Catalytic Oxidation Performance Research Articles

Highly efficient and selective organic pollutants degradation via peroxymonosulfate activation over micron-sized Co-MOF: Nearly 100% singlet oxygen mechanism

Singlet oxygen-based advanced oxidation processes (1O2-AOPs) have attracted extensive interest in selective removal of organic pollutants in the complicated water matrices. However, both the highly efficient 1O2 production and selective pollutants oxidation degradation are challenging. In this work, a 2D Co-MOF (Co-tib) was synthesized and applied to accomplish nearly 100% 1O2 production during peroxymonosulfate (PMS) activation, which exhibited excellent selective catalytic oxidation performance toward multiple organic pollutants. More importantly, ＞99% selective removal efficiencies for rhodamine B (RhB), bisphenol A (BPA) and sulfamethoxazole (SMX) are achieved in the mixed RhB/BPA/SMX/Benzoic acid (BA) solutions, and ＞90% selective removal efficiencies for RhB, BPA and SMX are achieved in the mixed RhB/BPA/SMX/P-nitrobenzoic acid (NBA) solutions. The influences of PMS dosage, pH, pollutant concentrations and inorganic ions for pollutants degradation were investigated. The reaction mechanisms were proposed via active species quenching tests, probe experiments and electron spin resonance (ESR). This work will provide new inspiration for 1O2 production and selective degradation toward multiple pollutants in a complicated aqueous matrix via the catalytic PMS activation over MOFs catalysts.

Enhanced Catalytic Aryl Alkene Oxidation by Constructing Hierarchical Polyoxometalate‐Based Metal‐Organic Framework

AbstractAchieving highly selective oxidation of aryl alkenes to aldehydes is of great significance in chemical industry. Herein, the performance of catalytic aryl alkene oxidation is enhanced via constructing a hierarchical fractal polyoxometalate‐based metal–organic framework (POM@MOF) containing hierarchical pores and layered surface structure, which improve the mass transfer efficiency of substrates and increase the accessibility to active POMs clusters. Accordingly, the activity of fractal POM@MOF is increased by 4.8 times compared with microporous counterpart in 4‐tert‐butylstyrene oxidation to aldehyde product. This work paves a way for designing efficient catalysts for selective oxidation of aryl alkenes via increasing the accessibility of active sites and broadening the diffusion channels by hierarchical construction.

Unraveling the morphology and crystal plane dependence of bifunctional MnO2 catalyst for simultaneous removal of NO and CO at low temperature

It is indeed a challenging problem to simultaneously remove NO and CO from the steel sintering flue gas, in which a bifunctional catalyst has proven to be an efficient solution for removing both pollutants at low temperature. In this study, four different crystalline phases of MnO2 (α-, β-, γ-, and δ-) catalysts were synthesized via a facile hydrothermal method, and the effects of their crystal structure, morphology, and physicochemical properties on the catalytic performance for NO reduction and CO oxidation were elucidated. The results indicated that γ-MnO2 catalyst exhibited the best catalytic activity, achieving 90% NO removal efficiency and 82% CO conversion rate at 175 °C. Reaction kinetics confirmed that γ-MnO2 catalyst exhibited a lower Ea for both NO reduction and CO oxidation compared to α-MnO2, β-MnO2 and δ-MnO2 catalysts. Meanwhile, the interaction of between NH3-SCR and CO catalytic oxidation reactions over the catalysts was also studied. Intriguingly, it was found that the presence of CO enhanced the catalytic activity of γ-MnO2 catalyst in the NH3-SCR reaction. The results of NO + O2-TPD and in situ DRIFTS experiments revealed that CO contributed to the adsorption and oxidation of NO, thus promoting the L-H pathway over γ-MnO2 catalyst. Finally, a possible mechanism model for simultaneous removal of NO and CO over γ-MnO2 catalyst was proposed.

Enabling High Activity Catalyst Co3O4@CeO2 for Propane Catalytic Oxidation via Inverse Loading.

Propane catalytic oxidation is an important industrial chemical process. However, poor activity is frequently observed for stable C-H bonds, especially for non-noble catalysts in low temperature. Herein, we reported a controlled synthesis of catalyst Co3O4@CeO2-IE via inverse loading and proposed a strategy of oxygen vacancy for its high catalytic oxidation activity, achieving better performance than traditional supported catalyst Co3O4/CeO2-IM, i.e., the T50 (temperature at 50% propane conversion) of 217 °C vs. 235 °C and T90 (temperature at 90% propane conversion) of 268 °C vs. 348 °C at the propane space velocity of 60,000 mL g-1 h-1. Further investigations indicate that there are more enriched oxygen vacancies in Co3O4@CeO2-IE due to the unique preparation method. This work provides an element doping strategy to effectively boost the propane catalytic oxidation performance as well as a bright outlook for efficient environmental catalysts.

Microporous exposure on catalytic performance of MoVNbTeOx mixed metal oxides in the oxidative dehydrogenation of ethane

The catalytic performance of the non-purified MoVNbTeOx catalyst was optimized by changing the composition of the synthesis gel method in the hydrothermal synthesis process. However, the enhancement in activity was more pronounced for the post-treatment process of the non-purified catalyst. The catalytic performance of non-purified MoVNbTeOx catalysts and phase-pure M1 catalysts in the oxidative dehydrogenation of ethane (ODHE) were enhanced by water agitation post-treatment. The results showed that the phase-pure M1 catalyst obtained by treating the MoVNbTeOx catalyst with nitric acid had an increased activity per unit mass, but with a mass loss of catalyst materials during the purification process. After several days of post-treatment with water agitation, the catalytic activity of the non-purified MoVNbTeOx and the M1 samples gradually increased and stabilized, where both catalysts had a comparable catalytic performance. All the samples were systematically characterized, showing that the catalytic performance of the samples was mainly correlated with the enhanced specific surface area/pore volume. The results show that for the hydrothermally synthesized MoVNbTeOx catalysts, the reaction takes place in the micropores and the key to improve the performance of MoVNbTeOx catalysts is to effectively expose the active sites. Physical post-treatment process that does not require nitric acid or hydrogen peroxide for purification is also effective in enhancing catalyst activity by boosting the active site.

Preparation of Ce-MnOx Composite Oxides via Coprecipitation and Their Catalytic Performance for CO Oxidation.

Ce-MnOx composite oxide catalysts with different proportions were prepared using the coprecipitation method, and the CO-removal ability of the catalysts with the tested temperature range of 60-140 °C was investigated systematically. The effect of Ce and Mn ratios on the catalytic oxidation performance of CO was investigated using X-ray diffraction (XRD), X-ray energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), H2 temperature programmed reduction (H2-TPR), CO-temperature programmed desorption (CO-TPD), and in situ infrared spectra. The experimental results reveal that under the same test conditions, the CO conversion rate of pure Mn3O4 reaches 95.4% at 170 °C. Additionally, at 140 °C, the Ce-MnOx series composite oxide catalyst converts CO at a rate of over 96%, outperforming single-phase Mn3O4 in terms of catalytic performance. With the decrement in Ce content, the performance of Ce-MnOx series composite oxide catalysts first increase and then decrease. The Ce MnOx catalyst behaves best when Ce:Mn = 1:1, with a CO conversion rate of 99.96% at 140 °C and 91.98% at 100 °C.

Synthesis of a novel magnetic CuFe2O4/zeolite composite catalyst and its catalytic oxidation performance

A new magnetic CuFe2O4/zeolite (CFZ) catalyst was synthesized via a simple hydrothermal method. Characterization results suggest that CuFe2O4 and the zeolite are compounded together. CFZ has a specific surface area of 149.2 m2/g, indicating that CFZ has a porous structure. The removal rate of methyl orange in the CFZ/PMS system could reach 97.3%, showing the excellent catalytic oxidation performance of CFZ. After 5 cycles, the degradation efficiency declined by only 1.6%. In the catalytic degradation process, O2•− and 1O2 are the main reactive oxygen species.

Ti doped CeO2 nanosheets supported Pd catalyst for alcohol oxidation: Catalysis of interfacial sites

AbstractThe oxidation of alcohols is a significant chemical reaction, and the efficient oxidation of alcohols over heterogeneous catalysts using oxygen as oxidant has attracted much attention in recent years. Among them, Pd/CeO2 exhibits excellent alcohol oxidation performance. However, the structure-activity relationship between the catalyst's structure and its catalytic performance for alcohol oxidation is still not clearly understood. This study involved the preparation of CeO2 nanosheets with different concentrations of surface oxygen vacancies (Ov) and their subsequent loading with Pd to explore their catalytic performance for alcohol oxidation. The findings obtained through XPS, Raman, and XAS indicated a positive correlation between the surface Ov concentration of CeO2 as well as the ratio of Pd2+ fraction. The alcohol oxidation results and structure-performance relationship studies showed that there was a good linear relationship between the Pd2+ ratio as well as the surface Ce3+ concentration and the TOF of benzyl alcohol oxidation reaction, respectively. And the interfacial site (Pd–O–Ce) formed by Pd and CeO2 was the main catalytic site for this type of alcohol oxidation catalysts. This study contributes to the understanding of the catalytic role of interfacial sites in metal and oxide support for the development of better alcohol oxidation catalysts.

In-situ reduced ultrathin molybdenum oxide nanorods-Au heterojunction for boosted catalytic oxidation performance of cyclohexane

The production of cyclohexane oxidation to cyclohexanol and cyclohexanone (KA oil) in the chemical industry is still constrained by low conversion, low selectivity, and drastic reaction conditions. To address this, we have developed MoO3-x ultrafine nanorods-Au nanoparticles composite by in situ uniform growth for the boosted photocatalytic oxidation of cyclohexane. The resulting MoO3-x-Au Schottky heterojunction possesses significantly improved catalytic performance in cyclohexane oxidation, achieving a conversion rate of 9.99% and the KA oil selectivity of 96.37%. Using the Finite-Difference Time-Domain (FDTD) method, we interpreted the enhanced electric field distribution of the composite. Moreover, the photocatalytic mechanism was validated by H2O2 production and in-situ FTIR characterization. The adsorption experiments validated that the high selectivity of KA oil is originated from the superior adsorption capability of MoO3-x-Au for cyclohexane over cyclohexanol and cyclohexanone. Our study showcases the potential of MoO3-x ultrafine catalysts in the green synthesis of industrial organic chemical products.

Transition metal modified manganese-based catalysts for soot oxidation promoted by noncompetitive adsorption of oxygen: Experiments and DFT calculations

A series of manganese-based oxide catalysts were synthesized by the hydrothermal method. By adjusting the doping amounts of W and Cu in the system to study the catalytic performance of transition metal-doped manganese oxides on soot combustion. They were deeply studied through various characterizations and theoretical calculations. The results show that W and Cu doping modifications can significantly improve the activity of manganese-based oxides in soot oxidation. W-Cu0.1/MnOx prepared by co-modification of W and Cu at 395 °C can convert 90% of soot into CO2. The multiple characterization results show that by adjusting the doping amount of copper and tungsten, the nano-flower-like morphology can be obtained and the crystal plane can be reconstructed, which is helpful to increase the specific surface area, Mn3+ content, and oxygen vacancy content. The theoretical calculation results show that the oxygen vacancy on the surface of the catalyst shows the ability to activate O2 and H2O, and they show non-competitive adsorption. In addition, W-Cu0.1/MnOx has a good application prospect in the catalytic oxidation of soot because of its excellent catalytic stability. This work provides a reference for the design and preparation of non-noble metal-based catalysts for the elimination of soot particles from diesel engine exhaust.

Fe-N-C Catalyst Derived from MOFs with Enhanced Catalytic Performance for Selective Oxidation of Emerging Contaminants

Fe-N-C/peroxymonosulfate (PMS) systems have demonstrated selective oxidation of pollutants, but the underlying mechanism and reasons for variability remain unclear. In this work, we synthesized a highly active Fe-N-C catalyst derived from MOFs using a pyrolysis protection strategy. We assessed its catalytic activity by employing PMS as an activator for pollutant degradation. The presence of Fe-Nx sites favored the catalytic performance of FeMIL-N-C, exhibiting 23 times higher activity compared to N-C. Moreover, we investigated the degradation performance and mechanism of the FeMIL-N-C/PMS system through both experimental and theoretical analyses, focusing on pollutants with diverse electronic structures, namely bisphenol A (BPA) and atrazine (ATZ)N-C. Our findings revealed that the degradation of ATZ primarily follows the free radical pathway, whereas BPA degradation is dominated by electron transfer pathways. Specifically, pollutants with a low LUMO- HOMO energy gap (BPA) can be degraded via the FeMIL-N-C/PMS system through the electron transfer pathway. Conversely, pollutants with a high LUMO-HOMO energy gap (ATZ) exhibit limited electron donation and predominantly undergo degradation through the free radical pathway. This work introduces novel insights into the mechanisms underlying the selective oxidation of pollutants, facilitating a deeper understanding of effective pollutant removal strategies.

Highly selective oxidation of styrene into benzaldehyde over nano CeWOx composite confined in N-doped carbon under solvent-free conditions

Highly selective oxidation of styrene into benzaldehyde with molecular oxygen under solvent-free conditions still remains a great challenge. Herein, Ce-modified heteropolyacid-based poly(ionic liquid)s were prepared as precursors followed by carbonization to obtain nano CeWOx composite confined in N-doped carbon (CeWOx@NC). Then, the as-prepared catalysts were further characterized by FT-IR, TG, XRD, XPS, BET, SEM, TEM-EDS and H2-TPR to discuss the relationship between the structure and performance. The nano CeWOx composite with a mixed valence state of W4+ and W6+ was formed and well dispersed in the N-doped carbon. Moreover, the valence ratio of W4+ to W6+, redox capacity and oxygen vacancies could be tailored by carbonization temperature and incorporation of Ce, which was strongly correlated with the catalytic performance of CeWOx@NC catalysts. Benefited from that, the CeWOx@NC800 catalyst displays outstanding catalytic performance for solvent-free oxidation of styrene into benzaldehyde with styrene conversion of 45.1%, benzaldehyde selectivity of 89.2% and TOF of 310.1 h−1 at the optimum reaction conditions. Furthermore, the catalyst has shown robust stability and reusability.

Investigation of the Active-Site Structure of Cu-CHA Catalysts for the Direct Oxidation of Methane to Methanol Using In Situ UV–Vis Spectroscopy

Among Cu-containing zeolites, Cu-CHA exhibits relatively high catalytic performance in direct oxidation of CH4 to CH3OH in a continuous-flow reaction of a CH4–O2–H2O gas mixture. The catalytic activity of Cu-CHA varies with its composition, e.g., Cu loading and Si/Al ratio, suggesting formation of different Cu active-site structures depending on the composition. In the present study, to identify catalytically active structures of Cu species, 18 different Cu-CHA catalysts having three Si/Al ratios and six Cu loadings at each Si/Al ratio were prepared, and their catalytic performance was evaluated. Based on the catalytic performance, the Cu species in Cu-CHA catalysts were categorized into three groups: those having high selectivity but low catalytic activity were formed at a low Cu/Al ratio (group A); those having high selectivity and high catalytic activity for CH3OH production were formed at a medium Cu/Al ratio (group B); and those having high activity for the complete oxidation of CH4 to CO2 were formed at a high Cu/Al ratio (group C). Thus, three representative catalysts corresponding to the three groups were selected at each Si/Al ratio and analyzed using in situ UV–vis spectroscopy, from which the spectral features of Cu species involved in the catalytic reaction were extracted from the difference between the spectra under reduction conditions and those under oxidation conditions. Based on the comparison of the spectral features with the simulated spectra of various Cu active-site structures in the literature, the main species of the three groups were suggested: Cu2+ species in the six-membered ring of SSZ-13 zeolites and water-coordinated CuOH+ in the eight-membered ring of SSZ-13 zeolite for group A; mono-(μ-oxo) di-Cu species for group B; and μ-η2:η2 peroxide di-Cu, trans-μ-1,2-peroxo di-Cu and/or mono-/bis-(μ-hydroxo) di-Cu species for group C. Therefore, the mono-(μ-oxo) di-Cu species in Cu-CHA is proposed as the active species for the catalytic direct oxidation of CH4 to CH3OH.

Defective zeolite TS-1 confined Pt nanoclusters with superior performance for CO and soot catalytic oxidation

Catalytic oxidation is an important reaction in the treatment of diesel exhaust. Herein, a facile self-assembly strategy has been developed to synthesize defective zeolite confined-catalyst Pt@TS-1 with ultra-low Pt loading, which shows super catalytic activity in the CO conversion (T90 = 175 °C) and soot oxidation (T90 = 490 °C). Owing to the confinement effect of zeolite, the obtained catalyst Pt@TS-1 exhibits a high percentage of Pt2+, smaller Pt nanoparticles and sufficient Ti3+-VÖ defects, which can greatly accelerate the adsorption and conversion of CO, and the deep oxidation of soot. In-situ DRIFTS results demonstrate that rich and smaller Pt nanoparticles confined in zeolite may be responsible for excellent CO conversion. Significantly, the catalyst Pt@TS-1 also shows excellent catalytic stability and good resistance to water and sulfur, showing the potential for industrial applications.

Phase-Controlled Pd-Sn Nanostructures via Co-Digestive Ripening: Catalytic Performance for Base-Free Oxidation of Benzyl Alcohol.

Diluting the precious metal to be used for catalysis with an abundant and non-precious metal to form alloy/intermetallic nanostructures is of great interest owing to the cost-effectiveness of the catalyst. The physicochemical properties of such bimetallic nanostructures are influenced by the atomic ordering of different atoms in the system, generally enhancing the catalytic activity, selectivity, and durability compared to their monometallic counterparts. To understand the relationship between the structure and the activity of the catalyst, phase-controlled synthesis of alloy/intermetallic nanostructures is crucial. Easy and scalable synthesis of such nanostructures with phase control presents a true challenge. We exploited a colloidal-based synthetic route termed 'co-digestive ripening' to prepare Pd-Sn alloy/intermetallic nanostructures. Oleylamine capped Pd and Sn colloids were utilized to obtain network-like Pd3 Sn and grape-like Pd2 Sn nanostructures. Temperature and the stoichiometric ratio between Pd and Sn played significant roles in achieving phase control. The mixture of ligands (oleylamine and trioctylphosphine) in the synthetic procedure resulted in the formation of well-separated nanoparticles (2.9±0.5 nm) in the case of Pd3 Sn and few nm-sized particles along with aggregates in the case of Pd2 Sn. Pd-Sn nanostructures showed enhanced activity and selectivity as compared to their monometallic counterparts for the catalytic performance towards oxidation of benzyl alcohol.

The research on CO oxidation over Ce–Mn oxides: The preparation method effects and oxidation mechanism

A series of CeO2-MnOx for highly efficient catalytical oxidation of carbon monoxide were prepared by citrate sol-gel (C), hydrothermal (H) and hydrothermal-citrate complexation (CH) methods. The outcome indicates that the catalyst generated using the CH technique (CH-1:8) demonstrated the greatest catalytic performance for CO oxidation with a T50 of 98 °C, and also good stability in 1400 min. Compared to the catalysts prepared by C and H method, CH-1:8 has the highest specific surface of 156.1 m2 g−1, and the better reducibility of CH-1:8 was also observed in CO-TPR. It is also observed the high ratio of adsorbed oxygen/lattice oxygen (1.5) in the XPS result. Moreover, characterizations by the TOF-SIMS method indicated that obtained catalyst CH–Ce/Mn = 1:8 had stronger interactions between Ce and Mn oxides, and the redox cycle of Mn3++Ce4+ ↔ Mn4++Ce3+ was a key process for CO adsorption and oxidation process. According to in-situ FTIR, the possible reaction pathway for CO was deduced in three ways. CO directly oxidize with O2 to CO2, CO adsorbed on Mn4+ and Ce3+ reacts with O to form intermediates (COO−) (T > 50 °C) and carbonates (T > 90 °C), which are further oxidized into CO2.

Study on the performance efficiency, mechanism, power consumption and biochemical properties of E/Ce(IV)/PMS on the enhanced removal of RB19

In this study, an advanced oxidation process with E/Ce(IV) synergistic PMS (E/Ce(IV)/PMS) was established for the efficient removal of Reactive Blue 19 (RB19). The catalytic oxidation performance of different coupling systems was examined and the synergistic effect of E/Ce(IV) with PMS in the system was substantiated. The oxidative removal of RB19 in E/Ce(IV)/PMS was excellent, achieving a removal efficiency of 94.47% and a reasonable power consumption (EE/O value was 3.27 kWh·m−3). The effect of pH, current density, Ce(IV) concentration, PMS concentration, initial RB19 concentration and water matrix on the removal efficiency of RB19 were explored. Additionally, quenching and EPR experiments showed that the solution contains different radicals such as SO4·−, HO∙ and 1O2, where 1O2 and SO4·− played key roles, but HO∙ just acted a weaker role. Ce ion trapping experiment confirmed that Ce(IV) was involved in the reaction process and played a major role (29.91%). RB19 was subject to three possible degradation pathways, and the intermediate products displayed well biochemical properties. To conclude, the degradation mechanism of RB19 was explored and discussed. In the presence of current, E/Ce(IV)/PMS performed a rapid Ce(IV)/Ce(III) cycle, continuously generating strong catalytic oxidation Ce(IV), The reactive radicals derived from the decomposition of PMS, in conjunction with Ce(IV) and direct electro-oxidation, efficiently destroyed the molecular structure of RB19 and showed an efficient removal rate.

Single‐Atom Rh on High‐Index CeO2 Facet for Highly Enhanced Catalytic CO Oxidation

AbstractReducible oxide‐supported noble metal nanoparticles exhibit high activity in catalyzing many important oxidation reactions. However, atom migration under harsh reaction conditions leads to deactivation of the catalyst. Meanwhile, single‐atom catalysts demonstrate enhanced stability, but often suffer from poor catalytic activity owing to the ionized surface states. In this work, we simultaneously address the poor activity and stability issues by synthesizing highly active and durable rhodium (Rh) single‐atom catalysts through a “wrap‐bake‐peel” process. The pre‐coated SiO2 layer during synthesis of catalyst plays a crucial role in not only protecting CeO2 support against sintering, but also donating electron to weaken the Ce−O bond, producing highly loaded Rh single atoms on the CeO2 support exposed with high‐index {210} facets. Benefiting from the unique electronic structure of CeO2 {210} facets, more oxygen vacancies are generated along with the deposition of more electropositive Rh single atoms, leading to remarkably improved catalytic performance in CO oxidation.

Single-Atom Rh on High-Index CeO2 Facet for Highly Enhanced Catalytic CO Oxidation.

Reducible oxide-supported noble metal nanoparticles exhibit high activity in catalyzing many important oxidation reactions. However, atom migration under harsh reaction conditions leads to deactivation of the catalyst. Meanwhile, single-atom catalysts demonstrate enhanced stability, but often suffer from poor catalytic activity owing to the ionized surface state. In this work, we address the poor activity and stability issues simultaneously by synthesizing highly active and durable rhodium (Rh) single-atom catalysts through a "wrap-bake-peel" process. The pre-coated SiO2 layer during synthesis of catalyst plays a crucial role in not only protecting CeO2 support against sintering, but also donating electron to weaken the Ce-O bond, producing highly loaded Rh single atoms on the CeO2 support exposed with high-index{420}. Benefiting from the unique electronic structure of CeO2facets, more oxygen vacancies are generated along with the deposition of more electropositive Rh single atoms, leading to remarkably improved catalytic performance in CO oxidation.

Evolution hydrothermal aging mechanism for Ag/CeO2 catalysts in regeneration of catalytic diesel particulate filter with DFT calculation.

In order to avoid the high cost of existing precious metal catalyst like Pt, Ag/CeO2 was the most promising catalysts for mobile source soot emission control technologies, but there was a clear trade-off between hydrothermal aging resistance and catalytic oxidation performance hindered the application of this catalyst. In order to reveal the hydrothermal aging mechanism of Ag/CeO2 catalysts, the TGA (thermogravimetric analysis) experiments were investigated to reveal the mechanism of Ag modification on catalytic activity of CeO2 catalyst between fresh and hydrothermal aging and were also characterized with the related characterization experiments to in-depth research the lattice morphology and valence changes. The degradation mechanism of Ag/CeO2 catalysts in vapor with high-temperature was also explained and demonstrated based on density functional and molecular thermodynamics theories. The experimental and simulation data showed that the catalytic activity of soot combustion within Ag/CeO2 decreased more significantly after hydrothermal aging than CeO2 due to the less agglomerated, which caused by the decreased in OII/OI and Ce3+/Ce4+ compared with CeO2. As shown in density function theory (DFT) calculation, the decreased surface energy and the increased oxygen vacancy formation energy of the low Mille index surface after Ag modification led to the instability structure and the high catalytic activity. Ag modification also increased the adsorption energy and Gibbs free energy of H2O on the low Miller index surface compared to CeO2, indicating that the desorption temperature of H2O molecules in (1 1 0) and (1 0 0) was higher than (1 1 1) in CeO2 and Ag/CeO2, which led to the migration of (1 1 1) crystal surfaces to (1 1 0) and (1 0 0) in the vapor environment. These conclusions can provide a valuable addition to the regenerative application of Ce-based catalysts in diesel exhaust aftertreatment system the aerial pollution.