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.

Enhanced degradation of ibuprofen using a combined treatment of plasma and Fenton reactions.

Advanced oxidation technologies (AOTs) proved to be effective in the degradation of hazardous organic impurities like acids, dyes, antibiotics etc. in the last few decades. AOTs are mainly based on the generation of reactive chemical species (RCS) such as hydroxyl, superoxide radicals etc., which plays an important role in the degradation of organiccompounds. In this work, plasma supported AOT i.e. Fenton reactions have been applied for the degradation of ibuprofen. As compared to traditional AOTs plasma assisted AOT is technologically superior due to its capability to produce RCS at a controlled rate without using chemical agents. This process work at normal room temperature and pressure. Herein, we optimized better operating conditions to generate good plasma discharge and hydroxyl radicals based on critical parameters, including frequency, pulse width and different gases like O2, Ar etc. Also, the one-pot carbonization method is used for the synthesis of Fe-based ordered mesoporous carbon (OMC) as a heterogeneous catalyst for the Fenton reactions. Using plasma-supported Fenton reactions, 88.3 % degradation efficiency is achieved using Fe-OMC catalyst for the ibuprofen degradation. Also, the mineralization of the ibuprofen is studied using total organic carbon (TOC) analysis.

Enhanced Photocatalytic Degradation Activity Using the V2O5/RGO Composite.

Semiconductor-based photocatalyst materials played an important role in the degradation of organic compounds in recent years. Photocatalysis is a simple, cost-effective, and environmentally friendly process for degrading organic compounds. In this work, vanadium pentoxide (V2O5) and V2O5/RGO (reduced graphene oxide) composite were synthesized by a hydrothermal method. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Raman spectroscopy, and UV-Vis spectroscopic analysis, etc. Raman analysis shows the occurrence of RGO characteristic peaks in the composite and different vibrational modes of V2O5. The band gap of flake-shaped V2O5 is reduced and its light absorption capacity is enhanced by making its composite with RGO. The photocatalytic degradation of methylene blue (MB) was studied using both V2O5 and V2O5/RGO composite photocatalyst materials. The V2O5/RGO composite exhibits a superior photocatalytic performance to V2O5. Both catalyst and light play an important role in the degradation process.