Pt4 Cluster Research Articles

Dynamic stable Pt13 clusters anchored on isolated ZnOx nanorafts for efficient cycloparaffin dehydrogenation

Dynamic stable Pt13 clusters anchored on isolated ZnOx nanorafts for efficient cycloparaffin dehydrogenation

Shape-dependent CO chemisorption on Pt13 nanocluster deposited on reduced TiO2(110)

This article delves into the impact of nanoparticle shape on CO chemisorption and the reactivity of Pt13 nanocatalysts supported on reduced TiO2(110). Distinct reactivity in carbon monoxide adsorption is observed among nanoparticles, all composed of 13 platinum atoms but varying in shape. The calculated formation and CO adsorption energies are correlated to the electronic properties of the system and the oxidation states of the Pt atoms involved. Through an analysis of band shifting during the deposition of Pt clusters onto the oxide, and a comparison of the valence band maximum with the measured oxidation potential for the CO to CO2 reaction, we make predictions about the system's oxidation capability in this reaction. Our findings suggest that Pt13 clusters with cuboid, double triangle DT2 and octahedral Oh shapes, supported on the surface, are particularly advantageous for catalyzing the conversion of CO to CO2. Within these geometries, several configurations for CO adsorption are evaluated, focusing on the ratio between anionic and cationic Pt sites. This ratio appears to govern the activity for CO oxidation, aligning with recent experimental reports.

Effect of Oxidized Tin Interfacial Atoms on Methylcyclohexane Dehydrogenation Catalyzed by γ‐Alumina Supported Platinum Clusters

AbstractTin (Sn) doped platinum (Pt) nanoparticles supported on γ‐alumina are important materials catalyzing various reactions, such as the dehydrogenation of methylcyclohexane (MCH) into toluene, involved in liquid organic hydrogen carriers process, and naphtha catalytic reforming. The role of oxidized forms of Sn, remains misunderstood. Relying on catalysts' models made of a Pt13cluster on the (100) surface of γ‐alumina, the location and effects of Sn4+and Sn2+ interfacial atoms are investigated by density functional theory (DFT) calculations. A simulated annealing approach based on ab initio molecular dynamics enables to explore the configurations of the catalytic systems. The Pt clusters' stabilities and that of the adsorbed molecular intermediates are linked to the electronic properties of the cluster and to its ductility modulated by the adsorbed species, the alumina support and the Sn atoms. The Gibbs free energy profiles related to the reaction mechanism of the MCH dehydrogenation into toluene are quantified on the basis of transition state search. The energy span concept reveals that the dual (either detrimental or beneficial) impact of Sn oxidized forms on the intrinsic reactivity of the Pt13 cluster depends on temperature. Based on this DFT analysis, we attempt to clarify the debated role of Sn oxidized species.

Investigating Molecular Adsorption on Graphene-Supported Platinum Subnanoclusters: Insights from DFT + D3 Calculations.

Platinum (Pt) subnanoclusters have become pivotal in nanocatalysis, yet their molecular adsorption mechanisms, particularly on supported versus unsupported systems, remain poorly understood. Our study employs detailed density functional theory (DFT) calculations with D3 corrections to investigate molecular adsorption on Pt subnanoclusters, focusing on CO, NO, N2, and O2 species. Gas-phase and graphene-supported scenarios are systematically characterized to elucidate adsorption mechanisms and catalytic potential. Gas-phase Pt n clusters are first analyzed to identify stable configurations and assess size-dependent reactivity. Transitioning to graphene-supported Pt n clusters, both periodic and nonperiodic models are employed to study interactions with graphene substrates. Strong adsorbate interactions predominantly occur at single top sites, revealing distinct adsorption geometries and stabilization effects for specific molecules on Pt6 clusters. Energy decomposition analysis highlights the paramount role of graphene substrates in enhancing stability and modulating cluster-adsorbate interactions. The interaction energy emerges as a critical criterion within the Sabatier principle, crucial for distinguishing between physisorption and chemisorption. Hybridization indices and charge density flow tendencies establish direct relationships with stabilization processes, underscoring graphene's influence in stabilizing highly reactive subnanoclusters. This comprehensive investigation provides critical insights into molecular adsorption mechanisms and the catalytic potential of graphene-supported Pt nanoclusters. Our findings contribute to a deeper understanding of nanocatalysis, emphasizing the essential role of substrates in optimizing catalytic performance for industrial applications.

Unveiling Inequality of Atoms in Ultrasmall Pt Clusters: Oxygen Adsorption Limited to the Uppermost Atomic Layer

The concept of preferential atomic and molecular adsorption site is of primary relevance in heterogeneous catalysis. In the case of ultrasmall size‐selected clusters, distinguishing the role played by each atom in a reaction is extremely challenging due to their reduced size and peculiar structures. Herein, it is revealed how the inequivalent atoms composing graphene‐supported Pt12 and Pt13 clusters behave differently in the photoinduced dissociation of O2, with only those in the uppermost layer of the clusters being involved in the reaction. In this process, the epitaxial graphene support plays a fundamental active role: its corrugation and pinning induced by the presence of the clusters are crucial for defining the preferential adsorption site on the Pt atomic agglomerates, facilitating the lateral diffusion of physisorbed oxygen at a distance that induces its selective adsorption in the topmost layer of the clusters, and inducing an inhomogeneous charge distribution within the clusters which directly affects the O2 adsorption. The inhomogeneous oxidation of the clusters is resolved by means of synchrotron‐based X‐ray photoelectron spectroscopy and supported by ab initio density functional theory calculations. The possibility to identify the active sites on Pt clusters induced by cluster–support interactions has the potential to enhance the experimentally supported design of nanocatalysts.

Fully-Exposed Pt Cluster@Zeolite catalysts for efficient n-Hexane aromatization

Fully-Exposed Pt Cluster@Zeolite catalysts for efficient n-Hexane aromatization

Pt3 cluster doped SnS2 monolayer as a gas-sensing material to C4F7N decomposition: A DFT study

Pt3 cluster doped SnS2 monolayer as a gas-sensing material to C4F7N decomposition: A DFT study

Oxygen reduction reaction activity of Co3O4-modified Pt-graphene electrocatalysts

Abstract In this paper, the ORR activity of Pt/Co3O4-modified N-doped graphene electrocatalysts was investigated based on DFT theory. The Dmol3 module in Materials Studio software was used to optimize the construction of NG models under different doping conditions and to calculate the adsorption and desorption properties of oxygen molecules by optimizing the conformation of Pt13 clusters and substrates. A comparative analysis revealed that the Co3O4 modification reduced the oxygen adsorption energy of the Pt/G catalyst. However, after N doping, the oxygen adsorption energy of Pt/Co3O4/NG was superior to that of Pt/NG. After theoretical analysis, it was determined that it was because the doping of N atoms in graphene could promote the release of oxygen vacancies in Co3O4 and strengthen the adsorption interaction between Pt and graphene carriers to improve the oxygen adsorption energy.

Subnanometric Pt-Ga alloy clusters confined within Silicalite-1 zeolite for n-hexane dehydrogenation

Subnanometric Pt-Ga alloy clusters confined within Silicalite-1 zeolite for n-hexane dehydrogenation

Enhanced production of hydrogen via catalytic methane decomposition on a Pt7-Ni (110) substrate: a reactive molecular dynamics investigation

Abstract Numerous researchers in the energy field are engaged in a competitive race to advance hydrogen as a clean and environmentally friendly fuel. Studies have been conducted on the different aspects of hydrogen, including its production, storage, transportation and utilization. The catalytic methane decomposition technique for hydrogen production is an environmentally friendly process that avoids generating carbon dioxide gas, which contributes to the greenhouse effect. Catalysts play a crucial role in facilitating rapid, cost-effective and efficient production of hydrogen using this technique. In this study, reactive molecular dynamics simulations were employed to examine the impact of Pt7 cluster decoration on the surface of a Ni (110) catalyst, referred to as Pt7-Ni (110), on the rates of methane dissociation and molecular hydrogen production. The reactive force field was employed to model the atomic interactions that enabled the formation and dissociation of chemical bonds. Our reactive molecular dynamics simulations using the Pt7-Ni (110) catalyst revealed a notable decrease in the number of methane molecules, specifically ~11.89 molecules per picosecond. The rate was approximately four times higher than that of the simulation system utilizing a Ni (110) catalyst and approximately six times higher than that of the pure methane, no-catalyst system. The number of hydrogen molecules generated during a simulation period of 150 000 fs was greater on the Pt7-Ni (110) surface than in both the Ni (110) and pure methane systems. This was due to the presence of numerous dissociated hydrogen atoms on the Pt7-Ni (110) surface.

An efficient cathode electrocatalyst for anion exchange membrane water electrolyzer

An efficient cathode electrocatalyst for anion exchange membrane water electrolyzer

How do defects affect hydrogen spillover on graphene-supported Pt? A DFT study

How do defects affect hydrogen spillover on graphene-supported Pt? A DFT study

Activation of Molecules H<sub>2</sub> on Platinum and Platinovanadium Clusters: Quantum-Chemical DFT Modeling

The NEB DFT/PBE0/def2tzvp quantum-chemical method with the construction of minimum energy paths (MEP) was used to study the activation of H2 molecules by Pt4 and Pt3V clusters. It is shown that, in the case of Pt4 and Pt3V clusters, barrier-free dissociative adsorption of H2 molecules occurs on platinum centers, while molecular adsorption of hydrogen occurs on the vanadium atom in Pt3V with a slight weakening of the H–H bond, but without its breaking. The noted features of the coordination of H2 molecules are explained at the level of the MO method. It has been established that the migration of the H atom from one cluster metal center to another in the considered model clusters, as, possibly, in the phenomenon of hydrogen spillover, occurs at small activation barriers in the direction of the displacement vector corresponding to the normal vibration of the system in the transition state. In the process of hydrogen migration, a significant role of Pt–H–Pt and V–H–Pt bridging groups, which facilitate the transition of H atoms from one metal center of the cluster to another, has been revealed.

Effect of Pd doping on CH4 oxidation mechanism over Pt clusters: A systematic DFT study

Pt-Pd bimetallic catalyst exhibits excellent activity and promising stability in CH4 oxidation. In this study, the monometallic Pt13, bimetallic Pt12-Pd and [email protected]12 clusters were built and optimized via quantum chemistry method to uncover the effect of Pd doping on CH4 oxidation mechanism over Pt clusters. The feasible reaction paths for CH4 oxidation were systematically considered and the parameters of every step of the elementary reaction were obtained with density functional theory (DFT) calculations. On the Pt13 and [email protected]12 clusters, the optimal reaction path for CH4 oxidation is CH4* → CH3* → CH2* (+O*) → CH2O* → CHO* → CO* (+O*) → CO2* and the rate-determining step (RDS) is CH3* → CH2* with an energy barrier of 1.28 eV (for Pt13) and 1.20 eV (for [email protected]12) respectively. On the Pt12-Pd cluster, the optimal reaction path changes into CH4* → CH3*(+O*) → CH3O* → CH2O* → CHO* → CO* (+OH*) → COOH* → CO2* and the RDS is CH4* → CH3* with an energy barrier of 1.28 eV. Doping Pd in the center of the Pt13 cluster ([email protected]12) will improve the catalytic performance while doping Pd in the shell (Pt12-Pd) will change the reaction mechanism.

Dinuclear and tetranuclear group 10 metal complexes constructed from linear tetrasilane comprising both Si-H and Si-Si moieties

The activation of Si-H bonds and/or Si-Si bonds in organosilicon compounds by transition-metal species plays a crucial role for the production of functional organosilicon compounds. Although group-10-metal species are frequently used to activate Si-H and/or Si-Si bonds, so far, systematic investigation to clarify the preferences of these metal species with respect to the activation of Si-H and/or Si-Si bonds remain elusive. Here, we report that platinum(0) species that bear isocyanide or N-heterocyclic-carbene (NHC) ligands selectively activates the terminal Si-H bonds of the linear tetrasilane Ph2(H)SiSiPh2SiPh2Si(H)Ph2 in a stepwise manner, whereby the Si-Si bonds remain intact. In contrast, analogous palladium(0) species are preferably inserted into the Si-Si bonds of the same linear tetrasilane, whereby the terminal Si-H bonds remain intact. Substitution of the terminal hydride groups in Ph2(H)SiSiPh2SiPh2Si(H)Ph2 with chloride groups leads to the insertion of platinum(0) isocyanide into all Si-Si bonds to afford an unprecedented zig-zag Pt4 cluster.

Theoretical insights into the support effect on the NO activation over platinum-group metal catalysts.

We systematically explored NO activation at metal/oxide interfaces by the combination of Sr3Ti2O7, Sr3Fe2O7, CeO2, anatase-TiO2, ZrO2, and γ-Al2O3 supports and the platinum-group metal cluster (Pd4, Pt4, and Rh4) using slab-model density functional theory calculations. These metal clusters can be strongly adsorbed at these metal oxide surfaces. The Pt4 and Rh4 clusters show larger adsorption energies than the Pd4 cluster, yet the γ-Al2O3(100) surface shows smaller adsorption energies than other metal oxide surfaces. One oxygen vacancy close to the metal cluster was constructed to evaluate the NO activation at those metal/oxide interfaces. The O atom of NO refills the oxygen vacancy after NO dissociation, while the N adatom is left on the metal cluster. The exothermic process was identified for the NO activation except for the Sr3Fe2O7 case, indicating the significant role of the interplay between the metal cluster and oxygen vacancy.

Enhancing the Performance of Global Optimization of Platinum Cluster Structures by Transfer Learning in a Deep Neural Network.

The global optimization of metal cluster structures is an important research field. The traditional deep neural network (T-DNN) global optimization method is a good way to find out the global minimum (GM) of metal cluster structures, but a large number of samples are required. We developed a new global optimization method which is the combination of the DNN and transfer learning (DNN-TL). The DNN-TL method transfers the DNN parameters of the small-sized cluster to the DNN of the large-sized cluster to greatly reduce the number of samples. For the global optimization of Pt9 and Pt13 clusters in this research, the T-DNN method requires about 3-10 times more samples than the DNN-TL method, and the DNN-TL method saves about 70-80% of time. We also found that the average amplitude of parameter changes in the T-DNN training is about 2 times larger than that in the DNN-TL training, which rationalizes the effectiveness of transfer learning. The average fitting errors of the DNN trained by the DNN-TL method can be even smaller than those by the T-DNN method because of the reliability of transfer learning. Finally, we successfully obtained the GM structures of Ptn (n = 8-14) clusters by the DNN-TL method.

Fabricating Robust Pt Clusters on Sn-Doped CeO2 for CO Oxidation: A Deep Insight into Support Engineering and Surface Structural Evolution.

The size effect on nanoparticles, which affects the catalysis performance in a significant way, is crucial. The tuning of oxygen vacancies on metal-oxide support can help reduce the size of the particles in active clusters of Pt, thus improving catalysis performance of the supported catalyst. Herein, Ce-Sn solid solutions (CSO) with abundant oxygen vacancies have been synthesized. Activated by simple CO reduction after loading Pt species, the catalytic CO oxidation performance of Pt/CSO was significantly better than that of Pt/CeO2 . The reasons for the elevated activity were further explored regarding ionic Pt single sites being transformed into active Pt clusters after CO reduction. Due to more exposed oxygen vacancies, much smaller Pt clusters were created on CSO (ca. 1.2 nm) than on CeO2 (ca. 1.8 nm). Consequently, more exposed active Pt clusters significantly improved the ability to activate oxygen and directly translated to the higher catalytic oxidation performance of activated Pt/CSO catalysts in vehicle emission control applications.

Role of Fluxionality and Metastable Isomers in the ORR Activity: A Case Study

Understanding the dynamic reconstruction of active sites and the fluxional behavior of subnanoclusters has become the heart of operando modeling techniques. An accurate description of catalysis phenomena extends toward incorporating the activity of thermally accessible ensembles of metastable isomers in addition to the global minima (GM). Considering the Pt13 cluster as a model catalyst for gas-phase oxygen reduction reaction (ORR), we have studied the role of metastable isomers and unravelled their distinct catalyst dynamics leading to high fluxionality. The different adsorption energetics and ORR activity featured by the metastable isomers reveal the importance of addressing the fluxional behavior of subnanoclusters. A detailed mechanistic ORR investigation provided isomers possessing an activity comparable to GM. Furthermore, a statistical ensemble representation demonstrates the substantial role of metastable isomers within 0.4 eV relative energy difference from GM, with negligible activity enhancement of isomers with high energy at 300 K. Ab initio thermodynamics-based stability analysis represents different energetics associated with the Pt13 clusters at high oxygen coverage. This study highlights the importance of exploring the role of metastable isomers in determining the cumulative catalytic activity of subnanometer clusters.

Stability of Pt10Sn3 Clusters Supported on γ‐Al2O3 in Oxidizing Environment: a DFT Comparison of Alloying and Size Effects

AbstractThe understanding of the structure and properties of γ‐Al2O3 supported platinum‐tin catalysts in oxidizing conditions is of prominent importance for many catalytic reactions. By using density functional theory calculations and ab initio molecular dynamics simulations, we identify the adsorption sites of oxygen atoms on a Pt10Sn3/γ‐Al2O3(100) cluster model and analyze its reconstruction and electronic charge redistribution. A strengthening of O adsorption is found for the cluster with respect to the Pt3Sn(111) surface, due to the key role of Al−Pt interfacial sites at low coverage, the ductility and the metastability of the cluster. Moreover, the ab initio ( , T) thermodynamic phase diagrams show only minor differences between the supported Pt10Sn3 and Pt13 clusters. Both clusters are much more oxidized than their homologous Pt and Pt3Sn(111) surfaces, and their oxygen contents may exceed 1 ML. This suggests a stronger size effect than an alloying effect for the oxidation of the metallic PtSn nanoparticles at small size.