Silica-modified Pt/TiO_(2) catalysts with tunable suppression of strong metal-support interaction for cinnamaldehyde hydrogenation

Tuning Strong Metal-support Interactions(SMSI)is a key strategy to obtain highly active catalysts,but conventional methods usually enable TiO_(x) encapsulation of noble metal components to minimize the exposure of noble metals.This study demonstrates a catalyst preparation method to modulate a weak encapsulation of Pt metal nanoparticles(NPs)with the supported TiO_(2),achieving the moderate suppression of SMSI effects.The introduction of silica inhibits this encapsulation,as reflected in the characterization results such as XPS and HRTEM,while the Ti^(4+) to Ti^(3+) conversion due to SMSI can still be found on the support surface.Furthermore,the hydrogenation of cinnamaldehyde(CAL)as a probe reaction revealed that once this encapsulation behavior was suppressed,the adsorption capacity of the catalyst for small molecules like H_(2) and CO was enhanced,which thereby improved the catalytic activity and facilitated the hydrogenation of CAL.Meanwhile,the introduction of SiO_(2) also changed the surface structure of the catalyst,which inhibited the occurrence of the acetal reaction and improved the conversion efficiency of C=O and C=C hydrogenation.Systematic manipulation of SMSI formation and its consequence on the performance in catalytic hydrogenation reactions are discussed.

Achieving asymmetric redox chemistry for oxygen evolution reaction through strong metal-support interactions

Water electrolysis poses a significant challenge for balancing catalytic activity and stability of oxygen evolution reaction(OER)electrocatalysts.In this study,we address this challenge by constructing asymmetric redox chemistry through elaborate surface OO–Ru–OH and bulk Ru–O–Ni/Fe coordination moieties within single-atom Ru-decorated defective NiFe LDH nanosheets(Ru@d-NiFe LDH)in conjunction with strong metal-support interactions(SMSI).Rigorous spectroscopic characterization and theoretical calculations indicate that single-atom Ru can delocalize the O 2p electrons on the surface and optimize d-electron configurations of metal atoms in bulk through SMSI.The^(18)O isotope labeling experiment based on operando differential electrochemical mass spectrometry(DEMS),chemical probe experiments,and theoretical calculations confirm the encouraged surface lattice oxygen,stabilized bulk lattice oxygen,and enhanced adsorption of oxygen-containing intermediates for bulk metals in Ru@d-NiFe LDH,leading to asymmetric redox chemistry for OER.The Ru@d-NiFe LDH electrocatalyst exhibits exceptional performance with an overpotential of 230 mV to achieve 10 mA cm^(−2)and maintains high robustness under industrial current density.This approach for achieving asymmetric redox chemistry through SMSI presents a new avenue for developing high-performance electrocatalysts and instills confidence in its industrial applicability.

Strong metal–support interaction boosts the electrocatalytic hydrogen evolution capability of Ru nanoparticles supported on titanium nitride

Ruthenium(Ru)has been regarded as one of the most promising alternatives to substitute Pt for catalyzing alkaline hydrogen evolution reaction(HER),owing to its inherent high activity and being the cheapest platinum-group metal.Herein,based on the idea of strong metal–support interaction(SMSI)regulation,Ru/TiN catalysts with different degrees of TiN overlayer over Ru nanoparticles were fabricated,which were applied to the alkaline electrolytic water.Characterizations reveal that the TiN overlayer would gradually encapsulate the Ru nanoparticles and induce more electron transfer from Ru nanoparticles to TiN support by the Ru–N–Ti bond as the SMSI degree increased.Further study shows that the exposed Ru–TiN interfaces greatly promote the H_(2) desorption capacity.Thus,the Ru/TiN-300 with a moderate SMSI degree exhibits excellent HER performance,with an overpotential of 38 mV at 10 mA cm^(−2).Also,due to the encapsulation role of TiN overlayer on Ru nanoparticles,it displays super long-term stability with a very slight potential change after 24 h.This study provides a deep insight into the influence of the SMSI effect between Ru and TiN on HER and offers a novel approach for preparing efficient and stable HER electrocatalysts through SMSI engineering.

Boron Nanosheet-Supported Rh Catalysts for Hydrogen Evolution:A New Territory for the Strong Metal-Support Interaction Effect

High-efficiency electrochemical hydrogen evolution reaction(HER)offers a promising strategy to address energy and environmental crisis.Platinum is the most effective electrocatalyst for the HER.However,challenging scarcity,valuableness,and poor electrochemical stability still hinder its wide application.Here,we designed an outstanding HER electrocatalyst,highly dispersed rhodium(Rh)nanoparticles with an average diameter of only 3 nm supported on boron(B)nanosheets.The HER catalytic activity is even comparable to that of commercial platinum catalysts,with an overpotential of only 66 mV in 0.5 M H_(2)SO_(4) and 101 mV in 1 M KOH to reach the current density of 10 mA cm−2.Meanwhile,the catalyst exhibited impressive electrochemical durability during long-term electrochemical processes in acidic and alkaline media,even the simu-lated seawater environment.Theoretical calculations unraveled that the structure-activity relationship between B(104)crystal plane and Rh(111)crystal plane is beneficial to the release of hydrogen,and surface O plays a vital role in the catalysis process.Our work may gain insights into the development of supported metal catalysts with robust catalytic performance through precise engineering of the strong metal-supported interaction effect.

Dry Reforming of Ethane over FeNi/Al-Ce-O Catalysts:Composition-Induced Strong Metal-Support Interactions

Dry reforming of ethane(DRE)has received significant attention because of its potential to produce chemical raw materials and reduce carbon emissions.Herein,a composition-induced strong metal-support interaction(SMSI)effect over FeNi/Al-Ce-O catalysts is revealed via X-ray photoelectron spectroscopy(XPS),H_(2)-temperature programmed reduction(TPR),and energy dispersive X-ray spectroscopy(EDS)elemental mapping.The introduction of Al into Al-Ce-O supports significantly influences the dispersion of surface active components and improves the catalytic performance for DRE over supported FeNi catalysts due to enhancement of the SMSI effect.The catalytic properties,for example,C_(2)H_(6) and CO_(2) conversion,CO selectivity and yield,and turnover frequencies(TOFs),of supported FeNi catalysts first increase and then decrease with increasing Al content,following the same trend as the theoretical effective surface area(TESA)of the corresponding catalysts.The FeNi/Ce-Al_(0.5) catalyst,with 50%Al content,exhibits the best DRE performance under steady-state conditions at 873 K.As observed by with in situ Fourier transform infrared spectroscopy(FTIR)analysis,the introduction of Al not only increases the content of surface Ce3+and oxygen vacancies but also promotes the dispersion of surface active components,which further alters the catalytic properties for DRE over supported FeNi catalysts.

Strong metal-support interaction (SMSI) in environmental catalysis: Mechanisms, application, regulation strategies, and breakthroughs

The strong metal-support interaction(SMSI)in supported catalysts plays a dominant role in catalytic degradation,upgrading,and remanufacturing of environmental pollutants.Previous studies have shown that SMSI is crucial in supported catalysts'activity and stability.However,for redox reactions catalyzed in environmental catalysis,the enhancement mechanism of SMSI-induced oxygen vacancy and electron transfer needs to be clarified.Additionally,the precise control of SMSI interface sites remains to be fully understood.Here we provide a systematic review of SMSI's catalytic mechanisms and control strategies in purifying gaseous pollutants,treating organic wastewater,and valorizing biomass solid waste.We explore the adsorption and activation mechanisms of SMSI in redox reactions by examining interfacial electron transfer,interfacial oxygen vacancy,and interfacial acidic sites.Furthermore,we develop a precise regulation strategy of SMSI from systematical perspectives of interface effect,crystal facet effect,size effect,guest ion doping,and modification effect.Importantly,we point out the drawbacks and breakthrough directions for SMSI regulation in environmental catalysis,including partial encapsulation strategy,size optimization strategy,interface oxygen vacancy strategy,and multi-component strategy.This review article provides the potential applications of SMSI and offers guidance for its controlled regulation in environmental catalysis.

Exploration of Strong Metal-Support Interaction in Heterogeneous Catalysts by in situ Transmission Electron Microscopy

The phenomenon of strong metal-support interaction(SMSI)observed in supported metal catalysts,usually accompanied by the formation of the encapsulation layer on metal nanoparticles,has attracted extensive research attention due to its significance in heterogeneous catalysis.Notably,great progress has been made in recent years in investigating SMSI by in situ transmission electron microscopy(TEM),along with an enhanced comprehension of the underlying mechanisms governing SMSI formation.This emerging topic summarizes recent progress utilizing in situ TEM to study the interaction between metal and support and the relationship between the structure and performance of the supported catalyst under reaction conditions.A brief perspective about the use of in situ TEM for further study of SMSI is also presented,showing prospects in this field that will stimulate further upsurging research in promoting the catalytic efficiency of supported catalysts.

Pd single-atom catalysts derived from strong metal-support interaction for selective hydrogenation of acetylene

Selective hydrogenation of acetylene in excess ethylene is an important reaction in both fundamental study and practical application.Pd-based catalysts with high intrinsic activity are commonly employed,but usually suffer from low selectivity.Pd single-atom catalysts(SACs)usually exhibit outstanding ethylene selectivity due to the weakπ-bonding ethylene adsorption.However,the preparation of high-loading and stable Pd SACs is still confronted with a great challenge.In this work,we report a simple strategy to fabricate Pd SACs by means of reducing conventional supported Pd catalysts at suitable temperatures to selectively encapsulate the co-existed Pd nanoparticles(NPs)/clusters.This is based on our new finding that single atoms only manifest strong metal-support interaction(SMSI)at higher reduction temperature than that of NPs/clusters.The derived Pd SACs(Pd1/CeO2 and Pd1/a-Fe2O3)were applied to acetylene selective hydrogenation,exhibiting much improved ethylene selectivity and high stability.This work offers a promising way to develop stable Pd SACs easily.

New routes for the construction of strong metal-support interactions

Supported metal nanoparticles(NPs)on solid carriers are highly efficient catalysts in many industrial reactions.However,the sintering and/or leaching of metal NPs occurred under harsh reaction conditions that caused the catalyst deactivation.Strong metal-support interactions(SMSIs)serve as an effective method to stabilize the metal NPs against sintering and leaching,which have been extensively studied.In addition to the classical route to construct SMSIs via high-temperature reduction treatments,new routes have emerged recently to extend the scope of catalysts with SMSIs and optimized their catalytic performances.In this review,we briefly summarize these routes that avoid the high-temperature reduction treatments for the construction of SMSIs.Their significant advantages in stabilizing metal NPs,modulating the geometric/electronic structure of metal species,and the mechanism on the SMSI formation are particularly discussed.Finally,the current challenges and developing trends in the construction of SMSIs for achieving more efficient catalysts are outlooked.

Low temperature one-pot synthesis of 1,1-diethoxyethane from ethanol on Bi/BiCeO_(x)with strong metal-support interactions

The direct conversion of ethanol to 1,1-diethoxyethane(DEE)through one-pot dehydrogenation-acetalization has attracted broad interest from both academia and industry.Based on thermodynamics,the oxidative dehydrogenation of alcohol to acetaldehyde requires high temperature to activate oxygen to realize the C-H cleavage,while the acetalization of acetaldehyde with ethanol is exothermic reversible reaction favorable at low temperature.The mismatching of the reaction condition for the two consecutive steps makes it a great challenge to achieve both high ethanol conversion and high DEE selectivity.This work reports a highly efficient bi-functional catalysis by Bi/BiCeO_(x)for one-pot oxidative dehydrogenation-acetalization route from ethanol to DEE under 150℃and ambient pressure,affording a selectivity of 98.5%±0.5%to DEE at an ethanol conversion of 87.0%±1.0%.An efficient tandem catalysis has been achieved on the interfacial Bi^(δ)+-Ov-Ce^(III)sites in Bi/BiCeO_(x)established by strong metal-support interaction,in which Biδ+-Ov-sites contribute to the oxidative dehydrogenation of ethanol at mild temperature,and-Ov-CeIII sites to the subsequent acetalization between the generated acetaldehyde and ethanol.

Strong metal-support interactions between gold nanoparticles and nonoxides

With the support of the National Natural Science Foundation of China,Prof.Zhang Tao(张涛)and Prof.Wang Junhu’s group at the Laboratory of Catalysts and New Materials for Aerospace,Dalian Institute of Chemical Physics,Chinese Academy of Sciences,recently discovered a new type of strong metalsupport interaction(SMSI)between gold nanoparticles(NPs)and nonoxides,which was published in

Investigating the impact of dynamic structural changes of Au/rutile catalysts on the catalytic activity of CO oxidation

The surface properties of oxidic supports and their interaction with the supported metals play critical roles in governing the catalytic activities of oxide‐supported metal catalysts.When metals are supported on reducible oxides,dynamic surface reconstruction phenomena,including strong metal–support interaction(SMSI)and oxygen vacancy formation,complicate the determination of the structural–functional relationship at the active sites.Here,we performed a systematic investigation of the dynamic behavior of Au nanocatalysts supported on flame‐synthesized TiO_(2),which takes predominantly a rutile phase,using CO oxidation above room temperature as a probe reaction.Our analysis conclusively elucidated a negative correlation between the catalytic activity of Au/TiO_(2) and the oxygen vacancy at the Au/TiO_(2) interface.Although the reversible formation and retracting of SMSI overlayers have been ubiquitously observed on Au/TiO_(2) samples,the catalytic consequence of SMSI remains inconclusive.Density functional theory suggests that the electron transfer from TiO_(2) to Au is correlated to the presence of the interfacial oxygen vacancies,retarding the catalytic activation of CO oxidation.

Precious metal-support interaction in automotive exhaust catalysts

Precious metal-support interaction plays an important role in thermal stability and catalytic performance of the automotive exhaust catalysts. The support is not only a cartier for active compotmds in catalysts but also can improve the dispersion of precious metals and suppress the sintering of precious metals at high temperature; meanwhile, noble metals can also enhance the redox performance and oxygen storage capacity of support. The mechanism of metal-support interactions mainly includes electronic interaction, formation of alloy and inward diffusion of metal into the support or covered by support. The form and degree of precious metal-sup- port interaction depend on many factors, including the content of precious metal, the species of support and metal, and preparation methods. The research results about strong metal-support interaction （SMSI） gave a theory support for developing a kind of new cata- lyst with excellent performance. This paper reviewed the interaction phenomenon and mechanism of precious metals （Pt, Pd, Rh） and support such as A1203, CeO2, and CeO2-based oxides in automotive exhaust catalysts. The factors that affect SMSI and the catalysts developed by SMSI were also discussed.

Light-enhanced metal-support interaction for synergetic photo/thermal catalytic formaldehyde oxidation

The strong metal-support interaction(SMSI)plays a pivotal role in regulating electronic properties and activating surface oxygen species.In this work,we report light-irradiation-modulated SMSI for enhanced formaldehyde(HCHO)oxidation.Specifically,the SMSI between Pt nanoparticles(NPs)and Bi_(2)MoO_(6)cre-ated surface-active oxygen at Pt-Bi_(2)MoO_(6)interfaces to activate HCHO to dioxymethylene(DOM).Notably,light irradiation boosted the SMSI and catalytic activity.Moreover,photogenerated holes in Bi_(2)MoO 6 im-proved HCHO adsorption and activation,while photogenerated electrons migrated from Bi_(2)MoO_(6)to Pt NPs to promote O_(2)adsorption and activation,accelerating the oxidation of DOM to CO_(2)and H_(2)O.The light-modulated SMSI and the synergy between photocatalysis and thermocatalysis lead to enhanced cat-alytic oxidation activity,providing a practical strategy for indoor volatile organic compound(VOC)de-composition under ambient conditions.

Direct environmental TEM observation of silicon diffusion-induced strong metal-silica interaction for boosting CO_(2)hydrogenation

For the high-temperature catalytic reaction,revealing the interface of catalyst–support and its evolution under reactive conditions is of crucial importance for understanding the reaction mechanism.However,much less is known about the atomic-scale interface of the hard-to-reduce silica-metal compared to that of reducible oxide systems.Here we reported the general behaviors of SiO_(2)migration onto various metal(Pt,Co,Rh,Pd,Ru,and Ni)nanocrystals supported on silica.Typically,the Pt/SiO_(2)catalytic system,which boosted the CO_(2)hydrogenation to CO,exhibited the reduction of Si0 at the Pt-SiO2 interface under H2 and further Si diffusion into the near surface of Pt nanoparticles,which was unveiled by in-situ environmental transmission electron microscopy coupled with spectroscopies.This reconstructed interface with Si diffused into Pt increased the sinter resistance of catalyst and thus improved the catalytic stability.The morphology of metal nanoparticles with SiO_(2)overlayer were dynamically evolved under reducing,vacuum,and oxidizing atmospheres,with a thicker SiO_(2)layer under oxidizing condition.The theoretical calculations revealed the mechanism that the Si-Pt surface provided synergistic sites for the activation of CO_(2)/H_(2)to produce CO with lower energy barriers,consequently boosting the high-temperature reverse water-gas shift reaction.These findings deepen the understanding toward the interface structure of inert oxide supported catalysts.

担体对Fe-MnO催化剂CO+H_2反应性能的影响

考察氧化物担体对Fe-MnO催化剂反应性能影响的结果表明,担体的类型对Fe-MnO催化剂CO加氢反应性能影响很大,其低碳烯烃选择性相差悬殊,Al_2O_3、SiO_2和MgO担载的Fe-MnO催化剂都不利于低碳烯烃的生成,而TiO_2担载的Fe-MnO催化剂则具有较高的烯烃选择性和催化活性。从担体-金属相互作用本质的差异,研究了担体对金属活性组分化学状态的影响及催化活性相与F-T合成烯烃的关系,发现担体-金属间的电子效应有利于催化剂活性和选择性的提高,其它物理化学效应引起的相互作用则不利于改善催化剂性能;还表明Fe_(?)C是催化活性相,Fe^(2+)物种的存在不利于提高烯烃的选择性。

微量TiO_2对Ni/SiO_2催化剂催化顺酐加氢制γ-丁内酯的促进作用

采用等体积浸渍法分别制备了Ni/SiO2和含TiO2的Ni/SiO2催化剂,采用XRD、TPR、XPS、N2吸附-脱附技术对催化剂进行了表征,并将催化剂应用于顺酐液相加氢制γ-丁内酯反应中,考察了Ni含量、TiO2添加量、催化剂还原温度对催化剂活性的影响。结果表明,Ni/SiO2催化剂对顺酐液相加氢制γ-丁内酯反应具有很高的催化活性,γ-丁内酯选择性很高;Ni/SiO2添加微量助剂TiO2,可以提高该反应的γ-丁内酯选择性。推测可能是由于TiO2促进了催化剂的还原,产生更多的活性中心,并且在400℃还原时,Ni和TiO2之间产生了强金属-载体相互作用(SMSI效应),TiO2富集到Ni的表面,将电子转移到Ni上,产生了更多有利于吸附羰基的活性中心,从而提高了γ-丁内酯选择性。

氧化物负载纳米金催化葡萄糖选择氧化

通过溶胶-固载法制备了不同氧化物负载的纳米金催化剂,并用于催化葡萄糖选择氧化。系统考察了pH值、反应温度、氧气体积分数、载体等对葡萄糖氧化的影响。结果表明:提高pH值、反应温度和氧气体积分数都有利于促进葡萄糖氧化反应进行;但过高的pH值及反应温度会导致副反应发生,降低葡萄糖酸的选择性;此外,对于不同氧化物负载的纳米金催化剂,结合ICP、BET、In situ DRIFT和TEM等表征可知,除了金纳米粒子尺寸,纳米金与载体间强相互作用也对葡萄糖选择氧化反应活性起重要影响。

Phosphorous-Modified Carbon Nanotube-Supported Pt Nanoparticles for Propane Dehydrogenation Reaction

The sintering of Pt nanoparticles is one of the main reasons for catalyst deactivation during the high-temperature propane dehydrogenation(PDH) reaction. Promoters and supports have been introduced to prolong the catalyst life.However, it is still necessary to develop novel catalysts with robust stability. Herein, the phosphorus-modified carbon nanotube-supported Pt nanoparticles were employed for the PDH process. Phosphorus modification improves the Pt dispersion, effectively promoting the activity of Pt/P-CNTs. Additionally, the phosphorus-modified CNTs can interact strongly with Pt nanoparticles by improving the electron transfer or hybridization, stabilizing Pt nanoparticles from agglomeration, and significantly enhancing the catalyst stability.

Enhanced catalytic performance of Cu-and/or Mn-loaded Fe-Sep catalysts for the oxidation of CO and ethyl acetate

The Fe-modi fied sepiolite-supported Mn–Cu mixed oxide(Cux Mny/Fe-Sep) catalysts were prepared using the co-precipitation method.These materials were characterized by means of the XRD,N_2 adsorption–desorption,XPS,H_2-TPR,and O_2-TPD techniques,and their catalytic activities for CO and ethyl acetate oxidation were evaluated.The results show that catalytic activities of the Cux Mny/Fe-Sep samples were higher than those of the Cu1/Fe-Sep and Mn2/Fe-Sep samples,and the Mn/Cu molar ratio had a distinct in fluence on catalytic activity of the sample.Among the Cux Mny/Fe-Sep and Cu1Mn2/Sep samples,Cu1Mn2/Fe-Sep performed the best for CO and ethyl acetate oxidation,showing the highest reaction rate and the lowest T50 and T90 of 4.4×10^(-6) mmol·g-1·s-1,110,and 140 °C for CO oxidation,and 1.9×10^(-6) mmol·g-1·s-1,170,and210 °C for ethyl acetate oxidation,respectively.Moreover,the Cu1Mn2/Fe-Sep sample possessed the best lowtemperature reducibility and the lowest temperature of oxygen desorption as well as the highest surface Mn^(4+)/Mn^(3+) and Cu^(2+)/CuO atomic ratios.It is concluded that factors,such as the strong interaction between the Cu or Mn and the Fe-Sep support,good low-temperature reducibility,and good mobility of chemisorbed oxygen species,might account for the excellent catalytic activity of Cu1Mn2/Fe-Sep.