Effect of the Solvent Ratio (Ethylene Glycol/Water) on the Preparation of an Iron Sulfide Electrocatalyst and Its Activity towards Overall Water Splitting

Abstract

The polyol method is an efficient procedure for metal sulfide preparation where polyol not only acts as a solvent but also as reducing and morphology‐modulating agent. Herein, iron sulfide particles were prepared via a modified polyol method by changing the ethylene glycol (EG) : water (H2O) ratio in the mixed solvent. Analytical techniques and electronic microscopy studies confirmed that the change in EG : H2O ratio modulated the crystal structure, morphology, and electronic structure of the prepared iron sulfide particles. The electrocatalytic activity of iron sulfide changed owing to these modulations. EG helped in the formation of a sheet‐like structure – a morphology that favours a higher accessibility to the catalytically active sites. As evidenced form electrochemical impedance studies, an increased electron density near the Fermi level, a faster substrate adsorption‐desorption rate at the active sites, and a faster charge transfer at the electrode‐electrolyte interface were the key factors for the amplification in catalytic activity. The prepared iron sulfide particles showed an overall water splitting efficiency that is comparable to that of the state‐of‐the‐art RuO2‐Pt/C couple in alkaline medium. This study shows the potential of the polyol method in the preparation and catalytic‐activity modulation of Fe−S‐based electrocatalysts.

Sulfur vacancy promoted peroxidase-like activity of magnetic greigite (Fe3S4) for colorimetric detection of serum glucose

“…However, the "flower" size decreased from~10 to~4 mm with increasing EG concentrations from 0 to 100%, which may be ascribed to differences in the dielectric constant, interionic attraction and solute-solvent interactions on crystal growth formation [33]. TEM images revealed that high ratios of EG in the solvent resulted in the bending of nanosheets, consistent with SEM images.…”

“…The Fe 3 S 4 nanosheets with varying degrees of SVs were synthesized using a one-step solvothermal method [33]. Briefly, homogenous solution A and B were prepared by dissolving 0.834 g FeSO 4 7H 2 O and 0.363 g L-cysteine in 30 mL of EG, respectively.…”

Mechanisms for hydroxyl radical production and arsenic removal in sulfur-vacancy greigite (Fe3S4)

“…Sulfur-vacancy (SV) Fe 3 S 4 nanosheets were synthesized using a one-step solvothermal method [31,37]. In the SV-rich Fe 3 S 4 synthesis process, 0.834 g FeSO 4 Á7H 2 O was dissolved in 30 mL of ethylene glycol (EG) to form solution I, and 0.363 g L-cysteine was dissolved in 30 mL of EG to form solution II.…”

“…Our previous studies demonstrated that Fe 3 S 4 efficiently reduced Cr(VI) and roxarsone, owing to the coupled reductive abilities of structural ferrous and sulfide moieties [28][29][30]. Importantly, the surface structure of Fe 3 S 4 can be tuned by synthesis methods to enhance various functional applications [31][32][33]. In spite of the previous studies investigating iron-sulfide materials, there is a paucity of information regarding specific Å OH production pathways associated with Fe 3 S 4 and the efficacy of utilizing Å OH production by Fe 3 S 4 for oxidation of environmental pollutants.…”

Binder-Free Growth of Nickel-Doped Iron Sulfide on Nickel Foam via Electrochemical Deposition for Electrocatalytic Water Splitting

“…Therefore, a significant attention has been paid to synthesize the materials mimicking the active centers of Fe–S-containing hydrogenase; however, they showed inferior activity and were less stable. , The HER catalytic activity of a few solid-state iron sulfide electrocatalysts was investigated previously. − The main drawback behind the inferior HER catalytic activity of the Fe–S-based electrocatalyst is its weak hydrogen adsorption capability. , Zou et al showed that the hydrogen adsorption Gibb’s free energy (Δ G H* ) gets significantly reduced and reaches almost near to that for Pt when O atoms are present on the Fe–S surface . Although there are a few reports regarding HER activity of Fe–S-based materials, the OER activity is rarely investigated. ,− Therefore, there is a huge scope for investigating the bifunctionality of the Fe–S-based electrocatalysts toward overall water splitting.…”