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At least 163 records · Page 9

Ni Anchored to Hydrogen-Substituted Graphdiyne for Lithium Sulfide Cathodes in Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries are promising candidates for next-generation energy storage systems due to their high theoretical energy density and the low cost of sulfur. However, slow conversion kinetics between the insulating S and lithium sulfide (Li 2 S) remains as a technical challenge. In this work, we report a catalyst featuring nickel (Ni) single atoms and clusters anchored to a porous hydrogen-substituted graphdiyne support (termed Ni@HGDY), which is incorporated in Li 2 S cathodes. The rapidly synthesized catalyst was found to enhance ionic and electronic conductivity, decrease the reaction overpotential, and promote more complete conversion between Li 2 S and sulfur. The addition of Ni@HGDY to commercial Li 2 S powder enabled a capacity of over 516 mAh g Li 2 S –1 at 1 C for over 125 cycles, whereas the control Li 2 S cathode managed to maintain just over 200 mAh g Li 2 S –1 . In conclusion, these findings highlight the efficacy of Ni as a metal catalyst and demonstrate the promise of HGDY in energy storage devices.

25 ENERGY STORAGE↗

Size-Dependent Adsorption and Adhesion Energetics of Ag Nanoparticles on Graphene Films on Ni(111) by Calorimetry

Interest in the use of carbon supports for late transition metal nanoparticle catalysts has expanded rapidly due to the increasing importance of electrocatalysts for clean energy and environmental technologies and the use and storage of renewable electricity. Compared to oxide supports, almost nothing is known about the effect of metal nanoparticle size on the energies of the metal atoms within carbon-supported nanoparticles, yet these energies are crucial for understanding their surface reactivity and sintering kinetics. Here, the growth morphology and adsorption energetics of vapor-deposited Ag onto clean graphene/Ni(111) surfaces have been studied using a combination of single-crystal adsorption calorimetry (SCAC) and He + low-energy ion scattering (LEIS). The differential heat of Ag adsorption is 207 kJ/mol for making ~30 atom Ag particles on graphene terraces at 100 K and 16 kJ/mol higher for making ~9 atom Ag clusters at defect sites at the same temperature. The heat of adsorption increases rapidly with Ag coverage as 3D Ag nanoparticles nucleate and grow in size, asymptotically reaching within 5 kJ/mol of the bulk Ag sublimation enthalpy (285 kJ/mol) by 2 ML. The heats of adsorption and Ag nanoparticle densities from LEIS (~10 16 /m 2 ) were combined to provide the Ag/graphene adhesion energy (E adh = 1.8 J/m 2 in the large-particle limit) and the Ag chemical potential (μ) versus effective particle diameter (D). The Ag chemical potential was well-fitted by μ(D) = (3γ v /M – E adh )(1 + (1.5 nm)/D)(2V m /D), where γ v /M is the surface energy of bulk Ag and V m is its molar volume. The same equation is known to fit similar data for late transition metals on clean surfaces of metal oxide single crystals. The adhesion energy of Ag measured here on graphene falls within the wide range measured for Ag on those oxide surfaces and is almost as large as on the oxide that binds Ag particles most strongly, namely CeO 2 (111), which is well-known to be very effective at resisting catalyst deactivation by metal sintering. Furthermore, these results imply that carbon supports will be effective at resisting sintering and that Ag particles smaller than 6 nm on graphene will bind small adsorbed reaction intermediates more weakly than supports with weaker adhesion to Ag, like MgO(100).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Nature of Zirconia on a Copper Inverse Catalyst Under CO 2 Hydrogenation Conditions

The growing concern over the escalating levels of anthropogenic CO 2 emissions necessitates effective strategies for its conversion to valuable chemicals and fuels. In this research, we embark on a comprehensive investigation of the nature of zirconia on a copper inverse catalyst under the conditions of CO 2 hydrogenation to methanol. We employ density functional theory calculations in combination with the Grand Canonical Basin Hopping method, enabling an exploration of the free energy surface including a variable amount of adsorbates within the relevant reaction conditions. Our focus centers on a model three-atom Zr cluster on a Cu(111) surface decorated with various OH, O, and formate ligands, noted Zr 3 O x (OH) y (HCOO) z /Cu(111), revealing major changes in the active site induced by various reaction parameters such as the gas pressure, temperature, conversion levels, and CO 2 /H 2 feed ratios. Further, through our analysis, we have unveiled insights into the dynamic behavior of the catalyst. Specifically, under reaction conditions, we observe a large number of composition and structures with similar free energy for the catalyst, with respect to changing the type, number, and binding sites of adsorbates, suggesting that the active site should be regarded as a statistical ensemble of diverse structures that interconvert.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Modulating CO 2 Electrocatalytic Conversion to the Organics Pathway by the Catalytic Site Dimension

Electrochemical reduction of carbon dioxide to organic chemicals provides a value-added route for mitigating greenhouse gas emissions. Here, we report a family of carbon-supported Sn electrocatalysts with the tin size varying from single atom, ultrasmall clusters to nanocrystallites. High single-product Faradaic efficiency (FE) and low onset potential of CO 2 conversion to acetate (FE = 90% @ –0.6 V), ethanol (FE = 92% @ –0.4 V), and formate (FE = 91% @ –0.6 V) were achieved over the catalysts of different active site dimensions. The CO 2 conversion mechanism behind these highly selective, size-modulated p-block element catalysts was elucidated by structural characterization and computational modeling, together with kinetic isotope effect investigation.

10 SYNTHETIC FUELS↗

Hierarchically porous and single Zn atom-embedded carbon molecular sieves for H2 separations

Abstract Hierarchically porous materials containing sub-nm ultramicropores with molecular sieving abilities and microcavities with high gas diffusivity may realize energy-efficient membranes for gas separations. However, rationally designing and constructing such pores into large-area membranes enabling efficient H 2 separations remains challenging. Here, we report the synthesis and utilization of hybrid carbon molecular sieve membranes with well-controlled nano- and micro-pores and single zinc atoms and clusters well-dispersed inside the nanopores via the carbonization of supramolecular mixed matrix materials containing amorphous and crystalline zeolitic imidazolate frameworks. Carbonization temperature is used to fine-tune pore sizes, achieving ultrahigh selectivity for H 2 /CO 2 (130), H 2 /CH 4 (2900), H 2 /N 2 (880), and H 2 /C 2 H 6 (7900) with stability against water vapor and physical aging during a continuous 120-h test.

42 ENGINEERING↗

Revealing the Hidden Third Dimension of Point Defects in Two-Dimensional MXenes

Point defects govern many important functional properties of two-dimensional (2D) materials. However, resolving the three-dimensional (3D) arrangement of these defects in multi-layer 2D materials remains a fundamental challenge, hindering rational defect engineering. Here, we overcome this limitation using an artificial intelligence-guided electron microscopy workflow to map the 3D topology and clustering of atomic vacancies in Ti3C2TX MXene. Our approach reconstructs the 3D coordinates of vacancies across hundreds of thousands of lattice sites, generating robust statistical insight into their distribution that can be correlated with specific synthesis pathways. This large-scale data enables us to classify a hierarchy of defect structures-from isolated vacancies to nanopores-revealing their preferred formation and interaction mechanisms, as corroborated by molecular dynamics simulations. This work provides a generalizable framework for understanding and ultimately controlling point defects across large volumes, paving the way for the rational design of defect-engineered functional 2D materials.

2D materials↗

Interactions between fullerene derivatives and biological systems

Attention towards nanoparticles from the pharmaceutical and biomedical fields has significantly increased due to their attractive surface modification, high drug-loading, and improved pharmacokinetics. Fullerenes, an allotrope of carbon, stand out for their molecularly precise structure, potent radical-scavenging activity, photoactivatable reactive-oxygen species generation, and ability to definitively confine metal atoms and clusters. Accordingly, fullerene systems have been applied in various biological contexts, including increased and controlled drug delivery, antioxidative, anti-inflammatory, and photodynamic therapy, and magnetic resonance imaging. Ultimately, the pleiotropic activity of fullerenes, coupled with its precise structure and functionalization, can realize precise and tailorable medicines. Here, different from some excellent reviews focusing on the structure and chemistry of fullerene derivatives and their biomedical applications, this review highlights the interaction of fullerene materials with biological systems, with insights into their structural influence on their interactions with the cellular environment.

36 MATERIALS SCIENCE↗

Impact of environmental oxygen on nanoparticle formation and agglomeration in aluminum laser ablation plumes

Here, the role of ambient oxygen gas (O 2 ) on molecular and nanoparticle formation and agglomeration was studied in laser ablation plumes. As a lab-scale surrogate to a high explosion detonation event, nanosecond laser ablation of an aluminum alloy (AA6061) target was performed in atmospheric pressure conditions. Optical emission spectroscopy and two mass spectrometry techniques were used to monitor the early to late stages of plasma generation to track the evolution of atoms, molecules, clusters, nanoparticles, and agglomerates. The experiments were performed under atmospheric pressure air, atmospheric pressure nitrogen, and 20% and 5% O 2 (balance N 2 ), the latter specifically with in situ mass spectrometry. Electron microscopy was performed ex situ to identify crystal structure and elemental distributions in individual nanoparticles. We find that the presence of ≈20% O 2 leads to strong AlO emission, whereas in a flowing N 2 environment (with trace O 2 ), AlN and strong, unreacted Al emissions are present. In situ mass spectrometry reveals that as O 2 availability increases, Al oxide cluster size increases. Nanoparticle agglomerates formed in air are found to be larger than those formed under N 2 gas. High-resolution transmission electron microscopy demonstrates that Al 2 O 3 and AlN nanoparticle agglomerates are formed in both environments; indicating that the presence of trace O 2 can lead to Al 2 O 3 nanoparticle formation. The present results highlight that the availability of O 2 in the ambient gas significantly impacts spectral signatures, cluster size, and nanoparticle agglomeration behavior. These results are relevant to understanding debris formation in an explosion event, and interpreting data from forensic investigations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Methanol carbonylation to acetaldehyde on Au particles supported by single-layer MoS 2 grown on silica

Homogenous single-layer MoS 2 films coated with sub-single layer amounts of gold are found to isolate the reaction of methanol with carbon monoxide, the fundamental step toward higher alcohols, from an array of possible surface reactions. Active surfaces were prepared from homogenous single-layer MoS 2 films coated with sub-single layer amounts of gold. These gold atoms formed clusters on the MoS2 surface. A gas mixture of carbon monoxide (CO) and methanol (CH 3 OH) was partially converted to acetaldehyde (CH 3 CHO) under mild process conditions (308 kPa and 393 K). This carbonylation of methanol to a C 2 species is a critical step toward the formation of higher alcohols. Density functional theory modeling of critical steps of the catalytic process identify a viable reaction pathway. Imaging and spectroscopic methods revealed that the single layer of MoS 2 facilitated formation of nanoscale gold islands, which appear to sinter through Ostwald ripening. Here, the formation of acetaldehyde by the catalytic carbonylation of methanol over supported gold clusters is an important step toward realizing controlled production of useful molecules from low carbon-count precursors.

2D catalyst↗

Dynamic Observation of Dendritic Quasicrystal Growth upon Laser-Induced Solid-State Transformation

In this paper, we report the laser-induced solid-state transformation between a periodic “approximant” and quasicrystal in the Al-Cr system during rapid quenching. Dynamic transmission electron microscopy allows us to capture in situ the dendritic growth of the metastable quasicrystals. The formation of dendrites during solid-state transformation is a rare phenomenon, which we attribute to the structural similarity between the two intermetallics. Through ab initio molecular dynamics simulations, we identify the dominant structural motif to be a 13-atom icosahedral cluster transcending the phases of matter.

36 MATERIALS SCIENCE↗

Multi-kernel Edge Attention Graph Autoencoder

MEAGraph (Multi-kernel Edge Attention Graph Autoencoder) is a graph-based autoencoder model designed for unsupervised data mining for datasets used in machine learning potentials. It provides accurate clustering for atomic environment identification, unsupervised and unlabeled data pruning for dataset construction.

Sun, Hong↗

Metals and Quantum Materials with Spin-orbit Interactions by Quantum Monte Carlo methods

The key goals of this project were as follows: 1) Analysis and benchmarks of electron correlation effects recovered in the fixed-node approximation that is inherent to quantum Monte Carlo (QMC) method as applied to metallic states; 2) development of new algorithms for electron spin-degrees of freedom to be treated as explicit quantum variables; 3) designing electronic structure QMC algorithm for efficient evaluation of spin-orbit effects in systems with heavy atoms; 4) adapting the algorithm to complex wave functions and developing corresponding fixed-phase approximation; 5) design and testing of algorithm for valence-only non-local spin-orbit operators; 6) analysis of fixed-node vs fixed-phase errors and their comparisons. The key accomplishments: i) We carried out a systematic study of Li systems by the fixed-node diffusion Monte Carlo method. This involved Li atom, molecule, cluster and solid calculated by the full range of QMC methods including fixed-node QMC.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Compositionally-Driven Formation Mechanism of Hierarchical Morphologies in Co-Deposited Immiscible Alloy Thin Films

Co-deposited, immiscible alloy systems form hierarchical microstructures under specific deposition conditions that accentuate the difference in constituent element mobility. The mechanism leading to the formation of these unique hierarchical morphologies during the deposition process is difficult to identify, since the characterization of these microstructures is typically carried out post-deposition. We employ phase-field modeling to study the evolution of microstructures during deposition combined with microscopy characterization of experimentally deposited thin films to reveal the origin of the formation mechanism of hierarchical morphologies in co-deposited, immiscible alloy thin films. Our results trace this back to the significant influence of a local compositional driving force that occurs near the surface of the growing thin film. We show that local variations in the concentration of the vapor phase near the surface, resulting in nuclei (i.e., a cluster of atoms) on the film’s surface with an inhomogeneous composition, can trigger the simultaneous evolution of multiple concentration modulations across multiple length scales, leading to hierarchical morphologies. We show that locally, the concentration must be above a certain threshold value in order to generate distinct hierarchical morphologies in a single domain.

36 MATERIALS SCIENCE↗

Isomerization and Selective Hydrogenation of Propyne: Screening of Metal–Organic Frameworks Modified by Atomic Layer Deposition

Various metal oxide clusters upward of 8 atoms (Cu, Cd, Co, Fe, Ga, Mn, Mo, Ni, Sn, W, Zn, In, and Al) were incorporated into the pores of the metal–organic framework (MOF) NU-1000 via atomic layer deposition (ALD) and tested via high-throughput screening for catalytic isomerization and selective hydrogenation of propyne. Cu and Co were found to be the most active for propyne hydrogenation to propylene, and synergistic bimetallic combinations of Co and Zn, along with standalone Zn and Cd, were established as the most active for conversion to the isomerized product, propadiene. The combination of Co and Zn in NU-1000 diminished the propensity for full hydrogenation to propane as well as coking compared to its individual components. Finally, this study highlights the potential for high-throughput screening to survey monometallic and bimetallic cluster combinations that best affect the efficient transformation of small molecules, while discerning mechanistic differences in isomerization and hydrogenation by different metals.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

High‐Spin and Reactive Fe 13 Cluster with Exposed Metal Sites

Abstract Atomically defined large metal clusters have applications in new reaction development and preparation of materials with tailored properties. Expanding the synthetic toolbox for reactive high nuclearity metal complexes, we report a new class of Fe clusters, Tp* 4 W 4 Fe 13 S 12 , displaying a Fe 13 core with M−M bonds that has precedent only in main group and late metal chemistry. M 13 clusters with closed shell electron configurations can show significant stability and have been classified as superatoms. In contrast, Tp* 4 W 4 Fe 13 S 12 displays a large spin ground state of S =13. This compound performs small molecule activations involving the transfer of up to 12 electrons resulting in significant cluster rearrangements.

Scott, Anna G.↗

Materials Data on Te2As2SI6(OF6)2 by Materials Project

AsTeF4(AsF3)2AsTeIF5As3Te3SO6I13F25AsSI2F3OIS1SI2Te2OI4F4TeIF crystallizes in the triclinic P1 space group. The structure is one-dimensional and consists of one ctk7c3725 molecule; two trifluoroarsine molecules; one AsSI2F3 cluster; one AsTeF4 cluster; one AsTeIF5 cluster; one OIS1 cluster; one Te2OI4F4 cluster; one TeIF cluster; and one As3Te3SO6I13F25 ribbon oriented in the (1, 0, 0) direction. In the AsSI2F3 cluster, As5+ is bonded in a distorted T-shaped geometry to three F1- atoms. There is one shorter (1.77 Å) and two longer (1.78 Å) As–F bond length. S2- is bonded in a 3-coordinate geometry to two I and one F1- atom. There are one shorter (2.41 Å) and one longer (2.42 Å) S–I bond lengths. The S–F bond length is 3.11 Å. There are two inequivalent I sites. In the first I site, I is bonded in a single-bond geometry to one S2- atom. In the second I site, I is bonded in a single-bond geometry to one S2- atom. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one As5+ and one S2- atom. In the third F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the AsTeF4 cluster, As5+ is bonded in a distorted T-shaped geometry to three F1- atoms. There is two shorter (1.76 Å) and one longer (1.82 Å) As–F bond length. Te4+ is bonded in a distorted linear geometry to two F1- atoms. There are one shorter (1.96 Å) and one longer (2.60 Å) Te–F bond lengths. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the third F1- site, F1- is bonded in a distorted bent 120 degrees geometry to one As5+ and one Te4+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the AsTeIF5 cluster, As5+ is bonded in a distorted T-shaped geometry to three F1- atoms. There are a spread of As–F bond distances ranging from 1.75–1.91 Å. Te4+ is bonded in a 2-coordinate geometry to one I and three F1- atoms. The Te–I bond length is 2.86 Å. There are a spread of Te–F bond distances ranging from 1.91–2.39 Å. I is bonded in a 1-coordinate geometry to one Te4+ atom. There are five inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the third F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the fourth F1- site, F1- is bonded in a 2-coordinate geometry to one As5+ and one Te4+ atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the OIS1 cluster, S2- is bonded in a distorted single-bond geometry to one O2- and one I atom. The S–O bond length is 1.47 Å. The S–I bond length is 2.55 Å. O2- is bonded in a single-bond geometry to one S2- atom. I is bonded in a distorted single-bond geometry to one S2- atom. In the Te2OI4F4 cluster, there are two inequivalent Te4+ sites. In the first Te4+ site, Te4+ is bonded in a distorted linear geometry to two I and two F1- atoms. There are one shorter (2.70 Å) and one longer (2.71 Å) Te–I bond lengths. There are one shorter (1.97 Å) and one longer (2.19 Å) Te–F bond lengths. In the second Te4+ site, Te4+ is bonded in a 3-coordinate geometry to one O2- and two F1- atoms. The Te–O bond length is 2.29 Å. There is one shorter (1.92 Å) and one longer (1.95 Å) Te–F bond length. O2- is bonded in a 3-coordinate geometry to one Te4+ and two I atoms. There are one shorter (2.05 Å) and one longer (2.29 Å) O–I bond lengths. There are four inequivalent I sites. In the first I site, I is bonded in a 1-coordinate geometry to one O2- atom. In the second I site, I is bonded in a 1-coordinate geometry to one Te4+ atom. In the third I site, I is bonded in a linear geometry to one O2- and one F1- atom. The I–F bond length is 2.43 Å. In the fourth I site, I is bonded in a distorted single-bond geometry to one Te4+ atom. There are four inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the second F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the third F1- site, F1- is bonded in a distorted water-like geometry to one Te4+ and one I atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the TeIF cluster, Te4+ is bonded in a distorted single-bond geometry to one I and one F1- atom. The Te–I bond length is 2.69 Å. The Te–F bond length is 1.96 Å. I is bonded in a single-bond geometry to one Te4+ atom. F1- is bonded in a single-bond geometry to one Te4+ atom. In the As3Te3SO6I13F25 ribbon, there are three inequivalent As5+ sites. In the first As5+ site, As5+ is bonded in a distorted trigonal non-coplanar geometry to two O2- and one F1- atom. There is one shorter (1.79 Å) and one longer (1.83 Å) As–O bond length. The As–F bond length is 1.78 Å. In the second As5+ site, As5+ is bonded in a distorted rectangular see-saw-like geometry to one O2- and three F1- atoms. The As–O bond length is 2.19 Å. There are a spread of As–F bond distances ranging from 1.75–1.90 Å. In the third As5+ site, As5+ is bonded in a distorted T-shaped geometry to three F1- atoms. There is two shorter (1.80 Å) and one longer (1.82 Å) As–F bond length. There are three inequivalent Te4+ sites. In the first Te4+ site, Te4+ is bonded in a 3-coordinate geometry to four F1- atoms. There are a spread of Te–F bond distances ranging from 1.92–2.79 Å. In the second Te4+ site, Te4+ is bonded in a 3-coordinate geometry to one O2- and three F1- atoms. The Te–O bond length is 2.06 Å. There are a spread of Te–F bond distances ranging from 1.99–2.87 Å. In the third Te4+ site, Te4+ is bonded in a 3-coordinate geometry to four F1- atoms. There are a spread of Te–F bond distances ranging from 1.91–2.83 Å. S2- is bonded in a trigonal non-coplanar geometry to two I and one F1- atom. There are one shorter (2.40 Å) and one longer (2.44 Å) S–I bond lengths. The S–F bond length is 3.34 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to one As5+ and one I atom. The O–I bond length is 1.86 Å. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two I atoms. There are one shorter (2.00 Å) and one longer (2.13 Å) O–I bond lengths. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Te4+ and one I atom. The O–I bond length is 1.95 Å. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one I atom. The O–I bond length is 1.83 Å. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one As5+ and one I atom. The O–I bond length is 1.97 Å. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one As5+ and one I atom. The O–I bond length is 2.05 Å. There are thirteen inequivalent I sites. In the first I site, I is bonded in a linear geometry to two F1- atoms. There are one shorter (2.04 Å) and one longer (2.17 Å) I–F bond lengths. In the second I site, I is bonded in a single-bond geometry to one I and one F1- atom. The I–I bond length is 2.98 Å. The I–F bond length is 2.03 Å. In the third I site, I is bonded in a linear geometry to two F1- atoms. There are one shorter (2.03 Å) and one longer (2.38 Å) I–F bond lengths. In the fourth I site, I is bonded in a linear geometry to two F1- atoms. There are one shorter (1.96 Å) and one longer (2.45 Å) I–F bond lengths. In the fifth I site, I is bonded in a single-bond geometry to one O2- atom. In the sixth I site, I is bonded in a 1-coordinate geometry to one S2-, one I, and one F1- atom. The I–F bond length is 3.35 Å. In the seventh I site, I is bonded in a distorted single-bond geometry to one S2- and one F1- atom. The I–F bond length is 2.49 Å. In the eighth I site, I is bonded in a distorted single-bond geometry to one O2- and one F1- atom. The I–F bond length is 3.19 Å. In the ninth I site, I is bonded in a 4-coordinate geometry to one O2- and three F1- atoms. There are a spread of I–F bond distances ranging from 2.00–2.97 Å. In the tenth I site, I is bonded in a T-shaped geometry to one O2- and two F1- atoms. There are one shorter (1.98 Å) and one longer (2.09 Å) I–F bond lengths. In the eleventh I site, I is bonded in a T-shaped geometry to one O2- and two F1- atoms. There are one shorter (1.96 Å) and one longer (2.53 Å) I–F bond lengths. In the twelfth I site, I is bonded in a linear geometry to one O2- and one F1- atom. The I–F bond length is 2.48 Å. In the thirteenth I site, I is bonded in a distorted linear geometry to one O2- and one F1- atom. The I–F bond length is 2.73 Å. There are twenty-five inequivalent F1- sites. In the first F1- site, F1- is bonded in a single-bond geometry to one I atom. In the second F1- site, F1- is bonded in a single-bond geometry to one I atom. In the third F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the fourth F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the fifth F1- site, F1- is bonded in a single-bond geometry to one I atom. In the sixth F1- site, F1- is bonded in a distorted single-bond geometry to one I atom. In the seventh F1- site, F1- is bonded in a distorted single-bond geometry to one As5+ and one Te4+ atom. In the eighth F1- site, F1- is bonded in a distorted single-bond geometry to one Te4+ atom. In the ninth F1- site, F1- is bonded in a distorted bent 120 degrees geometry to two I atoms. In the tenth F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the eleventh F1- site, F1- is bonded in a distorted bent 120 degrees geometry to one As5+ and one I atom. In the twelfth F1- site, F1- is bonded in a single-bond geometry to one I atom. In the thirteenth F1- site, F1- is bonded in a distorted water-like geometry to three I atoms. In the fourteenth F1- site, F1- is bonded in a single-bond geometry to one Te4+ and one I atom. In the fifteenth F1- site, F1- is bonded in a single-bond geometry to one As5+ and one I atom. In the sixteenth F1- site, F1- is bonded in a distorted single-bond geometry to one Te4+ and one S2- atom. In the seventeenth F1- site, F1- is bonded in a single-bond geometry to one I atom. In the eighteenth F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the nineteenth F1- site, F1- is bonded in a single-bond geometry to one As5+ atom. In the twentieth F1- site, F1- is bonded in a distorted single-bond geometry to one As5+ and one Te4+ atom. In the twenty-first F1- site, F1- is bonded in a 3-coordinate geometry to one Te4+ and two I atoms. In the twenty-second F1- site, F1- is bonded in a distorted single-bond geometry to one As5+ and one I atom. In the twenty-third F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the twenty-fourth F1- site, F1- is bonded in a single-bond geometry to one Te4+ atom. In the twenty-fifth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two I atoms.

36 MATERIALS SCIENCE↗

Enhancing NO Reduction by CO Over NiO/CeO 2 Catalyst by Optimizing the Metal Oxide–Support Interaction

Noble metal catalysts are widely used in three-way catalysts (TWCs) due to their high efficiency, but their scarcity and high cost drive the need for effective, low-cost alternatives. Here, in this work, a series of NiO/CeO 2 catalysts were engineered by modulating the OH content and crystallite size of the CeO 2 support. This approach yielded Ni species ranging from isolated single atoms to small clusters and larger aggregates, with varied NiO/CeO 2 interaction strengths. Evaluation of their performance in NO reduction by CO, CO oxidation, and the water–gas shift reaction revealed that the NiO/CeO 2 -300 catalyst, featuring small CeO 2 crystallites and highly dispersed NiO clusters, delivered superior activity for NO reduction and CO oxidation. It was demonstrated that small NiO clusters, due to their efficient CO adsorption and activation, were more active than Ni single atoms. Furthermore, the presence of water was found to influence the catalyst stability, with NiO clusters less stable than single atoms likely due to the hydroxylation effect leading to the formation of Ni(OH) 2 . Oxygen storage capacity measurements revealed that performance was governed by a combination of CeO 2 crystallite size and the abundance of NiO/CeO 2 interfaces. These findings demonstrated that the catalytic performance of Ni/CeO 2 systems could be maximized by optimizing the Ni nanostructure and its interaction with CeO 2 support, positioning them as a promising, multifunctional nonprecious alternative for three-way catalysis application.

36 MATERIALS SCIENCE↗