In recent years, the development of energy storage devices has received much attention due to the increasing demand for renewable energy. Supercapacitors (SCs) have attracted considerable attention among various energy storage devices due to their high specific capacity, high power density, long cycle life, economic efficiency, environmental friendliness, high safety, and fast charge/discharge rates. SCs are devices that can store large amounts of electrical energy and release it quickly, making them ideal for use in a wide range of applications. They are often used in conjunction with batteries to provide a power boost when needed and can also be used as a standalone power source. They can be used in various potential applications, such as portable equipment, smart electronic systems, electric vehicles, and grid energy storage systems. There are a variety of materials that have been studied for use as SC electrodes, each with its advantages and limitations. The electrode material must have a high surface area to volume ratio to enable high energy storage densities. Additionally, the electrode material must be highly conductive to enable efficient charge transfer. Over the past several years, several novel materials have been developed which can be used to improve the capacitance of the SCs. This article reviews three types of SCs: electrochemical double-layer capacitors (EDLCs), pseudocapacitors, and hybrid supercapacitors, their respective development, energy storage mechanisms, and the latest research progress in material preparation and modification. In addition, it proposes potentially feasible solutions to the problems encountered during the development of supercapacitors and looks forward to the future development direction of SCs.

This review explores the recent advancements in catalyst technology for hydrogen production, emphasizing the role of catalysts in efficient and sustainable hydrogen generation. This involves a comprehensive analysis of various catalyst materials, including noble metals, transition metals, carbon-based nanomaterials, and metal–organic frameworks, along with their mechanisms and performance outcomes. Major findings reveal that while noble metal catalysts, such as platinum and iridium, exhibit exceptional activity, their high cost and scarcity necessitate the exploration of alternative materials. Transition metal catalysts and single-atom catalysts have emerged as promising substitutes, demonstrating their potential for enhancing catalytic efficiency and stability. These findings underscore the importance of interdisciplinary approaches to catalyst design, which can lead to scalable and economically viable hydrogen production systems. The review concludes that ongoing research should focus on addressing challenges related to catalyst stability, scalability, and the integration of renewable energy sources, paving the way for a sustainable hydrogen economy. By fostering innovation in catalyst development, this work aims to contribute to the transition towards cleaner energy solutions and a more resilient energy future.

Carbon black (CB) decorated Ni/Co oxide composite electrodes are fabricated in situ with variable CB percentages by using the successive ionic layer adsorption and reaction (SILAR) method. This green process tuned the metal ion concentration on carbon and offered binder-free, facile and scalable features. The structure, morphology and electrochemical performances of the developed nanocomposites are characterized using various sophisticated techniques. An elemental study suggested the substitution of more Ni²⁺ in Ni_xCo_1−xO₄ with varying carbon concentrations, which was correlated with the change in the relaxation rate of the composites. X-ray photoelectron spectroscopy confirmed the presence of Ni²⁺ and Ni³⁺ in the Ni/Co–carbon composites, which are additionally responsible for improving the conductivity of the developed electrodes. Also, conductive atomic force microscopy supported the improvement in the local conductivity of NC7 compared to NC0. NC7 electrodes demonstrated a specific capacitance of around 1811 F g⁻¹ at a current density of 0.5 mA cm⁻² with excellent cyclic retention (92% even after 8000 cycles) and energy density (91 W h Kg⁻¹). Further, NC7 electrodes are used to fabricate an asymmetric solid state supercapacitor device (capacitance around 258 F g⁻¹), and are connected to a commercial solar cell for storing energy, which is effective to light a commercial LED.