Ryouichi Ichino

Surface modification of antioxidated nanocopper particles’ preparation in polyol process

Abstract A simple and efficient chemical process, which is called two step reduction route in polyol process, for producing copper nanoparticles with satisfied antioxidation property, was described here. This process’s reaction mechanism was demonstrated by analysing as prepared copper particles’ XRD patterns, SEM images and size distribution plots. The analysis results shows that all the preparation subprocesses such as reduction of copper ion, nucleation of copper particles and growth of metallic copper particles can be controlled through using polyol process. This two step reduction method can not only compulsively disconnect nucleation and nucleation growth, but also weaken conventional eruptible nucleation, which made it convenient for delaying the nuclei process and for controlling copper particles size. In addition, protective mechanisms of adopted surfactant in this process also were analysed here. When a quantitative surfactant was added into the reaction solution at the end of the reduction reaction, the electrolyte polymer covered on the new generated copper particles, some of it could still adhere on the particles’ surface after lavation, which made this agent play a role not only in particles’ dispersion, but also in particles’ antioxidation.

Bi-Cu film deposition in aqueous solutions

Abstract The relatively uniform bismuth-copper film was electrodeposited between −15 and −20 mV in the sulfate electrolyte containing 4 mmol/L bismuth ion and 2 mmol/L copper ion. Only copper was electrodeposited at −5 mV. The dendritic bismuth-copper film was electrodeposited under −20 mV. The cathodic current became constant between −20 and −400 mV. Therefore, bismuth-copper electrodeposition changes from charge transfer controlling to diffusion controlling at −20 mV. On the other hand, the uniform bismuth-copper film was electrodeposited between −5 and −35 mV in the methanesulfonate electrolyte containing 4 mmol/L bismuth ion and 2 mmol/L copper ion. The dendritic bismuth-copper film was electrodeposited under −35 mV. The potential region for good electrodepositon in methanesulfonate electrolyte is wider than that in sulfate electrolyte. Therefore, it is easy to control electrodeposition conditions by using methanesulfonate electrolyte.