Browsing by Author "Nguyen, Van-Truong"

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Plasma-Induced Exfoliation Provides Onion-Like Graphene-Surrounded MoS2 Nanosheets for a Highly Efficient Hydrogen Evolution Reaction
(2020-03-11)
Nguyen, Van-Truong
;
Le, Phuoc Anh
;
Hsu, Yung-Chi
;
Wei, Kung-Hwa
;
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With the goal of obtaining sustainable earth-abundant electrocatalyst materials displaying high performance in the hydrogen evolution reaction (HER), here we propose a facile one-pot plasma-induced electrochemical process for the fabrication of new core-shell structures of ultrathin MoS2 nanosheets engulfed within onion-like graphene nanosheets (OGNs@MoS2). The resultant OGNs@MoS2 structures not only increased the number of active sites of the semiconducting MoS2 nanosheets but also enhanced their conductivity. Our OGNs@MoS2 composites exhibited high HER performance, characterized by a low overpotential of 118 mV at a current density of 10 mA cm(-2), a Tafel slope of 73 mV dec(-1), and long-time stability of 10(5) s without degradation; this performance is much better than that of the sheet-like graphene-wrapped MoS2 composite GNsgMoS(2) (182 mV, 82 mV dec(-1)) and is among the best ever reported for composites involving MoS2 and graphene nanosheets prepared through a simple one-batch process and using a low temperature and a short time for the HER. This approach appears to be an effective and simple strategy for tuning the morphologies of composites of graphene and transition metal dichalcogenide materials for a broad range of energy applications.
Porous carbon materials derived from areca palm leaves for high performance symmetrical solid-state supercapacitors
(1970-01-01)
Le, Phuoc-Anh
;
Nguyen, Van-Truong
;
Saho, Sumanta Kumar
;
Tseng, Tseung Yuen
;
Wei, Kung-Hwa
Areca palm leaves derived porous carbon material as the electrode for symmetrical solid-state supercapacitors (SSCs). The areca palm leaves biomass was processed using a fast carbonization method followed by in situ chemical activation. The structures and compositions of these biomass-derived carbon materials were characterized using X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy, respectively. One of the biomass-derived porous carbon materials, AR2, was a lightweight carbon material that possessed a large surface area of 876 m(2) g(-1). Electrochemical studies revealed that AR2 possessed a high specific capacitance of 262 F g(-1) at a scan rate of 5 mV s(-1). We fabricated symmetrical SSCs featuring these carbon material as major (80 wt%) components of the electrodes and poly(vinyl alcohol)-Li2SO4 as gel polymer electrolyte. The optimal supercapacitor (SAR2) involving AR2 exhibited a specific capacitance of 132 F g(-1) at a current density of 0.5 A g(-1) and an energy density of 10.3 W h kg(-1) at a power density of 375 W kg(-1), and durability of retaining 92% of its initial capacitance after 5000 cycles-performance that is the excellent values reported for devices featuring derived from biomass.