Green electrophoretic deposition of Bi2O3 coating

Abstract

Due to significant band gap, high refractive index, dielectric permittivity, photoluminescence, dielectric permittivity prominent photoconductivity and photocatalytic activity, preparation of bismuth oxide (Bi2O3) coating has been a topic of extensive research and has potential applications involving microelectronics, sensor technology, opticalcoating, etc. In this study, the coating of nano-Bi2O3 was successfully fabricated via environment-friendly aqueous electrophoretic deposition (EPD). The EPD behavior of nano-Bi2O3 in aqueous dispersion was affected by the addition of nitric acid. Some factors influencing deposition behavior such as addition amount of nitric and particle concentration were investigated. For a typical EPD with nano-Bi2O3 of 1 g L−1, the deposition rate increase with addition amount of nitric acid at first due to the improvement in surface charging of nano-Bi2O3 particles caused by absorption of hydrogen ion, and then would decline when higher concentration of nitric acid (>2 mM) was added due to serious water electrolysis. For the purpose of obtaining higher deposition rate of nano-Bi2O3 in aqueous suspension which was limited by lower deposition voltage, it was suggested to employ higher suspension concentration of Bi2O3. Correspondingly, higher addition amount of nitric acid is desired for sufficient surface charging for more nano-Bi2O3 particles. The environment-friendly aqueous deposition system provides a green EPD for successfully fabricating Bi2O3 coating with many potential applications.