Strong Metal-support Interaction Research Articles

Using Support Effects to Increase the Productivity of Immobilized Ruthenium Hydride Catalysts for the Hydrogenation of CO2.

Interfaces between catalytically active metal surfaces/sites and metal oxides (such as those formed by metal oxides covering metal nanoparticles by strong metal-support interactions) allow both the metal and metal oxide to react with substrates simultaneously and are important for the activity of many heterogeneously catalyzed reactions. However, similar interactions for well-defined immobilized catalysts have not been investigated, despite their potential for increasing catalytic activity. We test the reactivity of a ruthenium hydride [H2Ru(PPh3)2(Ph2P)2NC3H6Si(OEt)3 (1)] in the amine-promoted hydrogenation of CO2 as both a homogeneous catalyst and anchored on SiO2, Al2O3, ZnO, and SBA-15. Anchoring 1 on the surfaces resulted in varying degrees of surface collapse (formation of H-Ru-O linkages to the surface), with ZnO and confinement in SBA-15 pores giving the least surface collapse. Immobilization of 1 on ZnO gave a 6-fold improvement of the catalytic rate over the corresponding homogeneous catalyst. This increase in the catalytic productivity was only possible when the complex was in close contact with ZnO and is most likely due to a combination of increased catalytic activity and slower deactivation. These results demonstrate the ability of surface effects to vastly improve the productivity of even mediocre catalysts upon surface immobilization.

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.

Hydrotalcite-derived well-dispersed and thermally stable cobalt nanoparticle catalyst for ammonia decomposition

Ammonia is a carbon-free hydrogen carrier, and development of non-noble metal catalyst to decompose ammonia into hydrogen is desirable for practical applications. However, the metal catalyst is challenged by the sintering of metal particles under high-temperature reaction conditions. In this study, a series of Li-, Al-, and Co-containing hydrotalcite-like compounds (HTlc) were synthesized by co-precipitation and used as precursors to prepare well-dispersed and thermally stable Co nanoparticle catalysts for ammonia decomposition. The obtained precursors and catalysts were characterized by means of X-ray powder diffraction (XRD), temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and so on. All of the precursors formed hydrotalcite-like phase, which consisted of Li–Al–(Co) HTlc and/or Co–Al HTlc dependent on the Co content. Upon calcination at 500 °C, HTlc decomposed into an Al-substituted Co3O4 spinel oxide, as confirmed by two distinctly separated reduction steps in H2-TPR. Following reduction at 700 °C, well-dispersed Co metal nanoparticles with an average particle size of ∼9.2–12.4 nm were obtained. It was suggested that the incorporation of Al3+ into Co3O4 led to a strong interaction between cobalt and aluminum, which suppressed the crystal growth of Co3O4 and the sintering of Co metal during the thermal treatments, resulting in good Co dispersion. The optimal LiAlCo(1.5) catalyst showed superior activity than that prepared by impregnation method, giving almost complete conversion of ammonia at 575 °C under a space velocity of 5,000 mL gcat–1 h–1. More importantly, this catalyst maintained stable activity at 625 °C for 100 h, exhibiting high stability and sintering resistance. The good catalytic performance was attributed to the high Co metal dispersion and strong metal–support interaction benefiting from the uniform distribution of cobalt in the HTlc precursor. These results demonstrate the applicability of HTlc to the preparation of metal catalysts with improved dispersion and thermal stability.

In-situ reconstructing active sites during the surficial deposition of Pt isolated sites with strong metal-support interaction

The strong metal-support interaction (SMSI) has garnered significant attention for its effective enhancement in catalytic performance. However, the influence of interface structure evolution on sensing and catalytic performance has not been clearly elucidated yet. In this work, BiVO4 with different exposed crystal facets was synthesized and surface-modified with Pt. Through leveraging photo-assisted enhanced strong metal-support interaction to induce a highly active interface structure during the loading of Pt, the gas sensing performance was significantly improved. The single cycle photo-assisted (PA) ALD Pt deposited on BiVO4 (noted as PA-Pt1/BiVO4) exhibited an enhanced sensitivity (Ra/Rg) to hydrogen sulfide (21.3 @ 10 ppm), that to Pt1/BiVO4 and -BiVO4 are 1.9 and 1.6, respectively. It is 11 times and 13 times higher than non-illuminated Pt/BiVO4 and pristine BiVO4, respectively. Characterization results indicated the formation of novel interface structures under photo assistance, primarily attributed to the intensified SMSI through photo treatment. This study not only provides a promising approach for enhancing selectivity and sensitivity of gas sensing materials by designing high-performance materials based on robust metal-carrier interactions, but also give insight into the in-situ SMSI which shows great potential in design and preparation of high sensing/catalytic materials.

Ru-M (Fe, Co, Ni) onto Nitrogen-doped Two-dimensional Carbon Nanosheets through Microwave Approach with Strong Metal-support Interactions for overall Water-splitting

Developing Ru-based catalysts with strong metal-support interactions (SMSI) is a significant approach to achieve highly-efficient catalytic activity and satisfactory stability. Nevertheless, the current strategies to construct SMSI are generally time-consuming and tedious, and then leading to aggregation. In this research, ultrafast microwave (45 s) is employed to affix small Ru-M (Fe, Co, Ni) nanoparticles onto nitrogen-doped two-dimensional (2D) carbon nanosheets (NCN, Ru-M/NCN), leading to robust metal-support interactions that enhance reaction kinetics and boost stability. Furthermore, the electronic interplay between Ru and M is pivotal in augmenting catalytic efficacy. The small size of the Ru-M nanoparticles and high specific surface area also favor exposing active sites and abundant interconnected channels to accelerate mass transport. Subsequent low-temperature oxidation process, to prepare RuM@RuOx/NCN, which is conducted to achieve oxygen evolution reaction (OER) performance. Thus, the as-synthesized RuCo/NCN only requires 65 mV, 58 mV, and 98 mV to achieve 10 mA cm-2 for hydrogen evolution reaction (HER) in 0.5 M H2SO4, 1 M KOH and alkaline seawater. RuM@RuOx/NCN is obtained by low-temperature oxidation to achieve excellent oxygen reduction reaction performance in 1 M KOH, the low overpotential of only 273 mV, 256 mV and 284 mV can reach 10 mA cm-2 and satisfactory stability. Moreover, the prepared electrocatalysts also achieve satisfactory electrocatalytic activity for overall water-splitting in alkaline freshwater/seawater electrolytes. This work provides a superior pathway for multifunctional nanomaterials for sustainable energy storage and conversion.

Overturning CO2 Hydrogenation Selectivity from CH4 to CO by Strong Ru-FeOx Interaction Arising from a Multilayer Epitaxial Structure.

The catalytic conversion of CO2 to CO through hydrogenation has emerged as a promising strategy for CO2 utilization, given that CO serves as a valuable C1 platform compound for synthesizing liquid fuels and chemicals. However, the predominant formation of CH4 via deep hydrogenation over Ru-based catalysts poses challenges in achieving selective CO production. High reaction temperatures often lead to catalyst deactivation and changes in selectivity due to dynamic metal evolution or agglomeration, even with a classic strong metal-support interaction. Herein, we have developed a FeOx/Ru/Rutile multilayer epitaxial structure by depositing a FeOx layer onto the epitaxially grown RuO2 nanolayers on the surface of rutile nanoparticles. This multilayer epitaxial structure transformed into a structure in which Ru nanoparticles were decorated with FeOx layers with ultrastable strong metal-support interaction (SMSI). Subsequently, the FeOx decoration on Ru nanoparticles effectively shifted the dominant product from CH4 to 95% CO during CO2 hydrogenation. Remarkably, this catalyst exhibits exceptional stability and can be operated stably at 550 °C for a long time without apparent deactivation. Compared with the dynamic changes observed in supported Ru nanoparticles, the interaction between Ru and FeOx maintains their electronic states at different reaction temperatures. Furthermore, this Ru-FeOx interaction inhibits H2 activation capability, CO adsorption, and subsequent hydrogenation of CO. The transformation strategy employed here, which utilizes initial multilayer epitaxial structures, can be applied to construct SMSI to enhance metal catalysts' catalytic performance.

Impact of Ga, Sr, and Ce on Ni/DSZ95 Catalyst for Methane Partial Oxidation in Hydrogen Production

The greenhouse gas CH4 is more potent than CO2, although both these gases are solely responsible for global warming. The efficient catalytic conversion of CH4 into hydrogen-rich syngas, which also demonstrates economic viability, can deplete the concentration of CH4. This study examines the partial oxidation of methane (POM) prepared by the wetness impregnation process using 5% Ni supported over DSZ95 (93.3% ZrO2 + 6.7% Sc2O3) and promoted with 1% Ga (gallium), 1% Sr (strontium), and 1% Ce (cerium). These catalysts are characterized by surface area porosity, X-ray diffraction, FT-Infrared spectroscopy, Raman infrared spectroscopy, temperature programmed reduction, CO2 temperature-programmed techniques, desorption techniques, thermogravimetry, and transmission electron microscopy. The characterization results demonstrate that Ni is appropriate for the POM because of its crystalline structure, improved metal support contact, and increased thermal stability with Sr, Ce, and Ga promoters. The synthesized catalyst 5Ni+1Ga-DSZ95 maintained stability for 240 min on stream during the POM at 700 °C. Adding a 1% Ga promoter and active metal Ni to the DSZ95 improved the CH4 conversion from 70.00% to 75.90% and raised the H2 yield from 69.21% to 74.80%, while maintaining the reactants’ stoichiometric ratio of (CH4:O2 = 2:1). The 5Ni+1Ga-DSZ95 catalyst is superior to the other catalysts, given its rich catalyst surface, strong metal support interaction, high surface area and low amount of carbon deposit. The high H2/CO ratio (>2.6) and H2 yield close to 75% indicate that 5Ni+1Ga-DSZ95 is a potent industrial catalyst for hydrogen-rich syngas production through partial oxidation of methane.

Ni-Co nano-alloys confined by N-doped porous carbon overlayer to boost hydrodeoxygenation of 5-hydroxymethylfurfural

Ni-Co nano-alloys confined by in-situ formed N-doped porous carbon overlayer have been prepared through chelation of metal cations with citric acid and urea followed by carbonization for hydrodeoxygenation of 5-hydroxymethylfurfural (HMF) into 2, 5-dimethylfuran (DMF). The results indicated that the Ni-Co nano-alloys were formed and homogeneously distributed within the N-doped porous carbon overlayer. The electronic effect of the Ni-Co nano-alloys significantly boosted hydrodeoxygenation activity of the Co2Ni1@NC catalyst and simultaneously inhibited further hydrogenation and opening of furan ring. The N-doped porous carbon overlayer around Ni-Co nano-alloys not only facilitated to disperse and stable Ni-Co nano-alloys through strong metal-support interaction, but also protected the Ni-Co nano-alloys from aggregation. Therefore, the Co2Ni1@NC catalyst offered superior catalytic performance with the HMF conversion of 100 % and DMF selectivity of 93.0 %. Moreover, the Co2Ni1@NC catalyst displayed excellent stability without significant activity loss after five recycles due to the spatial confinement of N-doped carbon overlayer.

Nature of metal-support interaction for metal catalysts on oxide supports.

The metal-support interaction is one of the most important pillars in heterogeneous catalysis, but developing a fundamental theory has been challenging because of the intricate interfaces. Based on experimental ‎data, interpretable machine learning, theoretical derivation, and first-principles simulations, we established a ‎general theory of metal-oxide interactions grounded in ‎metal-metal and metal-oxygen interactions. The theory applies to metal nanoparticles and atoms on oxide supports and oxide films on metal supports. We found that for late-transition metal catalysts, metal-metal interactions dominated the oxide support effects and suboxide encapsulation over metal nanoparticles. A principle of strong metal-metal interactions for encapsulation occurrence is formulated and substantiated by extensive ‎experiments including 10 metals and 16 ‎oxides. The valuable insights revealed on (strong) metal-support interaction advance the interfacial design of supported metal catalysts.

Enhanced sintering resistance of NiFe‐based RWGS catalysts through Cu doping

AbstractThe reverse water‐gas shift (RWGS) reaction offers an effective method for mitigating CO2 emissions. Due to its affordability and physicochemical stability, iron has garnered significant attention as a potential catalyst for RWGS. The incorporation of nickel and copper promoters can enhance CO2 conversion and CO selectivity in Fe‐based catalysts. This study focuses on modifying the strength of the Strong Metal‐Support Interaction (SMSI) through particle size optimization. Doping Cu into NiFe‐based catalysts restricts particle size, which influences the curvature of the Ni0@FeOx interface. This curvature enhances the electron coupling between Ni0 and FeOx, promoting the formation of a denser and thicker Ni0 and FeOx layer. This results in a nearly 90% increase in the CO2 reaction rate during the sintering resistance test by anchoring Ni0 and facilitating electron transfer to active sites. Such morphological evolution improves high‐temperature resistance to sintering during RWGS. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

Au nanoparticle-sensitized nitrogen-doped carbon applied for localized surface plasmon enhanced hydrogen evolution reaction

Carbon-supported metal nanoparticles are indispensable catalysts to enabling catalytic water splitting technologies because of their unique size-dependent properties and strong metal-support interactions. Herein, we proposed a two-step synthesis strategy, using imine-type covalent organic frameworks (COFs) as a platform to synthesize nitrogen-doped carbon-supported Au with ultra-high specific surface area through the high-temperature pyrolysis. Thanks for the polarity of imine, the growth of Au NPs in Aux/NC are ultrafine, monodispersed, and the size of Au can be precisely controlled by adjusting the amount of the metal precursor during the carbothermal reaction. Such framework structure with numerous active sites provided by the COFs renders Aux/NC ultrahigh catalytic activity and durability for hydrogen evolution reaction (HER) in acid electrolyte. Most significantly, when illumination occurs, Au5nm/NC catalyst presents a reduced HER overpotential from 416 mV to 43 mV and a shrunken charge-transfer resistance from 258 to 17 Ω, making the Au5nm/NC a promising stable catalyst for the LSPR promoted hydrogen evolution reaction.

Controlling Metal-Support Interactions to Engineer Highly Active and Stable Catalysts for COx Hydrogenation.

This perspective focuses on the modulation of metal-support interaction (MSI) in catalysts for COx hydrogenation, highlighting their profound impact on catalytic performance. Firstly, it outlines different strategies, including the use of highly reducible oxides and moderate reduction treatments, which induce the classical strong metal-support interaction (SMSI) effect and the electronic metal-support interaction (EMSI) effect. Morphology engineering and crystalline phase manipulation of oxides presented as effective methods to control EMSI are also discussed. The discrimination of SMSI and EMSI can be achieved using oxides with low encapsulation tendencies, such as ZrO2, which supports electronic modifications without or minimizing the overgrowth issues, optimizing the catalytic performance for methanation. Then, the synergy between Cu and ZnO in methanol synthesis, enhanced by SMSI, is emphasized inside. Optimizing support oxides to control oxygen vacancies enhances the catalytic performance of CO2 hydrogenation to methanol. Perspectives for the future research on the fundamental understanding of structure-MSI-performance relationship for catalyst design is discussed.

Strong metal-support interaction induced excellent performance for photo-thermal catalysis methane dry reforming over Ru-cluster-ceria catalyst

The utilization of solar energy in driving methane dry reforming (MDR) reaction through photo-thermal synergetic catalysis could simultaneously realize the reduction of carbon footprint and the fixation of solar energy, which is an environmentally and economically beneficial route. However, the currently developed catalysts still require further optimization in catalytic performance and stability. Here, we prepared RuNC, a Ru nanoclusters catalyst anchored on CeO2 with strong metal-support interaction (SMSI) effect via a facile preparation method. The formation rates of H2 and CO over RuNC catalyst were 1.41 and 2.16 mol·gcat−1·h−1 respectively under photo-thermal catalysis (PTC) at 500 °C, which is up to one order of magnitude higher than existing PTC-MDR catalysts. Moreover, the prepared catalyst did not show significant deactivation under 100 hour test. The in-depth structure-function relationship between catalytic activity/stability and Ru nanocluster sites/induced SMSI effect were determined by systematic structural characterization. The advantages of RuNC catalyst structure under PTC catalytic conditions were demonstrated by optical characterization. Besides, the excitation-migration path of photo-electron under PTC conditions was determined by ISI-XPS experiments. Finally, the mechanism of PTC-MDR reaction and the specific reaction steps enhanced by light irradiation were determined by operando experiments. This work provided theoretical basis and excellent catalyst for the industrial application of PTC-MDR route.

Bimetallic NiCo Nanoparticles Embedded in Organic Group Functionalized Mesoporous Silica for Efficient Hydrogen Production from Ammonia Borane Hydrolysis.

In this study, bimetallic NiCo nanoparticles (NPs) were encapsulated within the mesopores of carboxylic acid functionalized mesoporous silica (CMS) through the chemical reduction approach. Both NaBH4 and NH3BH3 were used as reducing agents to reduce the metal ions simultaneously. The resulting composite was used as a catalyst for hydrolysis of ammonia borane (NH3BH3, AB) to produce H2. The bimetallic NiCo NPs supported on carboxylic group functionalized mesoporous silica, referred to as NixCo100-x@CMS, exhibited significantly higher catalytic activity for AB hydrolysis compared to their monometallic counterparts. The remarkable activity of NixCo100-x@CMS could be ascribed to the synergistic contributions of Ni and Co, redox reaction during the hydrolysis, and the fine-tuned electronic structure. The catalytic performance of the NixCo100-x@CMS nanocatalyst was observed to be dependent on the composition of Ni and Co. Among all the compositions investigated, Ni40Co60@CMS demonstrated the highest catalytic activity, with a turn over frequency (TOF) of 18.95 molH2min-1molcatalyst-1 and H2 production rate of 8.0 L min-1g-1. The activity of Ni40Co60@CMS was approximately three times greater than that of Ni@CMS and about two times that of Co@CMS. The superior activity of Ni40Co60@CMS was attributed to its finely-tuned electronic structure, resulting from the electron transfer of Ni to Co. Furthermore, the nanocatalyst exhibited excellent durability, as the carboxylate group in the support provided a strong metal-support interaction, securely anchoring the NPs within the mesopores, preventing both agglomeration and leakage.

Synergistic Electronic Interaction in PdCu Alloy/TiO2-NSs for Ambient Efficient Dehydrogenation of Formic Acid.

Palladium-based catalysts are remarkable in endorsing hydrogen (H2) generation through formic acid (HCOOH, FA) dehydrogenation under near-ambient conditions. Hydrogen energy efficiency depends on high-performance catalyst design. In this study, Pd-Cu nanoalloy catalysts with mutable atomic ratios are successfully fabricated on TiO2 nanosheets (TiO2-NSs).The synergistic electronic interactions between Palladium (Pd) and copper (Cu) are revealed through a density of states (DOS) analysis of alloy supported over a mixed valence state of Ti linked to oxygen vacancies (Vo) in TiO2-NSs, Enhanced adsorption of target molecules reveals novel active sites for Formic acid dehydrogenation (FAD), with O─H bond cleavage via HCOO formate intermediate preceding C─H and C─O bond cleavage. Experimental and theoretical research demonstrates that the Pd-Cu/TiO2-NSs (3:7) catalyst d electron redistribution and d-band center shift lower the activation energy for O─H bond cleavage, exhibit superior H2 production than pure Pd and Cu, increasing Pd electron density due to synergistic effects from reactive crystal facets, defects, and strong metal support interactions (SMSI), lowering the activation energy for HCOOH dissociation step, generating carbon dioxide (CO2) and H2 with a unprecedented high turnover frequency (TOF) of 6268 molH2.h-1.molPd-1 at 303K with activation energy (Ea) of 15 KJ mol-1. This attempt models an efficient HCOOH-to-hydrogen catalyst.

Non-noble Co supported on beta framework for hydrogenolysis of biomass-derived 5-hydroxymethylfurfural to renewable biofuel 2,5-dimethylfuran

Selective transformation of biomass platform molecule 5-hydroxymethylfurfural (HMF) into biofuel 2,5-dimethylfuran (DMF) through hydrogenolysis path has attracted significant attention in the field of biomass catalytic conversion. In general, this process required supported noble catalysts under elevated temperature (423–533 K) and enough H2 pressure (1–4 MPa). Herein, Co/Beta-DA catalysts with various Co loadings of 5–20 wt% were post-synthesized through wet impregnation. Benefiting from the relatively open channel systems and strong metal-support interactions, the obtained 10Co/Beta-DA with ∼10 wt% Co contents facilitated the hydrogenation of C=O bonds and the cleavage of C-O bonds, which was efficient for the selective hydrogenolysis from HMF to DMF (Conv.HMF ≥ 99.9 %, Sel.DMF ≥ 99.9 %) under mild reaction conditions (H2 pressure, 1.0 MPa; temp., 423 K; time, 3 h). The innovative strategy of designing and preparing rational non-noble impregnated zeolite provided brand-new perspectives to solve the problems of high cost and harsh reaction conditions in the HMF hydrogenolysis process, which has the potential to convert biomass into renewable liquid fuels.

Atomically Dispersed Ru Species Induced by Strong Metal-Support Interaction for Electrochemical Methane Reforming.

During the high-temperature oxygen evolution reaction for CO2 electrolysis in solid oxide electrolysis cells (SOECs), the key elementary process of O2- transfer is restricted by the high anodic oxygen pressure thermodynamically, thus requiring a high external voltage [open-circuit voltage (OCV)] to drive the electrolysis reaction. Herein, electrochemical CH4 reforming is introduced to the SOEC anode, which remarkably lowers the anodic oxygen pressure and OCV, finally reducing the energy demand from 3.12 to 0.11 kW h per cubic meter of CO. Meanwhile, atomically dispersed Ru species is anchored on the anode surface due to the strong metal-support interaction, which exhibits superior CH4 reforming activity (90% of CO selectivity) and stability (300 h) to the infiltrated Ru nanoparticles and doped Ru species in the bulk lattice at 600 °C. This work proposes an efficient strategy to boost the SOEC performance thermodynamically and produce value-added chemicals at both the cathode and anode of SOEC simultaneously.

Synergize Strong and Reactive Metal-Support Interactions to Construct Sub-2 nm Metal Phosphide Cluster for Enhanced Selective Hydrogenation Activities.

Strong metal-support interactions (SMSI) are crucial for stabilizing sub-2 nm metal sites, e.g. single atom (M1) or cluster (Mn). However, further optimizing sub-2 nm sites to break the activity-stability trade-off due to excessive interactions remains significant challenges. Accordingly, for the first time, we propose synergizing SMSI with reactive metal-support interactions (RMSI). Comprehensive characterization confirms that the SMSI stabilizes the metal and regulates the aggregation of Ni1 into Nin site within sub-2 nm. Meanwhile, RMSI modulates Nin through sufficiently activating P in the support and eventually generates sub-2 nm metal phosphide Ni2P cluster (Ni2Pn). The synergetic metal-support interactions triggered the adaptive coordination and electronic structure optimization of Ni2Pn, leading to the desired substrate adsorption-desorption kinetics. Consequently, the activity of Ni2Pn site greatly enhanced towards the selective hydrogenations of p-chloronitrobenzene and alkynyl alcohol. The formation rates of target products are up to 20.2 and 3.0 times greater than that of Ni1 and Nin site, respectively. This work may open a new direction for metal-support interactions and promote innovation and application of active sites below 2 nm.

Dynamics of strong metal-support interactions: Investigating Pt and Pt-based alloys on CdS nanorods through experimental and simulated approaches

The catalytic performance of supported metal nanoparticles (NPs) is greatly affected by metal-support interaction (MSI). Understanding the mechanisms and dynamics of MSI in heterogeneous catalysis remains challenging. Traditionally, MSI studies have focused on metal oxide supports and rarely compared MSI between Pt and Pt-based alloys, despite the importance of Pt in catalysis. In this study, we introduce CdS nanorods as a novel support material and investigate the MSI behavior of both Pt and Pt-based alloy NPs using in situ TEM electron beam irradiation. Our findings show that Pt NPs have strong MSI with CdS and that encapsulation layers form over Pt NPs because Pt has the high surface energy. On the other hand, Pt-based alloys have weaker MSI. These experiments were validated by direct thermal annealing for four hours. Molecular dynamics simulations were used to explain the observed behavior, providing insights into how the surface energy differences between Pt and Pt-based alloys influence their interactions with CdS nanorods. These findings offer valuable insights into catalyst design, highlighting the potential for controlling MSI strength to optimize catalytic performance in heterogeneous systems.

Unveiling the Role of Strong Metal-Support Interactions in Gold-Catalyzed CO Oxidation on MnO2 Polymorphs.

The effectiveness of gold (Au)-based catalysts in CO oxidation is significantly influenced by strong metal-support interactions with surface oxygen structures, the mechanisms of which remain elusive. To investigate this property, we selected γ-MnO2, featuring Mn(-O-)2Mn and Mn-O-Mn structural motifs, and β-MnO2, characterized by Mn-O-Mn linkages, as support materials. The CO oxidation process was investigated by fabricating Au nanoparticles supported on these two MnO2 polymorphs. Our findings reveal that Au supported on β-MnO2 substantially enhanced CO oxidation, in stark contrast to the inhibitory effect observed with Au on γ-MnO2. Using operando diffuse reflectance infrared Fourier transform spectroscopy coupled with mass spectrometry, we detected an increase in the production of surface-adsorbed oxygen following Au deposition on β-MnO2. Conversely, Au supported on γ-MnO2 resulted in a diminished capacity for surface oxygen adsorption. The presence of Au+ and Mn2+ ions was identified as pivotal for CO oxidation. Moreover, the engagement of the Mn(-O-)2Mn structure in the reaction was impaired after Au loading on γ-MnO2, and the regeneration of the Mn-O-Mn linkage was similarly hindered. We propose a mechanism for the interactions between Au and the oxygen species associated with Mn(-O-)2Mn and Mn-O-Mn structures on MnO2, offering insights into the divergent catalytic behaviors exhibited by different MnO2 polymorphs.