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Over the present material synthesis routes, the sonochemical route is highly efficient and comfortable way to produce nanostructured materials. In this way, the copper sulfide (CuS-covellite) and sulfur doped reduced graphene oxide (S-rGO) nanocomposite was prepared by sonochemical method. Interestingly, the structure of the as-prepared S-rGO/CuS was changed from the covellite to digenite phase. Herein, the S-rGO was act as a mild oxidizer and liable for the structural transformations. These structural changes are sequentially studied by various physicochemical characterizations such as Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Transmission electron microscopy (TEM). After scrupulous structural evaluations, the transformation of CuS phase was identified and documented. This oxidized CuS has an excellent electrocatalytic activity when compare to the bulk CuS. This S-rGO/CuS was further used for the determination of glucose and acquired good electrocatalytic performances. This S-rGO/CuS was exhibited a wide linear concentration range, 0.0001–3.88 mM and 3.88–20.17 mM, and a low-level detection limit of 32 nM. Moreover, we have validated the practicability of our developed glucose sensor in real biological samples.

The effect of Sn/Ti ratio on the electrochemical properties of the anode is studied in Sn-doped TiO 2 and SnO 2 –TiO 2 nanofibers synthesized using a pilot-scale electrospinning system. Changes in the lattice structure of TiO 2 due to the presence of Sn are studied through X-ray diffraction and high-resolution transmission electron microscopy. Lowering of electrochemical potential (vs Li/Li + ) is observed alongside the enhanced capacity (400–600 mAh g −1 ) with increasing Sn content. Formation of SnO 2 grain in sample with high Sn content (70 wt%) shows detrimental effect on cycling stability due to severe volume changes during lithiation/delithiation. We show that the relative fraction of TiO 2 and SnO 2 framework determines whether the composite is high capacity or high stability. In overall, SnO 2 –TiO 2 composite anode with optimized Sn/Ti ratio can be used for high energy density, cycling stability and working potential lithium-ion battery. Graphic abstract The relative fraction of TiO 2 and SnO 2 framework determines whether the composite is high capacity or high stability

Long–term cycling performance of electrodes for application in supercapcitor has received large research interest in recent years. Ultra-stable Mn 1- x Ni x CO 3 (x-0, 0.20, 0.25 and 0.30) nano/sub-microspheres were synthesized via simple co-precipitation method and the Mn 1- xNi x CO 3 was confirmed by XRD, FT-IR, XPS and their morphology was studied by SEM and TEM analysis. Among the various Mn 1-x Ni x CO 3 electrodes, the Mn 0.75 Ni 0.25 CO 3 electrode exhibited the higher specific capacitance (364 F g −1 at 1 A g −1 ) with capacity retention of 96% after 7500 cycles at 5 A g −1 . Moreover, the assembled solid-state asymmetric supercapacitor based on Mn 0.75 Ni 0.25 CO 3 //graphene nanosheets performed a high specific capacity of 46 F g −1 and energy density of 25 Wh kg −1 at a power density of 499 W kg −1 along with high capacity retention of 87.7% after 7500 cycles. The improved electrochemical performances are mainly owing to the intrinsic conductivity and electrochemical activity of MnCO 3 after Mn 1- x Ni x CO 3 (x-0.20, 0.25 and 0.30) with appropriate Ni concentration. This study highlights the potentiality of the Mn 0.75 Ni 0.25 CO 3 //GNS asymmetric supercapacitor device for promising energy storage applications.

Electronic absorption spectroscopy was used to study the ETR of surfactant–cobalt(III) complexes containing imidazo[4,5-f][1,10]phenanthroline, dipyrido[3,2-d:2′-3′-f]quinoxaline and dipyrido[3,2-a:2′,4′-c](6,7,8,9-tetrahydro)phenazine ligands by using ferrocyanide ions in unilamellar vesicles of dipalmitoylphosphotidylcholine (DPPC) and 1-butyl-3-methylimidazolium bromide ((BMIM)Br), at different temperatures under pseudo-first-order conditions using an excess of the reductant. The reactions were found to be second-order and the electron transfer is postulated as occurring in the outer sphere. The rate constant for the electron transfer reactions was found to increase with increasing concentrations of ionic liquids. Besides these, the effects of surfactant complex ions on liposome vesicles in these same reactions have also been studied on the basis of hydrophobicity. We observed that, below the phase transition temperature, there is an increasing amount of surfactant–cobalt(III) complexes expelled from the interior of the vesicle membrane through hydrophobic effects, while above the phase transition temperature, the surfactant–cobalt(III) complexes are expelled from the interior to the exterior surface of the vesicle. Kinetic data and activation parameters are interpreted in respect of an outer-sphere electron transfer mechanism. By assuming the existence of an outer-sphere mechanism, the results have been clarified based on the presence of hydrophobicity, and the size of the ligand increases from an ip to dpqc ligand and the reactants become oppositely charged. In all these media, the ΔS# values are recognized as negative in their direction in all the concentrations of complexes employed, indicative of a more ordered structure of the transition state. This is compatible with a model in which these complexes and [Fe(CN)6]4− ions bind to the DPPC in the transition state. Thus, the results have been interpreted based on the self-aggregation, hydrophobicity, charge densities of the co-ligand and the reactants with opposite charges.

LiFePO4 is one of the industrial, scalable cathode materials in lithium-ion battery production, due to its cost-effectiveness and environmental friendliness. However, the electrochemical performance of LiFePO4 in high current rate operation is still limited, due to its poor ionic- and electron-conductive properties. In this study, a zeolitic imidazolate framework (ZIF-8) and multiwalled carbon nanotubes (MWCNT) modified LiFePO4/C (LFP) composite cathode materials were developed and investigated in detail. The ZIF-8 and MWCNT can be used as ionic- and electron-conductive materials, respectively. The surface modification of LFP by ZIF-8 and MWCNT was carried out through in situ wet chemical and mechanical alloy coating. The as-synthesized materials were scrutinized via various characterization methods, such as XRD, SEM, EDX, etc., to determine the material microstructure, morphology, phase, chemical composition, etc. The uniform and stable spherical morphology of LFP composites was obtained when the ZIF-8 coating was processed by the agitator [A], instead of the magnetic stirrer [MS], condition. It was found that the (optimum of) 2 wt.% ZIF-8@LFP [A]/MWCNT composite cathode material exhibited outstanding improvement in high-rate performance; it maintained the discharge capacities of 125 mAh g−1 at 1C, 110 mAh g−1 at 3C, 103 mAh g−1 at 5C, and 91 mAh g−1 at 10C. Better cycling stability with capacity retention of 75.82% at 1C for 100 cycles, as compared to other electrodes prepared in this study, was also revealed. These excellent results were mainly obtained because of the improvement of lithium-ion transport properties, less polarization effect, and interfacial impedance of the LFP composite cathode materials derived from the synergistic effect of both ZIF-8 and MWCNT coating materials.

To reduce surface contamination and increase battery life, MoO3 nanoparticles were coated with a high-voltage (5 V) LiNi0.5Mn1.5O4 cathode material by in-situ method during the high-temperature annealing process. To avoid charging by more than 5 V, we also developed a system based on anode-limited full-cell with a negative/positive electrode (N/P) ratio of 0.9. The pristine LiNi0.5Mn1.5O4 was initially prepared by high-energy ball-mill with a solid-state reaction, followed by a precipitation reaction with a molybdenum precursor for the MoO3 coating. The typical structural and electrochemical behaviors of the materials were clearly investigated and reported. The results revealed that a sample of 2 wt.% MoO3-coated LiNi0.5Mn1.5O4 electrode exhibited an optimal electrochemical activity, indicating that the MoO3 nanoparticle coating layers considerably enhanced the high-rate charge–discharge profiles and cycle life performance of LiNi0.5Mn1.5O4 with a negligible capacity decay. The 2 wt.% MoO3-coated LiNi0.5Mn1.5O4 electrode could achieve high specific discharge capacities of 131 and 124 mAh g−1 at the rates of 1 and 10 C, respectively. In particular, the 2 wt.% MoO3-coated LiNi0.5Mn1.5O4 electrode retained its specific capacity (87 mAh g−1) of 80.1% after 500 cycles at a rate of 10 C. The Li4Ti5O12/LiNi0.5Mn1.5O4 full cell based on the electrochemical-cell (EL-cell) configuration was successfully assembled and tested, exhibiting excellent cycling retention of 93.4% at a 1 C rate for 100 cycles. The results suggest that the MoO3 nano-coating layer could effectively reduce side reactions at the interface of the LiNi0.5Mn1.5O4 cathode and the electrolyte, thus improving the electrochemical performance of the battery system.

A novel design and synthesis methodology is the most important consideration in the development of a superior electrocatalyst for improving the kinetics of oxygen electrode reactions, such as the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) in Li-O2 battery application. Herein, we demonstrate a glycine-assisted hydrothermal and probe sonication method for the synthesis of a mesoporous spherical La0.8Ce0.2Fe0.5Mn0.5O3 perovskite particle and embedded graphene nanosheet (LCFM(8255)-gly/GNS) composite and evaluate its bifunctional ORR/OER kinetics in Li-O2 battery application. The physicochemical characterization confirms that the as-formed LCFM(8255)-gly perovskite catalyst has a highly crystalline structure and mesoporous morphology with a large specific surface area. The LCFM(8255)-gly/GNS composite hybrid structure exhibits an improved onset potential and high current density toward ORR/OER in both aqueous and non-aqueous electrolytes. The LCFM(8255)-gly/GNS composite cathode (ca. 8475 mAh g−1) delivers a higher discharge capacity than the La0.5Ce0.5Fe0.5Mn0.5O3-gly/GNS cathode (ca. 5796 mAh g−1) in a Li-O2 battery at a current density of 100 mA g−1. Our results revealed that the composite’s high electrochemical activity comes from the synergism of highly abundant oxygen vacancies and redox-active sites due to the Ce and Fe dopant in LaMnO3 and the excellent charge transfer characteristics of the graphene materials. The as-developed cathode catalyst performed appreciable cycle stability up to 55 cycles at a limited capacity of 1000 mAh g−1 based on conventional glass fiber separators.

In the present work, potato-like silver molybdate (Ag 2 MoO 4 ) microstructures were synthesized through a simple hydrothermal method. The microstructures of Ag 2 MoO 4 were characterized by various analytical and spectroscopic techniques such as XRD, FTIR, Raman, SEM, EDX and XPS. Interestingly, the as-prepared Ag 2 MoO 4 showed excellent photocatalytic and electrocatalytic activity for the degradation of ciprofloxacin (CIP) and electrochemical detection of hydrogen peroxide (H 2 O 2 ), respectively. The ultraviolet-visible (UV-Vis) spectroscopy results revealed that the potato-like Ag 2 MoO 4 microstructures could offer a high photocatalytic activity towards the degradation of CIP under UV-light illumination, leads to rapid degradation within 40 min with a degradation rate of above 98%. In addition, the cyclic voltammetry (CV) and amperometry studies were realized that the electrochemical performance of Ag 2 MoO 4 modified electrode toward H 2 O 2 detection. Our H 2 O 2 sensor shows a wide linear range and lower detection limit of 0.04–240 μM and 0.03 μM, respectively. The Ag 2 MoO 4 modified electrode exhibits a high selectivity towards the detection of H 2 O 2 in the presence of different biological interferences. These results suggested that the development of potato-like Ag 2 MoO 4 microstructure could be an efficient photocatalyst as well as electrocatalyst in the potential application of environmental, biomedical and pharmaceutical samples.

This study explores the challenge of antimicrobial resistance by investigating the utilization of zinc oxide (ZnO) and copper oxide (Cu2O) nanoparticles (NPs) to combat antibiotic-resistant bacteria in wastewater treatment plants (WWTPs). The synthesized metal oxide NPs underwent thorough characterization through various analytical techniques, confirming their nanoparticulate nature. Electronic absorption and X-ray diffraction (XRD) analyses revealed successful reduction processes and crystalline properties, respectively. Fourier transform infrared spectroscopy (FTIR) results indicated the stabilization of nanoparticles in solution. Scanning electron microscopy (SEM) observations revealed well-defined spherical and flower-like morphologies for the zinc and copper oxide nanoparticles, with sizes approximately ranging from 50 nm to 25 nm Notably, the synthesized nanoparticles exhibited heightened efficacy in impeding biofilm formation, with zinc oxide NPs displaying superior antibacterial activity compared to copper. These findings suggest the promising potential of these nanoparticles in controlling antibiotic-resistant organisms, even following WWTP treatment processes. This research contributes to the ongoing advancements in nanotechnology aimed at combating antibiotic resistance, offering new prospects for the development of effective wastewater treatment strategies.

A rapid voltammetric method is described for the determination of the organophosphorus pesticide paraoxon-ethyl (PEL). A glassy carbon electrode (GCE) was modified with a composite consisting of a poly(N-isopropylacrylamide)-chitosan microgel with incorporated palladium nanoparticles. The microgel was characterized by FE-SEM, EDX, XPS, FTIR, XRD, and EIS. The modified GCE is shown to enable direct electro-reductive determination of PEL by using differential pulse voltammetry. The method works in pH 7 solution and in the 0.01 μM to 1.3 mM PEL concentration range. At a typical working potential of −0.66 V (vs. Ag/AgCl) (at 50 mV/s), the detection limit is as low as 0.7 nM, and the electrochemical sensitivity is 1.60 μA μM −1  cm −2 . Intriguingly, the modified GCE displays good recovery when applied to bok choy and water samples. Graphical abstract Schematic of an electrochemical method for determination of paraoxon ethyl (PEL) in bok choy extract and water by using poly(N-isopropyl acrylamide)-chitosan microgel decorated with palladium nanoparticle-modified glassy carbon electrodes (PdNPs/PNIPAM-CT microgel/GCE).