Synergetic effect over flame-made manganese doped CuO–CeO2 nanocatalyst for enhanced CO oxidation performance

Effect of Mn2+ incorporation on the photoelectrochemical properties of BiVO4

Mn2+–BiVO4 photoanodes (Mn2+ = 0.2–1%) to improve the charge-carrier separation and electrical conductivity of BiVO4 are reported.

Bi spheres SPR-coupled Cu2O/Bi2MoO6 with hollow spheres forming Z-scheme Cu2O/Bi/Bi2MoO6 heterostructure for simultaneous photocatalytic decontamination of sulfadiazine and Ni(II)

Environmental problem on the coexistence of organic pollutants and heavy metals in surface waters has become increasingly serious. Few relative researches have focused on their simultaneous decontamination. Herein, a ternary plasmonic Z-scheme Cu₂O/Bi/Bi₂MoO₆ heterojunction was synthesized via two-step route followed by a wet-impregnation, where Bi spheres coupled with Cu₂O particles were anchored on the surface of Bi₂MoO₆ with hollow microflower spheres. The composites were characterized via various measurements. The excellent photocatalytic activity of Cu₂O/Bi/Bi₂MoO₆ displayed in single sulfadiazine (SDZ) oxidation or Ni(II) reduction, and their simultaneous removal. The degradation pathway for SDZ was investigated via LC-MS and Gaussian theory. DFT and FDTD calculations confirmed the electronic structural characteristics in the Cu₂O/Bi/Bi₂MoO₆ heterostructure and the induced electric field enhancement around nearly touching Bi spheres. A possible photodegradation mechanism of the as-prepared photocatalyst was elucidated via combining scavenger experiments with EPR technique. The results suggested h⁺, •O₂^- and •OH all participated in SDZ oxidation, which verified that Z-Scheme electron transfer was major manner in Cu₂O/Bi/Bi₂MoO₆, while •O₂^- and e^-acted on Ni(II) reduction. The improved photocatalytic activity of Cu₂O/Bi/Bi₂MoO₆ could be ascribed to the unique Z-scheme electron transfer among Cu₂O, Bi and Bi₂MoO₆, particularly SPR and local electric field near Bi spheres.

A Novel Porous Ceramic Membrane Supported Monolithic Cu-Doped Mn–Ce Catalysts for Benzene Combustion

Porous ceramic membranes (PCMs) are considered as an efficient hot gas filtration material in industrial systems. Functionalization of the PCMs with high-efficiency catalysts for the abatement of volatile organic compounds (VOCs) during dust elimination is a promising way to purify the industrial exhaust gases. In this work, we prepared PCMs (porosity: 70%) in a facile sintering process and integrated Cu-doped Mn–Ce oxides into the PCMs as monolithic catalysts by the sol–gel method for benzene oxidation. Through this method, the catalysts are dispersed evenly throughout the PCMs with excellent adhesion, and the catalytic PCMs provided more active sites for the reactant gases during the catalytic reaction process compared to the powder catalysts. The physicochemical properties of PCMs and catalytic PCMs were characterized systematically, and the catalytic activities were measured in total oxidation of benzene. As a result, all the prepared catalytic PCMs exhibited high catalytic activity for benzene oxidation. Significantly, the monolithic catalyst of Cu0.2Mn0.6Ce0.2/PCMs obtained the lowest temperature for benzene conversion efficiency of 90% (T90) at 212 °C with a high gaseous hourly space velocity of 5000 h−1 and showed strong resistance to high humidity (90 vol.%, 20 °C) with long-term stability in continuous benzene stream, which is caused by abundant active adsorbed oxygen, more surficial oxygen vacancy, and lower-temperature reducibility.

Catalytic Behaviour of Flame-Made CuO-CeO2 Nanocatalysts in Efficient CO Oxidation

CuO-CeO2 nanocatalysts with varying CuO contents (1, 5, 9, 14 and 17 wt %) were prepared by one-step flame spray pyrolysis (FSP) and applied to CO oxidation. The influences of CuO content on the as-prepared catalysts were systematically characterized by X-ray diffraction (XRD), N2 adsorption-desorption at −196 °C, field emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and hydrogen-temperature programmed reduction (H2-TPR). A superior CO oxidation activity was observed for the 14 wt % CuO-CeO2 catalyst, with 90% CO conversion at 98 °C at space velocity (60,000 mL × g−1 × h−1), which was attributed to abundant surface defects (lattice distortion, Ce3+, and oxygen vacancies) and high reducibility supported by strong synergistic interaction. In addition, the catalyst also displayed excellent stability and resistance to water vapor. Significantly, in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) showed that in the CO catalytic oxidation process, the strong synergistic interaction led readily to dehydroxylation and CO adsorption on Cu+ at low temperature. Furthermore, in the feed of water vapor, although there was an adverse effect on the access of CO adsorption, there was also a positive effect on the formation of fewer carbon intermediates. All these results showed the potential of highly active and water vapor-resistive CuO-CeO2 catalysts prepared by FSP.