Supercapacitors are energy storage and conversion devices that display high power. In order to increase energy density, redox-active materials can be incorporated into the carbonaceous electrode(s). Although in recent years many studies have offered different redox-active candidates and composite methods, there is a constant search for an effective, easily producible and stable composite material. Here, we present a graphene/ferrocene composition as a redox active 3-D supercapacitor electrode material. The combination of highly reversible, conductive and strongly attached ferrocene with the high surface area and open porous structure of graphene results in high-power, high-energy density supercapacitors. The graphene scaffold is converted from graphene-oxide (GO) by laser irradiation, a facile, fast and eco-friendly method. The ferrocene is chemically bonded to the graphene by two different approaches that take advantage of the strong and stable pi–pi interactions between the carbon and the aromatic ligands. The excellent bonding between the components results in low internal resistance and high reversibility of the redox reaction. The composite demonstrated a 205% increase in specific capacitance from 87 F g⁻¹ for pure laser reduced graphene oxide to 178 F g⁻¹ for the composite with ferrocene. This is equivalent to an energy density of 6.19 W h kg⁻¹ while maintaining a power density of 26.0 kW kg⁻¹.

Carbon nanodots were chemically modified to control the fluorescence and identify fluorophores.

Supercapacitors (SCs) coupled with redox materials have been extensively investigated to maximize the energy density of SCs. Common metal–organic frameworks explicitly used for this purpose are Prussian blue analogs (PBAs). However, their low conductivity and number of external electroactive sites hinder their capacitance and reaction rate. Our work focuses on a material-level optimization strategy, including morphology modification and superstructure fabrication of PBA. We report the synthesis of Co–Co@Ni–Fe trimetallic core–shell PBA nanocubes containing an Fe^II/III redox couple in the Ni–Fe PBA shell over the conductive Co–Co PBA core. This complex underwent a reversible redox reaction and was further encapsulated in a polypyrrole (PPy) network as a redox additive to prepare a novel polymer-encapsulated double-PBA nanocube composite (Co–Co@Ni–Fe PBA–PPy). The composite exhibited a faradaic non-capacitive diffusion-dominated charge storage ability. It yielded an improved specific capacity of 318.1 C g⁻¹ at 1 A g⁻¹ with a capacity retention of 90% over 2000 cycles @15 A g⁻¹. Furthermore, an asymmetric supercapacitor based on Co–Co@Ni–Fe PBA–PPy and activated carbon electrodes delivered a maximum energy density of 20 W h kg⁻¹ at a power density of 808.9 W kg⁻¹ within a 1.6 V voltage window. The electrochemical analysis demonstrated a considerable improvement in the charge-storage performance due to an increase in electron transfer, electrolyte diffusion, and electroactive area via strong electronic coupling between the Co–Co@Ni–Fe core–shell PBA and the PPy. Furthermore, this work helps to differentiate the composite's current contributions from the PBA and PPy. The detailed electrochemical characterization steps of these methods concerning redox additives integrated into conducting polymers are provided in this work.

Among the methods employed for carbon capture, the electroreduction of CO₂ offers both a reduction in CO₂ levels and the possibility of recycling it into commodity chemicals. However, the most efficient catalysts for this reaction are precious metals. To achieve cost-effective processes, other elements should be used. Transition-metal atoms coordinated with metal-organic frameworks (MOFs) exhibit high performance as electrocatalysts. However, the isolating natures of MOFs limit their utilization as electrocatalysts. In this study, we grew MOF nanoparticles inside hierarchically mesoporous carbon instead of mixing the MOFs with conductive carbon. The incorporated MOF nanoparticles showed improved properties compared with those of MOFs mixed with carbon, indicating strong electronic interactions in the composites. The encapsulated MOF nanoparticles demonstrated high electric conductivity while preserving their original crystallinity. When used as electrodes in CO₂ electroreduction, the MOFs exhibited a high electroactive coverage of 155 nmol cm⁻². Moreover, in a CO₂-saturated electrolyte, the composites exhibited excellent electrochemical performance, including a small onset potential (−0.31 V vs. RHE) and large reduction currents (−18 mA. cm⁻² at −1.0 V); these were considerably higher than those usually reported for MOF-based materials except in CO electroreduction. Importantly, the composite produced valuable hydrogenated commodity chemicals, including formic acid.

Electrochemical reduction of nitrate to ammonia (eNO₃RR) is proposed as a sustainable solution for high-rate ammonia synthesis under ambient conditions. The complex, multistep eNO₃RR mechanism necessitates the use of a catalyst for the complete conversion of nitrate to ammonia. Our research focuses on developing a novel Pd-PdO doped in a reduced graphene oxide (rGO) composite catalyst synthesized via a laser-assisted one-step technique. This catalyst demonstrates dual functionality: palladium (Pd) boosts hydrogen adsorption, while its oxide (PdO) demonstrates considerable nitrogen adsorption affinity and exhibits a maximum ammonia yield of 5456.4 ± 453.4 μg/h/cm² at -0.6 V vs reversible hydrogen electrode (RHE), with significant yields for nitrite and hydroxylamine under ambient conditions in a nitrate-containing alkaline electrolyte. At a lower potential of -0.1 V, the catalyst exhibited a minimal hydrogen evolution reaction of 3.1 ± 2.2% while achieving high ammonia selectivity (74.9 ± 4.4%), with the balance for nitrite and hydroxylamine. Additionally, the catalyst's stability and activity can be regenerated through the electrooxidation of Pd.