Limits...
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.


TEM images.(A and B) Low-magnification TEM images of (A) MoS2/C and (B) Ni-Mo-S/C (1:1). (C and D) HRTEM images of (C) MoS2/C and (D) Ni-Mo-S/C (1:1). Insets: Corresponding cross-sectional HRTEM images. Dashed circles in (D) indicate the structure defects of Ni-Mo-S/C (1:1).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4643797&req=5

Figure 4: TEM images.(A and B) Low-magnification TEM images of (A) MoS2/C and (B) Ni-Mo-S/C (1:1). (C and D) HRTEM images of (C) MoS2/C and (D) Ni-Mo-S/C (1:1). Insets: Corresponding cross-sectional HRTEM images. Dashed circles in (D) indicate the structure defects of Ni-Mo-S/C (1:1).

Mentions: To better elucidate the morphological distinction between Ni-Mo-S/C (1:1) and MoS2/C, TEM images were carried out. Figure 4 (A and B) shows TEM images of MoS2/C and Ni-Mo-S/C (1:1). MoS2 has continuous and corrugated layered structures, where restacked and wrinkled parts can be clearly observed. In contrast, the introduction of Ni2+ during the synthesis leads to the formation of interconnected Ni-Mo-S flake-like structures. In the high-resolution TEM (HRTEM) images (Fig. 4, C and D), lattices with a spacing of 0.27 nm, which can be assigned to the (100) plane of 2H-MoS2, are identified in both samples. However, as compared to MoS2/C, the crystalline quality of Ni-Mo-S/C was significantly reduced. As indicated by dashed circles in Fig. 4D, numerous structure defects can be observed in the surface of nanoflakes (see fig. S8). The insets in Fig. 4 (C and D) show the cross-sectional views of stacked MoS2/C and Ni-Mo-S/C (1:1), respectively. We found that the (002) plane spacing of Ni-Mo-S/C (1:1), which correlates to the interlayer distance, is significantly enlarged to 0.92 nm from 0.63 nm observed in MoS2/C. To assess the distribution of Ni across the basal plane of Ni-Mo-S/C (1:1), EDS mapping was performed. As shown in fig. S9, both Mo and S are uniformly distributed in the entire detected region. Meanwhile, the distribution of incorporated Ni atoms on the structure is quite homogeneous, although its concentration is slightly higher near the defect-rich regions.


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)

TEM images.(A and B) Low-magnification TEM images of (A) MoS2/C and (B) Ni-Mo-S/C (1:1). (C and D) HRTEM images of (C) MoS2/C and (D) Ni-Mo-S/C (1:1). Insets: Corresponding cross-sectional HRTEM images. Dashed circles in (D) indicate the structure defects of Ni-Mo-S/C (1:1).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643797&req=5

Figure 4: TEM images.(A and B) Low-magnification TEM images of (A) MoS2/C and (B) Ni-Mo-S/C (1:1). (C and D) HRTEM images of (C) MoS2/C and (D) Ni-Mo-S/C (1:1). Insets: Corresponding cross-sectional HRTEM images. Dashed circles in (D) indicate the structure defects of Ni-Mo-S/C (1:1).
Mentions: To better elucidate the morphological distinction between Ni-Mo-S/C (1:1) and MoS2/C, TEM images were carried out. Figure 4 (A and B) shows TEM images of MoS2/C and Ni-Mo-S/C (1:1). MoS2 has continuous and corrugated layered structures, where restacked and wrinkled parts can be clearly observed. In contrast, the introduction of Ni2+ during the synthesis leads to the formation of interconnected Ni-Mo-S flake-like structures. In the high-resolution TEM (HRTEM) images (Fig. 4, C and D), lattices with a spacing of 0.27 nm, which can be assigned to the (100) plane of 2H-MoS2, are identified in both samples. However, as compared to MoS2/C, the crystalline quality of Ni-Mo-S/C was significantly reduced. As indicated by dashed circles in Fig. 4D, numerous structure defects can be observed in the surface of nanoflakes (see fig. S8). The insets in Fig. 4 (C and D) show the cross-sectional views of stacked MoS2/C and Ni-Mo-S/C (1:1), respectively. We found that the (002) plane spacing of Ni-Mo-S/C (1:1), which correlates to the interlayer distance, is significantly enlarged to 0.92 nm from 0.63 nm observed in MoS2/C. To assess the distribution of Ni across the basal plane of Ni-Mo-S/C (1:1), EDS mapping was performed. As shown in fig. S9, both Mo and S are uniformly distributed in the entire detected region. Meanwhile, the distribution of incorporated Ni atoms on the structure is quite homogeneous, although its concentration is slightly higher near the defect-rich regions.

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.