Browsing by Author "Manikandan, Arumugam"

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A critical review on two-dimensional quantum dots (2D QDs): From synthesis toward applications in energy and optoelectronics
(2019-11-01)
Manikandan, Arumugam
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Chen, Yu-Ze
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Shen, Chih-Chiang
;
Sher, Chin-Wei
;
Kuo, Hao-Chung
Recent advances in the development of quantum dots (QDs) have offered new possibilities for the exploration of sensors, bio imaging, batteries, electrochemical water splitting and optoelectronic applications because of their intriguing optical, electrical, catalytic and electrochemical properties. Among QDs, atomically thin two-dimensional quantum dots (2D QDs) derived from graphene sheets, transition metal dichalcogenide (TMD) layers and phosphorene have been of considerable interest for the past few years. There have been several intensive studies of carbon QDs, but TMD QDs and heterostructures based on 2D QDs are rapidly advancing. Herein, the synthesis and properties of 2D QDs, particularly carbon and TMD QDs, are reviewed for the recent progress in their application toward electrochemical water splitting, photocatalytic wastewater treatment, supercapacitors, batteries and photodetectors. Moreover, the assembly of such 2D QDs to achieve industrial-scale production and boost their performance in widespread applications is emphasized.
Electrochemically active novel amorphous carbon (a-C)/Cu3P peapod nanowires by low-temperature chemical vapor phosphorization reaction as high efficient electrocatalysts for hydrogen evolution reaction
(2019-09-20)
Manikandan, Arumugam
;
Sriram, Pavithra
;
Hsu, Kun-Chieh
;
Wang, Yi-Chung
;
Chen, Chia-Wei
Toward finding low-cost electrocatalysts with high catalytic properties to replace noble metals as high efficient electrocatalysts in electrochemical hydrogen evolution reaction (HER) of total water splitting plays a vital role to approach the green and sustainable energy supply. Here, we demonstrate the direct growth of novel copper phosphide coated with amorphous carbon, namely heterostructured a-C/Cu3P peapod nanowires from chemically synthesized copper nanowires (Cu NWs) followed by a chemical vapor phosphorization reaction (CVPR) process at a low temperature of 400 degrees C. The heterostructured a-C/Cu3P peapod nanowires exhibit a superior electrocatalytic activity by a lower overpotential of 287 mV at a current density of 10 mA cm(-2) with a low Tafel slope of 72 mV dec(-1) and excellent stability over 1000 cycles. The superior electrocatalytic performance can be explained by the superior contact of the electrolyte with active sites on the heterostructured a-C/Cu3P due to the high surface area of peapod nanowire structure covered by defective edges of graphene with the encapsulated amorphous carbon layer, which can tremendously enhance electrical conductivity at the surface. (C) 2019 Published by Elsevier Ltd.
Fabrication of highly efficient hybrid device structure based white light emitting diodes
(2020-07-10)
Verma, Akta
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Sharma, S. K.
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Lin, Chih-Hao
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Manikandan, Arumugam
;
Kuo, Hao-Chung
In this study, white light is generated from the combination of BaMgAl10O17:Mn2+ (BAM) green phosphor and colloidal red CdSe/ZnS quantum dots (QDs) via two different solid and hybrid type geometries. Problem of aggregation in solid type device is discussed in details and motivates us to move towards the fabrication of hybrid type device structure. The photoluminescence (PL) characterization was used to record the excitation and emission spectra of BAM and QDs materials. The size of CdSe/ZnS QDs was confirmed by transmission electron microscopy technique. The CdSe/ZnS QDs owned high quantum yield (>50%) and contributed to fabrication of high luminous efficiency of white light emitting diodes (WLEDs). The hybrid-type WLED showed 98% lm/W with outstanding color gamut values with a National Television System Committee (NTSC) value of 138% and Rec.2020 value of 105%. Moreover, the hybrid type device structure shows only 5% attenuation in luminous efficiency after 500 h of storage which maintains a great optical property.
Thermally Strained Band Gap Engineering of Transition-Metal Dichalcogenide Bilayers with Enhanced Light Matter Interaction toward Excellent Photodetectors
(2017-09-01)
Wang, Sheng-Wen
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Medina, Henry
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Hong, Kuo-Bin
;
Wu, Chun-Chia
;
Qu, Yindong
Integration of strain engineering of two-dimensional (2D) materials in order to enhance device performance is still a challenge. Here, we successfully demonstrated the thermally strained band gap engineering of transition-metal dichalcogenide bilayers by different thermal expansion coefficients between 2D materials and patterned sapphire structures, where MoS2 bilayers were chosen as the demonstrated materials. In particular, a blue shift in the band gap of the MoS2 bilayers can be tunable, displaying an extraordinary capability to drive electrons toward the electrode under the smaller driven bias, and the results were confirmed by simulation. A model to explain the thermal strain in the MoS2 bilayers during the synthesis was proposed, which enables us to precisely predict the band gap-shifted behaviors on patterned sapphire structures with different angles. Furthermore, photodetectors with enhancement of 286% and 897% based on the strained MoS2 on cone and pyramid-patterned sapphire substrates were demonstrated, respectively.
Wafer Scale Phase-Engineered 1T-and 2H-MoSe2/Mo Core-Shell 3D-Hierarchical Nanostructures toward Efficient Electrocatalytic Hydrogen Evolution Reaction
(2016-11-23)
Qu, Yindong
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Medina, Henry
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Wang, Sheng-Wen
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Wang, Yi-Chung
;
Chen, Chia-Wei
The necessity for new sources for greener and cleaner energy production to replace the existing ones has been increasingly growing in recent years. Of those new sources, the hydrogen evolution reaction has a large potential. In this work, for the first time, MoSe2/Mo core-shell 3D-hierarchical nanostructures are created, which are derived from the Mo 3D-hierarchical nanostructures through a low-temperature plasma-assisted selenization process with controlled shapes grown by a glancing angle deposition system.