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DOE OSTI2026

Influence of thermal treatment on structure and catalytic performance of ceria-zirconia supported copper oxide (CuO x /Ce y Zr 1-y O 2 ) catalysts for CO oxidation

Copper oxide (CuO x ) supported on ceria-zirconia (Ce y Zr 1-y O 2 , y = 1.0, 0.5, 0.0) catalysts were investigated to elucidate the effects of thermal treatment on their physicochemical properties and catalytic performance in carbon monoxide (CO) oxidation. Here, the catalysts were synthesized via a one-pot chemical vapor deposition (OP-CVD) method at 700˚C and 900˚C with controlled Cu loading. Characterization techniques, including synchrotron X-ray diffraction (S-XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), inductively coupled plasma spectroscopy (ICP), and N 2 adsorption-desorption, were implemented to probe the crystalline structure, molecular and electronic structure, oxygen vacancies, specific surface area (SSA) and metal loading. CO oxidation was chosen as a model reaction to explore the structure-catalytic performance relationship. A ∼100% CO conversion was achieved at < 150˚C, particularly with the CuO x /CeO 2 catalyst calcined at 700˚C. In contrast, calcination at 900˚C caused a ∼90% decrease in SSA and a ∼24% increase in T 50 . Activity tests revealed that increasing ZrO 2 content lowered CO oxidation activity despite generating more defect sites. In-situ measurement of the 700 °C calcined samples revealed the presence of stable and unstable defects in CuO x /Ce 0.5 Zr 0.5 O 2 and CeO 2 respectively, which play a key role in the activity of the catalysts. The results highlight that catalytic performance is closely related to the SSA. Furthermore, an optimum calcination temperature favor significant oxygen vacancy formation with required CuO x -support interactions, enhancing redox properties and catalytic performance.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Suppressing CO formation in low-temperature methanol steam reforming via Ce-modified CuZnGa layered oxide catalysts

Cu-based layered double hydroxides (LDHs) are widely recognized as effective catalysts for low-temperature methanol steam reforming, yet achieving high hydrogen productivity together with near-complete suppression of CO formation remains challenging. Here, we report the synthesis and evaluation of a series of CuZnGa LDH-derived catalysts and Ce-modified analogues prepared via an aqueous miscible organic method, which enables high metal dispersion and precise structural control. The optimized CuZnGa catalyst exhibits a hydrogen production rate of 16.9 µmol H 2 ·g cat −1 ·s −1 at 180 °C with an H 2 /CO ratio exceeding 3500, outperforming many state-of-the-art low-temperature systems. Importantly, the incorporation of small amounts of Ce further suppresses CO formation while maintaining high hydrogen productivity. Combined spectroscopic characterization and density functional theory calculations reveal that Ce is incorporated into the LDH lattice by substituting Ga 3+ sites up to a critical threshold, beyond which highly dispersed CeO x species are formed. These species provide mobile lattice oxygen that participates in a Mars-van Krevelen-type pathway, selectively oxidizing CO and suppressing the reverse water-gas shift reaction. This study establishes a clear relationship between Ce speciation, oxygen mobility, and catalytic selectivity in LDH-derived systems. The resulting catalysts demonstrate the potential of interface-engineered Cu-based materials for efficient low-temperature hydrogen production with minimal CO contamination.

09 BIOMASS FUELS↗

DOE OSTI2026

Comparative assessment of new oxygen carrier materials for gas switching reforming of natural gas: Techno-economics assessment, life cycle analysis, and experimental insights

The increasing demand for hydrogen and the CO 2 intensity of natural gas (NG) reforming motivate the development of low-carbon-emission hydrogen production technologies. Gas Switching Reforming (GSR) with integrated CO 2 capture, a technology based on Chemical Looping Reforming (CLR), has been experimentally proven and shows potential for scale-up. In this study, select oxygen carriers (OC) (NiO/Al 2 O 3 , Fe 2 O 3 -CeO 2 /Al 2 O 3 , and magnetite) were tested in methane steam reforming in a fixed bed reactor to determine their relative reactivities under relevant conditions for GSR (800 °C, 7 bar total pressure). Process models were then developed to perform techno-economic analysis (TEA) of GSR for hydrogen production (GSR-H 2 ) and a combined cycle (GSR-CC) in which high-purity H 2 is fired in a gas turbine to produce electricity. Operating at 10 bar and 1100 °C and with the additional recovery steps implemented increased H 2 production by ∼ 30% and improved efficiency relative to prior studies. For GSR-H 2 , the levelized cost of hydrogen (LCOH) is 1.61–1.64 $/kg-H 2 , competitive with a reference SMR case, though operating and maintenance costs are higher due to increased electricity demand. GSR-CC has a significantly higher levelized cost of electricity (LCOE) than its reference NGCC (natural gas combined cycle) plant, suggesting it is less competitive; however, increasing production scale could make it more attractive. Life-cycle results for GSR-H 2 indicate NG consumption drives ∼ 75% of total global warming impacts (∼2.3 kg CO 2 eq/kg H 2 ). An environmental, health, and safety screening suggests iron-based carriers are comparatively safer, whereas NiO may pose greater risks. Overall, GSR-H 2 is a scalable, competitive option for hydrogen production using nickel and non-nickel OC.

03 NATURAL GAS↗

DOE OSTI2025

Development and characterization of an aerosol-generated multi-method analytical particle test material

Ceria (CeO 2 ) particles with low to ultra-low loading of nickel dopant were produced using an aerosol-based, droplet-to-particle synthesis via an in-line calcination technique. This aerosol-based synthesis method enables the production of particles with a monodisperse size distribution. These produced and well-characterized, multi-element, ceria-based particles demonstrate a material exemplar for multi-method analytical testing. They were prepared from a cerium nitrate feedstock where low loading nickel dopant was added at target Ni/(Ni + Ce) atomic percents of 1 %, 0.1 %, and 0.01 %, using a nickel nitrate spike. This methodology proved to produce ceria particles doped with a dynamic range of low to ultra-low loadings of nickel over a 24-h period, with consistent size distribution, morphology, and composition. The successful incorporation of nickel was demonstrated with bulk and single particle inductively coupled plasma mass spectroscopy and revealed notable particle-to-particle elemental homogeneity. X-ray photoelectron spectroscopy demonstrated the presence of a high concentration of nickel dopant incorporated preferentially toward the surface of the particles, and that this dopant aided oxidation of surface Ce(III) atoms to Ce(IV). These particle test materials were then validated through X-ray absorption near edge spectroscopy, comparing the ultra-low 0.01 % Ni and low 1 % Ni-doped ceria samples. This revealed a more-reduced oxidation state of the nickel with an increase in dopant concentration. Finally, this work demonstrates a synthesis and systematic characterization scheme to produce multi-method analytical test particulates.

36 MATERIALS SCIENCE↗

DOE OSTI2024

Revisiting the influence of Ni particle size on the hydrogenation of CO 2 to CH 4 over Ni/CeO 2

Nickel nanoparticles were supported on CeO 2 and evaluated in the hydrogenation of CO 2 to CH 4 at 538 K and 1 atm. Chemisorption of H 2 was used to estimate the average Ni particle size, which ranged from 1.3 to 17 nm. The apparent activation energy for CH 4 formation and turnover frequency for CO 2 conversion was independent of Ni particle size. The smallest Ni particles (1.3 nm) were less selective to CH 4 . Comparisons to alumina-supported Ni reveal the same performance as Ni/CeO 2 when normalized to active Ni atoms counted by H 2 chemisorption. A beneficial effect of ceria relative to alumina is the enhanced reducibility of Ni as evaluated by H 2 temperature-programmed reduction. The constancy of the turnover frequency on Ni particles suggests the acid-base and/or redox properties of the support do not play a significant role in the CO 2 methanation reaction under the conditions of study, which contrasts many earlier works.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2026

Electric-field-assisted-sintering of rare-earth oxide dispersion strengthened Fe-Cr-Mo alloys

Oxide dispersion-strengthened (ODS) alloys are widely recognized for their exceptional high-temperature strength, creep resistance, and radiation tolerance, making them indispensable for advanced nuclear reactors, aerospace, and energy systems. Achieving a fine and stable dispersion of oxide nanoparticles is critical, as these particles act as strong barriers to dislocation motion and effective sinks for irradiation-induced defects, ensuring structural integrity under extreme conditions. Here, in this study, Fe–Cr–Mo-based ODS alloys were fabricated via mechanical alloying and consolidated using electric-field-assisted sintering (EFAS) with additions of Y 2 O 3 , La 2 O 3 , and CeO 2 . EFAS processing produced ultrafine-grained microstructures (average grain size <1 μm) with uniformly distributed oxide clusters (2–4 nm). Atom probe tomography revealed that La 2 O 3 -containing alloys exhibited the highest nanoparticle number density, resulting in superior tensile strength compared to yttria- and ceria-bearing counterparts. The combined effect of grain refinement and rare-earth oxide dispersion significantly enhanced mechanical performance, demonstrating the potential of EFAS for developing high-strength ferritic alloys for demanding environments such as nuclear systems.

36 - MATERIALS SCIENCE↗

DOE OSTI2026

Combustion-assisted ink-jet printing of nuclear targets

Advances in target fabrication are critical to high-precision measurements in nuclear physics. This work details the preparation of patterned CeO 2 and ThO 2 architectures and thin-film targets via ink-jet deposition of combustible solutions. The produced targets were characterized by scanning electron microscopy (SEM), and by alpha-particle spectroscopy for radioactive targets to determine densities. Ink jet printing of the targets, used both ethanol and 2-methoxyethanol as solvents, with cerium or thorium nitrate as the oxidizer and acetylacetone as the fuel. Additionally, we found that the distance between each droplet dispersion (step size) played the most significant role in determining the final pattern uniformity and thickness. A 50 μm step size leads to relatively thick targets with a density of 350 μg/cm 2 . Significant overlap in droplet sizes leads to a heterogeneous target with an undesirable cracked surface structure. In contrast, 150 μm spacing yields thinner (20 μg/cm 2 ) patterned structures with excellent surface coverage. This method of Ink-jet printing provides a straightforward, scalable, and high-efficiency pathway to prepare custom made, high-quality targets for nuclear physics experiments.

CeO2↗

DOE OSTI2025

Photon counting with intensified charge coupled device (ICCD) – I. In-depth detector characterization

While the adsorption properties of transition metal catalysts have been widely studied, leading to the discovery of various scaling relations, descriptors of catalytic activity, and well-established computational models, a similar understanding of semiconductor catalysts has not yet been achieved. In this work, we present a high-throughput density functional theory investigation into the adsorption properties of 5 oxides of interest to the photocatalytic CO 2 reduction reaction: TiO 2 (rutile and anatase), SrTiO 3 , NaTaO 3 , and CeO 2 . Using a systematic approach, we exhaustively identify unique surfaces and construct adsorption structures to undergo geometry optimizations. We then perform a data-driven analysis, which reveals the presence of weak adsorption energy scaling relations, the propensity of adsorbates of interest to interact with oxygen surface sites, and the importance of slab deformation upon adsorption. Our findings are presented in the context of experimental observations and in comparison to previously studied classes of catalysts, such as pure metals and tellurium-containing semiconductors, and reinforce the need for a comprehensive approach to the study of site-specific surface phenomena on semiconductors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Electronic and reactivity changes in epitaxially grown Ce 1-x Zr x O 2-δ (111) thin films

Ceria composite catalysts have long been used for ketonization reactions, which is a valuable chemistry for the upgrading of biomass-derived carboxylates. To better understand the interaction of zirconia with ceria in the context of ketonization, thin epitaxial films of ceria-zirconia mixed metal oxide Ce 1-x Zr x O 2-δ (x = 0-1) were grown on a Pt(111) substrate in ultrahigh vacuum conditions and studied with X-ray photoelectron spectroscopy (XPS). Core level and valence band XPS results suggest a strong interaction between ceria and zirconia cations, possibly due to increased filling of unoccupied 4f 0 orbitals of ceria from neighboring Zr cations in the lattice structure. This leads to a partial reduction of ceria from Ce 4+ to Ce 3+ , with Zr remaining predominantly in the 4+ oxidation state. Ketonization of acetic acid was studied using temperature programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). These results found ketonization over mixed Ce-Zr composite oxides exhibited lower activation energies than for pure CeO 2 and ZrO 2 , with Ce 0.38 Zr 0.62 O 2-δ exhibiting the highest yield of acetone among the studied surfaces. In conclusion, these results suggest the high activity of Ce-Zr catalysts appears to be a result of oxygen vacancy formation, stabilized by electron donation from Zr cations.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Systematic computational study of oxide adsorption properties for applications in photocatalytic CO 2 reduction

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2026

Thermal Gradient Effects on Redox Evolution and Volatility-Driven Fractionation in Ternary U/Ce/Cs Condensates

Understanding how thermal history influences redox evolution and chemical fractionation is essential for characterizing high-temperature condensation in complex materials, including nuclear debris. Here, we tested the hypothesis that distinct thermal regimes in a plasma flow reactor influence redox pathways and elemental partitioning in ternary U/Ce/Cs systems. A configurable plasma flow reactor was modified with an external tube furnace to impose two distinct thermal gradients: continuous ambient cooling and a furnace-assisted thermal hold-up near 1400 K followed by rapid cooling. Transmission electron microscopy characterized phase identity, morphology, and nanoscale element distributions, while inductively coupled plasma-mass spectrometry quantified bulk elemental ratios. Across both thermal regimes, uranium and cerium condensed as UO 2 and CeO 2 as dominant refractory oxide products. Uranium partially oxidized to α-UO 3 during extended ambient cooling, while furnace-assisted hold-up preserved UO 2 and produced partial reduction of cerium to Ce 2 O 3 . Cesium remained volatile upstream and condensed later in the reactor, forming Cs 2 O and Cs-uranate phases with the highest incorporation after thermal hold-up. Bulk ICP-MS measurements supported these observations. U/Ce ratios remained comparatively stable and Cs displayed delayed and apparent transient enrichment that matched the nanoscale measurements. This integrated approach provides a quantitative method for linking thermal gradients to redox evolution and volatility-driven fractionation. These results show how the plasma flow reactor can identify where equilibrium descriptions remain adequate and where kinetic effects from residence time and temperature history must be considered when interpreting condensation behavior in multicomponent systems.

and nuclear chemistry↗

DOE OSTI2026

Single-Particle Isotopic Analysis Using the Liquid Sampling-Atmospheric Pressure Glow Discharge Microplasma Coupled to an Orbitrap Mass Spectrometer

Isotope ratio (IR) determinations on individual particles can provide valuable information relative to the sample, including processing and dating, which could be valuable to geological and nuclear material analysis communities. In comparison to “bulk” measurements, in which all particle information is lost and homogenized within a sample, “particle” measurements allow for fingerprinting and can provide unique insights related to the sample’s nano- and micro- compositions. Furthermore, the complex nature of particles, with potential isobaric interferences from either the matrix or other elements within the same particle, poses a significant analytical challenge for conventional mass spectrometry platforms employed for elemental analysis due to their limited mass resolution. Presented here is the first demonstration of an ultrahigh resolution method for single particle (SP) isotopic analysis using the liquid sampling-atmospheric pressure glow discharge (LS-APGD) microplasma ionization source coupled to an Orbitrap mass spectrometer and FTMS Booster X2T acquisition/processing system. For proof of concept, well-characterized CeO 2 microparticles with a nominal diameter of 1.0 μm were analyzed at a mass resolution of ∼330,000. Important instrumental parameters were optimized to enable the detection of single particles. The 142 Ce/ 140 Ce ratio of individual particles and the population average were determined and compared to an SP inductively coupled plasma time-of-flight mass spectrometry (ICP-TOF-MS) analysis. The isotopic accuracy and precision were determined by two methods and found to be in good agreement with the SP-ICP-TOF-MS method, with the linear regression slope method providing a more accurate ratio, showing a ∼1.4% relative difference from the ratio determined from a particle digest. The encouraging performance of the method was further supported by a determined detection limit of 2.9 fg ( 142 Ce). The developed method is anticipated to overcome many of the challenges posed by isobaric interferences encountered in conventional mass spectrometry techniques when analyzing real-world samples for particle isotopic composition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2024

Impact of Sr-Containing Secondary Phases on Oxide Conductivity in Solid-Oxide Electrolyzer Cells

Solid-oxide electrolyzer cells (SOECs) based on a yttria-stabilized zirconia (YSZ) oxide electrolyte produce hydrogen from water with the assistance of excess thermal energy; however, Sr diffusion within the Gd-doped CeO 2 (GDC) barrier layer during processing or operation can lead to the formation of unwanted secondary phases such as SrO and SrZrO 3 . Here, to establish and compare the degree of impact of these phases on SOEC performance, we conduct first-principles calculations to study their bulk oxide conductivities and compare them to that of the YSZ electrolyte. We find that SrO has a low conductivity arising from the poor mobility and low concentration of mobile oxygen vacancies, and its presence in SOECs should therefore be avoided. SrZrO 3 also has a lower oxide conductivity than YSZ; however, this discrepancy is primarily due to lower vacancy concentrations rather than low mobility. We find that sufficient levels of Y-doping on the Zr site can increase oxygen vacancy concentrations in SrZrO 3 to achieve an oxide ionic conductivity on par with that of YSZ, thereby mitigating any potential deleterious effect on transport performance. Energy-dispersive X-ray spectroscopy confirms that Y is the most common minority element present in SrZrO 3 forming near the GDC–YSZ interface, alleviating concerns regarding the impact of SrZrO 3 on device performance. These results from our combined computational–experimental analysis can inform future engineering strategies designed to limit the detrimental effects of Sr-induced secondary phase formation on SOEC performance.

08 HYDROGEN↗

DOE OSTI2025

Microwave-Driven Nonoxidative and Selective Conversion of Methane to Ethylene over Mn-Based Catalysts

Recent advancements in microwave-driven nonoxidative catalytic synthesis of C 2 H 4 from CH 4 coupling offer a promising, energy-efficient, and eco-friendly alternative to conventional methods, where selective heating under microwave irradiation enables comparable conversions at substantially lower bulk temperatures and shorter reaction times. This study explores the performance of an MnO X -based catalyst supported on CeO 2 and HY zeolite (silica-toalumina ratio = 5.1) for the nonoxidative coupling of CH 4 (NOCM) under microwave irradiation. Inspired by the well-established efficacy of MnO X catalyst in oxidative CH 4 coupling (OCM), their application in NOCM has also shown significant performance. The catalytic system achieved 15% CH 4 conversion and 99% selectivity toward C 2 hydrocarbons and maintained 64% selectivity toward C 2 H 4 surpassing the yields reported in the literature even at higher temperatures (700−1000 °C). Catalyst performance was correlated with measurements by in situ Raman spectroscopy, and additional characterizations were performed using H 2 −temperature programmed reduction , NH 3 −temperature programmed desorption, and BET surface area analysis to understand structural changes during the reactions. These findings suggested that Mn functions as active sites for CH 4 activation in nonoxidative environments while also promoting efficient C−C coupling under microwave irradiation.

Catalysts↗

DOE OSTI2024

Combined Cyclohexene Dehydrogenation and Oxygenation over VO x /CeO 2 with O 2 and Vaporized H 2 O 2 as Oxidants

Selective oxidation of hydrocarbons over metal oxide catalysts frequently invokes Mars-van Krevelen (MvK) mechanisms involving lattice oxygens. At typical reaction temperatures, oxidative dehydrogenation reactions predominate and compete with total oxidation; production of more useful oxygenates is challenging. However, because regeneration of lattice oxygens has been previously hypothesized to involve transient formation of surface hydroperoxides or peroxides, MvK cycles should be capable of forming products derived from both lattice oxygen and surface (hydro)peroxide species, under certain conditions. In this report, we study the low temperature reaction of cyclohexene with O 2 over CeO 2 -supported VO x catalysts. Below 150°C and for higher VO x loading, cyclohexene converts to benzene and trans-1,2-cyclohexanediol with no appreciable CO 2 formation. Control experiments show similar behavior in other supported vanadia catalysts. Conversely, using vaporized H 2 O 2 as oxidant exclusively gives 1,2-cyclohexanedione, suggesting that MvK reoxidation cycles do not directly involve H 2 O 2 . Furthermore, these findings contribute to the current understanding of selective oxidation mechanisms, and demonstrate routes to the formation of industrially useful oxygenates with O 2 or vaporized H 2 O 2 over metal oxide catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2025

Breaking the Brønsted–Evans–Polanyi Relation with Dual-Metal Sites

Linear scaling relationships impose inherent limitations on catalyst activity; the Brønsted−Evans−Polanyi (BEP) relation, which correlates activation and reaction energies, is a prominent example. Here we report a dual-metal site catalyst (DMSC) on ceria that breaks the BEP relation for C−C coupling of methyl intermediates an elementary step in methane coupling to form ethane. The DMSC structure on CeO 2 (111) was discovered by density-functional theory (DFT) structural exploration and confirmed to be stable via ab initio thermodynamics and ab initio molecular dynamics. Homonuclear and heteronuclear DMSCs of Ni, Pd, Pt, Fe, Ru, Os, Co, Rh, and Ir (45 pairs in total) were examined for methyl affinity and methyl−methyl coupling activation energy. We found that many heteronuclear DMSCs break the BEP linear scaling due to a mixed low-affinity/high-affinity coadsorption of the two methyl groups, decoupling the step responsible for the activation energy (E a ) at the low-affinity site from the overall reaction energy (ΔE) determined by both sites. This mechanism of breaking the BEP relationship via the DMSCs offers a catalyst design principle for C−C coupling reactions.

Chen, Yiming [Vanderbilt Univ., Nashville, TN (Uni↗

DOE OSTI2025

Supported-Single Nickel Atom Catalysts for the Methanation of Carbon Dioxide

Synthesis of twenty-seven bimetallic catalysts consisting of nickel and one of nine different dopants (B, Co, Cu, Fe, Mg, Mn, Sn, V, and Zn) supported on three different metal oxides (Al 2 O 3 , CeO 2 , and SiO 2 ) is carried out via organometallic grafting. The catalysts are evaluated for their activity and selectivity for the CO 2 methanation reaction at a feed ratio of H 2 /CO 2 of 4 at 300 °C in a high-throughput flow reactor system. After in situ pre-activation (500 °C in H 2 ), Ni/Co/CeO 2 exhibited high conversion (84.3%) and selectivity for methane (99.6%). Ni/Co/CeO 2 was characterized by high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction, H 2 -temperature-programmed reduction (H 2 -TPR), and CO 2 -temperature-programmed desorption (CO 2 -TPD). HRTEM showed the presence of single Ni and Co atoms on ceria after pre-reduction at 500 °C and after the methanation reaction at 300 °C for 15 h. XPS determined that the strong interaction between Ni, Co, and ceria increased after the reduction, leading to a charge transfer between Ni and Ce that created oxygen vacancies in ceria. Nickel was found to be Ni 2+ in the as-prepared material and was partially reduced in the presence of cobalt and after the activation in H 2 at 500 °C. The DFT results show that both nickel and cerium exhibit lower Bader charges in the Ni/Co/CeO 2 system, confirming that the presence of cobalt enhances the reduction of both Ni and Ce through electronic interactions. This indicates that single cationic Ni atoms are highly effective for the methanation reaction. In conclusion, the organometallic grafting technique is found to be efficient for synthesizing catalysts with highly homogeneous dispersed species at low metal loadings (0.16 wt % Ni–0.15 wt % Co), which leads to high turnover frequency (up to 248.7 h –1 ) and durability for methanation.

CO2 conversion↗

DOE OSTI2026

N 2 O Formation Mechanism and Suppression Strategy on Pt Catalysts for NO x Removal from Hydrogen-Internal Combustion Engines

Pt-based catalysts exhibit excellent low-temperature activity in the selective catalytic reduction of NO x with H 2 (H 2 -SCR), but their tendency to form N 2 O poses a significant challenge for practical use. This issue is further complicated by unclear formation mechanisms, hindering the development of more efficient catalysts. This study explored the N 2 O generation mechanisms on Pt catalysts supported by MgO, Al 2 O 3 , SiO 2 , and TiO 2 , aiming to achieve a deep understanding that could advance the Pt catalysts with high NO x conversion and minimized N 2 O emissions. Through systematic kinetics and characterization analyses, the direct influence of the support acidity and reactant dynamics (O 2 and NO) on N 2 O formation was clearly revealed. Notably, the Pt catalysts with strong NO adsorption capacity showed reduced N 2 O generation, highlighting the critical role of NO adsorption sites in the H 2 -SCR process. By incorporation of NO adsorption sites (i.e., MgO, BaO, CeO 2 ) onto Pt/SiO 2 , both the H 2 -SCR efficiency and N 2 selectivity (reduced N 2 O selectivity) were significantly enhanced, effectively reducing the N 2 O emissions through optimized surface NO adsorption. These findings provide a design framework for more selective Pt-based catalysts, advancing H 2 -SCR systems for effective NO x abatement from hydrogen-internal combustion engines, which is a promising carbon-free transportation technology.

36 MATERIALS SCIENCE↗