Atomic Layer Deposition-A Versatile Toolbox for Designing/Engineering Electrodes for Advanced Supercapacitors.

Atomic layer deposition (ALD) has become the most widely used thin-film deposition technique in various fields due to its unique advantages, such as self-terminating growth, precise thickness control, and excellent deposition quality. In the energy storage domain, ALD has shown great potential for supercapacitors (SCs) by enabling the construction and surface engineering of novel electrode materials. This review aims to present a comprehensive outlook on the development, achievements, and design of advanced electrodes involving the application of ALD for realizing high-performance SCs to date, as organized in several sections of this paper. Specifically, this review focuses on understanding the influence of ALD parameters on the electrochemical performance and discusses the ALD of nanostructured electrochemically active electrode materials on various templates for SCs. It examines the influence of ALD parameters on electrochemical performance and highlights ALD's role in passivating electrodes and creating 3D nanoarchitectures. The relationship between synthesis procedures and SC properties is analyzed to guide future research in preparing materials for various applications. Finally, it is concluded by suggesting the directions and scope of future research and development to further leverage the unique advantages of ALD for fabricating new materials and harness the unexplored opportunities in the fabrication of advanced-generation SCs.

Unveiling the potential of PANI@MnO2@rGO ternary nanocomposite in energy storage and gas sensing.

The development of advanced materials for energy storage and gas sensing applications has gained significant attention in recent years. In this study, we synthesized and characterized PANI@MnO2@rGO ternary nanocomposites (NCs) to explore their potential in supercapacitors and gas sensing devices. The ternary NCs were synthesized through a multi-step process involving the hydrothermal synthesis of MnO2 nanoparticles, preparation of PANI@rGO composites and the assembly to the ternary PANI@MnO2@rGO ternary NCs. The structural, morphological, and compositional characteristics of the materials were thoroughly analyzed using techniques such as XRD, FESEM, TEM, FTIR, and Raman spectroscopy. In the realm of gas sensing, the ternary NCs exhibited excellent performance as NH3 gas sensors. The optimized operating temperature of 100 °C yielded a peak response of 15.56 towards 50 ppm NH3. The nanocomposites demonstrated fast response and recovery times of 6 s and 10 s, respectively, and displayed remarkable selectivity for NH3 gas over other tested gases. For supercapacitor applications, the electrochemical performance of the ternary NCs was evaluated using cyclic voltammetry and galvanostatic charge-discharge techniques. The composites exhibited pseudocapacitive behavior, with the capacitance reaching up to 185 F/g at 1 A/g and excellent capacitance retention of approximately 88.54% over 4000 charge-discharge cycles. The unique combination of rGO, PANI, and MnO2 nanoparticles in these ternary NCs offer synergistic advantages, showcasing their potential to address challenges in energy storage and gas sensing technologies.

Emerging Mesoporous Polyacrylamide/Gelatin-Iron Lanthanum Oxide Nanohybrids towards the Antibiotic Drugs Removal from the Wastewater.

The polyacrylamide/gelatin-iron lanthanum oxide (P-G-ILO nanohybrid) was fabricated by the free radical grafting co-polymerization technique in the presence of N,N-methylenebisacrylamide (MBA) as cross linker and ammonium persulfate (APS) as initiator. The P-G-ILO nanohybrid was characterized by the various spectroscopic and microscopic techniques that provided the information regarding the crystalline behavior, surface area, and pore size. The response surface methodology was utilized for the statistical observation of diclofenac (DF) adsorption from the wastewater. The adsorption capacity (qe, mg/g) of P-G-ILO nanohybrid was higher (254, 256, and 258 mg/g) than the ILO nanoparticle (239, 234, and 233 mg/g). The Freundlich isotherm model was the best fitted, as it gives the higher values of correlation coefficient (R2 = 0.982, 0.991 and 0.981) and lower value of standard error of estimate (SEE = 6.30, 4.42 and 6.52), which suggested the multilayered adsorption of DF over the designed P-G-ILO nanohybrid and followed the pseudo second order kinetic model (PSO kinetic model) adsorption. The thermodynamic study reveals that adsorption was spontaneous and endothermic in nature and randomness onto the P-G-ILO nanohybrids surface increases after the DF adsorption. The mechanism of adsorption of DF demonstrated that the adsorption was mainly due to the electrostatic interaction, hydrogen bonding, and dipole interaction. P-G-ILO nanohybrid was reusable for up to five adsorption/desorption cycles.

Nanomaterials for Catalysis and Energy Storage.

The development of nanomaterials with different shapes and sizes and which are utilized as effective materials for energy and environmental applications constitutes a challenge for researchers [...].

Microwave-mediated synthesis of tetragonal Mn3O4 nanostructure for supercapacitor application.

The development of electrode materials plays a vital role in energy storage applications to save and store energy. In the present work, the synthesis of nanorod shaped Mn3O4 supported with amorphous carbon (Mn3O4/AC) is reported by the microwave method for supercapacitor application. The as-prepared electrode material was then characterized using microscopic and spectroscopic techniques. The electrochemical supercapacitor performance of Mn3O4/AC was examined by the cyclic voltammetry and galvanostatic charge-discharge method inside the three-electrode assembly cell. The results showed that the Mn3O4/AC delivers the excellent capacitance value of the 569.5 Fg-1 at the current load of 1 Ag-1, higher than the previously reported Mn3O4 based electrodes. The better performance of the Mn3O4/AC is credited to the excellent redox behaviour of the Mn3O4 and the presence of the amorphous carbon, which facilitated the fast ion interaction between the electrode and electrolyte during the electrochemical reaction.

Hydrothermal Synthesis of Multifunctional Bimetallic Ag-CuO Nanohybrids and Their Antimicrobial, Antibiofilm and Antiproliferative Potential.

The rapidly growing global problem of infectious pathogens acquiring resistance to conventional antibiotics is an instigating reason for researchers to continue the search for functional as well as broad-spectrum antimicrobials. Hence, we aimed in this study to synthesis silver-copper oxide (Ag-CuO) nanohybrids as a function of Ag concentration (0.05, 0.1, 0.3 and 0.5 g) via the one-step hydrothermal method. The bimetallic Ag-CuO nanohybrids Ag-C-1, Ag-C-2, Ag-C-3 and Ag-C-4 were characterized for their physico-chemical properties. The SEM results showed pleomorphic Ag-CuO crystals; however, the majority of the particles were found in spherical shape. TEM results showed that the Ag-CuO nanohybrids in formulations Ag-C-1 and Ag-C-3 were in the size range of 20-35 nm. Strong signals of Ag, Cu and O in the EDX spectra revealed that the as-synthesized nanostructures are bimetallic Ag-CuO nanohybrids. The obtained Ag-C-1, Ag-C-2, Ag-C-3 and Ag-C-4 nanohybrids have shown their MICs and MBCs against E. coli and C. albicans in the range of 4-12 mg/mL and 2-24 mg/mL, respectively. Furthermore, dose-dependent toxicity and apoptosis process stimulation in the cultured human colon cancer HCT-116 cells have proven the Ag-CuO nanohybrids as promising antiproliferative agents against mammalian cancer.

Graphene Quantum Dots: Novel Properties and Their Applications for Energy Storage Devices.

Batteries and supercapacitors are the next-generation alternative energy resources that can fulfil the requirement of energy demand worldwide. In regard to the development of efficient energy storage devices, various materials have been tested as electrode materials. Graphene quantum dots (GQDs), a new class of carbon-based nanomaterial, have driven a great research interest due to their unique fundamental properties. High conductivity, abundant specific surface area, and sufficient solubility, in combination with quantum confinement and edge effect, have made them appropriate for a broad range of applications such as optical, catalysis, energy storage and conversion. This review article will present the latest research on the utilization of GQDs and their composites to modify the electrodes used in energy storage devices. Several major challenges have been discussed and, finally, future perspectives have been provided for the better implementation of GQDs in the energy storage research.

Label-free electrochemical aptasensor for the detection of SARS-CoV-2 spike protein based on carbon cloth sputtered gold nanoparticles.

The proliferation and transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), or the (COVID-19) disease, has become a threat to worldwide biosecurity. Therefore, early diagnosis of COVID-19 is crucial to combat the ongoing infection spread. In this study we propose a flexible aptamer-based electrochemical sensor for the rapid, label-free detection of SARS-CoV-2 spike protein (SP). A platform made of a porous and flexible carbon cloth, coated with gold nanoparticles, to increase the conductivity and electrochemical performance of the material, was assembled with a thiol functionalized DNA aptamer via S-Au bonds, for the selective recognition of the SARS-CoV-2 SP. The various steps for the sensor preparation were followed by using scanning electron microscopy, cyclic voltammetry and differential pulse voltammetry (DPV). The proposed platform displayed good mechanical stability, revealing negligible changes on voltammetric responses to bending at various angles. Quantification of SARS-CoV-2 SP was performed by DPV and chronopotentiometry (CP), exploiting the changes of the electrical signals due the [Fe(CN)6]3-/4- redox probe, when SARS-CoV-2 SP binds to the aptamer immobilized on the electrode surface. Current density, in DPV, and square root of the transition time, in CP, varied linearly with the log[ SARS-CoV-2 SP], providing lower limits of detection (LOD) of 0.11 ng/mL and 37.8 ng/mL, respectively. The sensor displayed good selectivity, repeatability, and was tested in diluted human saliva, spiked with different SARS-CoV-2 SP concentrations, providing LODs of 0.167 ng/mL and 46.2 ng/mL for DPV and CP, respectively.

Controllable synthesis of sphere-shaped interconnected interlinked binder-free nickel sulfide@nickel foam for high-performance supercapacitor applications.

The fabrication of energy storage electrode materials with high specific capacitance and rapid charge-discharge capability has become an essential and major issue of concern in recent years. In the present work, sphere-shaped interconnected interlinked binder-free nickel sulfide (NiS) grown on the surface of a three-dimensional nickel foam (3DNF) was fabricated by a one-step solvothermal method under optimized synthesis conditions, including different solvents, amounts of sulfur, and experimental reaction times. The fabricated binder-free SS-NiS@3DNF-E electrodes were characterized by a range of spectroscopic and microscopic techniques and further evaluated for their comparative electrochemical supercapacitive performance in half-cell assembly cells. The optimized sphere-shaped interconnected interlinked binder-free SS-NiS@3DNF-E-3 electrode showed an outstanding specific capacitance of 694.0 F/g compared to SS-NiS@3DNF-E-1 (188.0 F/g), SS-NiS@3DNF-E-2 (470.0 F/g), and SS-NiS@3DNF-E-4 (230.0 F/g) as well as excellent cycling stability up to 88% after 6700 continuous charge-discharge cycles, with an energy density of 24.9 Wh/kg at a power density of 250.93 W/kg. The obtained results demonstrate that the interconnected interlinked binder-free NiS@nickel electrode is a potential candidate for energy storage applications.

Critical Aspects of Various Techniques for Synthesizing Metal Oxides and Fabricating Their Composite-Based Supercapacitor Electrodes: A Review.

Supercapacitors (SCs) have attracted attention as an important energy source for various applications owing to their high power outputs and outstanding energy densities. The electrochemical performance of an SC device is predominantly determined by electrode materials, and thus, the selection and synthesis of the materials are crucial. Metal oxides (MOs) and their composites are the most widely used pseudocapacitive SC electrode materials. The basic requirements for fabricating high-performance SC electrodes include synthesizing and/or chemically modifying unique conducting nanostructures, optimizing a heterostructure morphology, and generating large-surface-area electroactive sites, all of which predominantly rely on various techniques used for synthesizing MO materials and fabricating MO- and MO-composite-based SC electrodes. Therefore, an SC's background and critical aspects, the challenges associated with the predominant synthesis techniques (including hydrothermal and microwave-assisted syntheses and chemical-bath and atomic-layer depositions), and resulting electrode electrochemical performances should be summarized in a convenient, accessible report to accelerate the development of materials for industrial SC applications. Therefore, we reviewed the most pertinent studies on these synthesis techniques to provide insight into the most recent advances in synthesizing MOs and fabricating their composite-based SC electrodes as well as to propose research directions for developing MO-based electrodes for applications to next-generation SCs.

One-Dimensional Nanoscale Si/Co Based on Layered Double Hydroxides towards Electrochemical Supercapacitor Electrodes.

It is well known that layered double hydroxides (LDHs) are two-dimensional (2D) layered compounds. However, we modified these 2D layered compounds to become one-dimensional (1D) nanostructures destined for high-performance supercapacitors applications. In this direction, silicon was inserted inside the nanolayers of Co-LDHs producing nanofibers of Si/Co LDHs through the intercalation of cyanate anions as pillars for building nanolayered structures. Additionally, nanoparticles were observed by controlling the preparation conditions and the silicon percentage. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermal analyses have been used to characterize the nanolayered structures of Si/Co LDHs. The electrochemical characterization was performed by cyclic voltammetry and galvanic charge-discharge technique in 2M KOH electrolyte solution using three-electrode cell system. The calculated specific capacitance results indicated that the change of morphology from nanoparticles or plates to nanofibers had a positive effect for improving the performance of specific capacitance of Si/Co LDHs. The specific capacitance enhanced to be 621.5 F g-1 in the case of the nanofiber of Si/Co LDHs. Similarly, the excellent cyclic stability (84.5%) was observed for the nanofiber. These results were explained through the attribute of the nanofibrous morphology and synergistic effects between the electric double layer capacitive character of the silicon and the pseudo capacitance nature of the cobalt. The high capacitance of ternary Si/Co/cyanate LDHs nanocomposites was suggested to be used as active electrode materials for high-performance supercapacitors applications.

Dielectric Properties of Bi2/3Cu3Ti4O12 Ceramics Prepared by Mechanical Ball Milling and Low Temperature Conventional Sintering.

In the current study, Bi2/3Cu3Ti4O12 (BCTO) ceramics were prepared by mechanical ball mill of the elemental oxides followed by conventional sintering of the powder without any pre-sintering heat treatments. The sintering temperature was in the range 950-990 °C, which is 100-150 °C lower than the previous conventional sintering studies on BCTO ceramics. All the ceramic samples showed body-centered cubic phase and grain size ≈ 2-6 µm. Sintering temperature in the range 950-975 °C resulted in comparatively lower dielectric loss and lower thermal coefficient of permittivity in the temperature range from -50 to 120 °C. All the BCTO ceramics showed reasonably high relative permittivity. The behavior of BCTO ceramics was correlated with the change in oxygen content in the samples with sintering temperature. This interpretation was supported by the measurements of the energy dispersive x-ray spectroscopy (EDS) elemental analysis and activation energy for conduction and for relaxation in the ceramics.

Dielectric Properties of Colossal-Dielectric-Constant Na1/2La1/2Cu3Ti4O12 Ceramics Prepared by Spark Plasma Sintering.

In the current study, we report on the dielectric behavior of colossal-dielectric-constant Na1/2La1/2Cu3Ti4O12 (NLCTO) ceramics prepared by mechanochemical synthesis and spark plasma sintering (SPS) at 850 °C, 900 °C, and 925 °C for 10 min. X-ray powder diffraction analysis showed that all the ceramics have a cubic phase. Scanning electron microscope observations revealed an increase in the average grain size from 175 to 300 nm with an increase in the sintering temperature. SPS NLCTO ceramics showed a room-temperature colossal dielectric constant (>103) and a comparatively high dielectric loss (>0.1) over most of the studied frequency range (1 Hz-40 MHz). Two relaxation peaks were observed in the spectra of the electrical modulus and attributed to the response of grain and grain boundary. According to the Nyquist plots of complex impedance, the SPS NLCTO ceramics have semiconductor grains surrounded by electrically resistive grain boundaries. The colossal dielectric constant of SPS NLCTO ceramics was attributed to the internal barrier layer capacitance (IBLC) effect. The high dielectric loss is thought to be due to the low resistivity of the grain boundary of SPS NLCTO.

The Controllable Ratio of the Polyaniline-Needle-Shaped Manganese Dioxide for the High-Performance Supercapacitor Application.

The nanohybrid development of metal oxide/conducting polymer as an energy storage material is an active research area, because of the device stability, conductive behavior, and easy fabrication. Herein, needle-like MnO2 was coupled with polyaniline fabricated through chemical polymerization followed by the hydrothermal process. The characterization results show that MnO2/polyaniline exhibited a needle-like morphology. Different characterization techniques such as X-ray diffraction patterns and scanning electron microscopy confirmed the formation of the MnO2/polyaniline nanohybrids. The electrochemical performance, including cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), specific capacitance (Csp), and cyclic stability, was examined using a three-electrode assembly cell. The optimized electrode displayed a Csp of 522.20 F g-1 at a current load of 1.0 A g-1 compared with the other electrodes. The developed synergism during MnO2/polyaniline fabrication provided enhanced conductive channels and stability during the charge-discharge process.

Nanostructured Titanium Nitride and Its Composites as High-Performance Supercapacitor Electrode Material.

Electrochemical supercapacitors as an energy storage device have become trademark in current electronic, medical and industrial applications, as they are sources of impressive power output. Supercapacitors supply fast power output, suitable to cover the energy demand of future electronic devices. Electrode material design is a subject of intense research in the area of energy development and advancement, due to its essential role in the electrochemical process of charge storage and the cost of capacitors. The nano-dimensions allow for more electroactive sites, different pore size distributions, and a large specific surface area, making nanostructured electrode materials more promising. Electrode materials based on metal oxides, metal nitrides, and metal carbides are considered ideal for highly efficient electrochemical supercapacitors. Recently, much effort has been devoted to metal nitride-based electrodes and their diverse compositions as they possess higher electrical conductivity and better corrosion resistance, electrochemical stability, and chemical reactivity. Among these, titanium nitride (TiN), possesses high electrochemical stability, outstanding electrical conductivity, and a unique electronic structure. Nanocomposites based on titanium nitrides are known to deliver higher electrochemical performance than pristine nanostructured TiNs due to potential synergetic effects from both the materials. In this paper, recent advancements made in the field of nanostructural TiN electrode materials for SCs are reviewed along with their challenges and future opportunities. Additionally, some of the major techniques involved in the synthesis process are discussed, along with some basic concepts.

Mechanistic insights into defect chemistry and tailored photoluminescence and photocatalytic properties of aliovalent cation substituted Zn0.94M0.06-xLixO (M: Fe3+, Al3+, Cr3+) nanoparticles.

In this work, we demonstrate the microwave assisted solution combustion synthesis of aliovalent cation substituted Zn0.94M0.06-xLixO (M: Fe3+, Al3+, Cr3+) nanoparticles. The structural features, photoluminescence and photocatalytic properties were characterized by X-ray powder diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and UV-visible and photoluminescence (PL) techniques. We have introduced aliovalent cations such as reducible Fe3+, stable Al3+ and oxidisable Cr3+ ions into ZnO and investigated its structural and optical properties. The charge balance and defect stoichiometric composition of ZnO were also studied by co-doping with Li+ ions. By understanding the photoluminescence and photocatalytic activity of doped and co-doped ZnO nanoparticles, the defect chemistry of ZnO is explained in detail. The photocatalytic efficiency of various doped and co-doped ZnO catalysts was compared with respect to the degradation of rhodamine B dye. Among them, the CZO, AZO and L3AZO catalysts showed enhanced photo-degradation efficiencies of 98.1%, 97.6% and 96.6%, respectively, which are high as compared to that of ZnO (89%). This work presents a novel and straightforward, low-cost, tunable and scalable fabrication protocol for highly efficient ZnO-based photocatalysts for practical applications.

Silver Nanoparticles Embedded on Reduced Graphene Oxide@Copper Oxide Nanocomposite for High Performance Supercapacitor Applications.

In this work, silver (Ag) decorated reduced graphene oxide (rGO) coated with ultrafine CuO nanosheets (Ag-rGO@CuO) was prepared by the combination of a microwave-assisted hydrothermal route and a chemical methodology. The prepared Ag-rGO@CuO was characterized for its morphological features by field emission scanning electron microscopy and transmission electron microscopy while the structural characterization was performed by X-ray diffraction and Raman spectroscopy. Energy-dispersive X-ray analysis was undertaken to confirm the elemental composition. The electrochemical performance of prepared samples was studied by cyclic voltammetry and galvanostatic charge-discharge in a 2M KOH electrolyte solution. The CuO nanosheets provided excellent electrical conductivity and the rGO sheets provided a large surface area with good mesoporosity that increases electron and ion mobility during the redox process. Furthermore, the highly conductive Ag nanoparticles upon the rGO@CuO surface further enhanced electrochemical performance by providing extra channels for charge conduction. The ternary Ag-rGO@CuO nanocomposite shows a very high specific capacitance of 612.5 to 210 Fg-1 compared against rGO@CuO which has a specific capacitance of 375 to 87.5 Fg-1 and the CuO nanosheets with a specific capacitance of 113.75 to 87.5 Fg-1 at current densities 0.5 and 7 Ag-1, respectively.

Effect of Washing on the Electrochemical Performance of a Three-Dimensional Current Collector for Energy Storage Applications.

The development of efficient materials for energy storage applications has attracted considerable attention, especially for supercapacitors and batteries that are the most promising and important power sources in everyday life. For this purpose, a suitable and efficient current collector must be determined and its behavior with respect to various solvents when it is used as an electrode material for energy storage applications should be understood. In this work, we studied the effect of washing three-dimensional nickel foam using different concentrations of hydrochloric acid and ethanol on the surface characteristics, electrochemical behavior, and storage performance of the foam. Additionally, we observed the different types of acidic treatments that improved the electrochemical and storage performances of the three-dimensional nickel foam. The surface characterization results show that acidic conditions with a concentration of 3M changes the surface morphology from a flat/hill-like structure to a nanosheet/nanoflake-like structure without any further treatment. This structure provides a nano-channel and a large number of surface charges during the electrochemical reaction. The results of this study show that pretreatment of 3D-NF is highly important and recommended. The present work also contributes to the knowledgebase on pretreatment of 3D-NF and its optimization.

VO2 Nanostructures for Batteries and Supercapacitors: A Review.

Vanadium dioxide (VO2 ) received tremendous interest lately due to its unique structural, electronic, and optoelectronic properties. VO2 has been extensively used in electrochromic displays and memristors and its VO2 (B) polymorph is extensively utilized as electrode material in energy storage applications. More studies are focused on VO2 (B) nanostructures which displayed different energy storage behavior than the bulk VO2 . The present review provides a systematic overview of the progress in VO2 nanostructures syntheses and its application in energy storage devices. Herein, a general introduction, discussion about crystal structure, and syntheses of a variety of nanostructures such as nanowires, nanorods, nanobelts, nanotubes, carambola shaped, etc. are summarized. The energy storage application of VO2 nanostructure and its composites are also described in detail and categorically, e.g. Li-ion battery, Na-ion battery, and supercapacitors. The current status and challenges associated with VO2 nanostructures are reported. Finally, light has been shed for the overall performance improvement of VO2 nanostructure as potential electrode material for future application.

A highly sensitive poly(chrysoidine G)-gold nanoparticle composite based nitrite sensor for food safety applications.

This work demonstrated the development of conducting poly(chrysoidine G) (PCG)-gold nanoparticle (AuNP)-modified fluorine-doped tin oxide (F : SnO2, FTO) film-coated glass electrodes for the sensitive electrochemical detection of nitrite (NO2-). The homogeneously distributed PCG nanoparticle layer was deposited onto the FTO electrode by cyclic voltammetry sweeping. AuNPs were then anchored onto the PCG/FTO electrode by the chemical reduction of pre-adsorbed Au3+ ions. The as-prepared AuNP/PCG/FTO electrode exhibited excellent electrocatalytic activity for the oxidation of NO2- with high sensitivity (approximately 0.63 µA cm-2µM-1) and a low limit of detection (0.095 µM), which is relevant within the normal concentration range of NO2- in human bodily fluids. The AuNP/PCG/FTO sensor showed sufficient reproducibility, repeatability, low interference, and strong recovery for NO2- detection in food samples. These results indicate that the AuNP/PCG nanocomposites have immense potential for the electrochemical detection of other biologically important compounds.