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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

From inanimate matter to living systems

Current understandings of the origin and evolution of life on earth from inaminate matter are reviewed. Approaches to the study of early life and its origin are considered, and it is noted that whereas the inference of origins from knowledge at hand is the approach favored by most theoreticians, only the laboratory simulation of the assembly of precellular polymers to protocells under geologically relevant conditions is capable of indicating the way in which life began. Progress in simulating the step-by-step emergence of a protocell composed of ordered macromolecules and having numerous protobiological activities through stages characterized by primordial matter, amino acids, proteinoids, protocells, light-active protocells and nucleic-acid instructed cells is discussed, with particular emphasis on experiments with proteinoid microspheres formed from self-ordered copolyamino acids. The subsequent development of ordered, protometabolic, infrastructured protoreproductive protocells is examined noting the importance of the formation of lysine-rich proteinoids with catalytic activities. Attention is also given to questions of the point of the actual emergence of life and scientific and creationist objections to the theory developed.

Fox, S. W.↗
DOE OSTI2024

Investigations of Relative Stability and Distribution of Mo Species in Pore Space of Mo/ZSM-5 Systems

Reduced forms of molybdenum (Mo) carbides anchoring in pore space of zeolites are considered as activated catalysts for the methane dehydroaromatization reaction. However, the atomic structure of the active sites and their stability under reactive conditions are still not clearly understood. Herein, we employ a synergistic theoretical and experimental approach to investigate this research gap. The Raman data shows the existence of the distributed binuclear and mononuclear Mo oxides in the pores that are corroborated by the hydrogen temperature-programmed reduction experiments. The binding free energies of mono- and bi-nuclear Mo carbides in straight and sinusoidal channels and their intersections as a function of temperature and anchoring sites have been determined. The catalysts with Mo coordinated at two anchoring sites are more stable compared to those located at the rings with one Al substitution. The activation energies of the catalysts migration to adjacent rings were estimated as a function of temperature and kinetics parameters of such migrations were determined. The migration is facilitated if there is one anchoring site shared between two rings. This process can contribute to an agglomeration mechanism leading to loss of catalytic activity.

Myshakin, Evgeniy↗
DOE OSTI2025

Nickel Enhances InPd-Catalyzed Nitrate Reduction Activity and N 2 Selectivity

Palladium–indium (PdIn) is a well-established bimetallic composition for reductively degrading nitrate anions, one of the most ubiquitous contaminants in the groundwater. However, the scarcity and the variable price of these rare-earth and platinum group critical metals may hinder their use for water treatment. Nickel (Ni), a nonprecious metal in the same element group as Pd, could partially replace and lower Pd usage if the resulting trimetallic composition is sufficiently catalytically active. Herein, we report the synthesis and nitrate reduction catalysis of activated carbon-supported “In-on-Pd-on-Ni” catalysts (InPdNi/AC). While bimetallic InPd/AC (0.05 wt % In, 1.3 wt % Pd) was expectedly active, trimetallic InPdNi/AC containing the same In amount, much less Pd (0.1 wt %), and 1 wt % Ni was >17 more active (k cat ≈ 20 vs 349 L min –1 g surface metal –1 ). X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations showed that Pd gained electron density from Ni, correlating to the increased nitrate reduction activity. Ammonium byproduct selectivity for InPdNi/AC (18% at 50% nitrate conversion) was lower compared to that of InPd/AC (48%), suggestive of the higher surface coverage of NO or its greater reactivity with NO 2 – , which led to more N 2 . Accounting for the catalyst precursor, manufacturing costs, and spent metal recovery, we calculated that Ni incorporation lowered the net catalyst cost significantly (from $\$$1028/kg to $\$$170/kg). The trimetallic composition lowered, by ∼26 times, the catalyst cost of a stirred tank reactor sized to the same treatment capacity as that for the bimetallic case. In conclusion, the results demonstrate that the partial replacement of the precious metal with an earth-abundant one leads to a higher efficiency and lower cost denitrification catalyst, via a material strategy that should be beneficial for other clean-water catalytic systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Elucidating the role of surface species in CO oxidation catalyzed by boron nitride nanotube supported transition metal oxides

Boron nitride nanotube (BNNT) is considered a highly promising catalyst support due to its outstanding thermal stability and chemical inertness. These characteristics make BNNT an attractive alternative for high-temperature applications. However, most studies to date have focused on incorporating platinum group metals (PGMs) to achieve high activity. Although BNNT-supported PGM catalysts are highly effective, their scarcity and high cost hinder widespread use in industrial processes. In this study, BNNT-supported transition metal oxides (TMO x /BNNT; TM = Fe, Co, Ni, and Cu) catalysts were investigated, and CO oxidation was applied as a model reaction to evaluate their catalytic performance. Several characterization techniques, including SEM-EDX, TEM, SXRD, H 2 -TPR, and XPS, were employed to examine their physicochemical properties. Notably, the particle size of the metal oxides differed significantly depending on the metal type. This variation is primarily attributed to the inherent metal–support interactions and the thermodynamic stability of each oxide during synthesis. These properties also affected catalytic activity, and various parameters, such as oxygen mobility and redox behavior, played important roles in determining performance. Finally, in situ DRIFTS, CO-TPSR, reaction-order analysis, and 18 O 2 isotope-labeling experiment were used to investigate the reaction mechanism. In conclusion, the findings provide insights into the design of cost-effective BNNT-supported catalysts and highlight their potential applicability in oxidation reactions.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Mechanistic Insights into CO 2 -to-CO Photoreduction by Proton-Responsive Imidazole–Pyridine Re(I) Complexes

Two Re(I) tricarbonyl complexes with imidazole-pyridine ligands, fac- [Re(CO) 3 (pbiH)Cl], (Re-pbiH), and fac-[Re(CO) 3 (bbzp)Cl] (Re-bbzp), where pbiH= 2-(2-pyridy)benzimidazole, bbzp = 2,6-bis(2-benzimidazolyl)pyridine, were synthesized, and their photophysical, electrochemical, and photochemical properties were investigated for application as photocatalysts for CO 2 -to-CO reduction. Upon light irradiation (λ > 370 nm) in CO 2 -saturated CH3CN using 1,3-dimethyl-2-phenyl-2,3-dihydro-1Hbenzo[ d]imidazole (BIH) as a sacrificial donor, Re-bbzp promotes CO formation with a turnover number (TON CO ) of 45 ± 2, whereas Re-pbiH displayed a significantly lower activity (TON CO = 8 ± 1). The role of the bbzp ligand in the photocatalytic behavior was examined in detail using IR spectroelectrochemistry (IR-SEC) together with in situ FTIR and UV−vis spectroscopy under photocatalytic conditions, revealing the formation of key intermediates involved in CO 2 activation. The superior activity of Re-bbzp was rationalized by its ability to function as a proton relay and two-electron acceptor. The role as a proton relay was further supported by the observation of a kinetic isotope effect (KIE = 1.5) when the deuterated electron donor BID was employed, in agreement with the unusual decrease in catalytic activity observed upon addition of Brønsted bases. Overall, these results provide new insights into the role of ligand-based proton-responsive sites in Re(I) tricarbonyl complexes and their impact on CO 2 reduction photocatalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Design of Twisted Two-Dimensional Heterostructures and Performance Regulation Descriptor for Electrocatalytic Ammonia Production from Nitric Oxide

The electrocatalytic reduction of nitric oxide (NO) to ammonia (NH 3 ) represents an attractive alternative for valorizing waste NO streams (NORR). However, discovering efficient catalysts for NO-to-NH 3 conversion remains challenging. We have designed metal-intercalated twisted graphene-BN heterostructures, in which metal atoms act as electron-transfer bridges. The twisted configuration facilitates cross-interface charge transfer, redistributing electrons from the graphene–metal interface to the metal–BN interface and BN surface. This electronic modulation enables boron atom adjacent to the metal center in BN to serve as active sites, promoting strong chemisorption and enhanced activation of NO. After high-throughput screening of the stability and NO capture ability of various transition metal-intercalated twisted heterostructures, we have investigated systematically the NORR pathways across 30 candidates. The results show that the rBN-Ti-Gθ and rBN-V-Gθ heterostructures exhibit exceptional NO-to-NH 3 catalytic performance under optimized twisting conditions. Additionally, using sure independence screening and sparsifying operator (SISSO) for model training, we propose a descriptor and establish a relationship between the twist angle and catalytic activity. This study bridges the gap in applying twisted heterostructures to NORR electrocatalysis and provides new insights and strategies for designing high-performance NORR catalysts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Mutation of an active site-adjacent residue in VIM indirectly dictates interactions with and blunts inhibition by D-captopril

Activity assays and X-ray crystallographic studies were undertaken to elucidate the inhibitory mechanism of captopril stereoisomers on Verona integron-encoded metallo-β-lactamases, specifically VIM-20, VIM-31, and VIM-15. All three VIM-2-like variants (VIM-20, VIM-31, and VIM-15) and VIM-2 expressed in Escherichia coli exhibited catalytic activity with comparable steady-state kinetic parameters. Among the tested thiol drugs (L- and D-captopril, D,L-thiorphan, and 2,3-dimercaprol), IC50 analyses indicated that D-captopril and 2,3-dimercaprol were more potent inhibitors against the VIM enzymes examined in this study. Notably, the IC50 value of D-captopril against VIM-31 was an exception, closely resembling that of L-captopril. To elucidate this exceptional inhibitory potency of D-captopril and its binding mode in the active site of VIM-31, high-resolution crystal structures of VIM-20, VIM-31, and VIM-15 in complex with both L- and D-captopril are reported. These findings will help evaluate whether the identified potent inhibitor D-captopril could be further developed as a pan inhibitor targeting the VIM-family enzymes.

Silwal, Surendra Bikram↗
DOE OSTI2025

Machine Learning‐Guided Discovery of High‐Entropy Perovskite Oxide Electrocatalysts via Oxygen Vacancy Engineering

Abstract High‐entropy perovskite oxides (HEPOs) have recently emerged as multifunctional catalysts. However, the HEPOs’ structural and compositional complexity hinders the easy and accurate extrapolation of activity indicators, which are essential for establishing structure‐property correlations. Here, OxiGraphX, is introduced as a novel graph neural network (GNN) model designed to capture the complex relationships among structure, composition, and atomic chemical environments for accurate prediction of oxygen vacancy formation energies (OVFEs) in HEPOs. By integrating machine learning (ML), density functional theory (DFT), and experimental validation, this work demonstrates an efficient framework for rapidly and accurately screening HEPO electrocatalysts for oxygen evolution reaction (OER). The OxiGraphX predicts OVFEs with a precision exceeding existing data, enabling the identification of compositions of higher oxygen vacancy content (OVC) and, thus, higher catalytic activity. Furthermore, the model explores latent spaces that translate effectively into experimental domains, bridging computational predictions with real‐world applications. This approach accelerates the discovery of high‐performance HEPO catalysts while providing deeper insights into their catalytic mechanisms.

Chemistry↗
DOE OSTI2024

The influence of exogenous amines on the electrochemical CO 2 reduction activity of a cobalt–pyridyldiimine catalyst

Studying the interactions between CO 2 sorbents and electrocatalysts for the electrochemical CO 2 reduction reaction (e-CO 2 RR) can offer viable strategies to advance the development of the Reactive Capture of CO 2 (RCC). In this report we studied the effect of amines on the performance of the [Co(PDI-Py)] catalyst for the e -CO 2 RR. The presence of amines shifts the onset potential for the e -CO 2 RR more positive and increases the catalytic activity while maintaining the high Faradaic efficiency (≥90%) for CO production.

Chemistry↗
NASA NTRS1994

Pr-specific phytochrome phosphorylation in vitro by a protein kinase present in anti-phytochrome maize immunoprecipitates

Protein kinase activity has repeatedly been found to co-purify with the plant photoreceptor phytochrome, suggesting that light signals received by phytochrome may be transduced or modulated through protein phosphorylation. In this study immunoprecipitation techniques were used to characterize protein kinase activity associated with phytochrome from maize (Zea mays L.). A protein kinase that specifically phosphorylated phytochrome was present in washed anti-phytochrome immunoprecipitates of etiolated coleoptile proteins. No other substrate tested was phosphorylated by this kinase. Adding salts or detergents to disrupt low-affinity protein interactions reduced background phosphorylation in immunoprecipitates without affecting phytochrome phosphorylation, indicating that the protein kinase catalytic activity is either intrinsic to the phytochrome molecule or associated with it by high-affinity interactions. Red irradiation (of coleoptiles or extracts) sufficient to approach photoconversion saturation reduced phosphorylation of immunoprecipitated phytochrome. Subsequent far-red irradiation reversed the red-light effect. Phytochrome phosphorylation was stimulated about 10-fold by a co-immunoprecipitated factor. The stimulatory factor was highest in immunoprecipitates when Mg2+ was present in immunoprecipitation reactions but remained in the supernatant in the absence of Mg2+. These observations provide strong support for the hypothesis that phytochrome-associated protein kinase modulates light responses in vivo. Since only phytochrome was found to be phosphorylated, the co-immunoprecipitated protein kinase may function to regulate receptor activity.

NASA Discipline Plant Biology↗
DOE OSTI2025

Mechanistic Insights into Molecular Copper Hydride Catalysis: the Kinetic Stability of CuH Monomers toward Aggregation is a Critical Parameter for Catalyst Performance

The activity of molecular copper hydride (CuH) complexes towards the selective insertion of unsaturated hydrocarbons under mild conditions has contributed significantly to versatile methodologies for upgrading these feedstocks. However, these catalysts are particularly susceptible to deleterious aggregation, leading to the depletion of active CuH species. Little is known about the mechanisms of CuH aggregation, how it influences overall catalyst performance, and how it can be controlled. We address these challenges with mechanistic studies on a model reaction of unactivated alkene hydroboration catalyzed by (IPr*CPh 3 )CuH (LCuH). Here, we report a comprehensive mechanistic investigation of this system, identifying an aggregation pathway that continuously depletes catalytically active LCuH to form inactive CuH clusters during turnover. Deactivation of LCuH is controlled primarily by the competition between the kinetics of the initial LCuH dimerization step and that of alkene insertion. We therefore propose that a more comprehensive understanding of CuH catalyst performance must account for the kinetics of the initial LCuH dimerization step, revising a previously explored thermodynamic understanding of CuH aggregation, where the concentration of active species is controlled by equilibria established between CuH dimers and monomers. With a series of (NHC)CuH congeners (NHC = N-heterocyclic carbene), we demonstrate that ostensibly minor structural modifications to the ligand peripheries can drastically affect the LCuH dimerization kinetics, while maintaining reactivity towards on–cycle alkene insertion. We employed a computational approach based on molecular dynamics simulations to provide an in-depth understanding of how specific structural ligand modifications can substantially increase the kinetic stability of monomeric CuH catalysts. Our combined experimental and computational studies suggest strategies for rational ligand design that can be broadly applied to molecular catalyst systems that are susceptible to deactivation via aggregation pathways.

Ryan, David E. [Pacific Northwest National Laborat↗
DOE OSTI2025

Facile Solvent-Free Synthesis of Manganese Nickel-Layered Double Hydroxide for Sustainable Water-Splitting Applications

The quest for efficient and sustainable water-splitting electrocatalysts has led to the development of a novel bifunctional material, manganese nickel-layered double hydroxide (MnNi-LDH), which demonstrates promising performance for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Although manganese-based materials are less explored than other transition metals, they offer significant potential owing to their widespread availability, affordability, and customizable electronic characteristics. MnNi-LDH exhibits a nanosheet morphology and a layered structure, which collectively provide numerous accessible active sites and facilitate efficient charge transfer and mass transport. Characterization using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy, and transmission electron microscopy reveals the structural and compositional properties of MnNi-LDH. The oxidation states of Mn and Ni, as determined by XPS, play a crucial role in improving the catalytic activity. Notably, MnNi-LDH demonstrates low overpotentials of 187 mV for OER and 225 mV for HER at 10 mA/cm 2 current density comparable to conventional catalysts. Long-term stability tests show minimal degradation in cell performance over 50 h, with a current density drop of only 0.6153% per hour for the OER and 0.37% per hour for the HER. Further, these findings highlight the potential of MnNi-LDH as a promising and environmentally friendly bifunctional electrocatalyst for water splitting, contributing to the advancement of renewable energy sources.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Dynamic control and quantification of active sites on ceria for CO activation and hydrogenation

Ceria (CeO 2 ) is a widely used oxide catalyst, yet the nature of its active sites remains elusive. This study combines model and powder catalyst studies to elucidate the structure-activity relationships in ceria-catalyzed CO activation and hydrogenation. Well-defined ceria clusters are synthesized on planar CeO 2 (111) and exhibit dynamic and tunable ranges of Ce coordination numbers, which enhance their interaction with CO. Reduced ceria clusters (e.g., Ce 3 O 3 ) bind CO strongly and facilitate its dissociation, while near-stoichiometric clusters (e.g., Ce 3 O 7 ) adsorb CO weakly and promote oxidation via carbonate formation. Unlike planar ceria surfaces, supported ceria clusters exhibit dynamic properties and enhanced catalytic activity, that mimic those of powder ceria catalysts. Insight from model studies provide a method to quantify active sites on powder ceria and guide further optimization of ceria catalysts for syngas conversion. This work marks a leap toward model-guided catalyst design and highlights the importance of site-specific catalysis.

03 NATURAL GAS↗
DOE OSTI2024

Synergistic Effects of the Electric Field Induced by Imidazolium Rotation and Hydrogen Bonding in Electrocatalysis of CO 2

The roles of the ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF₄]), and water in controlling the mechanism, energetics, and electrocatalytic activity of CO₂ reduction to CO on silver in non-aqueous electrolytes were investigated. The first electron transfer occurs to CO₂ at reduced overpotentials when it is trapped between the planes of [EMIM]⁺ ring and electrode surface due to cation re-orientation as determined from voltammetry, in-situ surface-enhanced Raman spectroscopy, and density functional theory calculations. Within this interface, water up to 0.5 M does not induce significant faradaic activity, opposing the notion of it as a free proton source. Instead, water acts as a hydrogen bond donor and the proton is sourced from [EMIM]⁺. Furthermore, this study demonstrates that alcohols with varying acidity tune the hydrogen bonding network in the interfacial microenvironment to lower the energetics required for CO₂ reduction. Here, the hydrogen bonding suppresses the formation of inactive carboxylate species, thus preserving the catalytic activity of [EMIM]⁺. The ability to tune the hydrogen bonding network opens new avenues for advancing IL-mediated electrocatalytic reactions in non-aqueous electrolytes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Pyrolysis in Molten Salts Converts Plastics into a Mesoporous Electrocatalyst with a High Density of Atomic Fe–N–C Active Site

Upcycling plastic waste into value-added products is a promising strategy for both economic and environmental sustainability. However, achieving control over structure–property correlations during the upcycling process remains challenging. Here, in this study, we investigate the modulation of active site formation during pyrolytic conversion of plastics to carbon by composition-controlled molten salts. Using melamine formaldehyde (MF) foams as a precursor, we demonstrate that their pyrolysis in eutectic chloride molten salts with Fe 2+ , Na + , and K + ions directs the carbonization process toward the formation of mesoporous functional carbon enriched with atomically dispersed Fe–N–C sites, which are well-known for their catalytic activity in oxygen reduction reaction (ORR). Compared to pyrolysis in the FeCl 2 -only salt, the incorporation of alkali metal ions (Na + , K + ) in the eutectic mixture facilitates nitrogen retention in the carbon matrix and modulates iron speciation. This synergistic environment promotes a higher density and more uniform dispersion of Fe–N–C moieties within the carbon matrix. Consequently, the resulting catalyst exhibits a high surface area, hierarchical porosity, and improved electrochemical properties. When tested as an ORR catalyst, the Fe–N–C-enriched catalyst delivers a high half-wave potential (E 1/2 = 0.875 V vs RHE) with nearly exclusive 4e – pathway. These properties are comparable to those of commercial Pt/C catalysts, along with improved stability.

Fe−N−C active sites↗
DOE OSTI2026

Active site design enables industrial scale H 2 O 2 electrosynthesis with metal-free catalysts

The electrosynthesis of hydrogen peroxide (H 2 O 2 ) via a two-electron oxygen reduction reaction enables decentralized H 2 O 2 production. While metal-free carbon catalysts are sustainable and low-cost, their performance is hindered by poorly defined active sites and uncontrolled defect states. Here, we resolve these challenges through active site design and catalyst screening using fluorine (F) and nitrogen (N) codoped carbons as model materials. Statistical analysis combined with density functional theoretical calculations reveals that F-induced structural modification and defect passivation optimize OOH* binding, with F-doping and adjacent F atoms predominantly lowering abs ΔG(OOH*). Experimental results confirm that semi-ionic C–F bonds passivate defects in nitrogen-doped carbon, enhancing catalytic activity and durability. The resulting (N, F)-codoped carbon achieves nearly 100% H 2 O 2 selectivity at 0.5–0.65 V versus the reversible hydrogen electrode and maintains > 95% across 0.01–0.65 V versus the reversible hydrogen electrode. In an electrolyzer, (N, F)-codoped carbon exhibits an H 2 O 2 yield rate of 74.35 mol g cat. −1 h -1 and sustains 300 mA cm -2 for 105 hours with ~95% faradaic efficiency. Coupling the two-electron oxygen reduction reaction with methanol oxidation further reduces cell voltage and enhances productivity. This work provides a means to design efficient catalysts for industrial H 2 O 2 electrosynthesis.

H2O2 electrosynthesis↗
DOE OSTI2026

Identification of In Situ Generated High-Spin Fe(II)-N 4 Active Sites for Acidic Oxygen Reduction Reaction via Operando 57 Fe Mössbauer Spectroscopy

Iron-nitrogen-carbon (FeNC) catalysts are considered among the most promising alternative to Pt catalysts in acidic oxygen reduction reaction (ORR), yet the geometric and electronic structures of the true active site under reaction conditions have not been clearly elucidated. Herein, we synthesized a representative FeNC catalyst by pyrolyzing Fe 3+ absorbed on ZIF-8-derived N-doped carbon at a mild temperature under the H 2 /Ar atmosphere, where a formation mechanism of FeN 4 sites through a Zn-mediated Fe nanoparticle atomization process was proposed. The resulting FeNC-750 catalyst shows high acidic ORR activity with a half-wave potential of 0.838 V and a peak power density of 1 W cm -2 in proton-exchange membrane fuel cell (PEMFC). By using operando 57 Fe Mössbauer spectroscopy on FeNC-750, it was revealed that the pyrrolic N-coordinated high-spin Fe 2+ N 4 sites, which are in situ generated from high-spin Fe 3+ N 4 during ORR, are identified as catalytic active states. Density functional theory calculations further verified that, compared to the pyridinic N-coordinated low-spin Fe 2+ N 4 , the pyrrolic N-coordinated high-spin Fe 2+ exhibits optimized adsorption energy for reaction intermediates, thereby lowering the energy barrier of the rate-determining step (RDS) and facilitating OH* desorption. In conclusion, this work provides both experimental and theoretical evidence of the true active site in the FeNC during acidic ORR, offering significant insights for the rational design of high-performance materials for acidic fuel cells.

FeNC catalyst↗
NASA NTRS1989

Modeling of carbon monoxide oxidation kinetics over NASA carbon dioxide laser catalysts

The recombination of CO and O2 formed by the dissociation of CO2 in a sealed CO2 laser discharge zone is examined. Conventional base-metal-oxide catalysts and conventional noble-metal catalysts are not effective in recombining the low O2/CO ratio at the low temperatures used by the lasers. The use of Pt/SnO2 as the noble-metal reducible-oxide (NMRO), or other related materials from Group VIIIA and IB and SnO2 interact synergistically to produce a catalytic activity that is substantially higher than either componet separately. The Pt/SnO2 and Pd/SnO2 were reported to have significant reaction rates at temperatures as low as -27 C, conditions under which conventional catalysts are inactive. The gas temperature range of lasers is 0 + or - 40 C. There are three general ways in which the NMRO composite materials can interact synergistically: one component altering the properties of another component; the two components each providing independent catalytic functions in a complex reaction mechanism; and the formation of catalytic sites through the combination of two components at the atomic level. All three of these interactions may be important in low temperature CO oxidation over NMRO catalysts. The effect of the noble metal on the oxide is discussed first, followed by the effect of the oxide on the noble metal, the interaction of the noble metal and oxide to form catalytic sites, and the possible ways in which the CO oxidation reaction is catalyzed by the NMRO materials.

Herz, Richard K.↗