Ion-Exchange Synthesis of Ternary FeCoNi-Layered Double Hydroxide Nanocage Toward Enhanced Oxygen Evolution Reaction and Supercapacitor

Abstract

To cater for the development of clean hydrogen energy, an efficient oxygen evolution reaction catalyst is urgently needed to increase the efficiency of water splitting. A novel three-dimensional (3D) ternary transition metal hydroxide, FeCoNi-layered double hydroxide (FeCoNi-LDH) nanocage has been successfully synthesized by the cation exchange reaction using the metal–organic framework as a template. The obtained ternary FeCoNi-LDH nanocage displays excellent electrocatalytic activity, such as the low overpotential of 299 mV at j = 10 mA cm–2 in 1.0 M KOH electrolyte with a Tafel slope of 50 mV dec–1. Moreover, the FeCoNi-LDH nanocage could also be used as a high-performance electrode for supercapacitor, which presents a high specific capacity of 980 F g–1 at 1 A g–1 in 3.0 M KOH. More importantly, the electrode possesses a superb rate capability with 93% capacity retention even at a current density of 20 A g–1. These results manifest that FeCoNi-LDH has a wide prospect in the application in the energy conversion and storage fields.

Synthesis of FeNiCo Ternary Hydroxides through Green Grinding Method with Metal‐Organic Frameworks as Precursors for Oxygen Evolution Reaction

“…Another new peak at 3412 cm −1 is attributed to O−H stretching vibration, which may be ascribed to metal‐hydroxide groups and water molecules. The signal at 1631 cm −1 belongs to the bending vibration of the water molecules [34,35] . Moreover, the supernatant after centrifugation was evaporated to dryness, and the precipitated solid was tested by FTIR spectroscopy.…”

Synthesis of CNTs/CoNiFe-LDH Nanocomposite with High Specific Surface Area for Asymmetric Supercapacitor

“…Compared with CoNiFe-LDH, CNTs/CoNiFe-LDH composite had a higher capacity and superior rate retention, which could be attributed to the large surface area of CNTs/CoNiFe-LDH and the synergistic effect of carbon material and CoNiFe-LDH. The excellent rate retention of CNTs/CoNiFe-LDH composite was also superior to the reported CoNiFe-LDH [ 21 , 23 , 24 , 25 ] and CNTs/Ni Co LDH composites (58% from 1 to 20 A g −1 ) [ 32 ] and the Ce-NiCo-LDH/CNT electrode (67.9% from 1 to 10 A g −1 ) [ 31 ] ( Table S1 ). Energy efficiency (η E ) is an important parameter to evaluate electrode materials, which can be determined from the GCD curves using the relation: η E = E int/D /E int/C , where E int/D and E int/C refer to the discharge and charge energy of the electrode or device [ 47 , 48 ].…”

“…The spin-energy separation of 17.6 eV was characteristic of Ni 2+ [ 27 , 28 ]. The Fe 2p spectrum in Figure 4 d displayed two peaks of Fe 2p 3/2 (713.0 eV) and Fe 2p 1/2 (725.4 eV), suggesting the existence of the Fe 3+ in the CNTs/CoNiFe-LDH composite [ 23 , 29 ].…”

“…For example, Rohit et al synthesized CoNiFe-LDH nanosheets with a specific capacity of 360 C g −1 at 0.4 A g −1 [ 21 ]. Li et al fabricated FeCoNi-LDH Nanocage, which has a capacitance of 980 F g −1 at 1 A g −1 [ 23 ]. Wang et al reported ternary LDH electrodes and studied the role of M 3+ .…”

High valence state metal-ion doped Fe–Ni layered double hydroxides for oxygen evolution electrocatalysts and asymmetric supercapacitors

“…Metal-organic frameworks (MOFs) with a uniform structure, steady pore size distribution and large specific area have been found to be suitable precursor materials toward construction of well-defined electrode materials 11,12 . MOFs-derived LDHs for SCs electrodes usually exhibit high specific capacitance 13,14 . Besides, metal ions in MOFs-derived LDHs (such as Fe 3+ in MIL-88A-derived LDHs) as the active sites have the fast OER kinetics because they have optimum bond energetics for the adsorption of OER intermediates 15,16 .…”