excitation at 400 nm) was immediately turned on specifically by Al3+. Job's plot and ESI-MS results suggested 1:1 molar stoichiometric ratio of metal ion and probe in their respective complexes. Probe 1 and 2 had demonstrated very low detection limit (9.9 and 2.5 nM respectively). Binding of Cu2+ with probe 1 was found chemically reversible on addition of EDTA, while complexation between Al3+ and probe 2 was not reversible. On the basis of density functional theory (DFT) and spectroscopic results, probable mode of sensing of the metal ions by the probes were proposed. Quenching of the fluorescence of probe 1 by Cu2+ was attributed to the extensive transfer of charge from the probe molecule to paramagnetic copper ion. Whereas, in the Al3+-complex of probe 2, photo-induced electron transfer (PET) process from the imine nitrogen to salicylaldehyde moiety was restricted and thereby the weak emission intensity of probe 2 was enhanced significantly. Effective pH range of sensing the metal ions by probe 1 and 2 were 4 to 8 and 6 to 10 respectively. Probe 1 was also applied in the design of a logic gate for Cu2+ detection. Moreover, probe 1 and 2 was also used in water sample analysis for quantitative estimation of Cu2+ and Al3+ respectively.
This study is focused on the preparation of the CuS/RGO nanocomposite via the hydrothermal method using GO and Cu–DTO complex as precursors. X-ray diffraction, Fourier-transform infrared ...spectroscopy, and Raman and X-ray photoelectron spectroscopy study revealed the formation of the CuS/RGO nanocomposite with improved crystallinity, defective nanostructure, and the presence of the residual functional group in the RGO sheet. The morphological study displayed the transformation of CuS from nanowire to quantum dots with the incorporation of RGO. The galvanostatic charge/discharge curve showed that the CuS/RGO nanocomposite (12 wt % Cu–DTO complex) has tremendous and outperforming specific capacitance of 3058 F g–1 at 1 A g–1 current density with moderate cycling stability (∼60.3% after 1000 cycles at 10 A g–1). The as-prepared nanocomposite revealed excellent improvement in specific capacitance, cycling stability, Warburg impedance, and interfacial charge transfer resistance compared to neat CuS. The fabricated nanocomposites were also investigated for their bulk DC electrical conductivity and EMI shielding ability. It was observed that the CuS/RGO nanocomposite (9 wt % Cu–DTO) exhibited a total electromagnetic shielding efficiency of 64 dB at 2.3 GHz following absorption as a dominant shielding mechanism. Such a performance is ascribed to the presence of interconnected networks and synergistic effects.
•3D-printed carbon electrodes are fabricated.•Their surface is modified by dip-coating with transition metal dichalcogenides and MXenes.•The modified electrodes are electrocatalytic for hydrogen ...evolution.
3D-printing technology is widely accepted as a scalable and advanced manufacturing procedure for the fabrication of electrodes for electrochemical applications. 3D-printed carbon-based electrodes can be used for electrochemical analysis, replacing conventional carbon electrodes. However, a bare 3D-printed carbon electrode exhibits poor electrochemical performance. Herein, a post-treatment of 3D-printed electrodes was carried out using catalytically active materials to improve their electrochemical performance. We used a dip-coating technique which is a more universal, facile, and cost-effective approach compared with other conventionally used techniques such as atomic layer deposition or electrodeposition. The 3D-printed nanocarbon electrodes were dip-coated with MXene (Ti3C2Tx) and different transition metal dichalcogenides such as MoS2, MoSe2, WS2, and WSe2 to study their catalytic activity towards the hydrogen evolution reaction (HER). This study demonstrates a simple method of improving the catalytic surface properties of 3D-printed nanocarbon electrodes for energy conversion applications.
•Review of fluorescence sensors working through ICT, paramagnetic effect and AIE.•Applications of three recognition mechanisms for fluorimetric detection of Cu2+ ion.•The structure, selectivity and ...sensitivity of such chemosensors have been summarized.•This would be useful for further design of fluorescent sensors for Cu2+ ion.
Copper is the third most abundant and a crucial metal for the biological processes. But, excessive accumulation of copper in body is linked with several disorders. In this article, recent advances (in between 2018 and 2020) on small molecule-based fluorescent sensors for the detection of Cu2+ ion have been reviewed. The probes working on the principle of internal charge transfer (ICT), paramagnetic effect and aggregation induced emission (AIE) are covered. Molecular design, sensitivity and the specificity of the sensors have been focused along with their applications.
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•3D printed nanocarbon electrodes are fabricated.•Electrodes are electrochemically coated with Cu and Ni layer.•Sugars sensing is performed on these catalytic surfaces.
The decentralized fabrication ...of sensors using 3D-printing technology and low power requirements of electrochemical detection promise to revolutionize point-of-care sensing. One of the obstacles is that the 3D-printed devices are often not catalytic to the target analytes. Here, we develop a non-enzymatic printed nanocarbon electrode sensor to detect sugars (glucose and sucrose) via copper and nickel electroplating over a 3D-printed conducting electrode. The morphological and spectroscopic characterizations of copper-plated and nickel-plated 3D-printed carbon electrodes were performed. Scanning electron micrographs show the formation of metal nanoparticles over the surface of a 3D-printed nanocarbon electrode. X-ray photoelectron spectroscopy reveals the composition and chemical states of the metal coating. Electrochemical characterization via cyclic voltammetry and chronoamperometry was carried out, and glucose and sucrose sensing were performed. This method of on-demand decentralized sensor fabrication and modifications should find broad applications.
Oxidative aggregation of γ-crystallins induced by copper in aged lens increases the lens opacity and causes cataract formation. Therefore, chelation of free Cu2+ by small molecules can inhibit ...metal-mediated aggregation of γ-crystallin. In this work, the inhibition potency of several naturally occurring flavonoid compounds was studied against aggregation of human γD-crystallin (HGD) mediated by copper ions. Among them, rutin demonstrated ~20% inhibition of HGD aggregation induced by Cu2+ through its metal chelation ability. Not only that, the chaperone activity of lens chaperone, human αA-crystallin (HAA) was found to be enhanced in the presence of rutin. Subsequently, the molecular interactions between HAA and rutin were investigated using fluorescence and CD spectroscopy to understand the molecular basis of the chaperone activity enhancement by rutin. Quenching of HAA fluorescence by rutin with a quenching constant in the order of ~105 M−1 depicts a complexation between them. Entropy driven process of complexation between HAA and rutin suggests significant involvement of hydrophobic interactions. Fluorescence resonance energy transfer between protein and ligand can occur at a distance of 2.73 nm. Synchronous fluorescence and circular dichroism spectroscopy revealed that protein-ligand interaction does not cause any notable conformational changes in HAA. Experimental observations have been well substantiated by docking.
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•Inhibition of Cu2+-mediated aggregation of human γD-crystallin by rutin•Enhancement of chaperone activity of human αA-crystallin (HAA) by rutin•Quenching of tryptophan fluorescence of HAA by rutin•Fluorescence resonance energy transfer between HAA and rutin•No conformational changes in HAA due to the binding of rutin in its chaperone site
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Human carbonic anhydrase-II (hCA-II) is the most dominant physiologic isoform amongst the sixteen reported hCA isoforms. Because of its high availability in the different anatomical, ...and cellular sites of the eye like retina and lens, it plays a more prominent role in the regulation of intraocular pressure than the other twelve catalytically active hCA isoforms. This isoform is also located in the brain, kidney, gastric mucosa, osteoclasts, RBCs, skeletal muscle, testes, pancreas, lungs, etc. Earlier, hCA-II inhibitors were designed based on the sulfonamides e.g. acetazolamide, dichlorphenamide, methazolamide, ethoxzolamide, etc. and they were used systemically in antiglaucoma therapy. Many successful attempts have been made by the researchers in order to design more potent and effective inhibitors by incorporating various moieties in sulphonamides. Some novel scaffolds like chalcones, thiophenes, organotellurium compounds, dithiocarbamate, selenide, and 2-benzylpyrazine, etc. were also designed as hCA-II inhibitors and their inhibitory efficacy was proved in the nanomolar range. In order to obtain relevant information from the insights of their structure-activity relationship, the reported hCA-II inhibitors from the year 1989 to 2019 were critically analysed. It gave a complete insight into the relationship between their structure-activity and hCA-II inhibition. The broad spectrum of our investigation may help researchers to summarize all the crucial structural information required for the development of more potent hCA-II inhibitors for glaucoma.
3D printing has emerged as an attractive manufacturing technique in supercapacitor electrodes owing to the precise and customisable fabrication of complex electrode designs, enhancing the performance ...and efficiency of the device. Despite the advantages, 3D-printed electrodes are limited by their low conductivity and electrochemical properties, predominantly due to the lack of availability of suitable conductive materials. To address this limitation, we modified the 3D-printed nanocarbon (3D-PnC) electrode by activation and surface deposition of Ti3C2Tx MXene. A solid-state asymmetric supercapacitor was fabricated by using 3D-PnC/Ti3C2Tx as the negative electrode and polyaniline (PANI) electrodeposited 3D-printed nanocarbon electrode (3D-PnC@PANI) as the positive electrode. The fabricated symmetric supercapacitor exhibits enhancement in overall voltage window, areal capacitance and energy density. The successful operation of the supercapacitor was demonstrated by the illumination of the red light-emitting diodes. Furthermore, this research opens the possibility of utilising MXene-modified 3D-printed electrodes for various electrochemical applications and devices.
ABSTRACTThere is a huge need for energy storage devices due to the depletion of natural gas and the increasing requirement for portable electronic gadgets. Fused deposition modeling (FDM) 3D-printing ...has drawn tremendous interest for the fabrication of batteries and supercapacitors (SCs) due to its tabletop manufacturing technique, bespoke design, fast prototyping and user-friendly process. However, there are fewer available conductive filaments for FDM printing that are ideal from an energy storage standpoint. 2D transition metal dichalcogenide WS2 has been discovered to be a favourable material for electrochemical energy storage. As a result, in this work, we modified a carbon electrode that was 3D-printed by incorporating WS2 in order to enhance the capacitive performance of the SC electrode. The WS2-coated 3D-printed carbon electrode (WS2/3D-PCE) exhibits 2.8 times higher specific capacitance than the 3D-printed carbon electrode at 50 mV s−1. A solid-state symmetric supercapacitor (SS-SC) was fabricated with WS2/3D-PCE and polyvinyl alcohol (PVA)/Li2SO4 as gel electrolytes. Such modified 3D-PCE opens up the opportunities to design any custom-shaped electrode with tailored properties and pave a route for future research that will lead to more electrochemical devices for portable electronics.
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