The purification efficiency of autoexhaust carbon strongly depends on the heterogeneous interface structure between active metal and oxide, which can modulate the local electronic structure of defect sites to promote the activation of reactant molecules. Herein, the high-dispersion CuO clusters supported on the well-defined CeO2 nanorods were prepared using the complex deposition slow method. The formation of heteroatomic Cu+-Ov-Ce3+ interfacial structural units as active sites can capture electrons to achieve activation of the NO and O2 molecules. Among all of the synthesized catalysts, the Cu10/CeO2 catalyst exhibits superior catalytic performance (T50 = 351 °C) along with remarkable tolerance to H2O and SO2 in the removal of soot particles. Through a combination of comprehensive characterizations and density functional theory calculations, it is proposed that the interfacial Cu+-Ov-Ce3+ site, acting as an electron enrichment center, can capture electrons from the Cu d-band and Ce d/f-band to obtain high delocalized electron density, and then enhance the oxidation of NO to NO2, which plays a crucial role in the NOx-assisted catalytic mechanism for soot oxidation. This study presents a novel strategy for developing highly efficient catalysts that exhibit resistance to H2O and SO2, aimed at enhancing the removal of soot particles.
A series of multifunctional catalysts of three-dimensionally ordered macroporous (3DOM) ZrO2-supported core–shell structural Au@CeO2−δ nanoparticles were successfully synthesized by the one-pot method of gas bubbling-assisted membrane reduction–precipitation (GBMR/P). All the catalysts possess a well-defined 3DOM structure with interconnected networks of spherical voids, and the Au@CeO2−δ core–shell nanoparticles with different molar ratios of Au/Ce are well dispersed and supported on the inner wall of the uniform macropore. 3DOM support facilitates the contact efficiency between solid reactant and catalyst, and the Au@CeO2−δ core–shell nanoparticles with strong metal-oxides interaction improve the amount of active oxygen species and the sintering resistance of supported Au nanoparticles due to the optimization of the interface area by formation of the metal-oxides core–shell (MOCS) nanostructure particles. 3DOM Au@CeO2−δ/ZrO2 catalysts exhibit high catalytic activity and stability for diesel soot oxidation. Among the as-prepared catalysts, 3DOM Au@CeO2−δ/ZrO2-2 catalyst with the moderate thickness of CeO2−δ nanolayer shell shows the highest catalytic activity for soot combustion, i.e., its T50 is 364 °C. In summary, 3DOM Au@CeO2−δ/ZrO2 catalysts are excellent systems for catalytic combustion of solid particles or macromolecules, and the design concept and facile synthesis method of 3DOM oxide-supported MOCS nanoparticle catalysts can be extended to other metal/oxide compositions.
Polymeric carbon nitride is reported to be a promising candidate in environmental catalysis for NO decomposition carried out at elevated temperature. Theoretical calculations support a mechanism where Lewis basic site of g-C3N4 can donate electrons to the adsorbed NO, decreasing the bond order of N–O thus facilitating the reaction.
In the pursuit of advancing electrolytic water hydrogen production technology, the development of a cost-effective alkaline hydrogen evolution reaction (HER) catalyst, characterized by high activity and stability, holds paramount importance. In this context, we synthesized a crystalline Ru nanoclusters (NCs) catalyst supported on a three-dimensional layered nitrogen-doped carbon (3DLNC) material through a straightforward impregnation pyrolysis method. The optimized Ru/3DLNC-500 catalyst demonstrated remarkable electrocatalytic performance, featuring an exceptionally low overpotential of 18.5 mV at 10 mA cm–2, an extraordinarily high mass activity (10-fold greater than a 20% platinum carbon catalyst), and commendable stability. Insights gained from in situ Raman characterization and theoretical calculations lead to two noteworthy conclusions. First, the alkaline HER activity of crystalline Ru NCs is attributed to their heightened water adsorption capacity and accelerated hydrogen desorption rate. Second, under reaction conditions, the nitrogen-containing defect sites on the surface of 3DLNC serve as additional sites for water molecule adsorption by forming quasi-hydrogen bonds, thereby facilitating the alkaline HER by enhancing the adsorption and dissociation capabilities of water molecules on the catalyst.
A series of alkali metals and cerium-modified La–Co-based perovskite catalysts were successfully prepared by a simple method using glucose as a complexing agent. The physicochemical properties of catalysts were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 adsorption, H2-temperature-programmed reduction (TPR), O2-temperature-programmed desorption (TPD), soot-TPR, NO-temperature-programmed oxidation (TPO), X-ray photoelectron spectroscopy (XPS), etc. Among the catalysts, La0.9Ce0.05K0.05CoO3 possesses the highest catalytic activity for soot combustion, with T10, T50, and T90 values of 269, 309, and 342 °C, respectively. In the presence of 10% H2O, T90 is significantly reduced to 327 °C. As far as we know, the catalytic performance of the La0.9Ce0.05K0.05CoO3 perovskite oxide catalyst is one of the best results in current reports for soot combustion, especially for T50 and T90. The substitution of A sites by K and Ce ions produces numerous active sites of Co2+–Ov on the surface of the La0.9Ce0.05K0.05CoO3 catalyst and enhances the oxygen storage capacity by redox recycling between Ce4+ and Ce3+. The La0.9Ce0.05K0.05CoO3 catalyst also possesses a stronger ability of NO adsorption, storage, and NO-to-NO2 oxidation compared to other prepared catalysts. Based on the results of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and density functional theory (DFT) calculations, Langmuir–Hinshelwood (L–H) and Mars–van-Krevele (MVK) mechanisms were proposed as the main reaction mechanisms for soot combustion. More importantly, the La0.9Ce0.05K0.05CoO3 catalyst exhibits good resistance ability for sulfur and water. These results provide a promising strategy for designing and preparing highly efficient and low-cost catalysts for the practical application of soot particle removal.
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