Nanograin deposition via an electroplating reaction in an emulsion of dense carbon dioxide in a nickel electroplating solution using nonionic fluorinated surfactant

We investigated an electroplating reaction in a series of emulsions between an electroplating solution and dense carbon dioxide (CO2) using a novel fluorinated surfactant F(CF(CF3)CF2O)3CF(CF3)COO(CH2CH2O)7CH3. The electroplating reaction took place in the emulsions as a function of the CO2 volume fraction, and electroplating was found to be possible in an emulsion composed of even 80 vol.% CO2 and 20 vol.% electroplating solution. Films composed of a nanograin structure with a grain size of about 10 nm were obtained. We elucidated the plating reaction by measuring the current values in the emulsion using minute terminals connected to a programmable power supply, while simultaneously observing the dispersion state of the emulsion through a high-pressure view cell. The flow of current values in the emulsion system fluctuated, and the current value decreased together with the amplitude of the fluctuant current when the pressure was increased. The fluctuant current flow in the emulsion was concluded to play an important role in the fabrication of the nanograin nickel structure in the plated film.