Catalytic Synergy Research Articles

One-pot construction of ionic liquid-functionalized MOF material as the catalyst for CO2 cycloaddition under atmospheric pressure

Carboxylic ionic liquid 1-propionic acid-3-methylimidazolium chloride (CFIL) was immobilized in a metal-organic framework (MOF) material NH2-MIL-101 in one-pot by the in-situ assembly method; as a heterogeneous catalyst with multiple active sites, the catalytic performance of NH2-FMOF-CFIL in the cycloaddition of CO2 with epichlorohydrin (ECH) to synthesize chloropropylene carbonate (CPC) was investigated. The immobilized of CFIL in NH2-MIL-101 was proved by Fourier transform infrared spectroscopy (FT-IR) and elemental analysis, while the powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and N2 adsorption-desorption measurements demonstrated that CFIL neither damages the crystal structure nor blocks the pore of NH2-MIL-101, but induce the formation of mesopores. The catalytic reaction results reveal that there is a catalytic synergy between imidazole N and Cl− on CFIL and Cr3+ and amino group on MOF, which endow the NH2-FMOF-CFIL composite excellent catalytic performance in the cycloaddition of CO2 with ECH; under mild conditions, viz., 0.1 MPa CO2, 25–70 °C and without using any solvent and cocatalyst, the CPC yield reaches 99% after reaction for 24 h. Moreover, the crystal structure and high activity of the NH2-FMOF-CFIL catalyst are well preserved even after reuse for 5 cycles.

Strengthening catalytic synergy of two function-complementary ZSM-5 by optimizing their spatial organizations in fixed-bed reactor to boost methanol aromatization

The effect of proximity of two different SiO 2 /Al 2 O 3 ratio ZSM-5 catalysts with complementary acidic properties on their catalytic synergy over methanol stepwise aromatization was specifically studied based on a series of different packing modes. The results showed that the powder mixing mode with high proximity excessively enhanced the synergy by intensifying mass transfer between two catalysts. Although it presented a high aromatics selectivity of 57.2%, but the catalyst lifetime was only 10 h due to the intense reverse of polymethylbenzene. The granule mixing mode with larger particle size only slightly improved the catalyst lifetime. Packing two ZSM-5 catalysts in separated dual beds mode could prolong the lifetime to 157 h but the aromatics selectivity was reduced to 21.0%, indicating that low proximity is not favored the catalytic synergy. Interestingly, the suitable proximity of designed alternative sequence beds mode not only intensified intermediates transport to some extent but also relieved the negative influence of aromatic reversion. The moderate synergy remarkably increased the aromatics selectivity to 28.9% with a satisfactory lifetime of 117 h. This work preliminarily elucidates the effect of proximity determined by the spatial organization of double ZSM-5 catalysts on their catalytic synergy for methanol aromatization. Packing Zn/Z-60 and NZ-500 in alternating sequence beds (packing mode) in the tubular fixed bed observably prolonged catalytic lifetime with a satisfied aromatics selectivity. • The effect of proximity on catalytic synergy of double ZSM-5 for MTA was studied. • The catalyst proximity was precisely regulated based on eight packing modes. • Enhanced mass transfer for aromatization was achieved under high proximity. • Catalytic stability was increased by decreasing catalyst proximity. • Mild catalyst proximity over alternate beds enhanced catalytic synergy for MTA.

Crystal Facet-Manipulated 2D Pt Nanodendrites to Achieve an Intimate Heterointerface for Hydrogen Evolution Reactions.

Despite the Pt-catalyzed alkaline hydrogen evolution reaction (HER) progressing via oxophilic metal-hydroxide surface hybridization, maximizing Pt reactivity alongside operational stability is still unsatisfactory due to the lack of well-designed and optimized interface structures. Producing atomically flat two-dimensional Pt nanodendrites (2D-PtNDs) through our 2D nanospace-confined synthesis strategy, this study tackles the insufficient interfacial contact effect during HER catalysis by realizing an area-maximized and firmly bound lateral heterointerface with NiFe-layered double hydroxide (LDH). The well-oriented {110} crystal surface exposure of Pt promotes electronic interplay that bestows strong LDH binding. The charge-relocated interfacial bond in 2D-PtND/LDH accelerates the hydrogen generation steps and achieves nearly the highest reported Pt mass activity enhancement (∼11.2 times greater than 20 wt % Pt/C) and significantly improved long-term operational stability. This work uncovers the importance of the shape and facet of Pt to create heterointerfaces that provide catalytic synergy for efficient hydrogen production.

Construction of a bioinspired Fe3O4/N-HCS nanozyme for highly sensitive detection of GSH

The catalytic synergy of different nanomaterials is a potential technique used to develop a highly active and stable nanozyme. Here, magnetite on nitrogen-doped hollow carbon sphere (Fe3O4/N-HCS) composites were prepared through solvent thermal method and exhibited excellent oxidase and peroxidase-like catalytic activity under different pH levels. The dual enzyme-like catalyzed reaction of Fe3O4/N-HCS conformed to the typical Michaelis–Menten kinetics, and Fe3O4/N-HCS had a strong affinity for substrate 3,3′,5,5′-tetramethylbenzidine (TMB) with H2O2. The remarkable performance of the composites was achieved by the synergistic effect of Fe3O4 and N-doped activated graphite carbon, which accelerated the formation of O2•- and •OH during the dual enzyme-like catalytic reaction. Furthermore, an effective colorimetric glutathione (GSH) sensor with a wide linear range from 0.02 µM to 250 µM and a detection limit as low as 9.3 nM was constructed based on the superior peroxidase-like activity of Fe3O4/N-HCS. The convenient colorimetric sensor monitored the content of GSH in the serum of mice, and the detection results were satisfactory, with a recovery of 96–103% and an RSD between 0.80% and 3.30%. This study discussed the internal mechanism of Fe3O4/N-HCS nanozyme and developed an efficient method for GSH detection to expand nanozyme application in bioanalysis.

Electronic modulation and vacancy engineering of Ni9S8 to synergistically boost efficient water splitting: Active vacancy-metal pairs

Developing easy-to-make and excellent bifunctional electrocatalysts for water splitting over a wide pH range is a challenging yet appealing topic. Herein, based on integration of vacancy engineering and electronic modulation, a high-performance vs-Ru-Ni9S8 electrocatalyst for water splitting was constructed via a cost-effective one-step hydrothermal method. Under the synergistic regulation of Ru-doping and sulfur vacancies, the vs-Ru-Ni9S8 exhibited the outstanding electrocatalytic performance and long-time durability, along with ultra-low OER overpotentials of 218 and 268 mV at 100 and 300 mA cm−2 in alkaline electrolyte and low HER overpotentials of 56, 131, 94 mV at 10 mA cm−2 in acidic, neutral, alkaline electrolyte. Impressively, 1.47 and 1.68 V of voltages were needed to achieve 10 and 300 mA cm−2 for the vs-Ru-Ni9S8 (+, -) cell. Our DFT results revealed that the doping Ru atom played a crucial role in regulating electron density in OER, rather than served as a catalytic active site. More importantly, we corroborated the active Ni-vacancy pair composed of Ni atom and sulfur vacancy, as an active site, and its catalytic synergy in OER. Especially, a vacancy-metal synergetic mechanism for OER was suggested to correctly describe the OER process and the role of vacancy in catalytic process. Our work provides a simple and effective strategy for fabricating high-performance catalysts and an in-depth understanding of OER.

Synergies of surface-interface multiple active sites over Al-Zr oxide solid solution supported nickel catalysts for enhancing the hydrodeoxygenation of anisole

Currently, the catalytic hydrodeoxygenation (HDO) of oxygen-containing compounds derived from biomass to highly valuable chemicals or hydrocarbon bio-fuels is attracting more and more attention. Concerning the design and synthesis of high-performance supported metal catalysts for HDO, the efficient deposition/immobilization of active metal species on supports, as well as the construction of the favorable properties of supports, is quite necessary. In this work, we fabricated series of aluminum-zirconium oxide solid solution supported Ni-based catalysts by a simple surfactant-assisted homogeneous coprecipitation and applied them in the HDO of anisole. Various structural characterizations showed that surface-interface properties of Ni-based catalysts (i.e., surface acidity, defective structures, and metal-support interactions) could be finely tuned by adjusting the amount of Al introduced into Al-Zr oxide solid solutions, thus profoundly governing their catalytic HDO activities. It was demonstrated that the introduction of an appropriate amount of Al could not only enhance surface acidity and promote the formation of defective Zr-Ov-Al structures (Ov: oxygen vacancy) but also facilitate the generation of interfacial Niδ+ species bound to the support. Over the Ni-based catalyst bearing an Al2O3:ZrO2 mass ratio of 5:2, a high cyclohexane yield of ∼77.4% was attained at 230 °C and 1.0 MPa initial hydrogen pressure. The high catalytic HDO efficiency was revealed to be correlated with the catalytic synergy between Ni0 and adjacent interfacial Niδ+ species, together with the promotion of neighboring defective oxygen vacancies and acidic sites, which contributed to the enhanced activation of the methoxy group in anisole and reaction intermediate and thus greatly improved HDO activity. The present findings offer a new and promising guidance for constructing high-performance metal-based catalysts via a rational surface-interface engineering.

Stabilizing Hydrous β-NiOOH for Efficient Electrocatalytic Water Oxidation by Integrating Y and Co into Amorphous Ni-Based Nanoparticles

A two-stage ball milling process was used to synthesize amorphous Ni79.2Nb12.5Y8.3 and Ni74.2Co5Nb12.5Y8.3 nanoparticles from elemental powders. The two-stage ball milling process provides a scalable and industrially applicable method for producing non-metalloid amorphous nanoparticles. The amorphous nanoparticles displayed excellent catalytic performance toward the oxygen evolution reaction (OER) in 1 M KOH, displaying lower overpotentials than IrO2 at 10 mA cm-2. The addition of Co in the amorphous alloy reduced the overpotential to 288 mV at 10 mA cm-2. The pairing of X-ray photoelectron spectroscopy and in situ X-ray absorption spectroscopy revealed that the improved OER activity of amorphous Ni74.2Co5Nb12.5Y8.3 was attributed to the catalytic synergy between Y and Co. The integration of Y supported proton-coupled electron-transfer processes that assisted with the electrostatic adsorption of OH- and formation of oxyhydroxide species, while Co sites enabled metal-oxo bonding to prevent Ni overcharging and the stabilization of β-NiOOH. The catalytic synergy between Y and Co reduces the amount of Co needed to enhance the OER activity of Ni-based alloys and lessens the dependence on Co, which is in high demand in many renewable energy and storage applications.

Heterogeneous catalytic activation of peroxymonosulfate by Ag@Cu2O composite for Au3+ detection

Although gold (Au) plays an important role in many fields, the residual Au3+ ion in our natural environment is one of the most noxious heavy metal ions for animals and plants. It is of great significance to develop an efficient and simple detection method for Au3+. Based on heterogeneous catalytic activation of peroxymonosulfate (PMS) by Ag@Cu2O nanoparticles (Ag@Cu2O NPs), a novel, visible and convenient strategy for Au3+ detection was developed. The well-dispersive Ag@Cu2O NPs could catalyze PMS to produce sulfate radicals (SO4 •−) and hydroxyl radicals (·OH) which could oxide 3, 3′, 5, 5′-tetramethylbenzidine (TMB) into oxidized TMB (oxTMB) in colorimetric detection. The introduced Au3+ could effectively enhance catalytic activation of PMS to produce more SO4 •− and ·OH. This was because there was the synergistic effect of Au and CuO, which reduced the charge transfer resistance and promoted electron transfer. This method had good specificity against 22 types of cationic or anionic interfering ions and the detection limit of Au3+ was about 290 nmol·L−1. In this study, a new substrate of PMS was used for colorimetric detection of heavy metal ions, and the catalytic synergy of Au and CuO in PMS/Ag@Cu2O NPs/Au3+ colorimetric detection system was analyzed in detail.

Compatibility between Activity and Selectivity in Catalytic Oxidation of Benzyl Alcohol with Au-Pd Nanoparticles through Redox Switching of SnOx.

A balance between catalytic activity and product selectivity remains a dilemma for the partial oxidation processes because the products are prone to be overoxidized. In this work, we report on the partial oxidation of benzyl alcohol using a modified catalyst consisting of nanosized Au-Pd particles (NPs) with tin oxide (SnOx) deposited on a mesoporous silica support. We found that the SnOx promotes the autogenous reduction of PdO to active Pd0 species on the Au-Pd NP catalyst (SnOx@AP-ox) before H2 reduction, which is due to the high oxophilicity of Sn. The presence of active Pd0 species and the enhancement of oxygen transfer by SnOx led to high catalytic activity. The benzaldehyde selectivity was enhanced with the increase of SnOx content on catalyst SnOx@AP-ox, which is ascribed to the modulated affinity of reactants and products on the catalyst surface through the redox switching of Sn species. After H2 reduction, SnOx was partially reduced and Au-Pd-Sn alloy was formed. The formation of Au-Pd-Sn alloy weakened both the catalytic synergy of Au-Pd alloy NPs and the adsorption of benzyl alcohol on the reduced catalyst, thus leading to low catalytic activity.

Catalytic Synergy Using Al(III) and Group 1 Metals to Accelerate Epoxide and Anhydride Ring-Opening Copolymerizations

Catalytic Synergy Using Al(III) and Group 1 Metals to Accelerate Epoxide and Anhydride Ring-Opening Copolymerizations

Selective Hydrogenation of Methyl Palmitate to Cetyl Alcohol via Ternary Synergistic Catalysis of Ni, Oxygen Vacancies, and Lewis Acid Sites under Mild Reaction Conditions

Selective hydrogenation of fatty esters into high-value-added fatty alcohols over non-noble-metal (e.g., Ni and Co) catalysts is highly desirable for the utilization of natural oils. Although these catalysts offer high hydrogenation activity and are reasonably economical, they suffer from low hydrodeoxygenation activity at low temperatures while promoting certain side reactions (e.g., C–C bond hydrogenolysis and decarbonylation/decarboxylation) at high temperatures, which are undesirable for the production of fatty alcohols. In this study, we tested and optimized the performance of Ni metal catalysts with various metal–oxide modifiers and supports for the selective hydrogenation of methyl palmitate to cetyl alcohol. The most efficient catalytic system (Ni-VOx/TiO2, Ni:V ≈ 1:1, mol/mol) achieved almost quantitative conversion with 90% selectivity for cetyl alcohol under mild conditions (220 °C and 4.0 MPa of H2), which was ascribed to the ternary synergistic action of Ni, oxygen vacancies, and Lewis acid sites. The catalytic synergy of the Ni metal and oxygen vacancies (formed by the reduction of TiO2) was primarily responsible for C–O bond cleavage in methyl palmitate to form palmitic aldehyde as the main intermediate. Furthermore, the V species engaged in metal–Lewis acid cooperation at the metal–oxide interface to efficiently promote the C═O bond hydrogenation of palmitic aldehyde and suppress the undesired C–C bond cleavage, thereby facilitating the highly selective production of cetyl alcohol. The obtained insights into the active phase of Ni-VOx/TiO2 catalysts are expected to facilitate the development of highly efficient catalysts for the selective hydrogenation of fatty esters and other biomass-derived compounds containing C═O/C–O groups.

Enhanced trichloroethylene degradation in the presence of surfactant: Pivotal role of Fe(II)/nZVI catalytic synergy in persulfate system

Trichloroethylene (TCE) removal performance in non-ionic surfactant Tween-80 (TW-80) and anionic surfactant sodium dodecyl sulfate (SDS) involved solution by Fe(II) activated persulfate (PS) was investigated through the strengthening of nanoscale zero valent iron (nZVI). 99.5% removal of TCE could be obtained at the PS/Fe(II)/nZVI/TCE molar ratio of 8/4/4/1 with 1.0 critical micelle concentration (CMC) of TW-80 presence (13 mg L−1), while this value was slightly decreased to 88.3% at the molar ratio of 40/20/20/1 with 1.0 CMC of SDS presence (2.3 g L−1) in 180 min. The addition of nZVI significantly promoted TCE degradation, while TW-80 or SDS definitely inhibited TCE removal. Further, TCE removal declined with TW-80 or SDS concentration increasing from 0 to 10 CMC, and continuously decreased at 20 CMC of TW-80 but elevated TCE removal at 20 CMC of SDS. Tests of radical scavengers revealed that HO and SO4− contributed a major part while O2− had less contribution to TCE degradation in PS/Fe(II)/nZVI system. The dichlorination of TCE in PS/Fe(II)/nZVI system was 94.5% with TW-80 and 97.2% with SDS. In addition, TCE (with TW-80) removal was decreased with the initial pH increase from 3.0 to 11.0, while TCE (with SDS) degradation was always beyond 83% in the initial pH change from 3.0 to 11.0. Moreover, the effects of inorganic anions (Cl−, HCO3−) in the solution were evaluated. Experimental results using the actual groundwater revealed the excellent availability of PS/Fe(II)/nZVI system in remediating TCE contaminated field involved with TW-80 or SDS surfactants. In summary, these findings provide a new direction in remediating groundwater from contaminated sites polluted by chlorinated organic solvents after pretreatment by surfactant solubilization.

Precisely regulating acid density and types to promote the stable two-step conversion of methanol to aromatics via light hydrocarbons

Acidic properties of ZSM-5 zeolites for the aromatization of light hydrocarbons strongly determined the final catalytic selectivity and stability for two-step methanol conversions of aromatics via light hydrocarbons. Herein, the density and types of acid sites of ZSM-5 were precisely adjusted to explore their influences on the final catalytic performance. Different from the indistinctive effect of SiO2/Al2O3 ratios on traditional one-step methanol conversion to aromatics, decreasing acid density by increasing SiO2/Al2O3 ratios from 36 to 70 decelerated coke formation and significantly extended the catalytic lifetime from 46.5 to 190.8 h. Further modification with low Zn loading decreased B/L ratio from 19.0 to 1.7 and established a good catalytic synergy between Zn-Lewis and Brønsted acid sites for aromatization of light hydrocarbons, which increased the aromatics selectivity from 27.5% to 31.4%. The decreased catalytic stability after introducing Zn species was attributed to the coke coverage on acid sites but not the final blockage of pore channels as mentioned in previous studies, which was indicated by the similar coke rate of the deactivated catalyst and their gradually increased surface area with increasing Zn content. This work provides more insights into the regulation of acid properties for aromatization catalyst to boost the conversion of methanol to aromatics.

Catalytic synergy between the low Si/Al ratio Zn/ZSM-5 and high Si/Al ratio HZSM-5 for high-performance methanol conversion to aromatics

Rational mixing of two kinds of catalysts with catalytic coupling functions could efficiently convert reactants to products via two successive steps. Herein, high Si/Al ratio ZSM-5 (Z220) was mixed with low Si/Al ratio Zn/ZSM-5 (ZnZ30) for two-step methanol conversion to aromatics (MTA). Sufficient experiments explored their catalytic synergy and found that methanol was firstly converted into light hydrocarbons on Z220, and then light hydrocarbons were converted into aromatics on neighboring ZnZ30. ZnZ30 not only catalyzed light alkenes into aromatics, but also catalyzed light alkanes to light alkenes and then to aromatics. Changing mixing ratio controlled the proportions of two steps for MTA reaction and achieved a good match between two processes, which increased aromatic selectivity from 30.3%–39.9% and prolonged lifetime by a factor of 10 compared with one-step aromatization. Optimizing reaction temperature, Si/Al ratio and granule size of catalysts further strengthened their catalytic synergy for improved catalytic performance.

Mesostructured cellular foam silica supported Au–Pt nanoalloy: Enrichment of d-state electrons for promoting the catalytic synergy

A mesostructured cellular foam (MCF) silica was applied to support gold (Au) – platinum (Pt) alloy nanoparticles (NPs) for benzyl alcohol partial oxidation. A catalytic synergy on bimetallic gold (Au)-platinum (Pt) nanoparticle (NP) catalyst, referring to that introducing Au to Pt leading to a higher catalytic performance has been observed. However, the essence of this synergistic effect is still under debate. In this work, a series of MCF supported Au–Pt NP catalysts are designed to reveal the essence . Well-developed porous structure of MCF support eliminated the mass transfer limitation and intrinsic catalytic activity was obtained. The improved catalytic performance on bimetallic catalyst is attributed to the geometric and electronic changes of active sites after formation of Au–Pt alloy NPs. Compared with monometallic catalyst, the formation of Au–Pt alloy results in the changes of particle size and lattice structure. Electronic property analyses confirmed the increase of d state electrons on Au–Pt alloy NPs, which are calculated from s-p-d hybridization and intra-atomic charge redistribution, leading to the increased abundance of transferable d electrons near Fermi level and further enhancing the catalytic activity. These findings gain new insights into the catalytic synergy of bimetallic nanoparticles and shed light on the optimization of these catalysts. The catalytic synergy of mesostructured cellular foam silica supported bimetallic Au–Pt catalysts for benzyl alcohol oxidation is attributed to the increased abundance of transferable d electrons near Fermi level which are calculated from s-p-d hybridization and intra-atomic charge redistribution. • Mesostructured cellular foam silica support Au–Pt alloy nanoparticles were prepared by a facile one-pot method. • The formation of Au–Pt alloy nanoparticles results in particle size variation and lattice distortions. • Electron polarization leads to the increase of transferable d-orbital electrons on Au and Pt atoms. • The catalytic activity on Au–Pt alloy catalyst was enhanced through accelerating the O 2 activation.

Catalytic synergy of Au@CeO2–rGO nanohybrids for the reductive transformation of antibiotics and dyes

Changes in morphology of Au@CeO2–rGO nanohybrids demonstrated synergistic effects of the ternary components for reductive transformation of antibiotics and dyes.

Development and Engineering of Nanostructured Ternary Catalyst for PEM Fuel Cells: The Role of Electrode Composition in Oxygen Reduction Kinetics

Low-temperature proton exchange membrane fuel cells (PEMFCs), offering significantly higher efficiency compared to conventional heat engines play a crucial role in responding to the growing energy demand, especially for transportation applications. The fundamental understanding of bulk electrocatalysis both in acidic and alkaline media at nanostructured electrodes that possess compositional and structural heterogeneity has a profound effect on electrode kinetics and reaction mechanisms. Because the electrocatalytic activity depends mainly upon the nanoscale size, composition as well as surface properties of the prepared catalyst, development and engineering of advanced electrocatalysts is needed for giving a lead towards unprecedented improvements in electrode performance so in fuel cell systems1. It has hypothesized2 and reported3 that alloying Pt with different metal components (herein Sn and Ni) brings about modifying the electrotonic states such as the d-band centers as well as geometric factors, which has attracted a great deal of attention in electrocatalysis. Moreover, the superior catalytic synergy of nanostructured binary4 and ternary5 electrocatalysts towards oxygen reduction activity was previously reported. To this end, highly active, robust and low-cost carbon-supported ternary nanoparticles (Pt2Sn1Ni1/C) were synthesized using a modified microwave-assisted polyol method6 in diethylene glycol (DEG) without additional protective agents. The morphostructural properties of the catalyst were determined via various advanced-characterization techniques. Cyclic voltammetry (CV) and rotating (ring) disk electrode (RRDE) measurements reveal that the alloying of Pt with Sn-Ni significantly boosts the catalytic activity towards oxygen reduction reaction (ORR) in O2-saturated 0.1M HClO4 electrolyte. The kinetic parameters were assessed through Koutecky-Levich approach. The influence of the alloying structure on the kinetic parameters such as exchange current density, limiting current density, Tafel slopes, reaction rate, and the number of exchanged electrons is extensively discussed.

Understanding the Synergistic Effects Observed When Using Tethered Dual Catalysts for Heat and Light Activated Catalysis

AbstractDual catalysis, where two different catalysts work cooperatively to promote a chemical reaction, is an important synthetic approach as it can allow a wide range of unique reactivity to be accessed. Whilst most dual catalysis strategies utilise separate catalysts in the reaction mixture, there is a growing interest in using tethered dual catalysts to increase cooperativity between the catalytic centres. In this current work we sought to determine the origin of the catalytic synergy observed for a series of Ir(I) based complexes tethered to a BODIPY type photocatalyst through different tethering modes. Kinetic analyses revealed that the tethered dual catalysts were more effective at promoting heat activated intermolecular hydroamination than the un‐tethered analogues. The tethering mode had a significant influence on the magnitude of this synergistic enhancement observed for the hydroamination reaction, likely due to a combination of steric and electronic ligand effects. Investigations into the effect of the tethered dual catalysts on the light activated oxidation of thioanisole demonstrated that chemical tethering leads to substantial increases in photocatalytic activity, which was once again impacted by the tethering mode. The origin of the observed enhancement was found to be due to both increased singlet oxygen generation through the heavy atom effect, as well as direct involvement of the Ir centre in the oxidation reaction pathway.

Surface oxygenation of multicomponent nanoparticles toward active and stable oxidation catalysts

The need for active and stable oxidation catalysts is driven by the demands in production of valuable chemicals, remediation of hydrocarbon pollutants and energy sustainability. Traditional approaches focus on oxygen-activating oxides as support which provides the oxygen activation at the catalyst-support peripheral interface. Here we report a new approach to oxidation catalysts for total oxidation of hydrocarbons (e.g., propane) by surface oxygenation of platinum (Pt)-alloyed multicomponent nanoparticles (e.g., platinum-nickel cobalt (Pt–NiCo)). The in-situ/operando time-resolved studies, including high-energy synchrotron X-ray diffraction and diffuse reflectance infrared Fourier transform spectroscopy, demonstrate the formation of oxygenated Pt–NiOCoO surface layer and disordered ternary alloy core. The results reveal largely-irregular oscillatory kinetics associated with the dynamic lattice expansion/shrinking, ordering/disordering, and formation of surface-oxygenated sites and intermediates. The catalytic synergy is responsible for reduction of the oxidation temperature by ~100 °C and the high stability under 800 °C hydrothermal aging in comparison with Pt, and may represent a paradigm shift in the design of self-supported catalysts.

Catalytic Synergy on PtNi Bimetal Catalysts Driven by Interfacial Intermediate Structures

Platinum-based bimetallic catalysts exhibit surface atomic rearrangement in various adsorbate environments, which significantly impacts catalysis. A molecular-level understanding of intermediate st...