Abstract:

In this work, a simple one-pot hydrothermal method was developed to synthetize CuS/C composite in one-step by using copper nitrate trihydrate (Cu(NO₃)₂·3H₂O) as copper source, thiourea as sulfur source and D-glucose sodium as complexing agent. The composition, microstructure and morphology of the CuS/C composite were characterized by X ray diffraction (XRD), Raman spectroscopy, organic element analyzer and scanning electron microscopy (SEM). It was found that the as-synthesized composite was mainly composed of novel petaloid CuS microspheres, which provided many paths for ion diffusion and increased specific area with about 6% of amorphous carbon microspheres (mass fraction). The composite exhibited a maximum specific capacitance of up to 719 F·g^-1 at 1 A·g^-1, while the specific capacitance was 382 F·g^-1 at 1 A·g^-1 for CuS prepared without using complexing agent. The long-term constant current charge-discharge test showed that the CuS/C composite exhibited excellent long cycle life with capacitance retention of 80% after 1000 cycles at 1 A·g^-1. Although due to low melting point (220℃) of CuS, heat treatment at high temperature cannot be employed to transform the amorphous carbon microspheres into crystalline carbon for further improving the electrochemical properties, the one-pot hydrothermal method was likely to open a new way for directly synthetizing transition metal compounds/carbon composite materials by a one-step process, especially for transition metal compounds with high melting point/carbon composites with the possibility of carbonization treatment at high temperature.

Key words: one-pot process, hydrothermal, CuS, carbon, composite, electrochemistry, supercapacitor

摘要：

采用三水合硝酸铜为铜源、硫脲为硫源、D-葡萄糖酸钠为络合剂，发展了简单的“一锅法”水热直接一步合成CuS/C复合材料。采用X射线衍射仪（XRD）、激光显微拉曼光谱仪（Raman）、扫描电子显微镜（SEM）和有机元素分析仪对复合材料组成、结构及形貌进行表征。研究发现，样品主要由花状CuS球组成，同时含有质量分数约为6%的光滑炭球，CuS球表面分布有花瓣状褶皱，形成的大量孔道有利于离子传输，并增大活性物质与电解液的接触面积。研究表明，在1 A·g^-1电流密度下，比电容高达719 F·g^-1，与不加络合剂制备得到的CuS（382 F·g^-1）相比，比电容显著提高，并且在充放电1000次后比电容保持在80%左右，显示出良好的循环稳定性。

关键词: "一锅法", 水热, 硫化铜, 碳, 复合材料, 电化学, 超级电容器