Ni Particle Size Research Articles

Hydrotalcite-derived Ni-LDO catalysts via new approach for enhanced performances in CO2 catalytic reduction

In this work, hydrotalcite-derived new Ni-LDO catalysts were synthesized via sequenced precipitation, for CO2 catalytic reduction to synthetic natural gas (SNG) with high performances, while the traditional sample via coprecipitation was prepared and measured as the comparison. By regulating precipitation procedure, a significant performance enhancement was attained, in which the CO2 conversion rate per gram nickel was 7-times higher than that of the conventional comparison, at the temperature of 573 K and atmospheric pressure. In addition, the desired product selectivity is up to 99%. Structural characterizations proved that the as-synthesized catalysts showed layered meso-porous properties. An increasing Ni particle size and higher coverage of medium-strong basic sites was observed over the optimized catalyst sample prepared when part of Mg2+ and Al3+ were precipitated at first step. Catalyst surface nickel enrichment and promoted reducibility were also achieved when using sequenced precipitation. This work achievements provided a new route for surface nickel enrichment of much more active hydrotalcite-derived Ni-LDO layered catalysts for enhanced performances.

Active and stable Cu doped NiMgAlO catalysts for upgrading ethanol to n-butanol

Upgrading ethanol to n-butanol is an attractive way for renewable n-butanol production. Herein, Cu was selected to modify NiMgAlO catalysts for improving ethanol conversion and n-butanol selectivity. Over the optimized 2%Cu-NiMgAlO catalyst, ethanol conversion and n-butanol selectivity were enhanced to 30.0% and 64.2%, respectively, in 200 h time on stream at 523 K. According to physicochemical characterizations and theoretical calculations, the key role of multiple active sites in this reaction was extensively investigated. The plate-like structure of hydrotalcite was maintained over 2%Cu-NiMgAlO catalysts, with an average Ni particle size of ca. 5.4 nm. The presence of Cu species created CuNi alloy sites and Lewis acid-base pairs, and increased hydrogen transfer and condensation reactions, resulting in elevated ethanol conversion and n-butanol selectivity. Additionally, CuNi alloy had a strong interaction with CuNiMgAl oxides, forming homogeneous boundary due to their close ionic radius and lattice matching, and afforded the long time stability in the ethanol to n-butanol reaction.

Ni-CeO2 Catalyst with High Ni Loading Prepared by Salt-Assisted Solution Combustion for CO2 Methanation

An Ni-CeO2 catalyst with high Ni loading (50 wt.%) prepared by a salt-assisted solution combustion method was characterized by different methods and used for CO2 methanation. The specific surface area of the Ni-CeO2 catalyst prepared by salt-assisted solution combustion is 7 times that of the catalyst prepared by conventional solution combustion. The Ni-CeO2 catalyst prepared by salt-assisted solution combustion has smaller particle sizes of Ni and exhibits excellent activity at low temperatures. The high Ni loading and small Ni particle size can provide more metal Ni site and Ni-CeO2 interface, which help to improve the CO2 methanation performance.

Controllable synthesis of yolk–shell nickel phyllosilicate for CO2 methanation: Identifying effect of pore structure of silica sacrificial template

A group of yolk-shell nickel phyllosilicate catalysts were synthesized via the hydrothermal reaction of fibrous silica (KCC-1) and nickel nitrate for CO2 methanation. For the sake of revealing the effect of the pore structure of silica material on the Ni-phyllosilicate morphology, a mesoporous MCM-41 material with a smooth outer surface was used as a sacrificial template for comparison. After the hydrothermal reaction at 180 °C for 36 h, the KCC-1-dervied Ni-phyllosilicate (Ni/K-36) displayed a typical yolk-shell nanosphere morphology covered by nanosheets, while MCM-41-derived Ni-phyllosilicate (Ni/M-36) obtained nanosheets-wrapped sphere morphology with core-shell structure. This result showed that the pore structure of silica material played an important role in the formation of Ni-phyllosilicate with different structures. The fibrous, drive-through channels of KCC-1 enhanced pore accessibility and mass transfer for the simultaneous growth of Ni-phyllosilicate on its external and internal section, and the rapid accumulation of Ni-phyllosilicate outside as “shell” could slow down the further hydrothermal reaction of internal KCC-1, resulting in the shell of Ni-phyllosilicate and yolk of unreacted KCC-1. The chamber between yolk and shell could be expanded by increasing hydrothermal time; however, too long hydrothermal time was adverse for the catalytic activity because of the increased Ni particle size. On the other hand, the gradual etching of MCM-41 sphere from the outer surface resulted in the external accumulation of Ni-phyllosilicate as “shell” and internally unreacted MCM-41 as “core”. The yolk-shell Ni/K-36 exhibited higher catalytic activity than the core-shell structural Ni/M-36 for CO2 methanation owing to high Ni content and similar Ni particle size. In situ DRIFTS analysis showed that the existence of more active formate and absorbed CO intermediates resulted in the high activity of Ni/K-36 for CO2 methanation.

Suppressing byproduct formation for high selective CO2 reduction over optimized Ni/TiO2 based catalysts

One of the challenges for catalytic CO2 reduction is to control product selectivity, and new findings that can modify selectivity would be transformative. Herein, two kinds of TiO2 (homemade and commercial) with the same crystal phase but different surface properties are chosen as supports to prepare Ni-based catalysts for CO2 reduction, which show distinctly different product selectivity for CO2 reduction to CH4 or CO, as well as the CO2 conversion. The catalysts based on the homemade TiO2 support are highly selective for CH4 formation, while the latter ones are about 100% selective for CO formation under the same reaction conditions. In addition, the former ones are much active (more than 3 times) than the latter ones. We found that the collaborative contribution of Ti3+ and Ni2+ species and the electronic metal-support interactions effect maybe the main driving force behind for determining the product selectivity. Methane is almost exclusively produced over the catalysts with abundant Ti3+ and Ni2+ species and greater electronic metal-support interaction, otherwise, it will give priority to CO generation. The addition of CeO2 can reduce the Ni particle size and improve the dispersion of Ni nanoparticles, as well as create more Ti3+ species, contributing to the enhancement of CO2 conversion, but shows a negligible effect on product selectivity. Furthermore, the in situ DRIFT experiments and kinetic experiments indicate that the CO route is probably involved in the CO2 reduction process over the homemade Ni-CeO2/TiO2-CO catalyst with abundant Ti3+ and Ni2+ species and a strong electronic transform effect.

Production of Heterocyclic Primary Amines from Heterocyclic Aldehydes on Ni‐Mo/ZrO2

AbstractNi‐Mo/ZrO2 catalysts with Ni‐Mo loadings of 10 wt % were prepared by a sol‐gel method on a ZrO2 support and subsequently applied in the simple reductive amination of heterocyclic aldehydes. Among the various catalysts prepared, Ni‐Mo/ZrO2 catalysts with Ni:Mo = 2:1 exhibited the highest metal dispersion and the smallest Ni particle size. The results showed that the catalyst has good catalytic performance, in which the yield of furfurylamine can reach 96.6 %. Initially, oximes were synthesized from the corresponding aldehydes and hydroxylamine hydrochloride, and then heterocyclic primary amines were synthesized by simple hydroreductive amination of the oximes with a 12 % methanolic solution of NH3 in the presence of an Ni‐Mo/ZrO2 catalyst. The methanolic solution of NH3 was found to be more effective in inhibiting the formation of secondary and tertiary amines.

Dissimilar joining of cemented carbide to low-carbon steel via combustion welding: Effect of process parameters on the interfacial microstructure and joint strength

An innovative method based on pressure-assisted combustion synthesis reactions in compressed powder mixtures of nickel and titanium was developed to join WC-Co cemented carbide to VCN-150 steel (Standard No. 1.6582). A specially-designed experimental setup was used for induction heating of the samples under uniaxial pressure in an argon atmosphere. Rapid heating of the samples provoked the exothermic reaction between Ni and Ti, resulting in the in-situ formation of an NiTi-based intermediate layer between the steel and carbide parts. XRD and SEM-EDS analyses as well as shear strength test were used to characterize the samples and evaluate the quality of the joint. XRD analysis showed NiTi as the main phase in the joining layer. It was found out that a decrease in Ni particle size led to an increase in the contact surfaces of the powders and intensity of the reaction, resulting in improved adhesion of the joining parts, decreased porosity within the interlayer, and increase in the average shear strength. Although increasing the thickness of the bonding layer resulted in more intensive reactions, higher liberated heat, and wider diffusion layers at the interface, it led to relatively weak joints due to a rise in the volume percentage of porosity. The most favorable results in welding were obtained by using fine particles of the reactants and minimum thickness of the green interlayer (2 mm). By increasing the applied force during the process to ~600 N, shear strengths up to ~77 MPa could be obtained.

B-Ni/MgAl2O4 catalyzed dry reforming of methane: The role of boron to resist the formation of graphitic carbon

The present contribution reports a single-step synthesis of B(x)-Ni/MgAl2O4 (where x = 1%, 3%, and 5% wt.%) via the NaBH4 reduction for dry reforming of methane (DRM) and investigates the effect of B promotion. Characterization (ICP-OES, XRD, H2-TPR, XPS, HR-TEM with EDS and HAADF) results suggested B incorporation facilitates the formation of Ni0 and Ni-B species and smaller Ni particle size (∼7 nm) compared to unpromoted catalyst. The results of the DRM reaction indicated that ∼ 2.8 wt% B-containing catalyst (B(3)-Ni/MgAl2O4) exhibited maximum activity and minimum decline in conversion (%) for both reactants (CH4 and CO2). The Turnover frequency (TOFCH4) observed for the B(3)-Ni/MgAl2O4 is ∼ 2.6 times higher than the non-B catalyst. The investigation of spent catalysts confirms the insignificant deactivation due to the absence of graphitic carbon. The carbon formation is (∼11.2 times) lesser for B(3)-Ni/MgAl2O4 than for the non-B catalyst. The enhanced activity and low carbon deposition for B (∼2.8 wt%) containing catalyst attributed to the occupancy of B in octahedral sites of the Ni-sub surface, which restricts the crystalline growth leading to a smaller Ni particle size, stabilize the metallic state of Ni, and affect the Ni-C interaction during DRM.

Tri-reforming of methane for syngas production using Ni catalysts: Current status and future outlook

Tri-reforming of methane (TRM) emerged as an attractive approach for syngas production that combines the methane steam reforming (SMR), dry reforming (DRM) and partial oxidation (POX) reactions in a single process. The key merits of the TRM process are the ability to use flue gas directly in the process feedstock, the great flexibility to control the H2/CO ratio for downstream processes, and the relatively lower energy demand and carbon footprint. Considerable progress was achieved over the past decade in catalyst development, process modeling and optimization for syngas production using the TRM process. In this work a critical review of the literature pertaining to Ni-based catalyst development, TRM reaction kinetics, process development, and economics is presented. The use of Ni-based catalysts has received significant attention in recent years; hence this work aims to provide a summary and a critical analysis of the advancement achieved in the design of Ni-based catalysts. Developing active Ni-based catalysts with enhanced resistance to coke formation for the TRM process is anticipated to pave the way for further commercialization ventures. Ni catalysts supported on a wide range of support materials such as Al2O3, CeO2, ZrO2, TiO2, MgO and their mixed oxides are the most widely used catalysts for TRM processes. This review provides a critical analysis of the different attempts made to tune the catalyst properties such as the use of different supports, promotors, and synthesis protocols. Catalyst properties such as Ni dispersion, basicity, Ni particle size, thermal stability is evaluated for various catalytic systems to develop structure-property relationship in TRM processes. Moreover, studies on TRM reaction kinetics, process modeling, and economics are also reviewed. Future outlook in catalysts and process development is also presented in this review to shed lights on the potential pathways to develop TRM processes in an environmentally friendly, and cost-effective manner.

Experiment and simulation of flexible CNT/SA/PDMS electromagnetic shielding composite

Flexible electromagnetic shielding composites have a great potential for wide range applications. In this study, two flexible composites were produced by plating Ni nanoparticles on carbon nanotubes (CNTs) or infiltrating carbon nanofibers/polydimethylsiloxane (CNF/PDMS) polymer into CNT/sodium alginate (CNT/SA) sponge skeleton (CNT/SA/CNF/PDMS composites). The composites are tested under the X band in the frequency range of 8.2 – 12.4 GHz, the electromagnetic interference shielding effectiveness (EMI-SE) values of the above two composites are almost as twice as that of CNT/SA/PDMS composite at a same CNT loading. Introducing nano-sized Ni particles on CNT improved the microwave absorption capacity of the composite, while adding CNF on the PDMS matrix enhanced the conductivity of these composites. Under 10% strain, both flexible composites show stable conductivity. Simulation and calculation results shown that increasing the cladding rate of Ni nanoparticles on the surface of CNT, reducing the average size of Ni particles, and increasing the loading of CNF in PDMS matrix can significantly improve conductivity and then EMI performance of the materials. All of these could benefit for the design of flexible electromagnetic shielding composites.

Developing Nickel/Graphene Nano Sheets as an alternative primary battery anode

In this paper, we report the development of Nickel (Ni)/Graphene Nano Sheets (GNS) as a primary battery anode. The research focuses on the effect of Ni particle sizes on the performance of Ni/GNS anode. GNS and Ni/GNS (Ni wt% from 10 to 40%) are synthesized using the modified Hummers and impregnation method. We employed the use of commercial Zn-plate as an anode reference material. The materials are characterized with XRD, EDX, SEM, TEM and electrical conductivity meter. The XRD spectra of Ni-GNS have the broad and weak peaks at 2θ = 26.77 and 44.55° identified as C (002) and Ni (111), respectively. The XRD data is consistent with data obtained from EDX analysis which showed the presence of C and Ni at 0.277 and 7.472 keV respectively. The smallest Ni particle sizes of 23.4 nm was synthesized from Ni(20%)/GNS, Interestingly, the small particle size of Ni may improve the electrical conductivity of Ni/GNS. We found that Ni(20%)/GNS (62.2 μS/cm2) has a higher electrical conductivity value than GNS (61.4 μS/cm2) with commercial primary battery anodes Zn plate showing electrical conductivities of 35 μS/cm2. We therefore proposed the potential of Ni/GNS to be developed as alternative materials for primary battery anode.

Hydrogen production from aqueous phase reforming of glycerol over attapulgite-supported nickel catalysts: Effect of acid/base treatment and Fe additive

In this paper, a series of nickel-based catalysts supported on modified attapulgite (ATP) by acid (citric acid and EDTA) and base (NaOH) were prepared and applied to the aqueous phase reforming of glycerol (APRG). The modified ATP (MA) and as-prepared catalysts were detected using N2 adsorption-desorption, ICP-OES, XRD, FT-IR, SEM-EDS, HRTEM, XPS, H2-TPR, NH3-TPD. The results manifested that the acid/base treatment of ATP significantly increased the surface area and pore volume, enhanced the metal-support interaction (MSI) and decreased the Ni particle size, resulting in the better glycerol conversion and H2 selectivity, especially for Ni/MA-E catalyst, where the ATP was pretreated using EDTA. In addition, the bimetallic NiFe/MA-E catalyst exhibited the highest conversion of glycerol to gas product (54.4%) and H2 selectivity (84.6%) at very low temperature (280 °C). These results were attributed to the strongest the interplay of active metal with support by the formation of Ni–Fe alloy, resulting in the highest active metal dispersion, smallest metal particle size, lowest the reducibility of active metal and most surface Ni0 content. According to the characterizations of spent catalysts, it demonstrated that monometallic Ni catalysts presented obvious sintering of Ni metal particle and larger accumulation of carbon deposition, which led to the deactivation of the catalyst. While NiFe/MA-E catalyst showed less particle agglomeration and coke formation attributed to the lower content of surface acid site. Apart from that, another cause of catalyst deactivation might be the destruction of ATP skeleton during APRG.

Catalytic oleic acid hydrotreating to bio-aviation fuel over highly dispersed Ni/SAPO-11 catalysts prepared by citric acid and ethylene glycol co-assistance impregnation

A range of Ni/SAPO-11 catalysts was generated via citric acid impregnation using various solvents (water, ethanol, and ethylene glycol); these catalysts were employed to oleic acid hydrogenation for generating bio-aviation fuel. The catalysts were characterized through powder X-ray diffraction, low-temperature nitrogen adsorption–desorption, transmission electron microscopy, hydrogen temperature-programmed reduction, X-ray photoelectron spectroscopy, in-situ thermogravimetry-Fourier transform infrared, temperature-programmed desorption of ammonia, and pyridine-adsorbed infrared spectroscopy. It was observed that the type of solvent used for the preparation of catalysts influenced the Ni particle size of the catalysts. Notably, in the catalyst preparation process, citric acid as a chelating ligand and ethylene glycol as a solvent, can enhance the interaction between Ni and SAPO-11 support, leading to the formation of small nickel nanoparticles (6.7 nm), meantime with a large surface area and strong total acid content of 0.087 mmol/g. During oleic acid hydrogenation, the Ni/SAPO-11 catalyst with citric acid and ethylene glycol co-assistance impregnation exhibited excellent catalytic performance, with 99.9% conversion and 75.9% iso-alkanes (iso-C8-C18) selectivity. Particularly, to create more multibranched iso-alkanes and show stable catalytic performance after five runs.

Effect of pore structure on Ni/Al2O3 microsphere catalysts for enhanced CO2 methanation

An understanding of the support effect is fundamental for guiding the rational design of heterogeneous catalysts. Herein, the role of pore structure on metal dispersion and catalytic performance was comprehensively investigated using Ni/Al2O3 catalysts. Three different Al2O3 supports, including Al2O3 microspheres prepared in microchannels and two commercially available Al2O3 supports named Sample 1 and Sample 2, were used and the Ni/Al2O3 catalysts were prepared by wetness impregnation method. X-ray diffraction, transmission electron microscopy, H2 temperature-programmed reduction, X-ray photoelectron spectroscopy, N2 adsorption–desorption, and H2 pulse chemisorption analyses combined with a sintering kinetic model were used to investigate the effect of the support pore structure. The narrow pore size distribution (3–15 nm) of Al2O3 microspheres and Sample 1 led to a uniform NiO dispersion for the calcined catalysts. Moreover, the high specific surface area (291 m2/g) and large pore volume (1.0 mL/g) of the Al2O3 microspheres were beneficial for the deposition of NiO particles inside mesopore to obtain a stronger metal–support interaction. Owing to the smaller NiO nanoparticles and stronger metal–support interaction, the reduced Ni/Al2O3 microspheres exhibited an average Ni particle size of 10.2 nm under 36 wt% nickel loading, whereas the average Ni particle size loaded on Sample 1 and Sample 2 were 12.6 nm and 13.2 nm, respectively. The optimized CO2 conversion of 87.0% at 300 °C under atmospheric pressure was attributed to the large pore volume and uniform Ni dispersion of Ni/Al2O3 microsphere catalysts while the same value for Sample 1 and Sample 2 catalysts was 81.5% and 55.0%, respectively. This work provides valuable guidelines for designing effective CO2 methanation support and proves the potential application of Al2O3 microspheres for CO2 methanation.

Nickel Quantum Dots Anchored in Biomass‐Derived Nitrogen‐Doped Carbon as Bifunctional Electrocatalysts for Overall Water Splitting

AbstractQuantum dots (QD), mixed with carbon materials, have gained increasing interest in the last few years as electrocatalysts due to their outstanding properties, such as excellent catalytic activity and good thermodynamic stabilities. However, most QD‐carbon hybrids show lower catalytic activities than that theoretically predicted due to the aggregation of the QD‐carbon nanostructures during processing. Herein, biomass is used as a carbon source to prepare QD carbon nanostructures (Ni@CN) to address the aforementioned issue. The cells walls and membranes in the biomass materials are usually rich in sites that could regulate the deposition and growth of Ni from a salt precursor by a simple solution impregnation method. Due to the abundance of the seeding sits and the limited supply of Ni+, the Ni particles size is restricted to the QD level with 3–4 nm. The formed Ni compounds QD are strongly linked to the cells walls and membranes, which could be maintained after subsequent heat treatment. The prepared 3D architecture has high catalytic activity, large surface area, strong physical integration, and rapid charge transfer capability, which collectively enhances the performance toward oxygen evolution reaction and hydrogen evolution reaction, opening the door to empower the next‐generation green fuel conversion for carbon neutral.

Ni-based catalysts with coke resistance enhance by radio frequency discharge plasma for CH4/CO2 reforming

Coke deposition has been considered to be one of the most important reasons hindering the stability of the catalyst during CH4/CO2 reforming. In this study, after the addition of P123 (PEG-PPG-PEG triblock copolymer), Ni2+ can be well-dispersed on the mesoporous molecular sieve MCM-41. And then, the catalysts were prepared by using N2 radio frequency (RF) discharge plasma for different treatment times to reduce the size of Ni particles, improve the anti-coking performance, and thereby improve the stability of the catalyst. The results showed that the catalyst NM-P123-PN2h exhibits superior catalytic properties in the CH4/CO2 reforming. The initial conversions of CH4 and CO2 were 90.80% and 89.60% at 750 °C, respectively. The catalyst NM-P123-PN2h showed highly coke resistance with less carbon deposition (1.12%) at 750 °C after 10 h of continuous reaction, while the carbon deposition of the catalyst NM-C was 37.32%. Compared with the traditional calcination method, the catalyst prepared by plasma treatment has a smaller particle size and better dispersibility of nickel. In particular, the nickel particle size of the catalyst NM-C was 8.37 nm, however, that of the catalyst NM-P123-PN2h was only 1.70 nm, and the nickel particle size was reduced by 5 times. Therefore, it can be concluded that the catalyst prepared under the combined action of P123 and RF plasma-treated can effectively improve the coke resistance of the catalyst and the stability of the CH4/CO2 reforming.

The Effect of Ni Particle Size and Carbon Support on Catalytic Activity for Glucose Hydrogenation Reaction

The Effect of Ni Particle Size and Carbon Support on Catalytic Activity for Glucose Hydrogenation Reaction

Structural effect of Ni/TiO2 on CO methanation: improved activity and enhanced stability.

CO methanation over a supported Ni catalyst has attracted increasing attention for its applications in synthetic natural gas production, CO removal for ammonia synthesis and fuel cells, among others. However, the deactivation of the Ni catalyst caused by sintering and carbon deposition hinders further application of the Ni catalyst. The activity of Ni catalysts needs further improvement as well. In this work, the structural effect of the Ni/TiO2 catalyst on CO methanation was investigated. A plasma decomposition, initiated at room temperature and operated around 150 °C, of the nickel precursor was applied to prepare the catalyst. Compared to the thermally decomposed Ni/TiO2 catalyst, the plasma-decomposed catalyst shows improved activity with enhanced stability. The catalyst characterization shows that the plasma-decomposed Ni/TiO2 catalyst possesses smaller Ni particle size and higher Ni dispersion, resulting in improved coke resistance and enhanced anti-sintering ability for CO methanation. The present study confirms that a catalyst with good activity for CO methanation possesses good activity for CO2 methanation as well, if the CO2 methanation takes the CO methanation pathway.

Fabrication strategies of Ni-based catalysts in reforming of biomass tar/tar model compounds

Tar formation is an urgent issue during syngas production from biomass gasification, and the application of advanced catalysts has been proved to be an effective method for tar elimination. Among the existed catalysts, Ni-based catalysts are the commonly used catalysts for tar removal because of their low cost and high activity in tar conversion. In the last decades, there have tremendous literatures reported the preparation and modification of Ni-based catalysts and then used for biomass tar reforming. However, these are lacking a comprehensive review in the fabrication of Ni-based catalysts, and the rational design for the active Ni-based catalyst is crucial to promote the industrialization of gasification technology. Based on these, this paper aims to understand the key properties of Ni-based catalysts in biomass tar reforming and unravel the fabrication strategies for the catalyst design. For instance, morphology tailoring, Ni particle size optimizing, defects engineering, regulation of metal-support interaction, and synergistic effect tuning of Ni-based catalysts for the reforming of biomass tar and tar model compounds are discussed. Besides, the existed challenges and future direction in optimization of Ni-based catalysts are also highlighted.

Why Ni/CeO2 is more active than Ni/SiO2 for CO2 methanation? Identifying effect of Ni particle size and oxygen vacancy

An impregnated Ni/CeO2 catalyst with an array structure and a phyllosilicate-based Ni/SiO2 catalyst prepared by hydrothermal method were designed for CO2 methanation. The as-synthetized Ni/SiO2 catalyst exhibits a high Ni content of 25.9 wt%, while its CO2 conversion at low temperature is far lower than that of Ni/CeO2, whose Ni content is only 10.0 wt%. TEM and XRD results show that the Ni/CeO2 catalyst possesses very tiny Ni particle size of around 1.2 nm, which leads to large H2 uptake capacity. XPS and Raman analyses indicate that Ni/CeO2 obtains more oxygen vacancies resulting in promotion of the CO2 activation. The combined effect of the Ni/CeO2 catalyst to enhance chemisorption of H2 and CO2 leads to high low-temperature activity.