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Mo2C is a unique material due to its tunable phase and electronic structures. Because of the interaction of molybdenum and carbon, the D band of molybdenum atoms expands, similar to Pt. This hybridization minimizes the energy required for hydrogen adsorption, thereby enhancing the electrocatalytic characteristics. In this article, we report the direct one-pot synthesis of Mo2C on N doped on a porous carbon sheet for electrocatalytic hydrogen evolution reactions using ammonium molybdate as a molybdenum source, glucose as a carbon source, and ammonia as a nitrogen source. The porosity and Mo2C nanostructure embedded in N-doped carbon have helped to facilitate the infusion of electrolytes and the detachment of hydrogen molecules from the surface of a Mo2C-N-doped porous carbon sheet. Besides, the prepared composite has shown the most efficient HER performances with the overpotential and Tafel slope of Mo2C and Mo2C-NC mA/cm2being 133 and 95 mV and 76 and 69 mV dec–1, respectively; it also has excellent stability in an acidic medium. Because of its easy resource, simple preparation, and excellent performance, the prepared Mo2C on a N-doped carbon sheet has a significant potential to be an alternative for cost-effective hydrogen production.

Electrode materials comprising SnO2quantum 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 SnO2quantum dots across ZnO. The integration of SnO2quantum 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⁻1for 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⁻1at 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.

Supercapacitors are rapidly emerging as a pivotal energy storage technology due to their high-power density, fast charging/discharging capabilities, and long cyclic life. This extensive review sheds light on the integral components of supercapacitors, emphasizing electrode materials and the diverse substrates they are interfaced with. The careful selection of appropriate electrode materials, along with their preparation and coating techniques on compatible substrates, significantly influences the performance and cost of supercapacitors. Recent research efforts have focused on enhancing supercapacitor performance by modifying various substrates with nanomaterials. This review covers a range of supercapacitor substrates, including carbon-based substrates, indium tin oxide-coated glass, fluorine-doped tin oxide-coated glass, nickel foam, stainless steel, and aluminum foil, discussing their modification with various nanomaterials such as carbon-based materials, metal oxides, metal hydroxides, metal sulfides, MOFs, COFs, MXenes, and conductive polymers. Techniques such as drop casting, electrochemical deposition, hydrothermal methods, and printing techniques are utilized for these modifications. The advantages and disadvantages of each substrate and modification process are examined, focusing on how nanomaterials impact energy storage capacity, power density, and cycling stability. Using nanomaterials increases electrode surface area, leading to higher energy density, while suitable substrates facilitate precise control over nanomaterial modifications, resulting in improved charge storage capabilities. By providing insights into the fundamental knowledge of supercapacitors and emphasizing the potential of nanomaterials and their modification methodologies on various substrates, this review paper offers valuable information for scientists and engineers in the field of energy storage.

The fabrication of composite electrodes has succeeded in boosting energy storage. This involves creating an interface through rational construction that may include doping or integration with their components. In this study, molybdenum- and nickel sulfide-based nanoflowers (MNS) coupled with Ni–Co nanorods (NiCo) constructed directly on Ni foam (MNS@NiCo NSs), which were designed to our delight via a simplistic hydrothermal technique. This technique reduced the resistance and maximized sample utilization. The entwined nanorods were spread over interconnected nanoflowers. This coupling-designed nanostructure could supply a network with plentiful mesopores to accelerate electrolyte penetration with many redox-active sites during the electrochemical process. The MNS@NiCo NS-designed mesoporous nanostructures improved the wettability by providing a higher capacitance of 455 C/g at 1 A/g. After being integrated with NiCo-nanoflowers, the MNS@NiCo NS composite delivered a higher capacitance of 505 C/g at 1 A/g. Also, the developed asymmetric supercapacitor (MNS@NiCo NSs//AC) achieved a higher energy density of 38.1 W h/kg at a power density of 775 W/kg, delivering superior cycling stability even over 5000 long cycles with a capacitance retention of 92% at a current density of 10 A/g. The noteworthy energy capability of MNS@NiCo NSs arises from the synergistic benefits of MNS nanoflowers and Ni–Co nanorods in engineering the synthesis of such potential heterostructures.

Supercapatteries have received great attention in recent years due to its excellent charging storage capabilities. The effective electrochemically active surface area of the electrode is crucial in obtaining high capacity in supercapatteries. Herein, we present a scalable synthesis of binder-free hierarchical MnCo2O4(MCO) nanospikes/Ni(OH)2(NiOH) nanosheets (MCO/NiOH) nanocomposites for supercapattery electrode application. The MCO/NiOH nanocomposites are synthesized by the two-step hydrothermal method at low-cost without affecting nanostructures and further used as electrodes in fabricating a supercapattery. The synergistic effect of the NiOH nanosheets and MCO nanospikes helps to enhance the electrochemical charge storage performance when compared to their counterparts. The growth of NiOH nanosheets over the MCO nanospikes helps to suppress the self-discharge nature of MCO nanospikes otherwise. The MCO/NiOH//activated carbon supercapattery fabricated in the asymmetric configuration delivers a maximum specific capacity of 890C/g with a high energy density of 75.2 Wh/kg. The MCO/NiOH//activated carbon supercapattery exhibits a capacity retention of 86 % after completing 5000 charge/discharge cycles. Therefore, MCO/NiOH nanocomposite electrodes are capable candidates for the next-generation electrochemical energy storage systems.

Emergence of supercapacitor's utilization is been clearly observed in recent years due to the advancement in energy conversion technologies as well as in energy storage systems. The supercapacitors are seemed to be attractive mainly due to its high-energy density, stable cycle life and longer lifetime. Additionally, sustainable nanotechnology played a crucial role in pushing the ongoing progress of supercapacitor technology. Among various popular materials, cerium oxide (CeO2) is one of the ceramic materials that have depicted positive electrochemical activity. CeO2and its nanostructured composite materials are broadly investigated as a promising active material for supercapacitor applications. The enhancement in electrochemical performance due to addition of different elements to CeO2was also been explained. The morphologies of prepared binary or ternary composite using CeO2were also briefly discussed in this article.

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.