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Herein, we present an in-depth investigation into the enhancement of catalytic soot oxidation through cerium-doped three-dimensional ordered macroporous (3DOM) La-Co-Ni-based perovskites synthesized with the colloidal crystal template (CCT) method. The 3DOM structure significantly contributes to the accessibility and interaction efficiency between soot and catalyst. Based on the results of powder X-ray diffraction (XRD), N2 adsorption-desorption measurements, scanning electron microscopy (SEM), temperature-programmed oxidation of NO (NO-TPO), temperature-programmed reduction of H2 (H2-TPR), in situ infrared Fourier transform spectroscopy (In-situ DRIFTS), and temperature-programmed oxidation (TPO) reactions, the role of cerium doping in modifying the structural and catalytic properties of 3DOM perovskite-type La2−xCexCoNiO6 catalysts was investigated systematically. The optimized cerium doping ratio in La2−xCexCoNiO6 catalysts can improve the microenvironment for efficient soot-catalyst contact, enhancing the catalytic activity of soot oxidation. Among the catalysts, the 3DOM La0.8Ce1.2CoNiO6 catalyst shows the highest catalytic activity for soot oxidation, whose T10, T50, and T90 values are 306 °C, 356 °C, and 402 °C, respectively. The mechanism of the cerium doping effect for boosting soot oxidation is proposed: The doping of Ce ions can increase the surface oxygen species, which is the main active species for promoting the key step of NO oxidation to NO2 in catalyzing soot oxidation. This research provides a new strategy to develop high-efficient non-noble metal catalysts for soot oxidation in pollution control and sustainable environmental practices. [ABSTRACT FROM AUTHOR]

Herein, the Ruthenium nanoparticles (NPs) with the size of 12 nm were decorated on the hexagonal prism silicalite-1 (Ru/S-1) by the gas bubbling-assisted membrane reduction method (GBMR). The adsorption/activation properties are improved for reactant molecules due to the formation of an interfacial structure that enhances the interaction between the Ru NPs and S-1. The Ru/S-1 catalyst displays the highest catalytic activity (T50 = 356 °C) and CO2 selectivity (SCO2m = 99.9%). Moreover, no obvious deactivation was observed over the Ru/S-1 catalyst even after five cycles, and the values of T50 and SCO2m after cycling five times are similar to the fresh catalyst. The Ru/S-1 catalyst with excellent catalytic performance can be compared with a series of noble metal catalysts for soot oxidation. The catalytic mechanism of the Ru/S-1 catalyst was revealed by in situ characterization for soot oxidation. The interfacial effect between Ru NPs and S-1 plays an important role in the conversion of NO to NO2 during soot oxidation. Preparation of Ru/S-1 catalyst provides a hopeful way to obtain considerably low-cost and highly stable auto-exhaust treatment catalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co x -CeO 2 nanosheet catalysts with porous structure were elaborately synthesized. • Co cations incorporated into CeO 2 induced the oriented lattice bending. • Active edge sites located at the oriented lattice bending of Co-CeO 2 nanosheets. • Co 2 -CeO 2 catalyst displays high activity and superior stability for soot oxidation. • Active edge sites can activate the O 2 molecule to reactive oxygen species. Herein, a series of Co x -CeO 2 nanosheet catalysts were elaborately synthesized by a one-step hydrothermal method. The CeO 2 microsphere with crossed nanosheets can improve the soot-catalyst contact efficiency and the lattice substitution of Co ions for cerium sites in CeO 2 results in the oriented lattice bending of Co-CeO 2 nanosheets for improving adsorption/activation properties of NO and O 2. Co 2 -CeO 2 catalyst displays the highest H 2 O-tolerance activity (T 50 = 334 °C, TOF = 1.32 h−1) and excellent stability during soot oxidation in the presence of H 2 O. Combined with characterizations and DFT calculations, the mechanism was proposed: the active edge sites located at the oriented lattice bending of Co-CeO 2 nanosheets can activate surface oxygen and gaseous O 2 , and active oxygen species can boost NO oxidation to NO 2 , which is a crucial step of NO x -assistant catalytic mechanism for soot oxidation. It provides a promising way for the rational design of high-performance non-noble metal catalysts for soot oxidation in practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn-modified near-surface atomic structure of CeO 2 nanorods was constructed. • Mn atoms diffuse into the crystal lattice of CeO 2 -{1 1 0} to form Mn-O-Ce bond chains. • Mn/CeO 2 -10 catalyst exhibits the highest catalytic activity for soot oxidation. • Heteroatomic interfacial oxygen in Mn-O-Ce bond chains was active oxygen species. • Mn2+-O v -Ce3+ active sites decrease desorption energy of NO 2. Herein, we synthesized the well-defined catalysts of Mn-decorated single-crystal CeO 2 nanorod (Mn/CeO 2) with dominantly exposed {1 1 0} facets by incipient wetness impregnation method. Surface-modified Mn atoms can diffuse into the crystal lattice of CeO 2 -{1 1 0} facet to form Mn-O-Ce bond chains. The heteroatomic interfacial oxygen atoms in Mn-O-Ce bond chains as active oxygen species have a high-efficient performance, and resulting oxygen vacancy (O v) sites can promote the adsorption and activation properties for O 2. Mn/CeO 2 -10 catalyst exhibits superior catalytic activities and high stability. The related characterizations and DFT calculations results reveal that the Mn2+-O v -Ce3+ active sites can decrease activation energy of O 2 and desorption energy of NO 2 in processes of NO oxidation to NO 2 , which is the crucial steps of NO 2 -assisted mechanism for soot oxidation. This work provides a new inspiration for rational modification of the near-surface atomic structure to obtain efficient catalysts for removal of soot or other pollutions. [ABSTRACT FROM AUTHOR]

• Hierarchical porous Pd/ZrO 2 catalyst was fabricated successfully with dual templates. • Three-dimensional ordered macro-mesoporous structure enhances contact efficiency. • Supported Pd nanoparticles can improve activation property for gaseous reactants. • Pd/3DOMM-ZrO 2 catalyst exhibits excellent catalytic activity for soot oxidation. • Hierarchical porous structure promotes performance involving multi-phase reactants. Herein, the hierarchical porous catalysts of three dimensional ordered macro-mesoporous (3DOMM) ZrO 2 -supported active Pd nanoparticles (NPs) were prepared by two-step methods of evaporation-induced self-assembly-colloid crystal template (EISA-CCT) and gas bubbling-assisted membrane reduction (GBMR). Ordered macroporous structure can enhance diffusion and mass transfer of soot particles; ordered mesoporous structure is beneficial to enhance activation ability for gaseous reactants. Synergistic effect of hierarchical porous structure in the catalysts is important to improve catalytic activity for soot oxidation. Pd/3DOMM-ZrO 2 catalyst exhibits the highest activity (T 50 = 404 °C) for soot oxidation compared with the single macroporous or mesoporous structure. The catalytic kinetics of hierarchical porous Pd/3DOMM-ZrO 2 catalyst for soot oxidation was systemically investigated, i.e., its reaction rate is 0.038 μmol g-1 s−1 at 310 °C, which is 2.7-fold of power-type Pd/normal-ZrO 2 catalyst (0.014 μmol g-1 s−1). The hierarchical porous structure is a good strategy to boost catalytic activity during soot oxidation. [ABSTRACT FROM AUTHOR]

Herein, the atomically dispersed manganese (Mn) sites on well-defined α-Fe 2 O 3 nanosheets (Mn 1 -Fe 2 O 3) were fabricated by a ligand-assisted in - situ crystallization method. Single-step surface engineering facilitates the in-situ replacement of Fe atoms in near-surface [FeO 6 ] octahedra with monodispersed Mn atoms, as well as the preservation of regularly exposed {001} surface. Under different NO x concentration (40, 500 and 2000 ppm), Mn 1 -Fe 2 O 3 -10 catalyst presented the superior catalytic performance, whose T 50 values are 455, 388 and 340 °C, respectively. By combining in-situ dynamic characterizations and DFT calculations, the surface [MnO 5 ] and adjacent [FeO 5 ] octahedra cooperatively boost two crucial steps: the dissociation of adsorbed O 2 and the desorption of molecular NO 2. The greater the amount of molecular NO 2 produced, the higher the efficiency of soot purification via the NO 2 -assisted oxidation mechanism. Insights into the near-surface modulation and structure-activity relationship provide a promising strategy to improve the availability of surface-active sites in future heterogeneous catalysis. [Display omitted] • Atomic Mn co-catalyst on well-defined α-Fe 2 O 3 nanosheets (Mn 1 -Fe 2 O 3) were fabricated. • Monodispersed Mn atoms achieve in-situ substitution of Fe atoms near {001} facet. • Mn 1 -Fe 2 O 3 -10 catalyst presented the highest catalytic efficiency for soot removal. • Surface Mn 5c and Fe 5c atoms boost the dissociation of O 2 and the desorption of NO 2. [ABSTRACT FROM AUTHOR]