Skillful Introduction of Urea during the Synthesis of MOF-Derived FeCoNi–CH/p-rGO with a Spindle-Shaped Substrate for Hybrid Supercapacitors

Abstract

A composite (FeCoNi–CH/p-rGO) with a spindle-shaped substrate is controllably prepared by combining FeCoNi carbonate hydroxide (FeCoNi–CH) and partially reduced graphite oxide (p-rGO) using a novel chemical strategy. In the synthetic process, urea is introduced as the precipitant and reducing agent. MIL-88A as a self-template is converted into a ternary-metal CH composite, maintaining the original morphology by the metal ion etching and coprecipitation method, and graphite oxide is reduced to rGO with stronger conductivity partially at the same time. The electrochemical performance of the FeCoNi–CH/p-rGO is superior to FeCoNi–CH, with a high specific capacitance (1346 F g –1 at 0.5 A g –1 ) and rate capability (55.5% at 10 A g –1 ). The better electrochemical performance of the FeCoNi–CH/p-rGO composite is attributed to the pseudocapacitive energy storage capacity caused by the synergistic action of ternary-metal CH and the high conductivity of p-rGO. Meanwhile, the uniform mixture of FeOOH/activated carbon (AC) is fabricated as an anode to instead of the pure FeOOH or AC, which leads to the balancing energy density and high cycle stability of the hybrid supercapacitor (HSC). The corresponding assembled FeCoNi–CH/p-rGO//FeOOH/AC HSC exhibits a high energy density of 46.93 W h kg –1 at 400 W kg –1 power density and a cycle stability of 66.7% after 3000 cycles. In addition, this work also provides a facile method to fabricate metal–organic framework-derived ternary-metal CH/p-rGO composite materials, which could be applied in the fields of supercapacitors and other fields.

Designing Symmetric Gradient Honeycomb Structures with Carbon-Coated Iron-Based Composites for High-Efficiency Microwave Absorption

“…It demonstrates that there are other forms of O present. Figure S2 illustrates the FT-IR results of MD 3 , with peaks observed at 1634 and 1400 cm −1 corresponding to the symmetric and asymmetric stretching modes, respectively, of the carboxyl groups in 2,6-NDC [ 32 ]. Furthermore, the fact that the derivative retained the basic shape of the precursor also indicated that the organic ligand had not completely collapsed.…”

A Novel High Entropy Hydroxide Electrode Material for Promoting Energy Density of Supercapacitors and Its Efficient Synthesis Strategy

“…The specific capacitance (C, F g −1 ) of the materials was calculated by using the Equation (3), where I (A), ∆t (s), m (g), and ∆V (V) are discharge current, discharge time, mass of active material, and potential window, respectively. [48]…”

Tailoring Metal–Organic Frameworks and Derived Materials for High-Performance Zinc–Air and Alkaline Batteries

“…As can be seen, the charge–discharge profiles of the MO-rGO||MOF-LDH device at lower rates consist of three regions: two sloping parts at high and low voltage ranges along with a voltage plateau with a moderate slope in between. Such a GCD profile reflects the dual supercapacitor–battery character of the MO-rGO||MOF-LDH device in which the steeper slope regions indicate the capacitive behavior and the moderate-slope region explains the battery-like character of the materials . Note, however, that at extremely high current values, the capacitive behavior dominates the mechanism due to the slow kinetics of the Faradaic processes at exceedingly high specific current values.…”

“…Such a GCD profile reflects the dual supercapacitor−battery character of the MO-rGO||MOF-LDH device in which the steeper slope regions indicate the capacitive behavior and the moderate-slope region explains the battery-like character of the materials. 94 Note, however, that at extremely high current values, the capacitive behavior dominates the mechanism due to the slow kinetics of the Faradaic processes at exceedingly high specific current values. The device exhibits a high specific capacity of 47.3 mA h g −1 (specific capacitance of 118.2 F g −1 ) at a specific current of 1 A g −1 .…”

“…Along with being an outstanding bifunctional electrocatalyst for the OER and ORR processes, we were keen to know how the MO-rGO nanocomposite would cope with the new role as a supercapacitive electrode material. This idea was inspired in part by other studies that have reported iron-based species as negative pseudocapacitive materials, ,,, although the carbonaceous part of the MO-rGO nanocomposite serves undoubtedly as a negative electrical double-layer capacitive (EDLC) material as well. This idea triggered the development of a new high-performance supercapacitive negative electrode.…”