纳米铜粉氧化反应动力学研究

Study on kinetics of nano-Cu powder oxidize reduction

以五水硫酸铜为原料，以Vc为还原剂，以EDTA为络合剂，聚乙烯吡咯烷酮（PVP）为保护剂和分散剂，采用液相还原法制备了纳米铜粉．不同粒度的纳米铜粉在空气中放置1h，再用XRD进行分析;对纳米铜粉氧化成氧化亚铜的反应进行了动力学分析；对纳米铜粉进行了TEM分析．结果表明：纳米铜粉的平均粒度大于75nm时，常温条件下在空气中不易被氧化；平均粒度为75nm铜粉120℃开始起氧化反应，粒度越大氧化反应起始温度和差热曲线的峰值温度越高；纳米铜粉氧化反应的活化能很低，平均粒度为75nm铜粉氧化成氧化亚铜的反应活化能在1～2kJ·mol^-1之间；纳米铜粉的熔点低，在TEM检测电子束照射下很快熔融长大．

Taken vitamin C（Vc） as reducers,CuSO4·5H2O as a raw material, EDTA as a complex agent and polyvinylpyrrolidone（PVP） as a protector, the copper nano-powder was prepared by the liquid reduction method. Placed the powder with the different granularity in the air for 1 hour, then the powder was examined by XRD. The oxidize kinetics analysis of copper nano-powders have been studied in air using TG/DTA. The copper nano-powders was analyzed by TEM. The result reveals that if the granularity of the powder is bigger than 75 nm,the powder is not easily oxidized in the air. The 75 nm copper powders begin to be oxidized at above 120℃. The surface activity of the copper nano-powder is very high, so that the activation energy of its oxidation reaction is very low, the activation of 4Cu＋ O2 =2Cu2O was 1～2 kJ·mol^-1. The melting point of the copper nano-powder is very low,accordingly the particle will melt and grow up quickly when it is hit by the TEM electron clusters.