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.

Interfacial molecular regulation of TiO2 for enhanced and stable cocatalyst-free photocatalytic hydrogen production.

On the basis of the inherent property limitations of commercial P25-TiO2, many surface interface modification methods have attracted substantial attention for further improving the photocatalytic properties. However, current strategies for designing and modifying efficient photocatalysts (which exhibit complicated manufacturing processes and harsh conditions) are not efficient for production that is low cost, is nontoxic, and exhibits good stability; and therefore restrict practical applications. Herein, a facile and reliable method is reported for in situ amine-containing silane coupling agent functionalization of commercial P25-TiO2 by covalent surface modification for constructing a highly efficient photocatalyst. As a consequence, a high efficiency of H2 evolution was achieved for TiO2-SDA with 0.95 mmol h-1 g-1 (AQE ∼45.6 % at 365 nm) under solar light irradiation without a co-catalyst. The amination modification broadens the light absorption range of the photocatalyst, inhibits the binding of photogenerated carriers, and improves the photocatalytic efficiency; which was verified by photochemical properties and DFT theoretical calculations. This covalent modification method ensures the stability of the photocatalytic reaction. This work provides an approach for molecularly modified photocatalysts to improve photocatalytic performance by covalently modifying small molecules containing amine groups on the photocatalyst surface.

Complete decomposition of sulfamethoxazole during an advanced oxidation process in a simple water treatment system.

A simple water treatment system consisting of a deep UV light (λ = 222 nm) source, a mesoporous TiO2/boron-doped diamond (BDD) photocatalyst, and a BDD electrode was prepared and used to decompose sulfamethoxazole (SMX) in an advanced oxidation process. The mesoporous TiO2/BDD photocatalyst used with the electrochemical treatment promoted SMX decomposition, but the mesoporous TiO2/BDD photocatalyst alone had a similar ability to decompose SMX as photolysis. Fragments produced through photocatalytic treatment were decomposed during the electrochemical treatment and fragments produced during the electrochemical treatment were decomposed during the photocatalytic treatment, so performing the electrochemical and photocatalytic treatments together effectively decomposed SMX and decrease the total organic carbon concentration to a trace.

Photocatalytic degradation of bisphenol A using titanium dioxide@nanodiamond composites under UV light illumination.

Different types of organic impurities such as dyes, acids, and alcohols are discharged into potable water sources. The removal of these hazardous organic pollutants from wastewater is an important task globally. However, the conventional methods used to remove organic impurities suffer from low efficiency and recycling problems. Photocatalysis is a promising advanced oxidation process for the degradation of organic compounds in aqueous solution. Titanium dioxide (TiO2) is commonly used as a photocatalyst. However, the wide bandgap of TiO2 means that it is activated by ultraviolet light, which restrains its ability to harvest solar energy. In this study, a simple water-based precipitation method was used to synthesize TiO2@nanodiamond composites. The ability of the composites to degrade bisphenol A as a model organic pollutant was investigated. It was found that 10 ppm of bisphenol A was completely degraded in 100 min by the TiO2@nanodiamond photocatalyst under ultraviolet illumination.