Supercapacitors have become a popular form of energy-storage device in the current energy and environmental landscape, and their performance is heavily reliant on the electrode materials used. Carbon-based electrodes are highly desirable due to their low cost and their abundance in various forms, as well as their ability to easily alter conductivity and surface area. Many studies have been conducted to enhance the performance of carbon-based supercapacitors by utilizing various carbon compounds, including pure carbon nanotubes and multistage carbon nanostructures as electrodes. These studies have examined the characteristics and potential applications of numerous pure carbon nanostructures and scrutinized the use of a wide variety of carbon nanomaterials, such as AC, CNTs, GR, CNCs, and others, to improve capacitance. Ultimately, this study provides a roadmap for producing high-quality supercapacitors using carbon-based electrodes.

In order to improve the electrochemical performance of the NiCo₂O₄ material, Ni ions were partially substituted with Cu²⁺ ions having excellent reducing ability. All of the electrodes were fabricated by growing the Ni_1−xCu_xCo₂O₄ electrode spinel-structural active materials onto the graphite felt (GF). Five types of electrodes, NiCo₂O₄/GF, Ni_0.875Cu_0.125Co₂O₄/GF, Ni_0.75Cu_0.25Co₂O₄/GF, Ni_0.625Cu_0.375Co₂O₄/GF, and Ni_0.5Cu_0.5Co₂O₄/GF, were prepared for application to the oxygen evolution reaction (OER). As Cu²⁺ ions were substituted, the electrochemical performances of the NiCo₂O₄-based structures were improved, and eventually the OER activities were also greatly increased. In particular, the Ni_0.75Cu_0.25Co₂O₄/GF electrode exhibited the best OER activity in a 1.0 M KOH alkaline electrolyte: the cell voltage required to reach a current density of 10 mA cm⁻² was only 1.74 V (η = 509 mV), and a low Tafel slope of 119 mV dec⁻¹ was obtained. X-ray photoelectron spectroscopy (XPS) analysis of Ni_1−xCu_xCo₂O₄/GF before and after OER revealed that oxygen vacancies are formed around active metals by the insertion of Cu ions, which act as OH-adsorption sites, resulting in high OER activity. Additionally, the stability of the Ni_0.75Cu_0.25Co₂O₄/GF electrode was demonstrated through 1000th repeated OER acceleration stability tests with a high faradaic efficiency of 94.3%.

The need for energy storage and conversion is growing as a result of the worsening consequences of climate change and the depletion of fossil fuels.

Herein, we report the design and synthesis strategy of a new class of five EDOT based co-sensitizers (CSGR1-5) by introducing different donors (2,3,4-trimethoxypheny, 2,4-dibutoxyphenyl, and 2,4-difluorophenyl) and anchoring groups (rhodamine-3-acetic acid and cyanoacetic acid) systematically. The synthesized metal-free organic co-sensitizers were employed for cocktail dye-sensitized solar cells along with N749 (black dye). The DSSC devices with a mixture of co-sensitizers (CSGR1-5) and N749 have shown a 7.95%, 8.40%, 7.81%, 6.56% and 6.99% power conversion efficiency (PCE) respectively, which was more than that of single N749 dye PCE (6.18%). Enhanced efficiency could be ascribed to the increased short circuit current (J_sc) and open circuit voltage (V_oc). The increased J_sc was achieved due to enhanced light harvesting nature of N749 device upon co-sensitization with CSGR dyes and feasible energy levels of both the dyes. The V_oc was improved due to better surface coverage which helps in decreasing the rate of recombination. The detailed optical and electrochemical properties were investigated and complimented with theoretical studies (DFT).