Pt4 Cluster Research Articles

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

Methylcyclohexane (MCH) has attracted wide attention as liquid organic hydrogen carriers for safe alternative and high gravimetric hydrogen density. Pt13 cluster with its fascinating structure exhibits excellent performance in cycloalkane dehydrogenation reactions accompanied by balanced C-H cleavage capability. However, the controllable synthesis of stable Pt13 clusters under reaction conditions remains challenging. Herein, we successfully synthesized low-coordinated Pt13 clusters anchored by isolated ZnOx nanorafts on silanol-rich self-pillared zeolite nanosheets (SP-S-1). In situ XAFS spectra combined with theoretical calculations revealed that Pt13 clusters exhibited strong interfacial Pt-Zn bonds and reduced d-band center through orbital hybridization (Zn 3d - Pt 5d), facilitating C-H bond cleavage and toluene desorption. The optimized catalyst exhibited superior MCH dehydrogenation activity and durability, achieving a hydrogen production rate of 3457.9 mmolH2 gPt−1 min−1 at 400 ˚C and maintaining stable for over 100 hours. This study precisely synthesizes dynamic stable Pt13 clusters and provides valuable insights into the dehydrogenation mechanism.

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

The exploration of Pt cluster catalysts with minimal or fully exposed Pt atoms for specific reactions is meaningful but challenging, aiming to maximize Pt atomic utilization. To answer the above question, we design 4Pt cluster catalysts within a KL zeolite (Ptn@KL, n represents Pt atom numbers) for an n-hexane aromatization (n-HAM) reaction. Pt species in Ptn@KL are identified as Pt1, and Pt4, Pt9, and Pt13 clusters, respectively; the corresponding Pt–Pt coordination number ranges from 0, 2, 3.3 to 4.5. When tested in n-HAM at 440 °C, Pt4@KL shows the highest benzene yield of 85.7 % with ∼ 100 % conversion and superior durability up to 600 h. In-situ characterizations and theoretical calculations demonstrate that the optimal Ptn@KL CTs towards n-HAM is a fully exposed Pt cluster with CNPt–Pt of 2.

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

Perfluoroisobutyronitrile (C4F7N) is a new type of eco-friendly insulating gas widely used in various gas insulation systems. An effective method for diagnosing the operational status of insulation equipment is to design gas sensor materials to detect C4F7N breakdown products. Using density functional theory, we investigated the sensing ability of the Pt3 cluster doped SnS2 monolayer for common C4F7N decomposition gases (CF4, COF2, C2N2, and CF3CN). We explored the adsorption energy, charge transfer, adsorption distance, and density of states of the Pt3-SnS2 monolayer as a C4F7N breakdown gas sensor. The results indicate that the doping of Pt3 clusters has a relatively small improvement in the adsorption capacity of CF4 and COF2 gases, indicating physical adsorption, but a significant improvement in the adsorption capacity of C2N2 and CF3CN gases, indicating chemical adsorption. This work provides additional potential applications for Pt3 cluster doped SnS2 monolayer gas sensing materials.

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

Dehydrogenation of light naphtha followed by catalytic cracking into high-value end products can meet the high demand in the world’s petrochemical market. In this work, at attempting synthesis of novel catalysts for hexane dehydrogenation, a series of bimetallic Pt-Ga clusters encapsulated within Silicalite-1 (S-1) catalysts were synthesized using the ligand-protected direct H2 reduction method. The reduced Pt-Ga@S-1-H catalysts comprised restricted ultra-fine Pt-Ga alloys with an average size 0.86–0.95 nm, mainly corresponding to the Pt3 clusters with coordinate number 1.5–2.1. Ga doping significantly improved the catalytic stability, depending on the Ga content, which ranged from 0.02 to 0.27 wt%. As confirmed by the XPS and EXAFS analysis, after the Ga addition, electron transfer occurred between the Pt-Ga alloys and the skeleton oxygen in zeolite, stabilizing the Pt clusters on the zeolite, thereby inhibiting the growth of Pt crystals. During the n-hexane dehydrogenation, the 0.40Pt0.04 Ga@S-1-H catalyst exhibited a hexene selectivity of 87.1 %, achieving a hexene formation rate of 101.4 molhexene∙gPt-1∙h−1 at 550 °C with a WHSV of 90 h−1. After 1000 min of reaction, this best catalyst experienced only slight deactivation with a deactivation constant of 0.066 h−1. The catalytic activity remained almost unchanged after consecutive five cycles of H2 regeneration. DFT calculation using the synchronous structural models showed that the Gibbs free energy changes (−ΔG) for the first three steps of hexane dehydrogenation over the 0.4Pt0.04 Ga@S-1-H catalyst were much lower than those obtained on the 0.4Pt/S-1-H catalyst, suggesting that the introduction of Ga energetically favored the 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

A high performance and durable electrocatalyst for the cathodic hydrogen evolution reaction (HER) in anion exchange membrane (AEM) water electrolyzers is crucial for the emerging hydrogen economy. Herein, we synthesized Pt–C core-shell nanoparticles (core: Pt nanoparticles, shell: N-containing carbon) were uniformly coated on hierarchical MoS2/GNF using pyrolysis of h-MoS2/GNF with a Pt-aniline complex. The synthesized Pt–C core-shell@h-MoS2/GNF (with 11.3 % Pt loading) showed HER activity with a lower overpotential of 30 mV at 10 mA cm−2 as compared to the benchmark catalyst 20 % Pt–C (41 mV at 10 mA cm−2) with improved durability over 94 h at 10 mA cm−2. Furthermore, we investigated the structural stability and hydrogen adsorption energy for Pt13 cluster, C90 molecule, h-MoS2 sheet, Pt13–C90 core-shell, and Pt13–C90 core-shell deposited h-MoS2 sheets using density functional theory (DFT) simulations. We investigated the Pt–C core-shell@h-MoS2/GNF catalyst active sites during HER performance using in-situ Raman analysis as well as DFT. We fabricated AEM water electrolyzers with cathode catalysts of Pt–C core-shell@h-MoS2/GNF and evaluated device performance with 0.1 and 1.0 M KOH at 20 and 60 °C. Our work provides a new pathway to design core-shell electrocatalysts for use in AEM water electrolyzers to generate hydrogen.

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

Hydrogen dissociation, adsorption, and spillover on Pt4 supported on defective graphene that contains vacancy defects, such as single and di-vacancy graphenes (SVG and DVG), have been studied using density functional theory (DFT) with dispersion correction (Grimme-D3). Vacancy defects lead to n-type doping of graphene from the Pt4 cluster, which is contrary to the p-type doping on pristine graphene. Also, the metal–support interactions increase with the presence of a vacancy defect as indicated by more negative Pt4 binding energies on the SVG, and 5-8-5, 5555-6-7777, and 555–777 DVGs of −8.60, −4.51, −4.15 and −3.63 eV, respectively, compared to that on pristine graphene (−2.16 eV). Atomic hydrogen adsorption is more stable on all defective graphenes with adsorption energies of −2.24, −0.16, 0.05, and −0.27 eV for SVG, 5-8-5, 5555-6-7777, and 555–777 DVGs, respectively, as compared to that on pristine graphene (+1.38 eV). Spontaneous hydrogen dissociative adsorption on the two-fold coordinated C site of bare SVG occurs with an adsorption energy per hydrogen atom of −1.77 eV, while those on the three types of DVGs are in the range of ∼0.03–0.29 eV; these are all more stable than those on pristine graphene that fall in the range of 0.89–1.53 eV. The energy barriers for hydrogen spillover from Pt4 to the defective graphene are 0.91, 1.09, 0.90, and 0.71 eV for SVG, 5-8-5, 5555-6-7777, and 555–777 DVGs, respectively. Ab initio molecular dynamics (AIMD) simulations show that the adsorption of up to six hydrogen molecules, with and without spillover, on the four Pt4/defective graphene systems, is stable at room temperature. This study demonstrates that the presence of vacancy defects on graphene could improve hydrogen adsorption and spillover. A trend is discovered—when the magnitude of binding energies of metal–support interaction is stronger than −3.5 eV and the adsorption energies of atomic hydrogen on the support are negative or close to zero, there is potential to facilitate the occurrence of hydrogen spillover, correlating with the hydrogen storage capacity of the materials. Thus, our findings could provide useful criteria for designing hydrogen storage materials and a fundamental understanding of the correlation between metal–support interactions and hydrogen spillover mechanisms.

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 Pd@Pt12 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 Pd@Pt12 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 Pd@Pt12) 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 (Pd@Pt12) 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.

Effects of multi-atom doping into Pt13 cluster using Ab initio method

Effects of multi-atom doping into Pt13 cluster using Ab initio method