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Few-layer MoSe₂ possessing high catalytic activity towards iodide/tri-iodide redox shuttles.

Lee LT, He J, Wang B, Ma Y, Wong KY, Li Q, Xiao X, Chen T - Sci Rep (2014)

Bottom Line: Here we present a new application in dye-sensitized solar cell as catalyst for the reduction of I₃(-) to I(-) at the counter electrode.In this electrode, Mo film is found to significantly decrease the sheet resistance of the counter electrode, contributing to the excellent device performance.Since all of the elements in the electrode are of high abundance ratios, this type of electrode is promising for the fabrication of large area devices at low materials cost.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin N. T., Hong Kong, P. R. China.

ABSTRACT
Due to the two-dimensional confinement of electrons, single- and few-layer MoSe₂ nanostructures exhibit unusual optical and electrical properties and have found wide applications in catalytic hydrogen evolution reaction, field effect transistor, electrochemical intercalation, and so on. Here we present a new application in dye-sensitized solar cell as catalyst for the reduction of I₃(-) to I(-) at the counter electrode. The few-layer MoSe₂ is fabricated by surface selenization of Mo-coated soda-lime glass. Our results show that the few-layer MoSe₂ displays high catalytic efficiency for the regeneration of I(-) species, which in turn yields a photovoltaic energy conversion efficiency of 9.00%, while the identical photoanode coupling with "champion" electrode based on Pt nanoparticles on FTO glass generates efficiency only 8.68%. Thus, a Pt- and FTO-free counter electrode outperforming the best conventional combination is obtained. In this electrode, Mo film is found to significantly decrease the sheet resistance of the counter electrode, contributing to the excellent device performance. Since all of the elements in the electrode are of high abundance ratios, this type of electrode is promising for the fabrication of large area devices at low materials cost.

No MeSH data available.


Related in: MedlinePlus

Scheme of materials synthesis, and structural and morphological characterizations.(a) Schematic setup for the selenization of Mo film on soda-lime glass for few-layer MoSe2 in a furnace tube; (b) Schematic illustration of the formation of few-layer MoSe2 from body-centred cubic Mo, where the volume expansion occurs; (c) Cross-sectional SEM image of the MoSe2 on Mo surface, inset showing an enlarged image with dotted line highlighting the borderline between MoSe2 and Mo substrate; (d) SEM image of the surface morphology of the as-synthesized MoSe2 nanostructures; (e) low magnification HRTEM image of the few-layer MoSe2 on the surface of MoSe2 nanostructures; (f) high magnification HRTEM image of the few-layer MoSe2 with interlayer spacing of 0.63−0.64 nm. HRTEM micrographs in (e) and (f) courtesy of Man Hau Yeung.
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f1: Scheme of materials synthesis, and structural and morphological characterizations.(a) Schematic setup for the selenization of Mo film on soda-lime glass for few-layer MoSe2 in a furnace tube; (b) Schematic illustration of the formation of few-layer MoSe2 from body-centred cubic Mo, where the volume expansion occurs; (c) Cross-sectional SEM image of the MoSe2 on Mo surface, inset showing an enlarged image with dotted line highlighting the borderline between MoSe2 and Mo substrate; (d) SEM image of the surface morphology of the as-synthesized MoSe2 nanostructures; (e) low magnification HRTEM image of the few-layer MoSe2 on the surface of MoSe2 nanostructures; (f) high magnification HRTEM image of the few-layer MoSe2 with interlayer spacing of 0.63−0.64 nm. HRTEM micrographs in (e) and (f) courtesy of Man Hau Yeung.

Mentions: The fabrication of few-layer MoSe2 on Mo film was conducted by selenizing the Mo-coated soda-lime glass (Mo/glass) in a tube furnace using Ar as carrier gas (Figure 1a). The as-prepared Mo film exhibits body-centered cubic (bcc) crystal structures on the ground of X-ray diffraction (XRD) analysis (Figure S1), and the thickness of the Mo film was controlled to be ~1 μm. Optimizations show that the selenization conducted at 550°C for around 5 min generates the best device performance. In principle, the formation of Mo-Se bond could lead to a gradual volume expansion (Figure 1b). Obviously, the limited volume is not able to afford a high-degree expansion; the surface cracking finally drives the formation of MoSe2 nanostructures. The cross-sectional scanning electron microscopy (SEM) image shows that the thickness of the MoSe2 layer is about 70 nm (Figure 1c). The surface of the selenized Mo/glass is composed of many plate-like nanoparticles (Figure 1d). The high resolution transmission electron microscopy (HRTEM) image of the selenized sample presents that there are few-layer structures at the edge of the nanostructures (Figure 1e); the high energy edge site is believed to be catalytically active3233. Furthermore, the interlayer spacing is measured to be 0.63−0.64 nm (Figure 1f), which falls into the typical value of layered MoSe22.


Few-layer MoSe₂ possessing high catalytic activity towards iodide/tri-iodide redox shuttles.

Lee LT, He J, Wang B, Ma Y, Wong KY, Li Q, Xiao X, Chen T - Sci Rep (2014)

Scheme of materials synthesis, and structural and morphological characterizations.(a) Schematic setup for the selenization of Mo film on soda-lime glass for few-layer MoSe2 in a furnace tube; (b) Schematic illustration of the formation of few-layer MoSe2 from body-centred cubic Mo, where the volume expansion occurs; (c) Cross-sectional SEM image of the MoSe2 on Mo surface, inset showing an enlarged image with dotted line highlighting the borderline between MoSe2 and Mo substrate; (d) SEM image of the surface morphology of the as-synthesized MoSe2 nanostructures; (e) low magnification HRTEM image of the few-layer MoSe2 on the surface of MoSe2 nanostructures; (f) high magnification HRTEM image of the few-layer MoSe2 with interlayer spacing of 0.63−0.64 nm. HRTEM micrographs in (e) and (f) courtesy of Man Hau Yeung.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3924216&req=5

f1: Scheme of materials synthesis, and structural and morphological characterizations.(a) Schematic setup for the selenization of Mo film on soda-lime glass for few-layer MoSe2 in a furnace tube; (b) Schematic illustration of the formation of few-layer MoSe2 from body-centred cubic Mo, where the volume expansion occurs; (c) Cross-sectional SEM image of the MoSe2 on Mo surface, inset showing an enlarged image with dotted line highlighting the borderline between MoSe2 and Mo substrate; (d) SEM image of the surface morphology of the as-synthesized MoSe2 nanostructures; (e) low magnification HRTEM image of the few-layer MoSe2 on the surface of MoSe2 nanostructures; (f) high magnification HRTEM image of the few-layer MoSe2 with interlayer spacing of 0.63−0.64 nm. HRTEM micrographs in (e) and (f) courtesy of Man Hau Yeung.
Mentions: The fabrication of few-layer MoSe2 on Mo film was conducted by selenizing the Mo-coated soda-lime glass (Mo/glass) in a tube furnace using Ar as carrier gas (Figure 1a). The as-prepared Mo film exhibits body-centered cubic (bcc) crystal structures on the ground of X-ray diffraction (XRD) analysis (Figure S1), and the thickness of the Mo film was controlled to be ~1 μm. Optimizations show that the selenization conducted at 550°C for around 5 min generates the best device performance. In principle, the formation of Mo-Se bond could lead to a gradual volume expansion (Figure 1b). Obviously, the limited volume is not able to afford a high-degree expansion; the surface cracking finally drives the formation of MoSe2 nanostructures. The cross-sectional scanning electron microscopy (SEM) image shows that the thickness of the MoSe2 layer is about 70 nm (Figure 1c). The surface of the selenized Mo/glass is composed of many plate-like nanoparticles (Figure 1d). The high resolution transmission electron microscopy (HRTEM) image of the selenized sample presents that there are few-layer structures at the edge of the nanostructures (Figure 1e); the high energy edge site is believed to be catalytically active3233. Furthermore, the interlayer spacing is measured to be 0.63−0.64 nm (Figure 1f), which falls into the typical value of layered MoSe22.

Bottom Line: Here we present a new application in dye-sensitized solar cell as catalyst for the reduction of I₃(-) to I(-) at the counter electrode.In this electrode, Mo film is found to significantly decrease the sheet resistance of the counter electrode, contributing to the excellent device performance.Since all of the elements in the electrode are of high abundance ratios, this type of electrode is promising for the fabrication of large area devices at low materials cost.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, The Chinese University of Hong Kong, Shatin N. T., Hong Kong, P. R. China.

ABSTRACT
Due to the two-dimensional confinement of electrons, single- and few-layer MoSe₂ nanostructures exhibit unusual optical and electrical properties and have found wide applications in catalytic hydrogen evolution reaction, field effect transistor, electrochemical intercalation, and so on. Here we present a new application in dye-sensitized solar cell as catalyst for the reduction of I₃(-) to I(-) at the counter electrode. The few-layer MoSe₂ is fabricated by surface selenization of Mo-coated soda-lime glass. Our results show that the few-layer MoSe₂ displays high catalytic efficiency for the regeneration of I(-) species, which in turn yields a photovoltaic energy conversion efficiency of 9.00%, while the identical photoanode coupling with "champion" electrode based on Pt nanoparticles on FTO glass generates efficiency only 8.68%. Thus, a Pt- and FTO-free counter electrode outperforming the best conventional combination is obtained. In this electrode, Mo film is found to significantly decrease the sheet resistance of the counter electrode, contributing to the excellent device performance. Since all of the elements in the electrode are of high abundance ratios, this type of electrode is promising for the fabrication of large area devices at low materials cost.

No MeSH data available.


Related in: MedlinePlus