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Enhanced Electrochemical and Photocatalytic Performance of Coreshell CuS@Carbon Quantum Dots@Carbon Hollow Nanospheres Bibekananda De, Jayaraman Balamurugan, Nam Hoon Kim, and Joong Hee Lee ACS Appl. Mater. Interfaces, Just Accepted Manuscript • DOI: 10.1021/acsami.6b13496 • Publication Date (Web): 27 Dec 2016 Downloaded from http://pubs.acs.org on December 28, 2016
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applications. Impressively, CuS@CQDs@C HNS nanostructure delivers an exceptional electrochemical energy storage characteristics with high specific capacitance (618 F g−1 at a current density of 1 A g−1), and an excellent rate capability with an extraordinary capacitance (462 F g−1 at current density of 20 A g−1), and long cycle life (95% capacitance retention after 4000 cycles). Further, the proposed photocatalyst exhibited superior photocatalytic activity under solar light due to the efficient electron transfer, which revealed by photoluminescence studies. Such superior electrochemical and photocatalytic performance can be ascribed to the mutual contribution of CuS, CQDs and CHNS and unique core–shell architecture. These results exhibit that the core-shell CuS@CQDs@C HNS nanostructure is one of the potential candidate for supercapacitors and photocatalytic applications.
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INTRODUCTION
Transition metal chalcogenides (TMCs) with attractive nanostructure have recently received excessive interest for potential applications because of their unique properties such as hierarchical architecture, excellent electrical conductivity, low-cost and environmental friendliness.1−6 TMCs like CoS, NiS, SnS, MoS2, etc., have been widely explored as novel electrode materials for electrochemical as well as photocatalytic applications because of their special architecture and high catalytic activities. The CoS and NiS are considered as promising electrode materials with a high capacitance, but it includes the drawback of poor cycling stability.7 SnS and MoS2 possess numerous interest in research community due to their attractive layered architecture, but they suffer from low capacitance values.8 On the whole, the development of alternative TMCs with combination of cost-effective, high specific capacitance,
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and outstanding electrochemically stable electrode materials are capable for enhanced electrochemical and photocatalytic properties which remains as a key issue for research society. Recently, CuS is widely used in solar cells, chemical sensors, catalysts, Li-ion batteries, supercapacitors and photocatalytic applications because of their extraordinary theoretical capacity (561 mA h g−1), metal-like electronic conductivity (0.1 S m−1) and complex structure.9 However, pure CuS is rarely used as electrode material in supercapacitors because of its semiconducting behaviour, low electrical conductivity compared to other carbon-based materials and also large volume change during galvanostatic charge-discharge (GCD), resulting in a short supercapacitor cycle life.10 In this context, researchers have combined CuS with more suitable materials; they comprise carbon coating, carbon nanotube encapsulation, graphene wrapping, and core-shell structures formation.4 Those approaches resulted in reducing the agglomeration, enhancing the electrochemical performance, and improving the electrochemical and environmental stability of the CuS. Recently, carbon based materials like activated carbon, carbon nanotubes, mesoporous carbon and graphene are widely used as support to make metal sulphide-carbon hybrids for various applications because of their excellent flexibility, extraordinary specific surface area, corrosion resistance, and chemical inertness.11,
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regards, many efforts have been devoted to replace the above high-cost carbon based materials and examining for new low-cost carbon based materials whose influence gives rise to prospective enrichments in electrochemical performances as hybrid electrode materials. CQDs is one of the recently developed carbon materials (
