Support effect of Ag/ZnO catalysts for partial oxidation of methanol

Insights into structural and functional regulation of chalcopyrite and enhanced mechanism of reactive oxygen species (ROS) generation in advanced oxidation process (AOP): A review

Chalcopyrite, renowned for its distinctive mixed redox-couple characteristics, exhibits excellent electron transfer properties both on its surface and within its crystal structure. This unique characteristic has attracted significant attention in various fields, including optics, electronics, and magnetism, as well as demonstrated remarkable catalytic efficacy in the environmental field. The rapid and effective electron transfer capability of a catalyst is crucial for advanced oxidation processes (AOPs). However, the performance of CuFeS2 in AOPs is hindered by its low electron transfer efficacy. This review aims to summarize the key steps and mechanisms of chalcopyrite-induced AOPs and provide strategies for enhancing effective electron transfer efficacies by controlling the structure and function of synthetic/natural chalcopyrite. These strategies include enhancing the catalytic performance of chalcopyrite and constructing composites to enhance catalytic activity (e.g., chelating agents, heterojunctions). Additionally, the factors influencing the generation of reactive oxygen species in chalcopyrite-induced AOPs are investigated, such as the types and properties of oxidants (e.g., H2O2, peroxymonocarbonate), the microstructure of catalysts, and reaction conditions in catalytic systems (e.g., pH values, dosage, temperature). Future perspectives on the applications of chalcopyrite are presented at the end of this paper. Overall, this review assists in narrowing the scope of chalcopyrite studies in AOPs and aids researchers in optimizing synthetic/natural catalysts for contaminant treatment.

Photoactive ZnO Materials for Solar Light-Induced CuxO-ZnO Catalyst Preparation

In this work, the solar light-induced redox photoactivity of ZnO semiconductor material was used to prepare Cu_xO-ZnO composite catalysts at room temperature with a control of the chemical state of the copper oxide phase. Cu₂^(I)O-ZnO and Cu^(II)O-ZnO composite catalysts were prepared by using Cu(acac)₂ in tetrahydrofuran-water and Cu(NO₃)₂ in water as metallic precursor, respectively. Prior to the implementation of the photon-assisted synthesis method, the most efficient photoactive ZnO material was selected from among different ZnO materials prepared by the low temperature polyol and precipitation methods with carbonates and carbamates as precipitation agents. The photocatalytic degradation of the 4-chlorophenol compound in water under simulated solar light was taken as a model reaction. The ZnO support materials were characterized by X-ray diffraction (XRD), surface area and porosimetry measurements, thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the synthesis method strongly influenced their photoactivity in terms of 4-chlorophenol degradation and of total organic carbon removal. The most photoactive ZnO material was prepared by precipitation with carbonates and calcined at 300 °C, benefitting from a high specific surface area and a small mean crystallite size for achieving a complete 4-chlorophenol mineralization within 70 min of reaction, with minimum Zn²⁺ released to the solution. Besides thermal catalysis applications, this work has opened a new route for the facile synthesis of Cu₂O-ZnO heterojunction photocatalysts that could take place under solar light of the heterojunction built between the p-type semi-conductor Cu₂O with direct visible light band gap and the ZnO semiconductor phase.