Abundant Surface Oxygen Vacancies Research Articles

Insights into the enhanced hydrogen adsorption on M/La2O3 (M = Ni, Co, Fe).

Lanthanum oxide (La2O3) possesses superior reactivity during catalytic hydrogenation, but the intrinsic activity of La2O3 toward H2 adsorption and activation remains unclear. In the present work, we fundamentally investigated hydrogen interaction with Ni-modified La2O3. Hydrogen temperature programmed desorption (H2-TPD) on Ni/La2O3 shows enhanced hydrogen adsorption with a new hydrogen desorption peak at a higher temperature position compared to that on the metallic Ni surfaces. By systematically exploring the desorption experiments, the enhanced H2 adsorption on Ni/La2O3 is due to the oxygen vacancies formed at the metal-oxide interfaces. Hydrogen atoms transfer from Ni surfaces to the oxygen vacancies to form lanthanum oxyhydride species (H-La-O) at the metal-oxide interfaces. The adsorbed hydrogen at the metal-oxide interfaces of Ni/La2O3 results in improved catalytic reactivity in CO2 methanation. Furthermore, the enhanced hydrogen adsorption on the interfacial oxygen vacancies is ubiquitous for La2O3-supported Fe, Co, and Ni nanoparticles. Benefiting from the modification effect of the supported transition metal nanoparticles, the surface oxyhydride species can be formed on La2O3 surfaces, which resembles the recently reported oxyhydride observed on the reducible CeO2 surfaces with abundant surface oxygen vacancies. These findings strengthen our understanding of the surface chemistry of La2O3 and shed new light on the design of highly efficient La2O3-based catalysts with metal-oxide interfaces.

A-site defective La2-xCuO4 perovskite-type oxides for efficient oxidation of cyclohexylbenzene.

Phenol production through the oxidation of cyclohexylbenzene (CHB) and the subsequent decomposition of tertiary hydroperoxide has attracted more and more attention. In this study, defective La2-xCuO4 perovskite-type oxide catalysts with tunable A-site deficient structures and abundant surface oxygen vacancies were developed for the liquid phase oxidation of CHB to produce cyclohexylbenzene-1-hydroperoxide (CHBHP). By tuning the amount of A-site La ions in the perovskite structure, more surface oxygen vacancies and Cu+ species were formed in catalysts. The A-site-deficient La1.9CuO4 catalyst achieved significant catalytic efficiency along with a high CHBHP yield of 27.6% at 48.6% CHB conversion under reaction conditions (i.e., 120 °C and 12 h), outperforming those of other transition metal-based catalysts previously reported in the literature. A series of structural characterization methods and catalytic reactions highlighted the crucial roles of surface oxygen vacancies and metal La and Cu ions in the oxidation process. It was revealed that metal ions favored CHB adsorption and activation, while surface oxygen vacancies facilitated the creation of active adsorbed oxygen species. The present study offers an opportunity for the future design of new high-efficiency heterogeneous catalyst systems for CHB oxidation to obtain phenol.

Green structure orienting and reducing agents of wheat peel extract induced abundant surface oxygen vacancies and transformed the nanoflake morphology of NiO into a plate-like shape with enhanced non-enzymatic urea sensing application.

Researchers are increasingly focusing on using biomass waste for green synthesis of nanostructured materials since green reducing, capping, stabilizing and orientation agents play a significant role in final application. Wheat peel extract contains a rich source of reducing and structure orienting agents that are not utilized for morphological transformation of NiO nanostructures. Our study focuses on the role of wheat peel extract in morphological transformation during the synthesis of NiO nanostructures as well as in non-enzymatic electrochemical urea sensing. It was observed that the morphological transformation of NiO flakes into nanoplatelets took place in the presence of wheat peel extract during the preparation of NiO nanostructures and that both the lateral size and thickness of the nanostructures were significantly reduced. Wheat peel extract was also found to reduce the optical band gap of NiO. A NiO nanostructure prepared with 5 mL of wheat peel extract (sample 2) was highly efficient for the detection of urea without the use of urease enzyme. It has been demonstrated that the induced modification of NiO nanoplatelets through the use of structure-orienting agents in the wheat peel has enhanced their electrochemical performance. A linear range of 0.1 mM to 13 mM was achieved with a detection limit of 0.003 mM in the proposed urea sensor. The performance of the presented non-enzymatic urea sensor was evaluated in terms of selectivity, stability, reproducibility, and practical application, and the results were highly satisfactory. As a result of the high surface active sites on sample 2, the low charge transfer resistance, as well as the high exposure to the surface active sites of wheat peel extract, sample 2 demonstrated enhanced performance. The wheat peel extract could be used for the green synthesis of a wide range of nanostructured materials, particularly metal/metal oxides for various electrochemical applications.

Enriched Surface Oxygen Vacancies of Fe2(MoO4)3 Catalysts for a PDS-Activated photoFenton System

The environmentally benign Fe2(MoO4)3 plays a crucial role in the transformation of organic contaminants, either through catalytically decomposing oxidants or through directly oxidizing the target pollutants. Because of their dual roles and the complex surface chemical reactions, the mechanism involved in Fe2(MoO4)3-catalyzed PDS activation processes remains obscure. In this study, Fe2(MoO4)3 was prepared via the hydrothermal and calcine method, and photoFenton degradation of methyl orange (MO) was used to evaluate the catalytic performance of Fe2(MoO4)3. Fe2(MoO4)3 catalysts with abundant surface oxygen vacancies were used to construct a synergistic system involving a photocatalyst and PDS activation. The oxygen vacancies and Fe2+/Fe3+ shuttle played key roles in the novel pathways for generation of •O2-, h+, and 1O2 in the UV-Vis + PDS + FMO-6 photoFenton system. This study advances the fundamental understanding of the underlying mechanism involved in the transition metal oxide-catalyzed PDS activation processes.

SnO2 grains with abundant surface oxygen vacancies for the Ultra-sensitive detection of NO2 at low temperature

N-type metal oxide semiconductors are widely used in the field of gas sensors, but achieving high sensor response at low temperatures with low concentrations is challenging. In this paper, we report a high-performance gas sensor for NO2. SnO2 grains with different sizes and oxygen vacancies were prepared by a simple hydrothermal method followed by high-temperature calcination, and the electronic and chemical properties of the SnO2 grains were significantly changed. The results demonstrate that the sensor prepared from SnO2 grains hydrothermally grown at 180 °C has the optimal gas sensing performance with a response up to 4358.8 for 1 ppm NO2 at a low temperature of 80 °C, a rapid response recovery (7 s), and a detection limit down to 9 ppb. Together with some series characterization, an empirical factor F between the sensor response and the influencing factors is proposed. In addition, through experimental and density generalization studies, the oxygen vacancies are distinguished into surface oxygen vacancies and subsurface oxygen vacancies. The dominance of the surface oxygen vacancies in dictating the gas response is demonstrated. The excellent sensor characteristics demonstrated and the elucidation of the gas-sensitive mechanism provide a clear framework for the preparation of high-performance gas sensors.

Tailoring morphology of MgO catalyst for the enhanced coupling reaction of CO2 and glycerol to glycerol carbonate

Developing efficient halogen-free catalysts is still a significant challenge for adsorption and activation of CO2 and further preparing glycerol carbonate. Herein, we successfully developed heterogeneous MgO catalyst via morphology-oriented regulation to catalyze the coupling reaction of glycerol and CO2. Specifically, cubic MgO displays more low-coordinated O2– originated from the unique atomic arrangement of (111) facet, resulting in abundant strong basic sites and surface oxygen vacancies. These strong basic sites promote the adsorption of CO2 to form thermodynamically stable monodentate carbonates near the oxygen vacancies. In addition, nearby surface oxygen vacancies could further enhance the transfer of electrons into the anti-bonding orbitals of CO2 molecules. The synergistic catalytic effect between the strong basic sites and the surface oxygen vacancies significantly facilitates the cycloaddition reaction (the most critical step in the coupling reaction). Therefore, under the optimal reaction conditions (140 °C, 2 MPa CO2, and 4 h), the MgO-C catalyst showed 83 % glycerol conversion and 44 % glycerol carbonate selectivity.

Rare earths modified highly dispersed fibrous Ni/KCC-1 nanosphere catalysts with superb low-temperature CO2 methanation performances

In this work, a series of rare earths (Pr, Sm, Ce, La) doped Ni/KCC-1 catalysts were prepared and used for CO2 methanation. It was found that doping the rare earths could greatly improve the low-temperature catalytic activities and promoting effect of Sm was more prominent than other doped counterparts (Pr, Ce, La). The effect of the Sm loading amount on the catalytic activity were further evaluated. The kinetic studies revealed that the rare earth doped catalysts performed lower apparent activation energies than the pristine Ni/KCC-1 catalyst. In order to reveal the behind reasons, these catalysts were comprehensively characterized via XRD, XPS, TEM, SEM-EDS, CO2-TPD, H2-TPR, etc. It was found that the presence of the rare earth dopants could evidently intensify the metal-support interaction, promote the dispersion of the metallic Ni active sites, generate abundant surface oxygen vacancies, and enhance the amount of the medium basic sites. Besides, the online TPSR and in-situ DRIFTS indicated that the addition of the rare earth oxides could affect the type of the reaction intermediates and the potential pathway of the CO2 methanation. In general, these rare earths doped catalysts were deemed to be the superb catalyst candidates for the low-temperature CO2 methanation.

Enhanced photo-synergetic persulfate catalytic properties of Fe-doped TiO2 with engineered facets

• Facet engineered Fe/TiO 2 was used as photocatalyst for persulfate activation. • The band gap of the prepared Fe-{0 0 1}TiO 2 nanocatalyst was decreased from 3.24 eV to 2.97 eV. • The degradation efficiency of 3 % Fe/{0 0 1}TiO 2 was 97.81 % for 80 min. • OH, SO 4 − , e − and h + were contributed to the degradation in photo-synergetic persulfate system. • Fe-{0 0 1}TiO 2 exhibited excellent stability even after five consecutive cycles. Photo-synergetic persulfate oxidation is a prospective technology for water decontamination. Understanding the engineering facet activity of TiO 2 based nanocatalyst for persulfate (PS) activation is vital. Herein, Fe-doped TiO 2 nanocrystal with {0 0 1} crystal face exposed (Fe/TiO 2 ) is used to improve the degradation efficiency of Rhodamine B (RhB). The experimental results show that the Fe is introduced into the TiO 2 lattice, resulting in abundant surface oxygen vacancies in Fe/TiO 2 nanocrystal. The band gap of the as-prepared nanocatalyst was reduced from 3.24 eV to 2.97 eV. The degradation efficiency of RhB (10 mg/L) reaches 97.81 % after 80 min reaction. The enhanced catalytic performance benefits from the synergistic effect of enhanced visible light absorption and persulfate activation. OH, SO 4 − , e − and h + are proved to contribute to the degradation of RhB. This work presents a new opportunity to improve the efficiency of photo-synergetic persulfate oxidation by Fe doped TiO 2 .

Constructing Cu1-Ti dual sites for highly efficient photocatalytic hydrogen evolution

Constructing dual sites is promising to break scaling relations between the adsorption energetics of reaction intermediates and ultimately improves the activity and selectivity due to the synergistic effect. However, it is a grand challenge to precisely form a dual-site configuration with one metal site adjacent to another active site. Loading single atoms onto oxides with pre-introduction of surface oxygen vacancies may be an alternative strategy to overcome such challenge. Motivated by our theoretical calculations that the dual sites formed by single Cu atoms and unsaturated Ti sites on TiO2 enables a higher activity towards hydrogen evolution from water splitting than corresponding single site, we successfully synthesized a Cu1-Ti dual-site catalyst by depositing Cu single atoms on TiO2 nanoparticles with abundant surface oxygen vacancies. The designed target catalyst significantly outperforms the benchmark Pt nanoparticle decorated TiO2 with a high and stable activity towards photocatalytic hydrogen production.

Oxygen-vacancy-induced charge localization and atomic site activation in ultrathin Bi4O5Br2 nanotubes for boosted CO2 photoreduction

Solar CO2 reduction into value-added carbon fuels emerges as a sustainable and significant approach for CO2 conversion. However, poor photoabsorption, sluggish dynamics of multi-electrons transfer and high CO2 activation barrier substantially hamper CO2 photoreduction efficiency. Herein, freestanding ultrathin Bi4O5Br2 nanotubes with abundant oxygen vacancies were initially fabricated for optimizing these crucial processes. The ultrathin-shelled topologies of open tubular scaffolds and abundant surface oxygen vacancies endow the Bi4O5Br2 nanotubes with extended photo-response region and boosted charge separation. Furthermore, the presence of oxygen vacancies alters charge density distribution and affords abundant localized electrons on the catalysts’ surface. These not only reinforce covalent interactions, electron exchange and transfer between CO2 and oxygen vacancies, but also lower the CO2 reaction energy barriers and stabilize the rate-limiting COOH* intermediate. As a result, the OV-rich Bi4O5Br2 ultrathin nanotubes exhibit an outstanding CO production rate of 19.56 µmol g−1h−1 without using any cocatalyst or sacrificial agent, approximately 11.2 times higher than the Bi4O5Br2 nanoplates counterpart. This work provides insights into the future design of ultrathin hollow scaffolds for solar fuel photosynthesis and other applications.

ZSM-5 nanocrystal promoted low-temperature activity of supported manganese oxides for catalytic oxidation of toluene

• Nano-sized ZSM-5 zeolite was prepared by amino acid assisted method. • Effect of the support size on the formation of MnO x species was studied. • Small-sized ZSM-5 can highly disperse active MnO x species. • Abundant oxygen vacancies are formed on the MnO x supported by small-sized ZSM-5. • MnO x /Z5-L 0.2 shows excellent low-temperature activity in toluene combustion reaction. Nanoscale zeolites are of great practical interest due to their advantages of favorable mass transfer, accessibility to active sites, and large external surface area. Herein, ZSM-5 ( MFI -type) nano-sized zeolites were prepared by conventional hydrothermal and amino acid-assisted approaches to support MnO x species. The morphology, acidity, textural properties, and chemical state of the prepared MnO x /ZSM-5 samples are comprehensively characterized. The size effect of ZSM-5 nanocrystals on the physicochemical properties of supported MnO x species and on their catalytic oxidation behavior for the combustion of toluene is investigated. Beneficially from the larger surface area and smaller crystal size, the smaller-sized ZSM-5 zeolite (Z5-L 0.2 , ∼100 nm) prepared by the amino acid-assisted method can highly disperse more active MnO x species than the larger ZSM-5 counterpart (∼500 nm). Owing to abundant surface oxygen vacancies and surface adsorbed oxygen, as well as superior low-temperature reducibility, the MnO x supported on nanosized Z5-L 0.2 zeolites exhibits remarkably enhanced low-temperature activity for the catalytic oxidation of toluene.

Ru/HxMoO3-y with plasmonic effect for boosting photothermal catalytic CO2 methanation

Utilizing localized surface plasmon resonance (LSPR) effect of catalysts to facilitate photothermal catalysis of CO2 to CH4 is an attractive strategy for mitigating CO2 emissions. Herein, we demonstrate that Ru/HxMoO3-y synthesized via H-spillover exhibits plasmonic absorption in the visible-near-infrared (Vis-NIR) region, achieving a CH4 yield of 20.8 mmol/gcat/h (520 mmol/gRu/h) with 100 % selectivity in the CO2 methanation under Vis-NIR light irradiation at 140 °C. Irradiation with Vis-NIR light substantialy increases the CH4 yield (~ 4.7 fold) compared with that under dark conditions. The abundant surface oxygen vacancies provide active sites for CO2 adsorption and activation. In situ infrared spectroscopic analysis reveals that photothermal catalytic CO2 methanation follows *CO pathway. This work represents a simple strategy for developing a plasmonic catalyst for efficient photothermal catalytic CO2 methanation.

Catalytic Oxidation of Toluene over Fe-Rich Palygorskite Supported Manganese Oxide: Characterization and Performance

A series of Fe–rich palygorskite supported manganese oxide (X%Mn–Pal) catalysts were prepared by co-precipitation method and used as catalysts for toluene oxidation. The components and structure of the as-prepared catalysts were characterized by XRD, Raman, TEM, XPS, and in situ DRIFTS. The results showed that the 15%Mn–Pal catalyst exhibited the highest catalytic activity (T90 = 227 °C) and excellent cycling stability for the oxidation of toluene compared with other catalysts. The characterization results indicated that remarkable activity of the 15%Mn–Pal catalyst for toluene oxidation should be ascribed to the abundant surface oxygen vacancies. In situ DRIFTS results elucidated that benzoate was the main intermediate, which can be further oxidized into H2O and CO2. The objectives of this study are to (i) investigate the synergistic effect between Fe and Mn for toluene oxidation, (ii) develop an efficient catalyst for toluene abatement with high activity and low–cost, and (iii) promote the application of natural Fe–rich palygorskite in the control of VOCs.

Micellar interface modulation self-assembly strategy towards mesoporous bismuth oxychloride-based materials for boosting photocatalytic pharmaceuticals degradation

The spontaneous recombination of photogenerated carriers greatly limits the improvement of photocatalytic efficiency for bismuth oxychloride-based catalysts. Constructing porous or heterostructure photocatalysts can effectively inhibit their recombination. However, owing to the fast hydrolysis/condensation rates and uncontrollable nucleation/growth kinetics of Bi3+ species, it is difficult to achieve inorganic–organic co-assembly, and form mesoscopic structure and heterostructure. Herein, a series of mesoporous bismuth oxychloride-based materials (Bi2O3 at a stoichiometric ratio of 0 for Cl, Bi12O17Cl2, heterostructured Bi12O17Cl2/BiOCl and BiOCl) with various stoichiometry, tunable compositions and large surface areas are synthesized by a micellar interface modulation self-assembly strategy. In this strategy, Pluronic P123 and cetyltrimethyl ammonium chloride (CTAC) form P123/CTA+ composite micelles, which assemble with Bi3+ precursors by Coulomb interactions. Moreover, the Cl- ions are induced and modulated through composite micelles to involve in the slow hydrolysis and condensation of Bi3+ precursors at the hydrophilic-hydrophobic interface of composite micelles to form mesophase, thereby realizing the synthesis of mesoporous bismuth oxychloride with various stoichiometry and compositions by regulating CTAC amount. The prepared mesoporous Bi12O17Cl2/BiOCl-OV shows superior photocatalytic activity (degrade 83% within 30 min for 10 mg/L carbamazepine and 99% within 10 min for 10 mg/L ciprofloxacin), which can be ascribed to the mesoporous architecture, intimate contact heterojunction and abundant surface oxygen vacancies. This work provides a new idea and strategy for design and synthesis of high-efficiency mesoporous bismuth oxychloride-based photocatalysts.

Solid-State Construction of CuOx/Cu1.5Mn1.5O4 Nanocomposite with Abundant Surface CuOx Species and Oxygen Vacancies to Promote CO Oxidation Activity.

Carbon monoxide (CO) oxidation performance heavily depends on the surface-active species and the oxygen vacancies of nanocomposites. Herein, the CuOx/Cu1.5Mn1.5O4 were fabricated via solid-state strategy. It is manifested that the construction of CuOx/Cu1.5Mn1.5O4 nanocomposite can produce abundant surface CuOx species and a number of oxygen vacancies, resulting in substantially enhanced CO oxidation activity. The CO is completely converted to carbon dioxide (CO2) at 75 °C when CuOx/Cu1.5Mn1.5O4 nanocomposites were involved, which is higher than individual CuOx, MnOx, and Cu1.5Mn1.5O4. Density function theory (DFT) calculations suggest that CO and O2 are adsorbed on CuOx/Cu1.5Mn1.5O4 surface with relatively optimal adsorption energy, which is more beneficial for CO oxidation activity. This work presents an effective way to prepare heterogeneous metal oxides with promising application in catalysis.

Oxygen vacancies enhancing performance of Mg-Co-Ce oxide composite for the selective catalytic ozonation of ammonia in water

Catalytic ozonation based on heterogeneous metal oxides is a promising approach to removing ammonia as gaseous nitrogen from water. Herein, MgO/Co3O4/CeO2 was prepared for catalytic ozonation of ammonia in an aqueous solution. The influence of various reaction conditions was systematically investigated and optimized, in which the reaction kinetics was also analyzed. After doping Ce, the catalyst with Mg-Co-Ce molar ratio of 4:1:1 and calcined at 700 °C for 3 h, has abundant surface oxygen vacancies and exhibited excellent performance for the selective catalytic oxidation of ammonia to gaseous nitrogen by ozone. It was found that the catalytic activity of catalysts was positively related to oxygen vacancies concentration on the composites surface, which might play a vital role in selective catalytic ozonation. Under the optimal conditions, the ammonia removal rate in MgO/Co3O4/CeO2 catalytic system was 0.03328 min−1 (R2 = 0.99942), about 2.1 times greater than that of MgO/Co3O4 (0.01597 min−1, R2 = 0.99813), and the selectivity was further enhanced from 73.57% to 86.94%. Moreover, the evolution of nitrogen and chlorine species was determined to discuss the mechanism of selective oxidation of ammonia in the low chlorine-containing solution. This study might promote the understanding of catalytic ozonation of ammonia to gaseous nitrogen selectively.

ZIF-8 derived NiFe hydroxide on nickel foam for robust water oxidation

Developing active water oxidation electrocatalysts with earth-abundant components is significant for bulk hydrogen supply via water electrolysis. Herein, nickel iron hydroxide nanosheets assembled particles on nickel foam are prepared through ion-assisted etching method with ZIF-8 as precursor. The sample achieves remarkable catalysis efficiency toward oxygen evolution reaction with ultralow overpotential of 259 mV at high current density of 100 mA cm−2. The superior catalysis efficiency is assigned to Ni/Fe synergisms of optimized intrinsic activity, abundant surface oxygen vacancies, enhanced charge flow, and increased active sites, as well as nanosheet structure benefits of approachable catalytic sites and shortened charge transform pathways.

Dual co-catalysts decorated Zn-WO3 nanorod arrays with highly efficient photoelectrocatalytic performance

WO3 has been recognized as a promising photoanode for the conversion of solar energy to hydrogen energy through photoelectrochemical water splitting. Herein, Zn-WO3 nanorod arrays were synthesized by a two-step solvothermal method and then decorated with FeOOH and CoOOH dual co-catalysts layer through electrodeposition. Characterizations confirm the presence of abundant surface oxygen vacancies in Zn-WO3, leading to the increase of carriers with high mobility and thus improving the separation (from 63.7% to 92.0%) and injection (from 61.9% to 95.3%) efficiency of carriers. Meanwhile, the dual co-catalysts layer accelerates the transfer of the hole at the interface and inhibits the photocorrosion. Consequently, the optimal 9-Zn-WO3-Fe/Co exhibits the photocurrent of 3.63 mA/cm2 at 1.23 V vs. RHE, which is 90.7% of the theoretical value of WO3 (ca. 4.0 mA/cm2). This work constructs a highly efficient and stable WO3 photoanode by an integration strategy of transition metal doping and dual co-catalysts modification.

Synergetic Nanoarchitectonics of Defects and Cocatalysts in Oxygen-Vacancy-Rich BiVO4/reduced graphene oxide Mott-Schottky Heterostructures for Photocatalytic Water Oxidation.

Water oxidation process is a pivotal step of photosynthesis and stimulates the progress of high-performance catalysts for renewable fuel production. Despite the performance benefit of cocatalysts, defect engineering holds promise to settle inherent limitations of semiconductors aiming at sluggish water oxidation. Here, we modify the in situ growth pathway of monoclinic BiVO4 (m-BiVO4) on reduced graphene oxide (rGO), constructing abundant surface oxygen vacancies (OV)-incorporated m-BiVO4/rGO heterostructure toward water oxidation reaction under visible light. Owing to the OV in the m-BiVO4 component, a vacancy-related defect level allows more electrons to be photoexcited by low-energy photons to cause the electron transition, boosting photoabsorption as well as photoexcitation. Besides, the OV can reinforce surface adsorption and reduce the dissociation energy of water molecules. Particularly because of the synergy of OV and cocatalyst rGO, the OV functions as electron-trapped sites to facilitate the carrier separation; the rGO not only receives electrons from m-BiVO4 promoted by internal electric field over Mott-Schottky heterostructures but also spurs further electron diffusion along a highly conductive carbon network. These merits enable the OV-incorporated m-BiVO4/rGO heterostructure with an over 209% growth in O2 yield relative to the counterpart. The increased performance is also validated by the significant rise of •OH radicals and •O2- radicals. The current work paves a novel avenue for the integration of defect engineering and cocatalyst coupling in artificial photosynthesis.

Enhanced catalytic performance of atomically dispersed Pd on Pr-doped CeO2 nanorod in CO oxidation

Single-atom noble metal catalysts have been widely studied for catalytic oxidation of CO. Regulating the coordination environment of single metal atom site is an effective strategy to improve the intrinsic catalytic activity of single atom catalyst. In this work, single atom Pd catalyst supported on Pr-doped CeO2 nanorods was prepared, and the performance and nature of Pr-coordinated atomic Pd site in CO catalytic oxidation are systematically investigated. The structure characterization using AC-HAADF-STEM, EXAFS, XRD and Raman spectroscopy demonstrate the formation of single atom Pd site and abundant surface oxygen vacancies on the surface of Pr-doped CeO2 nanorod. With the combination of the XPS characterization and DFT calculations, the oxidation state of Pd on Pr-doped CeO2 nanorod is determined lower than that on CeO2 nanorod. The turnover frequency of CO oxidation is markedly increased from 8.4 × 10−3 to 31.9 × 10−3 s with Pr-doping at 130 ºC and GHSV of 70,000 h−1. Combined with kinetic studies, DRIFT and DFT calculations, the doped-Pr atoms reduced the formation energy of oxygen vacancies and generate more oxygen vacancies around the atomically dispersed Pd sites on the surface of cerium oxide, which reduces the dissociation energy of oxygen, thereby accelerating the reaction rate of CO oxidation.