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Hierarchical Ni-Mo-S nanosheets on carbon fiber cloth: A flexible electrode for efficient hydrogen generation in neutral electrolyte.

Miao J, Xiao FX, Yang HB, Khoo SY, Chen J, Fan Z, Hsu YY, Chen HM, Zhang H, Liu B - Sci Adv (2015)

Bottom Line: The incorporation of Ni atoms in Mo-S plays a crucial role in tuning its intrinsic catalytic property by creating substantial defect sites as well as modifying the morphology of Ni-Mo-S network at atomic scale, resulting in an impressive enhancement in the catalytic activity.Furthermore, the Ni-Mo-S/C electrode has excellent electrocatalytic stability over an extended period, much better than those of MoS2/C and Pt plate electrodes.The intuitive comparison test was designed to reveal the superior gas-evolving profile of Ni-Mo-S/C over that of MoS2/C, and a laboratory-scale hydrogen generator was further assembled to demonstrate its potential application in practical appliances.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore.

ABSTRACT
A unique functional electrode made of hierarchal Ni-Mo-S nanosheets with abundant exposed edges anchored on conductive and flexible carbon fiber cloth, referred to as Ni-Mo-S/C, has been developed through a facile biomolecule-assisted hydrothermal method. The incorporation of Ni atoms in Mo-S plays a crucial role in tuning its intrinsic catalytic property by creating substantial defect sites as well as modifying the morphology of Ni-Mo-S network at atomic scale, resulting in an impressive enhancement in the catalytic activity. The Ni-Mo-S/C electrode exhibits a large cathodic current and a low onset potential for hydrogen evolution reaction in neutral electrolyte (pH ~7), for example, current density of 10 mA/cm(2) at a very small overpotential of 200 mV. Furthermore, the Ni-Mo-S/C electrode has excellent electrocatalytic stability over an extended period, much better than those of MoS2/C and Pt plate electrodes. Scanning and transmission electron microscopy, Raman spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and x-ray absorption spectroscopy were used to understand the formation process and electrocatalytic properties of Ni-Mo-S/C. The intuitive comparison test was designed to reveal the superior gas-evolving profile of Ni-Mo-S/C over that of MoS2/C, and a laboratory-scale hydrogen generator was further assembled to demonstrate its potential application in practical appliances.

No MeSH data available.


Low-magnification SEM images.(A) Bare carbon fiber cloth. (B) NiSx/C. (C) Ni-Mo-S/C (3:1). (D) Ni-Mo-S/C (1:1). (E) Ni-Mo-S/C (1:3). (F) MoS2/C. All scale bars, 2 μm.
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Figure 2: Low-magnification SEM images.(A) Bare carbon fiber cloth. (B) NiSx/C. (C) Ni-Mo-S/C (3:1). (D) Ni-Mo-S/C (1:1). (E) Ni-Mo-S/C (1:3). (F) MoS2/C. All scale bars, 2 μm.

Mentions: Figure 2 shows the typical low-magnification SEM images of bare carbon fiber from the cloth, NiSx/C, Ni-Mo-S/C, and MoS2/C. As displayed in Fig. 2A, the diameter of a single carbon fiber is ~10 μm. Oriented striations that formed during the manufacturing process are along the entire surface of fibers. Figure 2B shows the morphology of as-prepared NiSx/C, where the irregularly shaped NiSx particles with sizes ranging from 100 nm to 1 μm form a shell-like outer layer that covers the carbon fiber surface. However, the NiSx particles are loosely attached to the surface of carbon fibers with clear cracks formed between them (fig. S4). The introduction of Ni2+ in the precursor solution plays a critical role in tuning the nanoarchitectures of Ni-Mo-S/C. At a Ni-to-Mo precursor ratio of 3:1, the surface of carbon fibers was first covered with a rough and tight nanostructured film, followed by attachment of particles with random shape and size (Fig. 2C). The nanostructured film, which shows clear visible striations, is thinner as compared to NiSx/C. When the Ni-to-Mo precursor ratio is reduced to 1:1, a uniform and continuous nanostructured film could be grown on the entire surfaces of carbon fibers (Fig. 2D). However, further increase in the Mo content (Ni/Mo = 1:3) in the growth solution leads to the formation of large aggregates (Fig. 2E). Moreover, if no Ni2+ was added in the growth solution, non-uniform MoS2 aggregates would cover the entire surface of carbon fibers.


Hierarchical Ni-Mo-S nanosheets on carbon fiber cloth: A flexible electrode for efficient hydrogen generation in neutral electrolyte.

Miao J, Xiao FX, Yang HB, Khoo SY, Chen J, Fan Z, Hsu YY, Chen HM, Zhang H, Liu B - Sci Adv (2015)

Low-magnification SEM images.(A) Bare carbon fiber cloth. (B) NiSx/C. (C) Ni-Mo-S/C (3:1). (D) Ni-Mo-S/C (1:1). (E) Ni-Mo-S/C (1:3). (F) MoS2/C. All scale bars, 2 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 2: Low-magnification SEM images.(A) Bare carbon fiber cloth. (B) NiSx/C. (C) Ni-Mo-S/C (3:1). (D) Ni-Mo-S/C (1:1). (E) Ni-Mo-S/C (1:3). (F) MoS2/C. All scale bars, 2 μm.
Mentions: Figure 2 shows the typical low-magnification SEM images of bare carbon fiber from the cloth, NiSx/C, Ni-Mo-S/C, and MoS2/C. As displayed in Fig. 2A, the diameter of a single carbon fiber is ~10 μm. Oriented striations that formed during the manufacturing process are along the entire surface of fibers. Figure 2B shows the morphology of as-prepared NiSx/C, where the irregularly shaped NiSx particles with sizes ranging from 100 nm to 1 μm form a shell-like outer layer that covers the carbon fiber surface. However, the NiSx particles are loosely attached to the surface of carbon fibers with clear cracks formed between them (fig. S4). The introduction of Ni2+ in the precursor solution plays a critical role in tuning the nanoarchitectures of Ni-Mo-S/C. At a Ni-to-Mo precursor ratio of 3:1, the surface of carbon fibers was first covered with a rough and tight nanostructured film, followed by attachment of particles with random shape and size (Fig. 2C). The nanostructured film, which shows clear visible striations, is thinner as compared to NiSx/C. When the Ni-to-Mo precursor ratio is reduced to 1:1, a uniform and continuous nanostructured film could be grown on the entire surfaces of carbon fibers (Fig. 2D). However, further increase in the Mo content (Ni/Mo = 1:3) in the growth solution leads to the formation of large aggregates (Fig. 2E). Moreover, if no Ni2+ was added in the growth solution, non-uniform MoS2 aggregates would cover the entire surface of carbon fibers.

Bottom Line: The incorporation of Ni atoms in Mo-S plays a crucial role in tuning its intrinsic catalytic property by creating substantial defect sites as well as modifying the morphology of Ni-Mo-S network at atomic scale, resulting in an impressive enhancement in the catalytic activity.Furthermore, the Ni-Mo-S/C electrode has excellent electrocatalytic stability over an extended period, much better than those of MoS2/C and Pt plate electrodes.The intuitive comparison test was designed to reveal the superior gas-evolving profile of Ni-Mo-S/C over that of MoS2/C, and a laboratory-scale hydrogen generator was further assembled to demonstrate its potential application in practical appliances.

View Article: PubMed Central - PubMed

Affiliation: School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637459, Singapore.

ABSTRACT
A unique functional electrode made of hierarchal Ni-Mo-S nanosheets with abundant exposed edges anchored on conductive and flexible carbon fiber cloth, referred to as Ni-Mo-S/C, has been developed through a facile biomolecule-assisted hydrothermal method. The incorporation of Ni atoms in Mo-S plays a crucial role in tuning its intrinsic catalytic property by creating substantial defect sites as well as modifying the morphology of Ni-Mo-S network at atomic scale, resulting in an impressive enhancement in the catalytic activity. The Ni-Mo-S/C electrode exhibits a large cathodic current and a low onset potential for hydrogen evolution reaction in neutral electrolyte (pH ~7), for example, current density of 10 mA/cm(2) at a very small overpotential of 200 mV. Furthermore, the Ni-Mo-S/C electrode has excellent electrocatalytic stability over an extended period, much better than those of MoS2/C and Pt plate electrodes. Scanning and transmission electron microscopy, Raman spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and x-ray absorption spectroscopy were used to understand the formation process and electrocatalytic properties of Ni-Mo-S/C. The intuitive comparison test was designed to reveal the superior gas-evolving profile of Ni-Mo-S/C over that of MoS2/C, and a laboratory-scale hydrogen generator was further assembled to demonstrate its potential application in practical appliances.

No MeSH data available.