Synergistic effect of Ag decorated in-liquid plasma treated titanium dioxide catalyst for efficient electrocatalytic CO2 reduction application

Recently, the conversion of carbon dioxide (CO2) into a useful resource and its byproducts by electrocatalytic reduction has been studied. It is well known that CO2 can be selectively reduced by gold, lead, etc. supported on conductive carbon. However, the high pH in the vicinity of the electrode raises concerns about the catalyst and catalyst support degradation. Therefore, we considered that using chemically stable TiO2 (titanium dioxide) powder as an alternative to carbon. Surface treatment using in-liquid plasma was used to improve the electrochemical properties of TiO2. TiO2 maintained its particle shape and crystalline structure after in-liquid plasma treatment. Electrochemical properties were evaluated and the disappearance of Ti4+ and Ti3+ redox peaks derived from TiO2 and a decrease in hydrogen overvoltage were observed. The hydrogen overvoltage relationship suggested that tungsten coating or doping on a portion of the reduced TiO2 surface. Electrocatalytic CO2 reduction using the silver nanoparticle-supported in-liquid plasma treated TiO2 showed increased hydrogen production. In electrocatalytic CO2 reduction, the ratio of hydrogen to carbon monoxide gas is important. Therefore, in-liquid plasma treated TiO2 is useful for the electrocatalytic CO2 reduction application.