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Electrode materials comprising SnO2 quantum dots embedded within ZnO hexagonal prisms were successfully synthesized for building cost-effective energy-storage devices. Extensive structural and functional characterizations were performed to assess the electrochemical performance of the electrodes. SEM–EDS results confirm a uniform distribution of SnO2 quantum dots across ZnO. The integration of SnO2 quantum dots with ZnO hexagonal prisms markedly improved the electrochemical behavior. The analysis of electrode functionality conducted in a 3 M KOH electrolyte revealed specific capacitances of 949.26 and 700.68 F g⁻1 for SnO2@ZnO and ZnO electrodes, respectively, under a current density of 2 A g⁻1. After undergoing 5,000 cycles at a current density of 15 A g⁻1, the SnO2@ZnO and ZnO electrodes displayed impressive cycling stability, maintaining specific capacitance retention rates of 89.9 and 92.2%, respectively. Additionally, a symmetric supercapacitor (SSC) device constructed using the SnO2@ZnO electrode showcased exceptional performance, exhibiting a specific capacitance of 83 F g⁻1 at 1.2 A g⁻1. Impressive power and energy densities were achieved by the device, with values reaching 2,808 and 70.2 W kg⁻1, respectively. Notably, the SnO2@ZnO SSC device maintained a capacity preservation of 75% throughout 5,000 galvanostatic charge–discharge sequences. The outcomes highlight the potential of SnO2@ZnO hexagonal prisms as candidates for energy-storage applications, offering scalability and cost-effectiveness. The proposed approach enhances the electrochemical performance while ensuring affordability, facilitating the creation of effective and financially feasible energy storage solutions.

A trimetallic heterojunction-derived Co3S4/NiS2/Cu2S with different ratios through a two-step hydrothermal method was successfully synthesized, showing multifunctional properties such as excellent electrochemical behavior and high photocatalytic activity. Both electrochemical and photocatalytic performances were optimized by adjusting the concentration of Cu without any change in Co and Ni concentrations. Among the synthesized nanocomposites, CNCS-0.15 (Co3S40.5/NiS20.5/Cu2S0.15) depicted the maximum specific capacity of 464.16 C g–1 at 1 A g–1 as revealed from electrochemical measurements. Further for real-time usage, assembling of a hybrid supercapacitor CNCS-0.15-(+)||activated carbon(−) furnished an energy density of 84.95 W h kg–1 at a power density of 1134 W kg–1 with good capacity retention of 93.64% for 5000 cycles. In addition, CNCS-0.15 also displayed remarkable photocatalytic performance under visible light illumination by utilizing Congo red (CR) dye. It could effectively degrade 91% of CR (40 mg L–1) through a double Z-scheme mechanism owing to the charge carriers' availability with higher redox ability. The Mott–Schottky analysis along with the scavenging experiment confirmed the involvement of h+ and O2–. radicals in the photodegradation. Due to highly interconnected nanoflake architectures, CNCS-0.15 holds a promising application as a supercapacitor electrode and visible light active photocatalyst. [ABSTRACT FROM AUTHOR]

High‐performance supercapacitive electrode materials have received significant attention from researchers worldwide, thus aiming for comparable performance similar to the extensively used rechargeable batteries. For emerging energy storage technologies like flexible supercapacitors, transition metal chalcogenides (TMCs) have been in the spotlight due to their promising electrochemical features compared to other electrode materials. Among the synthesis techniques, electrodeposition‐mediated preparation of thin films of TMCs offered an affordable binder‐free approach for electrode fabrication that effectively improved the supercapacitor performance. Hence, this review mainly focussed on the electrodeposition‐based syntheses of single/ multinary chalcogenides and their composites for supercapacitors applications. Further, the effects of different deposition parameters were discussed for boosting the supercapacitor performance. Finally, this review outlined the existing challenges and future perspectives in this research domain, which will assist the upcoming exploration in the energy storage field. [ABSTRACT FROM AUTHOR]

In the recent times research towards solid state supercapacitors (SSS) have increased drastically due to the promising performance in futuristic technologies particularly in portable and flexible electronics like smart watches, smart fabrics, foldable smartphones and tablets. Also, when compared to supercapacitors using liquid electrolyte, solid electrolyte has several advantages like high energy density, safety, high cycle life, flexible form factor, and less environmental impact. The crucial factor determining the sustainability of a technology is the eco‐friendliness since the natural resources are being exploited in a wide scale. Numerous studies have focused on biodegradable materials for supercapacitor electrodes, electrolytes, and other inactive components. Making use of these biodegradable materials to design a SSS enables the technology to sustain for a very long time since biodegradable materials are not only environment friendly but also, they show relatively high performance. This review focuses on recent progress of different biodegradable electrodes, and electrolytes along with their properties, electrochemical performance and biodegradable capabilities for SSS have been analyzed and provides a concise summary enabling readers to understand the importance of biodegradable materials and to narrow down the research in a more rational way. [ABSTRACT FROM AUTHOR]

This work reports the synthesis of semiconductor selenium nanoparticles/micro-rods (Se-NP/MRs) using the bio-fabrication approach and studies its photocatalytic activity under natural sunlight irradiation. Cabbage leaf extract was used as a reducing agent to fabricate Se-NP/MRs. X-ray diffraction patterns shown the crystalline structure with a crystallite size of 28.17 nm, conferring to planes of hexagonal structure. A characteristic sharp resonance peak in Raman spectra at 235 cm−1 endorsed to the Se – Se bond of crystalline Se-NP/MRs. The prominent peak in the FTIR spectra at 621 cm−1 supported the formation of Se-NP/MRs. Scanning electron micrograph revealed a nearly spherical shape with irregular layers in the 35‒95 nm size range. In contrast, the dimension of the micro-rods was observed to be ~ 10 µm in length and 2.5 µm in diameter. The bandgap energy of Se-NP/MRs was analysed to be 2.14 eV using the Tauc plot. The exciting photocatalytic performance of the bio-fabricated Se-NP/MRs revealed that the methylene blue degradation was ~ 86% in 40 min and ~ 97% in 140 min. Kinetic analysis shows that the pseudo-second-order correlation coefficient is well fitted compared to the pseudo-first-order. Therefore, this work opens the door to further exploration of nano-materials/composites with mixed nanoparticles/micro-rods morphology for sustainable applications in the removal of various textile and industrial contaminants. [ABSTRACT FROM AUTHOR]

Mixed multimetallic-based nanocomposites have been considered a promising functional material giving a new dimension to environmental remediation and energy storage applications. On this concept, a hybrid ternary CoO/Ni(OH)2/Cu(OH)2 (CNC) composite showing sea-urchin-like morphology was synthesized via one-pot hydrothermal approach, and its photocatalytic and electrochemical performances were investigated. The photocatalytic performance was explored using Congo red (CR) as a dye pollutant under visible light illumination. The presence of mixed phases of ternary metal ions could minimize the recombination efficacy of photogenerated charge carriers on the basis of the heterojunction mechanism, resulting in 90% degradation of CR dye (40 mg L−1). The effect of scavengers coupled with electrochemical experiments revealed O2−. radical as the predominating species responsible for the degradation of CR. From the electrochemical analysis of CNC, the well-distinguished redox peaks indicated the redox-type nature with a specific capacity of 405 C g−1. For practical applications, an supercapattery (CNC(+)|KOH|AC(−)) was assembled furnishing an energy density of 42 W h kg−1 at a power density of 5160 W kg−1 at 5 A g−1 along with a high capacity retention and coulombic efficiency of 98.83% over 5000 cycles. [ABSTRACT FROM AUTHOR]

Energy storage is one of the most stimulating requirements to keep civilization on the wheel of progress. Supercapacitors generally exhibit a high‐power density, have a maximum life cycle, quick charging time, and are eco‐friendly. Polyaniline (PANI), a conductive polymer, is considered an efficacious electrode material for supercapacitors due to its good electroactivity, including pseudocapacitive behavior. Here, we present the fabrication of a symmetric supercapacitor device based on steel mesh electrodeposited with PANI. Due to its effective conductivity, porous nature, and low cost, steel mesh is a good choice as a current collector to fabricate a high‐performance supercapacitor at a low cost. The optimum fabricated supercapacitor has a high specific capacitance of ∼353 mF cm−2. Furthermore, the supercapacitor obtained an energy density of ∼26.4 μW h cm−2 at a power density of ∼400 μW cm−2. The fabricated supercapacitor shows high stability, as the initial capacitance remained almost the same after 1000 charge/discharge cycles. PANI is a promising candidate for mass production and wide applications due to its low cost and high performance. [ABSTRACT FROM AUTHOR]

The electrocatalytic reduction of nitrate waste into ammonia allows both the removal of nitrate contaminants and an alternative production of ammonia compared to the classical Haber–Bosch industrial process. Ammonia is useful in agriculture for manufacturing fertilizers, and as a reagent in pharmaceuticals, metallurgy, explosives, and the textile industry; ammonia is also an energy carrier in the automobile industry for next-generation fuel cells. Here we review the nitrate-to-ammonia conversion by electrocatalysis of industrial and agricultural waste, with focus on catalysts, reaction intermediates, side reactions, and reaction conditions. Electron transfer is facilitated by electrocatalysts with transition metals having occupied d-orbitals with similar energy levels to that of the nitrate lowest unoccupied molecular orbital. Green electro-conversion using carbon-based materials is also discussed. Results show nitrate conversion from 53 to 99.8% and ammonia selectivity from 70 to 97.4%. [ABSTRACT FROM AUTHOR]

Attaining a sustainable environment has become a prime area of research interest, as it is an utmost necessity for a healthy life. Hence, ample studies have been carried out in adopting different processes and utilizing various materials to attain the goal. Herein, we present an exclusive discussion on one such material, i.e., polyaniline (PANI) and its derivatives. Being an intrinsic conducting type, it has grabbed more attention due to its durability in different doped/un-doped states, promptness in structural alteration, and solution processability. This review presents an exhaustive discussion on published reports showing utilization of PANI and its derivative in various forms like pure and composites, for cleaning the environment through adsorption, photodegradation, etc., and the various methods adopted in order to achieve an optimum operating condition to obtain the maximum outcome. In addition to these merits and demerits, various technical challenges faced with materials have been also presented. Therefore, it is expected that this piece of work, presenting the exhaustive discussion on PANI and; its derivatives would help to develop a better understanding of this excellent conducting polymer PANI and provide a state of art on the role of this material for attaining sustainable surroundings for the living beings. [ABSTRACT FROM AUTHOR]

Herein, this report uses Co3O4 nanoneedles to decorate Mo-Co3O4 nanosheets over Ni foam, which were fabricated by the hydrothermal route, in order to create a supercapacitor material which is compared with its counterparts. The surface morphology of the developed material was investigated through scanning electron microscopy and the structural properties were evaluated using XRD. The charging storage activities of the electrode materials were evaluated mainly by cyclic voltammetry and galvanostatic charge-discharge investigations. In comparison to binary metal oxides, the specific capacities for the composite Co3O4@Mo-Co3O4 nanosheets and Co3O4 nano-needles were calculated to be 814, and 615 C g−1 at a current density of 1 A g−1, respectively. The electrode of the composite Co3O4@Mo-Co3O4 nanosheets displayed superior stability during 4000 cycles, with a capacity of around 90%. The asymmetric Co3O4@Mo-Co3O4//AC device achieved a maximum specific energy of 51.35 Wh Kg−1 and power density of 790 W kg−1. The Co3O4@Mo-Co3O4//AC device capacity decreased by only 12.1% after 4000 long GCD cycles, which is considerably higher than that of similar electrodes. All these results reveal that the Co3O4@Mo-Co3O4 nanocomposite is a very promising electrode material and a stabled supercapacitor. [ABSTRACT FROM AUTHOR]

Summary: The electrocatalysis have a crucial role in the journey towards sustainable energy‐economy. By observing present scenario, it can be inferred that the electrochemical energy technologies have become an inseparable system in our everyday‐life. From generating green fuels to fabrication of high rechargeable electrochemical systems, are being achieved with the help of electrocatalyst. But, the shortage of pertinent catalysts has hindered this process. The desirable factors mainly required in a suitable electrocatalyst are its economic feasibility, robustness, reusability, and performance efficiency. To achieve that, scientists from all over the globe recommended various options, where tuning the MXenes are one of them. Characteristics like hydrophilicity, superior conductivity, and facile processing techniques have made them prominent choice for the applications. Further, enhancements like forming hybrids, different procedures of synthesis of its sheets are done to alter the electronic and structural features to achieve better catalytic activity. In this article, we are going to illustrate some of the important synthesis strategies, applications along with their pros and cons. This article promotes recent advancements in the surface engineering of MXene and its composites such as electrocatalyst in hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR); meanwhile invites researchers from different fields of science applications to contribute in this research to expand its extent. [ABSTRACT FROM AUTHOR]

In order to upgrade existing electronic technology, we need simultaneously to advance power supply devices to match emerging requirements. Owing to the rapidly growing wearable and portable electronics markets, the demand to develop flexible energy storage devices is among the top priorities for humankind. Flexible supercapacitors (FSCs) have attracted tremendous attention, owing to their unrivaled electrochemical performances, long cyclability and mechanical flexibility. Carbon nanotubes (CNTs), long recognized for their mechanical toughness, with an elastic strain limit of up to 20%, are regarded as potential candidates for FSC electrodes. Along with excellent mechanical properties, high electrical conductivity, and large surface area, their assemblage adaptability from one-dimensional fibers to two-dimensional films to three-dimensional sponges makes CNTs attractive. In this review, we have summarized various assemblies of CNT structures, and their involvement in various device configurations of FSCs. Furthermore, to present a clear scenario of recent developments, we discuss the electrochemical performance of fabricated flexible devices of different CNT structures and their composites, including additional properties such as compressibility and stretchability. Additionally, the drawbacks and benefits of the study and further potential scopes are distinctly emphasized for future researchers. [ABSTRACT FROM AUTHOR]

The influence of Ag doping on the SnO2 sensor operating at room temperature is reported in this work. The SnO2 and Ag-doped SnO2 films are deposited by the nebulizer spray pyrolysis method with different Ag (1, 2, 3, and 4 wt%) concentrations. The characterization of doped thin films was done using multiple advanced techniques to understand their crystallization, morphology, optical and electrical properties to find the optimized Ag concentration on the SnO2 surface. It was found that the doping of different concentrations into the SnO2 lattice increases the preferential orientation of the peak along (211) plane up to 3wt% Ag and starts decreasing at 4 wt%. The estimated crystallite size of the 3wt% Ag-doped SnO2 thin films shows larger value of 98 nm with improved thickness and decreased strain. The morphologies of all the prepared thin films exhibits small leafy flakes structure with change in the particle size and improved agglomeration with increased Ag concentration. The optical studies showed better transparency in the visible and near-IR regions with decreased transmittance and increase in bandgap with increasing Ag concentration in SnO2. The PL results suggest that the 3wt% Ag-doped SnO2 has high-intensity emission peaks over the visible regions indicating the presence of more oxygen vacancies which acts as recombination centers to trap large amount of target gas. Finally, the gas sensing properties of the samples at different concentration of ammonia gas (i.e., 50, 100, 150, 200, and 250 ppm) are studied, which revealed that the 3wt% Ag-doped SnO2 showed better sensitivity/response of 120% with maximum response and recovery times of 32 and 17 s at 250 ppm of ammonia gas. Thus, the undoped SnO2 has been optimized with different doping amounts of Ag ions to obtain the best ammonia sensor. [ABSTRACT FROM AUTHOR]

The wastewater treatment is a challenging research area to reduce the increasing pressure on limited fresh water resources. Amongst several techniques adopted and practiced, adsorption is one of the most effective and sustainable ecofriendly processes. In recent years, MXene nanomaterials, a new family of transition metal carbides, have gained increasing attention as the potential adsorbent for pollutants due to their unique features such as large surface area with abundant active sites and hydrophilicity. A wide range of pollutants viz. heavy metal ions, organic dyes, radionuclides, and toxic gas molecules have been sensed by 2D MXenes. An inclusive understanding on the adsorptive behavior of MXene-based materials is needed to explain the removal mechanism and effects of different adsorption parameters. This review gives a general overview on recent research progress on MXene materials with special reference to their applications for the adsorptive removal of different pollutants. The general trends in the synthesis of MXenes, their stability and different factors affecting the adsorption process along with the main challenges in understanding the full potential of MXenes for environmental applications are discussed. [ABSTRACT FROM AUTHOR]

There is a growing interest in supercapacitors as energy storage systems due to their high specific power, fast charge/discharge rates, and long cycling stability. Researchers have focused recently on developing nanomaterials to enhance the capacitive performance of supercapacitors. The inclusion of electroactive components, such as transition metal oxides (TMOs), carbonbased materials, and conducting polymers (CPs), is believed to play an important role in improving the electrochemical behavior of the electrode materials. Nevertheless, supercapacitors containing TMOs, carbon-based materials, and CPs commonly suffer from inferior ion-transport kinetics and poor electronic conductivity, which can affect the rate capability and cycling stability of the electrodes. Therefore, the development of TMO/CP and TMO/carbon-based electrode materials has gained widespread attention because they synergistically combine the advantages of both materials, enabling revolutionary applications in the electrochemical field. In general, TMOs have given good performance as electrodes for supercapacitors by further increasing the performance of the electrode when two metal cations are introduced into a single crystal structure. This Review describes and highlights recent progress in the development of bimetallic oxides regarding their design approach, configurations, and electrochemical properties for supercapacitor applications, at the same time providing new opportunities for future energy storage technologies. [ABSTRACT FROM AUTHOR]

Recycling electronic wastes (e‐wastes) is one of the steps to build greener and cleaner environment. In this work, re‐using of disposed dry cell (zinc‐carbon battery) components to generate graphene and manganese oxide for energy storage application has been demonstrated. The obtained materials have been characterized by X‐ray diffraction, Fourier transformed infrared spectroscopy, Raman spectroscopy and scanning electron microscope. The electrochemical performances of the generated graphene and the MnO2 have been examined in 1M H2SO4. The symmetric (MnO2|PVA:H2SO4|MnO2) and asymmetric (Graphene|PVA:H2SO4|MnO2) supercapacitors were fabricated and their performances were evaluated. The fabricated proto‐type asymmetric device delivered energy density as high as 68 W h kg‐1 at power density of 8010 W kg‐1 with a wide operating potential up to 1.6 V. The device had a long life of 5000 cycles with high Coulombic efficiency as high as 90 %. The observed such an excellent electrochemical performances are attributed to the large surface area and high conductivity of the graphene nanonetwork and nanoporous MnO2 extracted from the disposed dry cell. The two asymmetric proto‐type devices connected in series could light an LED for about 10 min in one charge. Recycling disposed dry cells is one of the sustainable step towards cleaner environment. The carbon rod of spent dry cell was used to generate graphene and spent bobbin for extracting manganese oxide. The electrochemical performances of the generated graphene and the MnO2 have been examined in 1 M H2SO4. The symmetric and asymmetric supercapacitors were fabricated and their performances were evaluated. [ABSTRACT FROM AUTHOR]

Owing to the nanometer size range, Quantum Dots (QDs) have exhibited unique physical and chemical properties which are favourable for different applications. Especially, due to their quantum confinement effect, excellent optoelectronic characteristics is been observed. This considerable progress has not only uplifted the singular usage of QDs, but also encouraged to prepare various hybrid materials to achieve superior efficiency by eliminating certain shortcomings. Such issues can be overcome by compositing QDs with polymers. Via employing polymer composite with QDs (PQDs) for supercapacitor applications, adequate conductivity, stability, excellent energy density, and better specific capacitance is been achieved which we have elaborately discussed in this review. Researchers have already explored various types of polymer nanocomposite with different QDs such as carbonaceous QDs, transition metal oxide/sulphide QDs etc. as electrode material for supercapacitor application. Synthesis, application outcome, benefits, and drawbacks of these are explained to portray a better understanding. From the existing studies it is clearly confirmed that with using PQDs electrical conductivity, electrochemical reactivity, and the charge accumulation on the surface have prominently been improved which effected the fabricated supercapacitor device performance. More comprehensive fundamentals and observations are explained in the current review which indicates their promising scopes in upcoming times. [ABSTRACT FROM AUTHOR]

Energy generation can be clean and sustainable if it is dependent on renewable resources and it can be prominently utilized if stored efficiently. Recently, biomass-derived carbon and polymers have been focused on developing less hazardous eco-friendly electrodes for energy storage devices. We have focused on boosting the supercapacitor's energy storage ability by engineering efficient electrodes in this context. The well-known conductive polymer, polyaniline (PANI), deposited on nickel foam (NF) is used as a positive electrode, while the activated carbon derived from jute sticks (JAC) deposited on NF is used as a negative electrode. The asymmetric supercapacitor (ASC) is fabricated for the electrochemical studies and found that the device has exhibited an energy density of 24 µWh/cm2 at a power density of 3571 µW/cm2. Furthermore, the ASC PANI/NF//KOH//JAC/NF has exhibited good stability with ~86% capacitance retention even after 1000 cycles. Thus, the enhanced electrochemical performances of ASC are congregated by depositing PANI on NF that boosts the electrode's conductivity. Such deposition patterns are assured by faster ions diffusion, higher surface area, and ample electroactive sites for better electrolyte interaction. Besides advancing technology, such work also encourages sustainability. [ABSTRACT FROM AUTHOR]

• Facile, solid-state, low temperature synthesized layered molybdenum boride found out to be of thin nanosheets. • MoB are found to be electrochemically active in acid and neutral electrolyte, where the nanosheets provide a higher surface area for the electrolyte ion interaction. • MoB was directly employed as a negative electrode, against the activated carbon as a positive electrode for the asymmetric supercapacitors. • The device was found to deliver a high energy density and power density with long-term stability in charge/discharge cyclings. • Interestingly, it was discovered that the outcomes of the electrochemical performance of asymmetric supercapacitors could be tuned by the electrolyte. [Display omitted] The survey of 2D materials has triggered the energy storage and conversion research. In molybdenum-based 2D layered materials are of great significance, due to their remarkable properties. In this work, simple solid-state synthesis and formation of molybdenum boride has been explored with various characteristic techniques. The advanced characterization techniques like XRD, TEM, XPS, BET, have been used to understand the crystallinity, morphology, and surface area of the layered MoB (LMB). The electrochemical performances of LMB electrode were verified with different aqueous electrolytes. The LMB electrode has been found to store higher charge in H 2 SO 4 than Na 2 SO 4 electrolyte. The LMB electrode delivered a specific capacitance of 445 F g−1 in H 2 SO 4 where 130 F g−1 in Na 2 SO 4 at a current density of 1 A g−1. Such behavior may be due to ionic size and mobility of ions in the electrolyte. The asymmetric supercapacitors have been fabricated with LMB and activated carbon (AC) electrode then the device performance was examined in both the electrolyte. On optimization, it was found the device works well in potential window 1.4 V in H 2 SO 4 while the potential window was extended to 1.8 V in Na 2 SO 4 electrolyte. The device was found to deliver an energy density of 14 W h kg−1 at a power density of 16.8 kW kg−1 for H 2 SO 4 with a better capacity retention of 98% for 2000 cycles. Thus, LMB electrode in supercapacitor application has been demonstrated for the first time, which can instigate more investigations for layered molybdenum-based electrodes for energy storage devices. [ABSTRACT FROM AUTHOR]