High-entropy alloys (HEAs) have exhibited large potential to serve as excellent heterogeneous catalysts in a variety of reactions. Although several synthetic procedures have been reported, developing novel routes to facilely...

Photocatalytic degradation of organic pollutants has become a hot research topic because of its low energy consumption and environmental-friendly characteristics. Bismuth oxide (Bi2O3) nanocrystals with a bandgap ranging from 2.0 eV to 2.8 eV have attracted increasing attention due to high activity of photodegradation of organic pollutants by utilizing visible light. Though several methods have been developed to prepare Bi2O3-based semiconductor materials over recent years, it is still difficult to prepare highly active Bi2O3 catalysts in large scale with a simple method. Therefore, developing simple and feasible methods for the preparation of Bi2O3 nanocrystals in large scale is important for the potential applications in industrial wastewater treatment. In this work, we successfully prepared porous Bi2O3 in large scale via etching commercial BiSn powders, followed by thermal treatment with air. The acquired porous Bi2O3 exhibited excellent activity and stability in photocatalytic degradation of methylene blue. Further investigation of the mechanism witnessed that the suitable band structure of porous Bi2O3 allowed the generation of reactive oxygen species, such as O2−· and ·OH, which effectively degraded MB.

Aerobic oxidation by using molecular oxygen (O2) as the oxidant is highly attractive, in which activating O2 to reactive oxygen species (ROS) is a prerequisite. Although some progress has been achieved in regulating ROS by heterogeneous catalysts, the strategies to efficiently control ROS in aerobic oxidation are still urgently desired. Herein, grain boundaries (GBs) in metal oxides are discovered to be able to facilely regulate ROS. Impressively, MoO3 nanocrystals with high density of GBs (MoO3‐600) deliver a mass activity of 83 mmol g‐1 h‐1 in aerobic oxidation of benzyl alcohol, 7 and 8 times as high as that of MoO3 nanoparticles without GBs and Pt/C, respectively. In addition, the selectivity of benzoic acid is 100% during whole reaction process over MoO3‐600. Mechanistic studies reveal that the oxygen atoms at GBs in MoO3‐600 are highly active to form ∙OH radicals with the generation of oxygen vacancies, while the oxygen vacancies are replenished by O2. The reaction path directly contributes to the excellent catalytic performance.