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Developing an energy storage electrocatalyst that excels in efficiency, cost-effectiveness, and long-term stability over numerous charge–discharge cycles is paramount for advancing energy storage technologies. In this work, we present a simple and environmentally friendly method to fabricate an asymmetric supercapacitor device (ASCD) as a viable energy storage system. The ASCD features binder-free, oxygen–nitrogen dual functionalized, and sulfurized iron–nickel hydroxysulfide (FNMOS) electrocatalysts, self-grown on nickel foam as a positive electrode, and waste biomass-derived activated carbon (CFAC) as a negative electrode. The FNMOS electrode in a 3-electrode configuration has the highest area-specific capacity of 1.6 mA h cm−2 at 1 mA cm−2, and even at a high current density of 10 mA cm−2, it maintained 0.94 mA h cm−2. The enhanced electrocatalytic activity is due to the synergistic contribution of the sulfurized NiFe composite along with the meticulous oxygen–nitrogen co-functionalization. Additionally, the ASCD with the FNMOS positive electrode and the CFAC negative electrode achieves maximum energy density (ED) and power density (PD) values of 350 μW h cm−2 (825 μW per cm2 PD) and 7960 μW cm−2 (200 μW h per cm2 ED). Furthermore, the device demonstrated exceptional rate capability by maintaining over 96% of its initial capacity even after 25 000 cycles of charge and discharge. The exceptional stability was further characterized by the ex situ post-mortem analysis of the FNMOS electrode after the stability test. These encouraging electrochemical results, paired with some practical use cases, demonstrate the applicability of FNMOS as a next-generation energy storage material. [ABSTRACT FROM AUTHOR]

Recently, Zeolitic Imidazolate Frameworks (ZIFs) and their hybrid composites have incited a lot of interest in the research community and have shown promising potential in supercapacitors owing to their excellent conductivity, high surface area, tunable structure, rich redox chemistry, composition diversity, etc. Even though many ZIFs are being studied for the advancement of electrode materials used for energy storage applications, in this review, we are focused on ZIF-8 and ZIF-67 only. The electrochemical performance of pure ZIFs is poor due to low electronic conductivity and poor cycling life. To counter this, ZIFs are mixed with other materials like conducting polymers, other transitional metals composites, and activated carbons to prepare hybrid composites. Furthermore, the highly porous structure and large surface area of the ZIFs cage act as an ideal template for designing composites with excellent supercapacitor applications. This reviewis focus on the synthesis and electrochemical performance of such materials. This review is divided into two main parts: the design and synthesis of ZIF-8 and ZIF-67 derivatives for supercapacitor applications and the electrochemical performance of ZIF-8 and ZIF-67-based derivatives in three-electrode and two-electrode setups. Lastly, the challenges and obstacles encountered while employing ZIF-8 and ZIF-67-based composites in supercapacitors will be reviewed and commented on. [ABSTRACT FROM AUTHOR]

We report a greener, effortless, and scalable approach involving the synthesis of a self-grown nanomaterial on a flexible conductive substrate along with the synthesis of activated carbon derived from biomass waste. Contrary to the popular idea of using a variety of additives for the synthesis of nanomaterials, such as surface-activating agents, 3d metal-oxide nanoplates were synthesized on a highly hydrophobic carbon cloth substrate using no foreign elements except the metal precursors. The activated carbon was derived from biomass waste in that it was synthesized using withered cherry flower petals. The two as-synthesized materials were combined to fabricate an asymmetric supercapacitor, the design of which is presented as a greener and sustainable way to obtain an alternative energy storage unit. The three-dimensional nanoplate architecture from the positive electrode combined with the densely populated meso-/microporous structures of the negative electrode delivered an energy density of 106.3 μWh cm–2 for a power density of 657 μW cm–2, which is maintained at 57.5 μWh cm–2 even at a high power density of 5283.4 μW cm–2. Furthermore, a highly stable rate performance was achieved with high capacity retention even after charging–discharging for over 6000 cycles. The fabricated device exhibits highly satisfactory results in practice and hence presents itself as a highly capable candidate for a green energy solution. [ABSTRACT FROM AUTHOR]

An essential key to enhancing the specific capacity and cyclic stability of transition metal oxide materials is the hybridization of carbon compounds by binder-free methods for supercapacitors. Carbonaceous compounds shorten the electron-ion diffusion pathways due to their high active surface area and conductivity. Herein, we focus on improving the specific energy, stability, and conductivity of the electrode by the incorporation of nanosized carbon material. The integration of nano carbons from viable eco-friendly glucose with CoMoO4 enhanced the experimental specific capacity of the electrode. The self-grown CoMoO4 on a nickel foam (CMO-NF) was confirmed as the best approach after extensive optimization process by the feasible hydrothermal (HT) method. The amount of carbon deposited and the structural morphology on the fabricated CoMoO4-glucose-derived carbon (CMO-GC) electrode was varied by adjusting the concentration of glucose by the viable HT technique. Notably, the hybrid CMO-GC-2 achieved a maximum specific capacity of 851.85 C g−1 at 1 A g−1, and it is relatively higher than that of CMO-NF (301.4 C g−1). The asymmetric supercapacitor device (CMO-GC-2//AC) demonstrated excellent energy density (36.86 W h kg−1 for 152.84 W kg−1), power density (3209.35 W kg−1 for 11.19 W h kg−1), and extensive capacity retention of 87% for up to 5000 cycles. The high performance is related to the synergetic effect of EDLC and the redox reaction, with nano-architecture and well-defined morphology of the electrode material. [ABSTRACT FROM AUTHOR]

An essential key to enhancing the specific capacity and cyclic stability of transition metal oxide materials is the hybridization of carbon compounds by binder-free methods for supercapacitors. Carbonaceous compounds shorten the electron-ion diffusion pathways due to their high active surface area and conductivity. Herein, we focus on improving the specific energy, stability, and conductivity of the electrode by the incorporation of nanosized carbon material. The integration of nano carbons from viable eco-friendly glucose with CoMoO4 enhanced the experimental specific capacity of the electrode. The self-grown CoMoO4 on a nickel foam (CMO-NF) was confirmed as the best approach after extensive optimization process by the feasible hydrothermal (HT) method. The amount of carbon deposited and the structural morphology on the fabricated CoMoO4-glucose-derived carbon (CMO-GC) electrode was varied by adjusting the concentration of glucose by the viable HT technique. Notably, the hybrid CMO-GC-2 achieved a maximum specific capacity of 851.85 C g-1 at 1 A g-1, and it is relatively higher than that of CMO-NF (301.4 C g-1). The asymmetric supercapacitor device (CMO-GC-2//AC) demonstrated excellent energy density (36.86 W h kg-1 for 152.84 W kg-1), power density (3209.35 W kg-1 for 11.19 W h kg-1), and extensive capacity retention of 87% for up to 5000 cycles. The high performance is related to the synergetic effect of EDLC and the redox reaction, with nano-architecture and well-defined morphology of the electrode material.