CeO₂ coatings on conductive polyethylene foams via gas-assisted liquid phase deposition and their humidity sensor performance

Abstract

CeO₂ coatings were fabricated on conductive polyethylene foams below 100 °C by a gas-assisted liquid phase deposition process. It is possible to coat the foams more deeply with CeO₂ by utilizing a mixture of deionized water and ethanol as a solvent of a starting material solution instead of deionized water. The samples showed a change in resistance with increasing and decreasing humidity. An amount of the change increased with the addition of ethanol in the starting material solution. Decrease in response and recovery times were observed with an increase in the coating temperature due to a larger crystallite size of CeO₂ coatings. The humidity response was evaluated using the formula ΔR/R₀ (%) = (R₀ − R)/R₀ × 100, where R and R₀ are resistance at 80 % relative humidity and minimum one, respectively. The largest value among the samples was 46.16 %. The response and recovery times for this sample were 125 and 132 s, respectively. This research has made it easy to add functionality to porous materials.