Hydrothermal route to crystallization of FeOOH nanorods via FeCl₃·6H₂O: effect of Fe³⁺concentration on pseudocapacitance of iron-based materials

Abstract

In this work, we study the crystallization of FeOOH nanorods via hydrolysis of FeCl 3 ⋅6H 2 O solution with low-temperature hydrothermal route (100°C). The effect of Fe 3+ concentration and the solution pH value on the crystallized morphology and size of FeOOH nanorods were systematically studied based on chemical reaction and crystallization process. The electrochemical performance of the as-obtained FeOOH materials is evaluated as supercapacitor and the effect of Fe 3+ concentration on the pseudocapacitance of iron-based materials are also discussed. FeOOH electrode materials obtained in 0.2M FeCl 3 ⋅6H 2 O solution display the highest specific capacitance of 714.8 F/g, which is higher than reported values of FeOOH electrode materials. The present work demonstrates a simple hydrolysis route to synthesize high capacitance electrode materials.

A High‐Energy Density Asymmetric Supercapacitor Based on Fe2O3 Nanoneedle Arrays and NiCo2O4/Ni(OH)2 Hybrid Nanosheet Arrays Grown on SiC Nanowire Networks as Free‐Standing Advanced Electrodes

“…In terms of SiC@Fe 2 O 3 , it is prepared via a simple hydrothermal route followed by an annealing treatment. First, FeOOH precursor ( Figure S1a, Supporting Information) is grown homogeneously on the entire surface of the SiC NWs directly deposited on CC by a hydrolysis reaction under low-temperature hydrothermal conditions (120 °C) for 8 h, as expressed by the following formula [48,49] Fe 2H O FeOOH 3H…”

“…at 718.8 eV, which suggests Fe 3+ exists in Fe 2 O 3 . [8,49] Figure 3d depicts that the O 1s spectrum is divided into two peaks of 530.2 and 531.8 eV (labeled as O1 and O2), respectively. The O1 peak located at 530.2 eV is assigned to the O −2 come from Fe 2 O 3 , and O2 peak situated at 531.8 eV is ascribed to OH − deriving from some oxygen-containing groups on Fe 2 O 3 NNs, probably because the surface of the products is hydrolyzed to some extent.…”

Fabrication of rod-shaped β-FeOOH: the roles of polyethylene glycol and chlorine anion

“…Meanwhile, the size and shape of -FeOOH doi: 10.1007/s11426-016-5587-y particles are closely related with the hydrolysis rate of Fe 3+ and the subsequent growth rate of -FeOOH. This kinetic process could be mediated by adjusting the synthetic parameters such as the concentration of ferric cation, the temperature, the pH value, and the anion species [15][16][17][18][19]. For example, hydrolysis of FeCl 3 at 120 °C under hydrothermal conditions, in the presence of urea, produced -FeOOH nanorod arrays; the slow release of OH  from urea neutralized the positive surface charge of the initially formed -FeOOH nanorods and then directed their self-assembly [20].…”

Colloidal supercapacitor electrode materials

“…The specific capacitances of electrode materials can be adjusted by various materials design methods, i.e. size control, structure control, morphology control [9][10][11]. For electrode materials with charge storage mechanism of electrical double-layer capacitance (EDLC), their specific capacitances are mainly determined by their surface area.…”