Strong Metal-support Interaction Research Articles

Crystal Facet Controlled Metal-Support Interaction in Uricase Mimics for Highly Efficient Hyperuricemia Treatment.

The effect of strong metal-support interaction (SMSI) has never been systematically studied in the field of nanozyme-based catalysis before. Herein, by coupling two different Pd crystal facets with MnO2, i.e., (100) by Pd cube (Pdc) and (111) by Pd icosahedron (Pdi), we observed the reconstruction of Pd atomic structure within the Pd-MnO2 interface, with the reconstructed Pdc (100) facet more disordered than Pdi (111), verifying the existence of SMSI in such coupled system. The rearranged Pd atoms in the interface resulted in enhanced uricase-like catalytic activity, with Pdc@MnO2 demonstrating the best catalytic performance. Theoretical calculations suggested that a more disordered Pd interface led to stronger interactions with intermediates during the uricolytic process. In vitro cell experiments and in vivo therapy results demonstrated excellent biocompatibility, therapeutic effect, and biosafety for their potential hyperuricemia treatment. Our work provides a brand-new perspective for the design of highly efficient uricase-mimic catalysts.

Tuning Adsorbate-Mediated Strong Metal-Support Interaction by Oxygen Vacancy: A Case Study in Ru/TiO2.

The adsorbate-mediated strong metal-support interaction (A-SMSI) offers a reversible means of altering the selectivity of supported metal catalysts, thereby providing a powerful tool for facile modulation of catalytic performance. However, the fundamental understanding of A-SMSI remains inadequate and methods for tuning A-SMSI are still in their nascent stages, impeding its stabilization under reaction conditions. Here, we report that the initial concentration of oxygen vacancy in oxide supports plays a key role in tuning the A-SMSI between Ru nanoparticles and defected titania (TiO2-x). Based on this new understanding, we demonstrate the in-situ formation of A-SMSI under reaction conditions, obviating the typically required CO2-rich pretreatment. The as-formed A-SMSI layer exhibits remarkable stability at various temperatures, enabling excellent activity, selectivity and long-term stability in catalyzing the reverse water gas-shift reaction. This study deepens the understanding of the A-SMSI and the ability to stabilize A-SMSI under reaction conditions represents a key step for practical catalytic applications.

Atomic-Scale Interface for Pt Nanoparticles on SrTiO3 (001).

The interfacial structure formed by Pt nanoparticles grown epitaxially on a SrTiO3 (001) surface by pulsed laser deposition was studied by X-ray standing-wave (XSW) excited core-level photoelectron emission. The XSW-generated 3D atomic map of the Pt and interfacial oxygens for the oxidized Pt/SrTiO3 interface differs significantly from that of the as-deposited interface. After oxidation, the Pt atoms shifted upward and their atomic occupation at fcc-like sites evolved as the oxidation temperature increased. Interfacial oxygen atoms were differentiated from bulk O atoms by the chemical shift in the binding energy of their 1s electrons. After oxidation, the interfacial oxygen atoms rearranged to form a TiO2 bilayer at the interface. These results provide a more complete description of the strong metal-support interaction process at the interface.

Effects of Intrinsic Defects in Pt-Based Carbon Supports on Alkaline Hydrogen Evolution Reaction.

Carbon material has widely been utilized in the synthesis of efficient carbon-supported Pt (Pt/C) catalysts, in which the structural properties greatly influence the electrocatalytic performances of Pt/C catalysts. However, the effects of intrinsic defects in carbon supports on the performance of the alkaline hydrogen evolution reaction (HER) have not been systematically investigated. Herein, porous carbon supports with different degrees of intrinsic defects were prepared by a simple template-assisted strategy, and the resulting samples were systematically studied by various analytical methods. The results suggested that the presence of abundant intrinsic defects (vacancy and topological defects) in the carbon support was advantageous in terms of favoring the dispersion and anchoring of Pt species, promoting electron transfer between Pt atoms and the carbon support, and tuning the electronic states of Pt species. These features improved the HER performance of Pt/C catalysts. Compared to the nontemplate-assisted carbon-supported Pt catalyst (Pt/NTC) with an overpotential of 178 mV, the optimized template-assisted carbon-supported Pt catalyst (Pt/TC) exhibited a lower overpotential of 58 mV at 10 mA cm-2. Besides, the Pt/TC catalyst displayed better HER durability than the Pt/NTC catalyst owing to its strong metal-support interaction. The DFT calculations confirmed the important role played by intrinsic defects (vacancy and topological defects) in stabilizing Pt atoms, with Pt-C3 coordination identified as the most favorable structure for improving the HER performance of Pt. Overall, novel insights on the significant contribution of intrinsic defects in porous carbon supports on the HER performances of Pt/C catalysts were provided, useful for future design and fabrication of advanced carbon-supported catalysts or other carbon-based electrode materials.

Supported highly dispersed molybdenum nitride derived from molybdate-intercalated Mg‒Al hydrotalcite-like compounds as a catalyst for ammonia decomposition

Molybdate-intercalated magnesium–aluminum hydrotalcite-like compounds (HTlc) were synthesized by anion-exchange and used as precursor to prepare supported molybdenum nitride catalyst for ammonia decomposition. The as-synthesized precursors and the derived mixed metal oxides and nitride catalysts were characterized by ICP, XRD, Raman spectroscopy, XPS, H2-TPR, and HAADF-STEM-EDX. The characterizations indicated that molybdate was well intercalated into the HTlc interlayer as MoO42– and the Mo content was tunable by altering the intercalation degree of molybdate. Upon calcination, molybdena was dominantly presented as isolated tetrahedrally coordinated MoOx species. Upon nitridation with ammonia at 700 ºC, highly dispersed and composition-uniform molybdenum nitride (Mo2±xN) was formed. The Mo0.5Mg3Al nitride catalyst showed good activity for ammonia decomposition, providing nearly full conversion of ammonia at 625 ºC under a space velocity of 5,000 mL gcat–1 h–1. The optimal catalyst also exhibited high catalytic stability during 100 h operation at 625 ºC, and no obvious aggregation took place, attributable to the strong metal–support interaction between molybdenum nitride and Mg–Al mixed oxide. It is suggested that the hydrotalcite-derived Mg–Al mixed oxide supported highly dispersed Mo2±xN species was active and stable for ammonia decomposition.

Facet‐Junction Induced Strong Metal Support Interaction for Enhanced Alkaline Hydrogen Evolution Reaction

AbstractStrong metal‐support interaction (SMSI) plays a critical role in enhancing the catalytic performance of electrocatalysts. Currently, effective approaches to enhance the SMSI effect in supported electrocatalysts still need to be developed, and a comprehensive atomic‐level understanding of the underlying reaction mechanisms remains unclear. In this study, a novel facet‐junction strategy is proposed to enhance the SMSI between the loaded Ru atoms and the Co3O4 support. By modulating the ratio of exposed facet for (111)/(100) crystal plane in Co3O4, the hydrogen evolution reaction (HER) performance can be dramatically enhanced by 560% and can achieve a Pt‐like HER activity with the overpotential of 45 mV. Detailed analysis with atomic‐resolution integrated differential phase contrast (iDPC)‐scanning transmission electron microscopy (STEM), atomic‐resolution high angle annular dark field (HADDF)‐STEM, and electron energy loss spectroscopy (EELS) further proved that with proper (111)/(100) crystal plane ratio, the intensified charge distribution near the facet‐junction region would modify the electronic structure around the active sites. This work provides new insights to enhance the SMSI and will contribute to the rational design of highly efficient electrocatalysts for water splitting.

Substitutional phosphorus doping stimulates strong metal-support interactions for anion exchange membrane based alkaline seawater electrolysis

The development of electrocatalysts with high catalytic activity and resistant to chlorine has become crucial for the large-scale implementation of seawater electrolysis. Here, the strong metal support interaction (SMSI) between Pt and NiMoO4 is enhanced by substitutional P atom-doping (P-Pt/NiMoO4@NF) to optimize the metal surrounding environment, realizing the efficient and anticorrosive seawater electrolysis. Density functional theory (DFT) reveals that substitutional P atom-doping can adjust the electronic structure to optimize the hydrogen adsorption free energy (ΔGH*) and decrease the adsorption energy of Cl- for the HER process. Benefiting from the SMSI caused by substitutional P atom-doping, the prepared P-Pt/NiMoO4@NF catalyst achieves a current density of 1.0 A cm−2 at an ultra-low overpotential of only 80 mV, surpassing the most reported Pt-based electrocatalysts. More importantly, in the anion exchange membrane (AEM) electrolyzer, the catalyst used as the cathode can drive 500 mA cm−2 under industrial conditions with only 1.75 V, while running steadily for 120 h, and with high efficiency and low price of H2 per gallon gasoline equivalent (GGE).

Silica-assisted Pt1/CeO2 single-atom catalyst for enhancing the catalytic combustion performance of VOCs by inducing H2O activation

Due to the competitive adsorption of water and reactants at the active sites, especially the water toxicity of platinum-based single-atom catalysts, it is of great importance to improve the low-temperature activity and the water resistance of catalysts for the catalytic combustion of benzene. In this work, it was found that constructing a SiO2 shell layer on the catalyst not only "immobilized" the Pt single atoms, but also effectively weakened the adsorption of H2O on the Pt active sites, which resulted in excellent water resistance of the Pt single-atom catalysts. The comprehensive characterization results demonstrated that the participation of water molecules in the catalytic oxidation reaction of benzene could be effectively promoted by enhancing the strong metal-support interactions (SMSI) at the core-shell interface, which would change the electronic structure of the catalyst surface. As a result, the Pt1/CeO2@SiO2-4 catalyst with a Pt-O-Si active interface exhibits good activity (T = 190 °C) as well as excellent water resistance under the wet condition (10 vol%). This project provides a promising strategy for the design of Pt-based core-shell catalysts with excellent water resistance.

Highly dispersed active sites and strong metal-support interaction for boosting CO2 hydrogenation to methanol

As global energy demand continues to increase and global climate change issues caused by greenhouse gas emissions gradually heat up, the effective conversion of carbon dioxide into high value-added methanol has become a key challenge in the energy and environmental fields. However, due to the chemical inertness of CO2 molecules, it is difficult to activate CO2 at low temperatures, resulting in extremely low conversion rates. Although increasing the reaction temperature is beneficial for the conversion of CO2, there is also competition in the reverse water gas reaction, resulting in lower methanol selectivity. Therefore, developing efficient catalysts is the key to improving CO2 conversion rate and methanol selectivity. In this work, we used zirconium-based UIO-66 metal-organic framework as a precursor, replaced the original terephthalic acid ligand with thermally unstable aminoterephthalic acid, and supported Cu on the MOF precursor by equal volume impregnation method. After heat treatment, the Cu/ZrO2-DM catalyst was prepared. The catalyst was compared with Cu/ZrO2 catalyst prepared by co-precipitation method, hydrothermal method and unmodified Cu/ZrO2-D catalyst. The Cu/ZrO2-DM catalyst exhibited the highest CO2 conversion and methanol selectivity in the hydrogenation reaction, reaching 13.95% and 90.78%, respectively. The main reason is attributed to the large specific surface area of the copper-based catalyst derived from MOF materials, the good dispersion of the active center and the strong interaction between Cu and the precursor. This work may provide a new perspective for the design and synthesis of related catalytic materials for efficient CO2 hydrogenation to methanol.

Tuning the strong metal support interaction of the Fischer-Tropsch synthesis silica-coated cobalt-based nano-catalyst

The catalyst is crucial in enhancing productivity within the Fischer-Tropsch synthesis (FTS). The metal support interaction (MSI) plays a pivotal role in the FTS catalyst performance, impacting activity, stability, and selectivity. he configuration and composition of the catalyst dramatically impact MSI, with a strong MSI (SMSI) specified for the core-shell structure. In this study, two methods consisting of chemical treatment of etching and adding a promoter (Ru) for tuning the SMSI of the FTS catalyst are presented, and their footprints on the catalysts’ performance are screened by utilizing various characterization tests, molecular dynamic simulation, and catalytic tests. It is recognized that the silica interfacial perimeter acts as a barrier that restricts the charge transfer and boosts the SMSI in the silica-coated catalyst. Conversely, the etched catalyst exhibits a moderate MSI, contributing to increased reducibility, stability, and activity. Furthermore, the Ru-doped etched catalyst represents the optimum MSI, resulting in the highest overall performance.

Electrostatic Self-assembly Synthesis of Pd/In2O3 Nanocatalysts with Improved Performance Toward CO2 Hydrogenation to Methanol.

CO2 hydrogenation to methanol has emerged as a promising strategy for achieving carbon neutrality and mitigating global warming, in which the supported Pd/In2O3 catalysts are attracting great attention due to their high selectivity. Nonetheless, conventional impregnation methods induce strong metal-support interaction (SMSI) between Pd and In2O3, which leads to the excessive reduction of In2O3 and the formation of undesirable PdIn alloy in hydrogen-rich atmospheres. Herein, we innovatively synthesized Pd/In2O3 nanocatalysts by the electrostatic self-assembly process between surface-modified composite precursors with opposite charges. And the organic ligands concurrently serve as Pd nanoparticle protective agents. The resultant Pd/In2O3 nanocatalyst demonstrates the homogeneous distribution of Pd nanoparticles with controllable sizes on In2O3 supports and the limited formation of PdIn alloy. As a result, it exhibits superior selectivity and stability compared to the counterparts synthesized by the conventional impregnation procedure. Typically, it attains a maximum methanol space-time yield of 0.54 gMeOH h-1gcat-1 (300 °C, 3.5 MPa, 21,000 mL gcat-1 h-1). Notably, the correlation characterization results reveal the significant effect of small-size, highly dispersed Pd nanoparticles in mitigating MSI. These results provide an alternative strategy for synthesizing highly efficient Pd/In2O3 catalysts and offer a new insight into the strong metal-support interaction.

Photocatalytic CO2 methanation over the Ni/SiO2 catalysts for performance enhancement

CO2 methanation produces synthetic natural gas, which reduces CO2 emission and generates sustainable energy. Exploring effective approach and developing high performance Ni catalysts are the main focus for the reaction. In this study, we report photocatalytic methanation over Ni/SiO2 catalysts. Through physicochemical properties of BET, XRD, H2-TPR and TEM, optical properties of UV-visual light absorbance and light-illuminated H2-TPR, and the performance of photocatalytic methanation, the structure-performance relationship is tentatively discussed. The strong absorbance of light, the small size of Ni nanoparticles and the strong metal-support interaction of the Ni/SiO2 catalysts, as well as the low activation energy of CH4 production, are correlated to the enhanced photocatalytic performance compared to the conventional catalytic performance. The photocatalytic pathway of methanation on Ni nanoparticles are suggested to understand the enhanced performance. The work demonstrates the higher photocatalytic methanation performance than conventional catalytic methanation, which is applicable for other reactions using photo-sensitive catalysts.

TiO2 nanolayer coated carbon support for highly durable high-temperature polymer electrolyte membrane fuel cell cathode

Carbon corrosion of Pt/C electrocatalyst in the cathode is a critical issue for the practical application of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs). Herein, we introduce a nanolayer composed of TiO2 nanoparticles between Pt and carbon support, which not only protects the carbon from corrosion but also forms a strong metal-support interaction between Pt and TiO2. The Pt nanoparticles are uniformly dispersed on the prepared C@TiO2 support (mean size: 2.27 nm). After potential sweeping for 5000 cycles in the acid solution, the electrochemical surface area loss of the homemade Pt/C@TiO2 is 10.9%, which is approximately half of that of commercial Pt/C (19.1%). In the practical HT-PEMFC single cell, Pt/C@TiO2 exhibits superior durability than Pt/C as well. After the accelerated durability test, the maximum power density of Pt/C@TiO2-MEA decreases by 8.6%, which is significantly lower than that of Pt/C-MEA (23.9%), suggesting a great potential application of Pt/C@TiO2 in HT-PEMFCs.

Unique role of silica in MOF-Derived High-Loading Palladium-on-Ceria single atom catalysts with excellent efficiency and durability

In most cases, the sintering tendency of supported metal single atoms could be attributed to the unstable structural characteristics of supports in demanding operating conditions, particularly for high-loading single-atom catalysts (SACs), ultimately resulting in deactivation. To address this issue, SiO2 is employed to enhance the structural stability of both supports and the supported Pd single atoms. SiO2 serves not only to prevent the collapse of support structures but also to promote the activation of surface oxygen species by facilitating electron transfer with the supports. This, in turn, establishes strong metal-support interactions (MSIs) to stabilize and activate atomically dispersed Pd species. Additionally, the electrons donated from Ce-O and Si-O to Pd atoms further catalyze the formation of oxygen vacancies, ultimately leading to significantly improved activity and durability in CO oxidation. Without SiO2, the instability of support structure, coupled with the weak MSIs, promotes the aggregation of Pd atoms, resulting in relatively lower catalytic activity and durability.

Non-Photochemical Origin of Selectivity Difference between Light and Dark Catalytic Conditions.

The interest in introducing light into heterogeneous catalysis is driven not only by the urgent need of replacing fossil energy but also by the promise of controlling product selectivity by light. The product selectivity differences observed in recent studies between light and dark reactions are often attributed to photochemical effects. Here, we report the discovery of a non-photochemical origin of selectivity difference, at essentially the same CO2 conversion rate, between photothermal and thermal CO2 hydrogenation reactions over a Ru/TiO2-x catalyst. While the presence of the photochemical effect from ultraviolet light is confirmed, it merely enhances the catalytic activity. Systematic investigation reveals that the gradual formation of an adsorbate-mediated strong metal-support interaction under catalytic conditions is responsible for the variation in the catalytic selectivity. We demonstrate that differences in product selectivity under light/dark reactions do not necessarily originate from photochemical effects. Our study refines the basis for determining photochemical effects and highlights the importance of excluding non-photochemical effects in mechanistic studies of light-controlled product selectivity.

Highly Active and Sintering-Resistant Pt Clusters Supported on FeOx-Hydroxyapatite Achieved by Tailoring Strong Metal-Support Interactions.

The catalytic performance of supported metal catalysts is closely related to their structure. While Pt-based catalysts are widely used in many catalytic reactions because of their exceptional intrinsic activity, they tend to deactivate in high-temperature reactions, requiring a tedious and expensive regeneration process. The strong metal-support interaction (SMSI) is a promising strategy to improve the stability of supported metal nanoparticles, but often at the price of the activity due to either the coverage of the active sites by support overlay and/or the too-strong metal-support bonding. Herein, we newly constructed a supported Pt cluster catalyst by introducing FeOx into hydroxyapatite (HAP) support to fine-tune the SMSIs. The catalyst exhibited not only high catalytic activity but also sintering resistance, without deactivation in a 100 h test for catalytic CO oxidation. Detailed characterizations reveal that FeOx introduced into HAP weaken the strong covalent metal-support interaction (CMSI) between Pt and FeOx while simultaneously inhibiting the oxidative strong metal-support interaction (OMSI) between Pt and HAP, giving rise to both high activity and thermal stability of the supported Pt clusters.

Promote the efficient co-combustion of toluene & CO in Pt/CeO2 catalyst: Orientally adjusting the oxidized SMSI to optimize acid site and oxygen vacancy

By effectively controlling the strong metal-support interaction (SMSI), the formation of acid sites and oxygen vacancies (Ov) on the Pt/CeO2 catalyst was optimized. The efficient co-combustion of toluene and CO on Pt/CeO2-450 was achieved. In the dual-pollutant system, when the conversion rate was 90 %, the corresponding conversion temperatures of toluene and CO were 165 °C and 173 °C, respectively. With the increase of SMSI, the catalytic activity of Pt/CeO2 showed a trend of first increase and then decrease. This was proportional to the content of weak acid sites, medium acid sites, and Ov generated on their surfaces. Compared with the combustion of a single pollutant, the result displays that toluene and CO had significant competitive adsorption on Pt/CeO2. The inhibition of toluene on CO also showed the same trend as the catalytic activity with the increase of SMSI. Under the double inhibition, Pt/CeO2 exhibited preferential selectivity for toluene combustion. However, the in situ DRIFTS results showed that this competitive adsorption phenomenon did not interfere with the combustion reaction path. The co-combustion of toluene and CO follows independent reaction paths. This work provides valuable insights and ideas for realizing the development of efficient and environmentally friendly catalysts through SMSI regulation.

Coupling phyllosilicate and NiCo alloy nanoparticles on sepiolite to enhance stability for hydrogen production by ethanol steam reforming

For hydrogen production from ethanol steam reforming (ESR), The NiCo alloy immobilized on sepiolite (SEP) support by a phyllosilicate precursor was deemed as an effective strategy to improved catalyst stability. The Ni/Co ratio was regulated to optimized the ESR reactivity of the bi-metallic catalysts prepared by the NH4F assisted urea hydrothermal method. The synergy effect of NiCo alloy with a Ni-rich surface on ESR reactivity and anti-deactivation was investigated. The 5Ni10Co/SEP catalyst presented the highest conversion (99.4 %) and H2 yield (68.2 %) at 700 °C, which was benefited from the downsized nanoparticle size and strong metal-support interaction. The proposal structure-activity relationship suggested that the NiCo alloy was exsolved from the phyllosilicate precursor grafted on SEP framework, providing an excellent mitigation for metal sintering. In addition, the synergy of NiCo alloy was elaborated by a combination of enhanced ethanol adsorption/dissociation on Ni sites and restrained methanation on Co sites, offering a 50 h catalyst stability during ESR consisting of the ethanol dehydration route. The developed NiCo alloy catalyst based on SEP support with phyllosilicate precursor provided a prospect on the application to H2 production from ESR over the bimetallic catalysts with simple preparation, high economy and structure stability.

Study on the effect of promotors in CO2 utilization for syngas production via dry reforming of methane over Co-MOX/TiO2-Al2O3 (MOX = La, Ce, Mg, and K) catalysts

In this study, Co-based catalysts supported over Ti-Al oxide and promoted with La, Ce, Mg, and K metals were assessed for CO2 reforming of methane reaction to produce syngas. Titania-alumina mixed oxide supports were prepared using the template-assisted-solvothermal method, and then Co and promotors were co-impregnated over the as-prepared support. Different characterizations of catalysts showed that variation in promotor metal impacts these catalysts' physical and chemical properties. The Ti-Al oxide support possessed the perfect hexagonal morphology. Potassium-promoted catalysts possessed the highest number of basic sites, whereas the La-promoted catalyst possessed the highest number of acidic sites. La promotion improved the Co dispersion, while Mg promotion enhanced the metal support integration. La-promoted catalysts are deactivated because of active metal oxidation and the generation of hard carbon. The carbon was deposited in all catalysts; however, the activity of the Mg-promoted catalyst was unaffected. The intermediate surface basicity and strong metal support interaction improved the Mg-promoted catalyst's stability. The La and Mg-promoted catalysts possessed lower apparent activation energies.

Solvent-free selective hydrogenation of nitroaromatics to azoxy compounds over Co single atoms decorated on Nb2O5 nanomeshes

The solvent-free selective hydrogenation of nitroaromatics to azoxy compounds is highly important, yet challenging. Herein, we report an efficient strategy to construct individually dispersed Co atoms decorated on niobium pentaoxide nanomeshes with unique geometric and electronic properties. The use of this supported Co single atom catalysts in the selective hydrogenation of nitrobenzene to azoxybenzene results in high catalytic activity and selectivity, with 99% selectivity and 99% conversion within 0.5 h. Remarkably, it delivers an exceptionally high turnover frequency of 40377 h–1, which is amongst similar state-of-the-art catalysts. In addition, it demonstrates remarkable recyclability, reaction scalability, and wide substrate scope. Density functional theory calculations reveal that the catalytic activity and selectivity are significantly promoted by the unique electronic properties and strong electronic metal-support interaction in Co1/Nb2O5. The absence of precious metals, toxic solvents, and reagents makes this catalyst more appealing for synthesizing azoxy compounds from nitroaromatics. Our findings suggest the great potential of this strategy to access single atom catalysts with boosted activity and selectivity, thus offering blueprints for the design of nanomaterials for organocatalysis.