Cathodic deposition of TiO2 thin films with supercritical CO2 emulsified electrolyte

•First report on cathodic deposition of TiO2 with supercritical CO2 emulsion•Pore structure of the porous TiO2 films was affect by the emulsified electrolyte.•Grain coarsening effect was observed when the emulsified electrolyte was used.•Increase in grain size was observed with increase in experimental pressure.

TiO2 thin films were fabricated by cathodic deposition with a supercritical CO2 (sc-CO2) emulsified TiCl3 + NaNO3 electrolyte. Morphology and average grain size were evaluated by SEM, TEM and XRD. SEM micrographs showed that the TiO2 films fabricated by TiCl3 + NaNO3 electrolyte were porous, and the films were composed of particles and aggregates of the particles. Also, size of the particles increased when the sc-CO2 emulsified electrolyte was used. Average grain size of the TiO2 films was calculated using Scherrer equation. The average grain size was found to increase when the sc-CO2 emulsified electrolyte was used. In addition, both particle sizes observed from SEM and average grain size calculated using Scherrer equation were found to increase when pressure was increased from atmospheric pressure to 20 MPa.

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