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

Abstract

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.

Keywords: Electrocatalytic CO(2) reduction; In-liquid plasma; Noble metals; Reduction sintering; Titanium dioxide.