Hierarchical Cobalt Sulfide/Molybdenum Sulfide Heterostructure as Bifunctional Electrocatalyst towards Overall Water Splitting

Hydrogen evolution reaction (HER) was improved through nitrogen (N) doping in molybdenum disulfide (MoS2) due to the formation of 1T‐metallic phase as compared to the thermodynamically stable 2H‐semiconducting phase. Generally, the phase transition of MoS2 from semiconducting 2H to metallic 1T was carried out by chemical intercalation method. A facile solvothermal synthetic procedure is used to organize 1T@2H MoS2 nanoflower by incorporating N in MoS2 crystal lattice which improved the catalytic activity with the generation of metallic property of MoS2. Optimized N doping is an effective strategy for the development of mixed phase MoS2. Physicochemical characterization techniques confirmed the formation of hybrid phase (1T@2H) MoS2 by N incorporation. A tuned dopant concentration in MoS2 crystal lattice effectively enhanced the catalytic performance by modifying the physical and chemical properties. Moreover, optimal N doped MoS2 offered a very low overpotential of ∼108 and ∼141 mV to reach the benchmarking current density of 10 mA cm−2 for HER in acidic and basic medium, respectively. This work elucidated a rational implantation of phase engineering, which is an efficient strategy to develop efficient electrocatalysts, shedding light on the improvement of transition metal‐based electrocatalyst in renewable energy technologies.

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“…The prepared samples had Tafel slopes of 37–68 mVdec −1 in acidic solution, which follows the Volmer‐Heyrovsky mechanism [Eq. ]

true 2 H^{+} + 2 e^{-} \to H_{2}

…”

Section: Resultsmentioning

confidence: 86%

“…(1)]. [28,37,43] 2H þ þ 2e À ! H 2 (1) In the Volmer-Heyrovsky reactions, the hydrogen (H 2 ) is formed through two elementary steps [Eqs.…”

Section: Resultsmentioning

confidence: 99%

Doping‐Assisted Phase Changing Effect on MoS₂ Towards Hydrogen Evolution Reaction in Acidic and Alkaline pH

et al. 2020

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“…Along with that CPE 2 -R p couple was also there at the medium frequency region which implied the adsorptiondesorption kinetics of substrates at the active sites. [38][39] The charge transfer resistance (R ct ) emerged at the lower frequency region. The EIS fitted data are presented in Table S2 of supporting information.…”

Section: Resultsmentioning

confidence: 99%

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

et al. 2019

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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.

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“…Interconnecting Co and Mo atoms through sulfur can improve electron transfer properties as compared to the same individual components, leading to optimized adsorption property of hydrogen species. [ 11b,12 ] However, in depth investigation of the role of each phases and eventual active sites for the heterostructure are rare.…”

Section: Introductionmentioning

confidence: 99%

Covalent 0D–2D Heterostructuring of Co₉S₈–MoS₂ for Enhanced Hydrogen Evolution in All pH Electrolytes

Kim

Anjum

Choi

et al. 2020

Adv Funct Materials

119

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Ultrasmall Co 9 S 8 nanoparticles are introduced on the basal plane of MoS 2 to fabricate a covalent 0D-2D heterostructure that enhances the hydrogen evolution reaction (HER) activity of electrochemical water splitting. In the heterostructure, separate phases of Co 9 S 8 and MoS 2 are formed, but they are connected by CoS -Mo type covalent bonds. The charge redistribution from Co to Mo occurring at the interface enhances the electron-doped characteristics of MoS 2 to generate electron-rich Mo atoms. Besides, reductive annealing during the synthesis forms S defects that activates adjacent Mo atoms for further enhanced HER activity as elucidated by the density functional theory (DFT) calculation. Eventually, the covalent Co 9 S 8-MoS 2 heterostructure shows amplified HER activity as well as stability in all pH electrolytes. The synergistic effect is pronounced when the heterostructure is coupled with a porous Ni foam (NF) support to form Co 9 S 8-MoS 2 /NF that displays superior performance to those of the state-ofthe-art non-noble metal electrocatalysts, and even outperforms a commercial Pt/C catalyst in a practically meaningful, high current density region in alkaline (>170 mA cm −2) and neutral (>60 mA cm −2) media. The high HER performance and stability of Co 9 S 8-MoS 2 heterostructure make it a promising pH universal alternative to expensive Pt-based electrocatalysts for practical water electrolyzers.

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Hierarchical Cobalt Sulfide/Molybdenum Sulfide Heterostructure as Bifunctional Electrocatalyst towards Overall Water Splitting

Cited by 52 publications

References 53 publications

Doping‐Assisted Phase Changing Effect on MoS₂ Towards Hydrogen Evolution Reaction in Acidic and Alkaline pH

Doping‐Assisted Phase Changing Effect on MoS₂ Towards Hydrogen Evolution Reaction in Acidic and Alkaline pH

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

Covalent 0D–2D Heterostructuring of Co₉S₈–MoS₂ for Enhanced Hydrogen Evolution in All pH Electrolytes

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Hierarchical Cobalt Sulfide/Molybdenum Sulfide Heterostructure as Bifunctional Electrocatalyst towards Overall Water Splitting

Cited by 52 publications

References 53 publications

Doping‐Assisted Phase Changing Effect on MoS2 Towards Hydrogen Evolution Reaction in Acidic and Alkaline pH

Doping‐Assisted Phase Changing Effect on MoS2 Towards Hydrogen Evolution Reaction in Acidic and Alkaline pH

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

Covalent 0D–2D Heterostructuring of Co9S8–MoS2 for Enhanced Hydrogen Evolution in All pH Electrolytes

Contact Info

Product

Resources

About

Doping‐Assisted Phase Changing Effect on MoS₂ Towards Hydrogen Evolution Reaction in Acidic and Alkaline pH

Doping‐Assisted Phase Changing Effect on MoS₂ Towards Hydrogen Evolution Reaction in Acidic and Alkaline pH

Covalent 0D–2D Heterostructuring of Co₉S₈–MoS₂ for Enhanced Hydrogen Evolution in All pH Electrolytes