A novel method of redox precipitation was applied for the first time to synthesize a Au-doped α-MnO catalyst with high dispersion of the Au species. Au nanoparticles (NPs) can be downsized into approximate single atoms by this method, thereby realizing highly efficient utilization of Au element as well as satisfying low-temperature oxidation of formaldehyde (HCHO). Under catalysis of the optimal 0.25% Au/α-MnO catalyst, a polluted stream containing 500 ppm HCHO can be completely cleaned at 75 °C with the condition of a weight hourly space velocity (WHSV) of 60000 mL/(g h). Meanwhile, the catalyst retains good activity for removal of low-concentration HCHO (about 1 ppm) at ambient temperature with a high WHSV, and exhibits a high tolerance to water and long-term stability. Our characterization of Au/α-MnO and catalytic performance tests clearly demonstrate that the proper amount of Au doping facilitates formation of surface vacancy oxygen, lattice oxygen, and charged Au species as an active site, which are all beneficial to catalytic oxidation of HCHO. The oxidation of HCHO over Au-doped α-MnO catalyst obeys the Mars-van Krevelen mechanism as evidenced by in situ diffuse reflectance infrared Fourier transform spectroscopy.

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Single‐atom noble metals on a catalyst support tend to migrate and agglomerate into nanoparticles owing to high surface free energy at elevated temperatures. Temperature‐induced structure reconstruction of a support can firmly anchor single‐atom Pt species to adapt to a high‐temperature environment. We used Mn3O4 as a restructurable support to load single‐atom Pt and further turned into single‐atom Pt‐on‐Mn2O3 catalyst via high‐temperature treatment, which is extremely stable under calcination conditions of 800 °C for 5 days in humid air. High‐valence Pt4+ with more covalent bonds on Mn2O3 are essential for anchoring isolated Pt atoms by strong interaction. An optimized catalyst formed by moderate H2O2 etching exhibits the best performance and excellent thermal stability of single‐atom Pt in high‐temperature CH4 oxidation on account of more exposed Pt atoms and strong Pt‐Mn2O3 interaction.

Surface coatings developed in different natural waters were used to study the role of the composition of surface coatings in controlling Cd adsorption in aquatic environments. To investigate the adsorption property of each component, the method of extraction techniques followed by Cd adsorption and statistical analysis were employed. Hydroxylamine hydrochloride was used to remove Mn oxides selectively, sodium dithionite was used to remove Mn and Fe oxides, and oxalic acid was used to remove most metal oxides and part of the organic material. Adsorption of Cd to surface coatings was measured before and after extraction under controlled laboratory conditions. The observed Cd adsorptions to unextracted and extracted surface coatings were analyzed using nonlinear least-squares fitting to estimate the adsorption property of each surface coating constituent. In different waters, the relative contribution to Cd adsorption of each component was different, but in all the waters studied, ferromanganese oxides contributed most with lesser roles indicated for organic phase and Al oxides. The Cd adsorption ability of manganese oxides was significantly higher than that of the other components.

Enhancing the surface acidity has been seen as an effective strategy to optimize the performance of catalysts for the degradation of chlorinated volatile organic compounds (CVOCs). Herein, a series of...

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Constructing rGO nanosheet-adsorption layer-supported Pt nanoparticles to achieve efficient photo-thermal catalytic decomposition of volatile organic compounds.