Zhao Chunxia, Cao Jinqiao, Yang Yunxia, Chen Wen, Li Junshen
State Key Laboratory of Advanced Technology for Materials Synthesis and Progressing, School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, PR China.
Earth Science and Resource Engineering, CSIRO, VIC 3168, Australia.
J Colloid Interface Sci. 2014 Aug 1;427:73-9. doi: 10.1016/j.jcis.2013.11.086. Epub 2013 Dec 10.
Hierarchical or micro-nano structured porous VOx@carbon composites were synthesized by a one-step method using phenolic resin as the carbon precursor and ammonium metavanadate as the source of vanadium oxides. The effects of the vanadium source loading on the microstructure and electrochemical properties of the composites were investigated. X-ray diffraction results showed that as the vanadium oxides source loading increased, vanadium oxides in the composites changed oxidation states from V2O3 to mixed states of V2O3 and VO2. Electrochemical test results indicated that the micro-nano porous structure of the composites could facilitate the ion diffusion in the rich porous structure and then promote the electrochemical reaction. More importantly, we found that vanadium oxides greatly enhanced the electrochemical performance of the materials, due to the faradic capacitance generated from vanadium oxide nanoparticles. A maximum specific capacitance of 171 F/g was obtained from VOx@carbon composite with vanadium loading of ∼44 wt%. Further increasing the VOx loading over this fraction was not beneficial. Our results suggested that hierarchical porous VOx@carbon composites were promising candidates for supercapacitor applications.
采用一步法，以酚醛树脂为碳前驱体、偏钒酸铵为钒氧化物源，合成了分级或微纳结构的多孔VOx@碳复合材料。研究了钒源负载量对复合材料微观结构和电化学性能的影响。X射线衍射结果表明，随着钒氧化物源负载量的增加，复合材料中的钒氧化物氧化态从V2O3变为V2O3和VO2的混合态。电化学测试结果表明，复合材料的微纳多孔结构可促进富孔结构中的离子扩散，进而促进电化学反应。更重要的是，我们发现钒氧化物极大地提高了材料的电化学性能，这归因于钒氧化物纳米颗粒产生的法拉第电容。钒负载量约为44 wt%的VOx@碳复合材料的最大比电容为171 F/g。超过该比例进一步增加VOx负载量并无益处。我们的结果表明，分级多孔VOx@碳复合材料是超级电容器应用的有前途的候选材料。
