Systematic Investigation on Supported Gold Catalysts Prepared by Fluorine-Free Basic Etching Ti3AlC2 in Selective Oxidation of Aromatic Alcohols to Aldehydes

Conventional methods to prepare supported metal catalysts are chemical reduction and wet impregnation. This study developed and systematically investigated a novel reduction method based on simultaneous Ti₃AlC₂ fluorine-free etching and metal deposition to prepare gold catalysts. The new series of Au_pre/Ti₃Al_xC₂Ty catalysts were characterized by XRD, XPS, TEM, and SEM and were tested in the selective oxidation of representative aromatic alcohols to aldehydes. The catalytic results demonstrate the effectiveness of the preparation method and better catalytic performances of Au_pre/Ti₃Al_xC₂T_y, compared with those of catalysts prepared by traditional methods. Moreover, this work presents a comprehensive study on the influence of calcination in air, H₂, and Ar, and we found that the catalyst of Au_pre/Ti₃Al_xC₂T_y-Air600 obtained by calcination in air at 600 °C performed the best, owing to the synergistic effect between tiny surface TiO₂ species and Au NPs. The tests of reusability and hot filtration confirmed the catalyst stability.

Construction of Bi2WO6 with double active sites of tunable metallic Bi and oxygen vacancies for photocatalytic oxidation of cyclohexane to cyclohexanone

Oxygen-containing organics, which are generated from the selective oxidation of their corresponding hydrocarbons, have high value in the chemical and pharmaceutical industries. However, their oxidation reactions are very challenging as the products are more active than the substrates, especially for the oxidation of cyclohexane (CHA). Herein, we focused on the one-step preparation of Bi₂WO₆ with double active sites of tunable metallic Bi and oxygen vacancies (OV-Bi/Bi₂WO₆) by a facile solvothermal treatment. Then, OV-Bi/Bi₂WO₆ was used as an efficient photocatalyst for the partial oxidation of CHA to cyclohexanone (CHA-one) for the first time in air as an oxidant under solvent-free and room temperature conditions. The Bi : Bi₂WO₆ ratio in the as-prepared OV-Bi/Bi₂WO₆ heterojunction could be tailored from 0.08 to 8.43 by controlling the solvothermal temperature, and the synergistic effect between DMF and EG could increase the reduction of MDF/EG and promote the production of Bi. Moreover, OV-Bi/Bi₂WO₆-160 yielded 4.4 and 8.8 times more CHA-one (128.8 μmol) than pure Bi₂WO₆ and metallic Bi, respectively, and achieved 93.6% selectivity to CHA-one in air as an oxidant under solvent-free conditions. The results revealed that the highly enhanced photocatalytic activity was mainly attributed to the superior specific surface area, outstanding photo-absorption, abundant oxygen vacancies, and efficient electron-hole separation. Moreover, for the unique double active sites in OV-Bi/Bi₂WO₆, oxygen vacancies can enhance the adsorption and activation capacity of Bi₂WO₆ for O₂, while metallic Bi can improve the adsorption and activation capacity of Bi₂WO₆ for CHA. Meanwhile, OV-Bi/Bi₂WO₆ also exhibited excellent durability due to the strong interaction between metallic Bi and Bi₂WO₆. The present work provides a flexible approach for tailoring the Bi : Bi₂WO₆ ratio and outlines an effective method for producing CHA-one from CHA under mild conditions.

Highly improved acetone oxidation performance over mesostructured CuxCe1−xO2 hollow nanospheres

Mesostructured CuxCe1−xO2 hollow nanospheres with porous shells and controllable Cu/Ce molar ratios exhibit highly improved catalytic acetone oxidation performance.

Facet effect of Bi5O7I nanocrystals on selective oxidation of benzylamine under visible light

Boosting photocatalytic activity in benzylamine oxidation was found for Bi5O7I with a (010) facet through facet engineering.

Hierarchical WO3 microflowers with tailored oxygen vacancies for boosting photocatalytic dye degradation

Hierarchical WO3 microflowers with tailored surface oxygen vacancies show a remarkably boosted activity toward visible-light-driven photocatalytic dye degradation.