Metal-support Interaction Research Articles

Fuel-driven design of NiOx/AlOx catalysts for methane decomposition through tuning of metal-support interaction

Fuel-driven design of NiOx/AlOx catalysts for methane decomposition through tuning of metal-support interaction

Fermi Level Equilibration and Charge Transfer at the Exsolved Metal-Oxide Interface.

Exsolution is a promising approach for fabricating oxide-supported metal nanocatalysts through redox-driven metal precipitation. A defining feature of exsolved nanocatalysts is their anchored metal-oxide interface, which exhibits exceptional structural stability in (electro)catalysis. However, the electronic interactions at this unique interface remain unclear, despite their known impact on catalytic performance. In this study, we confirm charge transfer between the host oxide and the exsolved metal by demonstrating a two-stage Fermi level (EF) evolution on SrTi0.65Fe0.35O3-δ (STF) during metallic iron (Fe0) exsolution. Combining ambient pressure X-ray photoelectron spectroscopy with theoretical analysis, we show that EF initially rises due to electron doping from oxygen vacancy formation in STF. Subsequently, upon Fe0 precipitation, EF stabilizes and becomes insensitive to further oxygen release in STF, driven by EF equilibration and charge transfer between STF and the exsolved Fe0. These findings highlight the importance of considering electronic metal-support interactions when optimizing exsolved nanocatalysts.

Enhancing Alkaline Hydrogen Evolution by Regulating H and OH Binding Strength through Strong Metal-Support Interactions.

Establishing optimized metal-support interaction (MSI) between active sites and the substrate is essential for modulating the adsorption properties of key reaction intermediates during catalysis, thereby enhancing the catalytic performance. In this study, catalyst composites with varying degrees of MSI are constructed using ruthenium (Ru) and different carbon nanotubes, and their performance for alkaline hydrogen evolution reaction (HER) is systematically investigated. Detailed kinetic assessments reveal that catalysts with a strong MSI exhibit superior HER activity. For instance, Ru-O-CNT catalyst composite demonstrates an encouragingly low overpotential of 11 mV at 10 mA cm-2 and excellent stability. Electrochemical voltammetry analysis indicates that an effective MSI optimizes the binding strength of both *H and *OH, accelerating the HER process. Furthermore, we showcase that an industrial-level electrolyzer, assembled using Ru-O-CNT as the cathodic catalyst, achieves impressive performance with a low cell voltage of 1.72 V and high stability at a current density of 1 A cm-2.

The Stability of Cathode Catalyst Layer With Platinum‐Based Catalysts in Proton Exchange Membrane Fuel Cells

AbstractProton exchange membrane fuel cells (PEMFCs) have attracted significant interest as one of the most promising green energy technologies. However, the stability of platinum‐based catalyst layer at the cathode hinders the large‐scale application of the PEMFCs. This review systematically summarized the latest research progress on the stability of catalyst layer from the stability of nanoparticles, corrosion resistance of carbon support, chemical stability of ionomer and weakened toxic effect of ionomer on platinum particles. Strategies to enhance the stability of the catalyst layer were discussed as well, including increasing the dissolution potential of the nanoparticles, enhancing the metal–support interaction, modifying the structure and composition of the carbon support, and improving the distribution of the ionomer. This review aims to provide a comprehensive overview of the stability of cathode catalyst layer, serving as a reference for the design of catalyst layer with stability in the future.

Tuning the electronic structure and SMSI by integrating trimetallic sites with defective ceria for the CO2 reduction reaction

Heterogeneous catalysts have emerged as a potential key for closing the carbon cycle by converting carbon dioxide (CO2) into value-added chemicals. In this work, we report a highly active and stable ceria (CeO2)-based electronically tuned trimetallic catalyst for CO2 to CO conversion. A unique distribution of electron density between the defective ceria support and the trimetallic nanoparticles (of Ni, Cu, Zn) was established by creating the strong metal support interaction (SMSI) between them. The catalyst showed CO productivity of 49,279 mmol g-1 h-1 at 650 °C. CO selectivity up to 99% and excellent stability (rate remained unchanged even after 100 h) stemmed from the synergistic interactions among Ni-Cu-Zn sites and their SMSI with the defective ceria support. High-energy-resolution fluorescence-detection X-ray absorption spectroscopy (HERFD-XAS) confirmed this SMSI, further corroborated by in situ electron energy loss spectroscopy (EELS) and density functional theory (DFT) simulations. The in situ studies (HERFD-XAS & EELS) indicated the key role of oxygen vacancies of defective CeO2 during catalysis. The in situ transmission electron microscopy (TEM) imaging under catalytic conditions visualized the movement and growth of active trimetallic sites, which completely stopped once SMSI was established. In situ FTIR (supported by DFT) provided a molecular-level understanding of the formation of various reaction intermediates and their conversion into products, which followed a complex coupling of direct dissociation and redox pathway assisted by hydrogen, simultaneously on different active sites. Thus, sophisticated manipulation of electronic properties of trimetallic sites and defect dynamics significantly enhanced catalytic performance during CO2 to CO conversion.

Improving Photocatalytic Hydrogen Production over Pd Nanoparticles Decorated with g-C3N5 Photocatalyst

A uniform distribution of Pd nanoparticles on g-C3N5 layers is achieved through wet-chemical reduction (Pd/g-C3N5-EG). Pd/g-C3N5-EG demonstrates superior hydrogen production yield compared to heterojunctions synthesized via photoreduction (Pd/g-C3N5-PR), attributed to improved metal–support interaction. Pd/g-C3N5-EG demonstrates an average hydrogen evolution rate of 891.304 µmol g−1 h−1, representing a 7.8-fold increase over Pd/g-C3N5-PR and a 34.5-fold increase over bare g-C3N5. Pd/g-C3N5-EG also maintains its hydrogen production capability after five recycling cycles, with only a slight decrease in efficiency.

Boosting catalytic efficiency of nanostructured CuO-supported doped-CeO2 in oxidative coupling of benzyl amines to N-benzylidenebenzyl amines and benzimidazoles: impact of acidic and defect sites

This study presents the rational synthesis of Cu-supported doped-CeO2 catalysts designed for the oxidation of benzylamine, both in the absence and presence of 1,2-diaminobenzene. The catalysts were prepared using a two-step method and characterized by various techniques, including XRD, Raman spectroscopy, BET surface area analysis, NH3-TPD, pyridine-FTIR, H2-TPR, XPS, SEM, and TEM. Raman and XPS analyses confirmed the presence of oxygen vacancy sites, with CuO/CeO2-ZrO2 displaying the highest concentration of these sites. H2-TPR revealed strong metal-support interactions, while NH3-TPD indicated that CuO/CeO2-ZrO2 possessed the greatest number of acidic sites. The pyridine-FTIR results indicates both the acidic sites present on the catalyst surface. The Cu/CeZr sample exhibits the lowest Iu////ITotal ratio (0.0567) compared to the Cu/Ce (0.0843) and Cu/CeSi (0.0672) samples, indicating a higher number of Ce3+ species or a greater number of oxygen defect sites in the sample. The catalyst demonstrated excellent performance in converting benzylamine to imines and was also highly effective in the synthesis of benzimidazole from benzylamine and 1,2-diaminobenzene, broadening its application potential. The superior catalytic activity is attributed to the abundant oxygen vacancies, redox properties, strong metal-support interactions, and acidic sites. Furthermore, the CuO/CeO2-ZrO2 catalyst maintained its efficiency over five consecutive cycles, exhibiting robustness, high functional group tolerance, and reduced reaction times, making it a promising system for diverse catalytic applications.

Adjustment of Molecular Sorption Equilibrium on Catalyst Surface for Boosting Catalysis.

ConspectusFor chemical reactions with complex pathways, it is extremely difficult to adjust the catalytic performance. The previous strategies on this issue mainly focused on modifying the fine structures of the catalysts, including optimization of the geometric/electronic structure of the metal nanoparticles (NPs), regulation of the chemical composition/morphology of the supports, and/or adjustment of the metal-support interactions to modulate the reaction kinetics on the catalyst surface. Although significant advances have been achieved, the catalytic performance is still unsatisfactory.It is accepted that the chemical equilibrium of a reaction can be disturbed by changing the concentration of the reactants or products, and the equilibrium will shift to another side to offset the perturbation until a new equilibrium is established. This is known as Le Chatelier's principle. Following this understanding, we show that the catalytic performance can be significantly modulated by adjusting the molecular sorption equilibrium on the catalyst surface. For example, enriching the reactants and/or intermediates on the catalyst surface pushes the reaction forward, thus increasing the catalytic conversion; removing the product away from the catalyst surface improves the catalytic conversion and product selectivity; and inhibiting the side reactions enhances the product selectivity and catalyst durability. Using these strategies has successfully enhanced the catalytic performances in many challenging reactions, such as increasing H2O2 concentration around the metal active sites to enhance methane oxidation, enriching olefin on the catalyst surface to boost hydroformylation, selective combustion of H2 to shift the reaction equilibrium and improve ethane conversion in ethane dehydrogenation, and removing water from the reaction system to enhance Fischer-Tropsch synthesis. The key to these successes is effectively shifting the molecular sorption equilibrium under the working conditions.In this Account, we briefly summarize recent advances in adjusting molecular sorption equilibrium for boosting catalysis, with a focus on the equilibrium shift for a desired pathway by the unique functions of zeolites and polymers such as silanol nests on zeolite for olefin adsorption, the "molecular fence" effect of zeolite for H2O2 enrichment, MFI zeolite nanosheets for olefin diffusion, and the hydrophobic zeolite sheath and polymer for water separation/diffusion. We report the adjustment of the molecular sorption equilibrium on the catalyst surface via enriching the reactants and intermediates, removing the products, and inhibiting the side reactions to enhance the catalytic performance. As a result, high activity, excellent selectivity, and outstanding durability of the catalysts were achieved. In addition, current challenges and perspectives of applying this strategy to more important industrial reactions are discussed. Applications of advanced characterization tools, machine learning, and artificial intelligence for monitoring the dynamic structural changes of the catalyst and predicting the structural evolutions under working conditions are anticipated to continuously play important roles in catalyst design. We believe that this strategy will open a door for the development of highly efficient catalysts with potential applications in the future.

Workflow-driven catalytic modulation from single-atom catalysts to Au–alloy clusters on graphene

Gold-based (Au) nanostructures are efficient catalysts for CO oxidation, hydrogen evolution (HER), and oxygen evolution (OER) reactions, but stabilizing them on graphene (Gr) is challenging due to weak affinity from delocalized carbon orbitals. This study investigates forming metal alloys to enhance stability and catalytic performance of Au-based nanocatalysts. Using ab initio density functional theory, we characterize sub-nanoclusters (M = Ni, Pd, Pt, Cu, and Ag) with atomicities , both in gas-phase and supported on Gr. We find that M atoms act as “anchors,” enhancing binding to Gr and modulating catalytic efficiency. Notably, /Gr shows improved stability, with segregation tendencies mitigated upon adsorption on Gr. The d-band center () model indicates catalytic potential, correlating an optimal range of eV for HER and OER catalysts. Incorporating Au into adjusts closer to the Fermi level, especially for Group-10 alloys, offering designs with improved stability and efficiency comparable to pure Au nanocatalysts. Our methodology leveraged SimStack, a workflow framework enabling modeling and analysis, enhancing reproducibility, and accelerating discovery. This work demonstrates SimStack’s pivotal role in advancing the understanding of composition-dependent stability and catalytic properties of Au-alloy clusters, providing a systematic approach to optimize metal-support interactions in catalytic applications.

Coke deposition mechanisms of propane dehydrogenation on different sites of Al2O3 supported PtSn catalysts

Propane dehydrogenation (PDH) Pt-based catalysts are facing the serious challenge of coke deactivation. The locations would greatly influence the coke formation, while the detailed mechanism is not fully explored. Herein, the coke mechanisms on different locations including Al2O3, Sn, Pt, and Pt-Sn sites were deeply investigated via in situ Fourier transform infrared spectroscopy (FTIR) technology, and the key factors triggering catalyst coke deactivation were proposed. Excessive dehydrogenation of propyl species is a crucial initial step in the formation of coke, whether at metal sites or supports. These propyl species on Al2O3 supports then cyclize to form monocyclic aromatic and bicyclic aromatic species, while those on SnOx sites cyclize to form monocyclic aromatic species. As for the Al2O3 supported PtSn catalysts, the strong dehydrogenation function and the interaction between Pt and Al2O3 supports trigger the complex coke formation mechanism. The surface Pt sites with saturated coordination are prone to coke deposition, leading to rapid deactivation at the initial stage of the reaction. However, the low-coordination Pt sites with ultra-small size are found to be highly resistant to coke formation in the PDH reaction, which selectively catalytic the PDH. Owing to the metal-support interaction, the extensive active hydrogen species generated from Pt can regulate the formation of coke precursors on the Al2O3 supports. Furthermore, the effect of hydrogen co-feed on coke deposition is also explored. The hydrogen co-feed inhibits the coke formation and results in a higher H/C ratio (3.96) for aromatic coke precursors. This study can enhance the understanding of the coke formation in PDH, which is important to designing efficient PDH Pt-based catalysts.

Support effect on methane combustion over iridium catalysts: Unraveling the metal-support interaction mechanism.

The redox properties of iridium (Ir) active component are critically important in methane combustion. Interface engineering is highly effective in modulating the redox properties of active metals via tailoring the metal-support interaction (MSI). Herein, Ir catalysts supported on different carriers (TiO2, CeO2, Al2O3) were synthesized and evaluated for methane combustion. The methane combustion performance varied depending on the support, following the order: Ir/TiO2>Ir/CeO2>Ir/Al2O3 catalysts. Detailed experimental characterizations indicate that, compared with stronger Ir-CeO2 and Ir-Al2O3 interfaces, the unique moderate Ir-TiO2 interface facilitates the generation of an electron-rich Ir structure with a higher Irδ+ ratio. Theoretical simulations further suggest that the initial cleavage of the CH bond in methane molecules is favored at the superior Ir-TiO2 interface. The more reactive Irδ+ species with electron-rich structures in Ir/TiO2 catalysts not only greatly enhance their redox performance but also lower the activation energy barrier for methane activation, ultimately leading to improved catalytic activity in the total oxidation of methane. This work provides valuable insights for the ingenious catalyst design of more efficient Ir-based catalysts for methane combustion through tailoring MSI.

Controlled Growth of Silver Nanoparticles by Metal–Support Interaction for Enhanced Tandem Catalytic Oxidation of HCHO at Low Temperature

Controlled Growth of Silver Nanoparticles by Metal–Support Interaction for Enhanced Tandem Catalytic Oxidation of HCHO at Low Temperature

Strong Metal-Support Interaction Facilitates the Separation of Electron-Hole Pairs at Au13/BiOCl Interface: Insight from Quantum Dynamics.

Focusing on Au13/BiOCl, we investigated the effects of the metal-support interaction (MSI) on the photogenerated charge carrier separation using nonadiabatic molecular dynamic simulations combined with time-domain density functional theory. Our results show that the time scales of electron transfer from the Au13 cluster to BiOCl are distinct depending on the intensity of MSI. Oxygen vacancy (OV) can enhance the interaction between the Au13 cluster and BiOCl, leading to a stronger nonadiabatic (NA) coupling in Au13/BiOCl with an OV system compared to that in a pristine Au13/BiOCl system. The time scale of electron transfer in Au13/BiOCl with the OV system is reduced by a factor of 1.65 compared to that of the pristine Au13/BiOCl system. Our study suggests that the electron transfer can be facilitated by enhancing the MSI and provides valuable principles for the design of high-performance photocatalysts.

Dynamically Stable Cu0Cuδ+ Pair Sites Based on In Situ-Exsolved Cu Nanoclusters on CaCO3 for Efficient CO2 Electroreduction.

Copper-based catalysts are the choice for producing multi-carbon products (C2+) during CO2 electroreduction (CO2RR), where the Cu0Cuδ+ pair sites are proposed to be synergistic hotspots for C-C coupling. Maintaining their dynamic stability requires precise control over electron affinity and anion vacancy formation energy, posing significant challenges. Here, we present an in situ reconstruction strategy to create dynamically stable Cu0Cu0.18+OCa motifs at the interface of exsolved Cu nanoclusters and CaCO3 nanospheres (Cu/CaCO3). In situ XAFS analysis confirmed the low-valency state of Cuδ+ during CO2RR. DFT calculations demonstrated that the nanocluster size arises from the balance between metal-support interactions and Cu-Cu cohesive energy, while the dynamic stability of rich interfacial Cuδ+ sites is attributed to their low electron affinity and high CO3 2- vacancy formation energy, which collectively contribute to reduced reducibility. The transformed Cu/CaCO3 exhibits an impressive C2+ Faradaic efficiency of 83.7 % at a partial current density of 393 mA cm-2, facilitated by adsorption of *CO with varying electronegativity at heterogeneous copper sites that lowers the C-C coupling energy barrier. Our findings establish insoluble carbonate as an effective anion pairing for Cu0Cuδ+ sites, highlighting the effectiveness of the in situ reconstitution strategy in producing a high density of dynamically stable Cu0Cuδ+ pair sites.

Generating Strong Metal-Support Interaction and Oxygen Vacancies in Cu/MgAlOx Catalysts by CO2 Treatment for Enhanced CO2 Hydrogenation to Methanol.

Strong metal-support interactions (SMSIs) are essential for optimizing the performance of supported metal catalysts by tuning the metal-oxide interface structures. This study explores the hydrogenation of CO2 to methanol over Cu-supported catalysts, focusing on the synergistic effects of strong metal-support interaction (SMSI) and oxygen vacancies introduced by the CO2 treatment to the catalysts on the catalytic performance. Cu nanoparticles were immobilized on Mg-Al layered double oxide (LDO) supports and modified with nitrate ions to promote oxygen vacancy generation. Further calcination in a 15% CO2/85% N2 atmosphere at various temperatures not only resulted in the formation of SMSI and electronic metal-support interaction (EMSI) between Cu and MgO, but also generated abundant oxygen vacancies on MgO. The optimized 7.5%Cu/MA-C700 catalyst (Cu supported on MgAl-LDO treated in CO2 at 700 °C) exhibited significantly higher methanol production and turnover frequency compared to the air-calcined counterparts. In situ FTIR studies further revealed that oxygen vacancies led to the formation of more monodentate formate species, thus enhancing methanol production. This research provides a novel approach to engineering the catalyst interface structure and the interaction between the active metal and the support, particularly for the irreducible metal oxide support, for efficient hydrogenation of CO2 to methanol.

Direct solid–vapor approach to 2D FeCoNiP@N-graphene-CNTs as robust electrode material for high-performance supercapacitors

Carbon supported bi(tri)-metallic phosphides are well known high-active electrode nanomaterials as it poses multiple redox sites, excellent electrochemical reversibility, and stability. In spite of that the synthesis of metal phosphides are limited as it involves multiple steps, harsh preparation conditions and often pose poor metal-support interactions. Herein, a simple and direct one-step solvent-free solid–vapor method was developed for the fabrication of bi(tri)-metallic phosphides supported N-graphene/N-CNTs 2D-nanosandwidch, first report to the best of our knowledge. Unique surface morphology, high surface area, good thermal stability and strong metal-support interaction, were confirmed for the as prepared electrocatalysts (FeNiP/NCNTs, FeCoP/NCNTs and FeNiCoP/NCNTs). In three electrode system, the FeNiCoP/NCNTs showed highest specific capacitance of 1479F/g at 1 A/g in 3 M KOH and excellent cycling stability, with capacitance retention of 90.8 % over 5000 cycles. Interestingly in the two-electrode system, the FeNiCoP/NCNTs demonstrated impressive capacitance of 245F/g at 1 A/g, power density of 10567 W/kg and energy density of 66.7 Wh/kg, with excellent retention of 91.5 % over 5000 cycles. The direct one-step preparation and high electrochemical performance inclusively promote the present FeNiCoP/NCNTs (with low metal loading of less than 10 wt%) as a promising supercapacitor electrode nanomaterial for energy storage applications.

Progress in palladium-based bimetallic catalysts for lean methane combustion: Towards harsh industrial applications

<p>Significant volumes of lean methane (0.1–1.0 vol%) are released untreated into the atmosphere during industrial operations, contributing to the greenhouse effect and energy wastage. Catalytic methane combustion presents a promising avenue to mitigate these emissions. Depending on their active components, catalytic systems are predominantly categorized into noble metal-based and non-noble metal-based catalysts, with palladium (Pd)-based catalysts recognized for their superior low-temperature oxidation activity. Nevertheless, enhancing the thermal stability of Pd remains challenging, complicated by impurities such as H<sub>2</sub>O, SO<sub>2</sub> and H<sub>2</sub>S in the lean methane stream, which can cause catalyst poisoning and deactivation. Recent research has focused on the design of Pd-based bimetallic catalysts, offering improved stability, activity, and resistance to poisoning in harsh industrial conditions. This review examines advancements in improving the deactivation resistance of Pd-based bimetallic catalysts for lean methane combustion, covering active site characterization, dispersion and metal-support interactions, the role of auxiliary metals, and structural modulation strategies. It also investigates the impact of harsh industrial environments on Pd-based catalyst performance, focusing on deactivation mechanisms and mitigation strategies. Ultimately, this review identifies current research trends and challenges for Pd-based catalysts in demanding applications. By providing insights into the design of Pd-based catalysts with enhanced stability, activity, and resistance to poisoning, this review aims to guide the development of catalysts that meet industrial demands.</p>

Ni/Ce0.8Zr0.2O2−x solid solution catalyst: a pathway to coke-resistant CO2 reforming of methane

The CO2 reforming of methane effectively produces syngas from two major greenhouse gases, CO2 and CH4. Ni/Ce0.8Zr0.2O2−x catalyst shows outstanding performance, with improved stability from oxygen vacancies and strong metal–support interactions.

Reactive metal–support interaction of In2O3/crystalline carbon hybrid support for highly durable and efficient oxygen reduction reaction electrocatalyst

Reactive metal–support interaction of In2O3/crystalline carbon hybrid support for highly durable and efficient oxygen reduction reaction electrocatalyst

Electronic Metal–Support Interaction on Pd/CoNi-hydroxides with enhanced CO adsorption for boosting CO2 methanation

CO2 conversion to value-added chemical products is of significance for carbon cycling. Pd-based catalysts show great potential in CO2 methanation reaction by virtue of synergistic effect between the Pd and...