Core-shell Catalysts Research Articles

Cobalt Nitride-Implanted PtCo Intermetallic Nanocatalysts for Ultrahigh Fuel Cell Cathode Performance.

Stable and active oxygen reduction electrocatalysts are essential for practical fuel cells. Herein, we report a novel class of highly ordered platinum-cobalt (Pt-Co) alloys embedded with cobalt nitride. The intermetallic core-shell catalyst demonstrates an initial mass activity of 0.88 A mgPt-1 at 0.9 V with 71% retention after 30,000 potential cycles of an aggressive square-wave accelerated durability test and loses only 9% of its electrochemical surface area, far exceeding the US Department of Energy 2025 targets, with unprecedented stability and only a minimal voltage loss under practical fuel cell operating conditions. We discover that regulating the atomic ordering in the core results in an optimal lattice configuration that accelerates the oxygen reduction kinetics. The presence of cobalt nitride decorated within PtCo superlattices guarantees a larger barrier to Co dissolution, leading to the excellent endurance of the electrocatalysts. This work brings up a transformative structural engineering strategy for rationally designing high-performing Pt-based catalysts with a unique atomic configuration for broad practical uses in energy conversion technology.

Enhancement of visible light adsorption and photocatalytic degradation activity of organic dye by coating semiconducting TiO2 shell on plasmonic Au particles

The plasmonic effect enhances light absorption in semiconductor photocatalysts, while the noble metal-semiconductor interface promotes charge carrier transfer and separation, boosting photocatalytic activity. However, current methods for synthesizing metal-core TiO2-shell nanoparticles face challenges, such as keeping stable and preventing aggregation. This study presents a simple and moderate synthesis method for Au@TiO2 core-shell nanoparticles, enabling precise control over the TiO2 shell thickness and stable photocatalytic performance. Various characterization techniques were employed to assess the optical and structural properties of the synthesized Au@TiO2 core-shell nanostructures. The results demonstrated that increasing the Au core concentration led to a gradual decrease in TiO2 shell thickness. The adsorption properties and photocatalytic degradation efficiency of the synthesized Au@TiO2 core-shell nanostructured catalysts were thoroughly examined, particularly focusing on their performance with methyl orange (MO) and methylene blue (MB). Au@TiO2 achieved excellent adsorption performance for MO, with a maximum capacity of 231±6 mg/g. Furthermore, Au@TiO2 exhibited higher photocatalytic degradation activity of both MO and MB than pure TiO2. The mechanism study indicated that it attributed to enhanced visible light absorption, reduced bandgap, and higher valence band energy. Additionally, the Au@TiO2 catalysts showed good cyclic stability, making them promising for future applications. This research offers insights into designing efficient photocatalysts, addressing existing synthesis challenges, and contributing valuable references for future advancements.

Sulfur-resistant mechanism of MnOx@CeO2@MgO core-shell catalyst in simultaneous removal of NOx and chlorobenzene

Herein, Mn-Ce based catalysts with different structures were rationally designed to explore their sulfur-resistant mechanism for simultaneous removal of NOx and chlorobenzene (CB) from waste incineration at low temperature. In the presence of SO2, MnOx@CeO2@MgO exhibits the highest sulfur resistance among prepared catalysts. Both NOx and CB conversion over MnOx@CeO2@MgO can reach up to 80% at 300 °C. However, the significant deactivation is observed for MnCeMgOx within all temperature ranges. For the selectivity of products, MnOx@CeO2@MgO displays the excellent N2 selectivity (93%) and good CO2 selectivity (80%) at 300 °C. Compared with NO reduction, SO2 has a greater impact on CB destruction due to the consumption of reactive oxygen species during SO2 oxidation. The reduction of active oxygen is proposed to be the reason for the significant inhibition of CB oxidation. The addition of MgO shell increases the proportion of lattice oxygen, which is beneficial to improving the sulfur resistance of MnOx@CeO2@MgO catalyst. In addition, SO2 can react with MgO preferentially to protect the active sites and improve the sulfur resistance. This work indicates that MnOx@CeO2@MgO core-shell catalyst with good sulfur tolerance and stability is expected to be applied in the potential application.

Core-Shell catalyst-mediated hydrodeoxygenation of guaiacol for the preparation of cyclohexanol

Abstract The conversion of lignin-derived phenolic compounds into high-value chemicals through value-added reactions holds significant importance. Cyclohexanol, an essential chemical raw material and organic intermediate, was synthesized in this study from guaiacol, a phenolic compound derived from lignin, through a hydrodeoxygenation reaction. When compared to mechanically mixed and supported catalysts, the use of the HZSM-5@Pd-SiO2 core-shell catalyst resulted in a cyclohexanol yield of 51.1% after a reaction conducted at 493K and 2 MPa H2 for 8h. The core-shell catalyst was characterized using TEM, N2 adsorption-desorption, and NH3-TPD, Py-FTIR revealing its rich acid sites, large specific surface area, and uniform mesopores.

Simulated sunlight-driven photocatalytic activation of peroxydisulfate by core–shell Ag@SiO2/TiO2 nanocomposite for efficient methyl orange degradation

Herein, core–shell Ag@SiO2/TiO2 nanocomposites were synthesized and applied to activate peroxydisulfate (PDS) for wastewater purification. The Ag core and Ag-doped TiO2 shell were obtained by stober method and calcination method. The dispersion degree and size of Ag in TiO2 would influence the oxygen vacancy. Ag enhanced the visible absorption of TiO2 and activated PDS. Improved degradation performance was attributed to enhanced PDS activation by photogenerated e−, which separated h+and thus promoted methyl orange(MO) degradation. Reactive oxidative species were verified under dark and light conditions via quenching experiments and electron paramagnetic resonance tests, demonstrating SO4•–, h+, O2•–, and1O2were formed in light,whereasSO4•–, •OH, O2•–, and 1O2were responsible for MO degradation under dark conditions. The Ag@SiO2/TiO2/PDS/light system showed selectivity for removal of cationic dyes (e.g., methylene blue and malachite green) through adsorption and photocatalysis, whereas anionic dyes (e.g., MO) were degraded by photocatalysis alone. Besides, we found excess adsorption of micropollutant onto catalyst may be adverse to the activation of PDS. Therefore, the adsorption of oxidant (such as PDS) onto the catalyst surface would be beneficial for catalytic activation and micropollutant degradation, especially onto active sites. This work aims to provide a new avenue for core-shell structure catalyst synthesis in wastewater purification.

Boosted Electrochemical Hydrogen Evolution Activity via the Core-Shell Heterostructure of Nickel Sulfide Nanoframe-Supported Layered Rhenium Disulfide.

The strategic design of a heterostructure catalyst with a core-shell nanoarchitecture is imperative for enhancing the efficiency of the electrocatalytic hydrogen evolution reaction (HER). Herein, the core-shell catalyst comprising the rhenium disulfide nanosheets was vertically integrated onto a hollow nickel sulfide (NiS@ReS2) via coprecipitation and hydrothermal treatment. The morphology involves the sulfurization of a nickel-based Prussian blue analogue, effectively mitigating the aggregation of ReS2 nanosheets and maximizing the exposed active sites. By the synergistic effect of morphological design and heterostructure formation, the overpotential of NiS@ReS2 is 136 mV at 10 mA cm-2 in an alkaline electrolyte, and the rapid kinetics is confirmed by the small Tafel slope and low charge transfer resistance during the HER process. Moreover, the electrocatalytic durability of NiS@ReS2 is elucidated, and the boosted catalytic activity of NiS@ReS2 is confirmed by density functional theory. This study unveils a promising method for advancing ReS2-based electrocatalysts with potential implications for producing hydrogen.

Polydopamine and NaCl template approach to develop a microporous RuO2@IrOx Core–Shell catalyst for an efficient oxygen evolution reaction in polymer electrolyte membrane water electrolyzers

To obtain a stable and active catalyst for the oxygen evolution reaction (OER) in polymer electrolyte membrane water electrolysis (PEMWE), a microporous RuO2@IrOx core–shell was synthesized using a polydopamine (PDA) coating and a NaCl filler method. A durable IrOx shell was homogeneously formed on the surface of the RuO2 core via impregnation of the PDA coating, which improved the catalytic stability. The NaCl filler created micropores within the nanostructures, increasing the number of active catalytic sites. The strong interaction between the RuO2 core and protective IrOx shell, along with the micropores, significantly improved OER activity, showing an overpotential of 182 mV at 10 mA cm−2. Furthermore, a PEMWE exhibited excellent performance, achieving a current density of 1 A cm−2 at a cell voltage of 1.57 V. These findings provide valuable insights into the potential of RuO2@IrOx as a robust and efficient catalyst for green hydrogen production.

Fabrication of core–shell Fe3O4@SiO2/graphite catalyst to improve the charge separation for enhanced photocatalytic toluene oxidation

Magnetite (Fe3O4) has been regarded as a potential photocatalyst for VOCs degradation. Nevertheless, the magnetism of Fe3O4 always leads to the aggregation of particles, which is adverse for gaseous VOCs degradation. Meanwhile, the fast charge recombination of Fe3O4 seriously limits the photocatalytic activity. Herein, a layer of SiO2 was coated on the surface of Fe3O4, and Fe3O4@SiO2 particles were combined with graphite to prepare the core–shell catalyst for photocatalytic toluene oxidation. Fe3O4@SiO2/G catalyst showed the toluene degradation efficiency of 85.09%, which was 3.2 and 1.3 times than those of Fe3O4 and Fe3O4/G. The coating of SiO2 prevented the aggregation of Fe3O4 and greatly enhanced the specific surface area. Experimental and theoretical calculation proved that the existence of SiO2 promoted the spatial charge separation and inhibited the charge recombination, resulting in the generation of abundant reactive oxygen species. These findings offered an insight into the catalyst design for photocatalytic VOCs oxidation.

Bimetallic FeCu-MOF derivatives as heterogeneous catalysts with enhanced stability for electro-Fenton degradation of lisinopril

A bimetallic FeCu/NC core-shell catalyst, consisting in nanoparticles where zero-valent Fe and Cu atoms, slightly oxidized on their surface, are encapsulated by carbon has been successfully prepared by modifying the synthesis route of MIL(Fe)-88B. FeCu/NC possessed well-balanced textural and electrochemical properties. According to voltammetric responses, in-situ Fe(III) reduction to Fe(II) by low-valent Cu was feasible, whereas the high double-layer capacitance confirmed the presence of a great number of electroactive sites that was essential for continuous H2O2 activation to •OH via Fenton's reaction. Electrochemical impedance and distribution of relaxation times (DRT) analysis informed about the strong leaching resistance of FeCu/NC. To validate the promising features of this catalyst, the advanced oxidation of the antihypertensive lisinopril (LSN) was investigated for the first time. The heterogeneous electro-Fenton (HEF) treatment of 16.1 mg L−1 LSN solutions was carried out in a DSA/air-diffusion cell. At pH 3, complete degradation was achieved within 6 min using only 0.05 g L−1 FeCu/NC; at near-neutral pH, 100 % removal was also feasible even in actual urban wastewater, requiring 60–75 min. The FeCu/NC catalyst demonstrated high stability, still maintaining 86.5 % of degradation efficiency after 5 cycles and undergoing low iron leaching. It outperformed the monometallic (Fe/NC and Cu/NC) catalysts, which is explained by the Cu(0)/Cu(I)-catalyzed Fe(II) regeneration mechanism that maintains the Fenton's cycle. LC-MS/MS analysis allowed the identification of two main primary LSN by-products. It can then be concluded that the FeCu/NC-based HEF process merits to be further scaled up for wastewater treatment.

Tailoring Pd/M@CoAlO core-shell catalyst morphology for efficient methane oxidation

The control of low-concentration methane (CH4) emissions is a critical component of the ‘dual carbon’ strategy, and catalytic combustion technology focused on catalyst design is recognized as a promising avenue for achieving it. However, the zeolite-based catalysts are highly prone to deactivation under hydrothermal environments, thus limiting their practical applicability. Herein, we have utilized layered double hydroxides (LDHs) as precursors and integrated them with Pd/M through a co-precipitation method to fabricate Pd/M@CoAlO composite catalysts with a core–shell structure, focused on the impact of CoAlO morphology on the activity and stability for CH4 oxidation. It revealed that the incorporation of CoAlO significantly enhanced the catalytic combustion efficiency and the hydrothermal stability of Pd/M. Furthermore, an increase in the calcination temperature led to a progressive degradation of the sheet-like or petal-shaped structure of CoAlO within the Pd/M@CoAlO composite catalysts. This structural collapse eventually resulted in the formation of CoAlO dense particles that enveloped the Pd/M, adversely affecting the adsorption of oxygen and the exposure of active sites. This work underscores the importance of morphological control, providing significant guidance for the strategic design and development of catalysts tailored for CH4 catalytic combustion.

Highly Efficient Ni@SiO2 Core–Shell Catalysts for Dry Reforming of Methane Prepared by One-Pot Microemulsion Nucleation and Coating Method

Highly Efficient Ni@SiO₂ Core–Shell Catalysts for Dry Reforming of Methane Prepared by One-Pot Microemulsion Nucleation and Coating Method

Design dual confinement Ni@S-1@SiO2 catalyst with enhanced carbon resistance for methane dry reforming

Methane dry reforming is a key method for converting greenhouse gases into valuable syngas, providing a pathway for the sustainable production of valuable compounds. Yet the challenges like particle sintering and carbon deposition have hindered the widespread application of nickel-based catalysts. This study explores innovative strategies to overcome these challenges by using zeolite supports to enhance nickel dispersity and prevent carbon deposition, as well as adopting core-shell structures to prevent metal sintering and carbon deposition. In pursuit of enhancing methane dry reforming efficacy, a Ni@S-1@SiO2 dual-shell nickel-based catalyst is designed in this study to confine exposed nickel particles on the S-1 surface within a robust mesoporous silica shell, reducing nickel particle mobility and preventing active site oxidation, thereby increasing resistance to sintering and carbon deposition. Compared to conventional single-core-shell catalysts, this design significantly reduces nickel particle mobility and active site oxidation, enhancing resistance to sintering and coking. It showed virtually no carbon deposition even after a rigorous 25-h reaction at 650 °C. In-situ DRIFTS analyses provided further insights into the underlying mechanism, confirming a Langmuir-Hinshelwood mechanism and highlighting the beneficial role of formates in preventing coke deposition. This study not only advances the understanding of core-shell catalyst structures but also paves the way for optimized nickel-based catalysts in methane dry reforming, promoting a sustainable future for syngas production.

Construction of Multi-Enzyme Integrated Catalysts for Deracemization of Cyclic Chiral Amines.

Multi-enzyme cascade catalysis has become an important technique for chemical reactions used in manufacturing and scientific study. In this research, we designed a four-enzyme integrated catalyst and used it to catalyse the deracemization reaction of cyclic chiral amines, where monoamine oxidase (MAO) catalyses the enantioselective oxidation of 1-methyl-1,2,3,4-tetrahydroisoquinoline (MTQ), imine reductase (IRED) catalyses the stereo selective reduction of 1-methyl-3,4-dihydroisoquinoline (MDQ), formate dehydrogenase (FDH) is used for the cyclic regeneration of cofactors, and catalase (CAT) is used for decomposition of oxidative reactions. The four enzymes were immobilized via polydopamine (PDA)-encapsulated dendritic organosilica nanoparticles (DONs) as carriers, resulting in the amphiphilic core-shell catalysts. The hydrophilic PDA shell ensures the dispersion of the catalyst in water, and the hydrophobic DON core creates a microenvironment with the spatial confinement effect of the organic substrate and the preconcentration effect to enhance the stability of the enzymes and the catalytic efficiency. The core-shell structure improves the stability and reusability of the catalyst and rationally arranges the position of different enzymes according to the reaction sequence to improve the cascade catalytic performance and cofactor recovery efficiency.

An ionic liquid in Core-shell structure: Halogen-free, metal-free bifunctional catalyst for olefin epoxidation and CO2 cycloaddition

We synthesized a core-shell resin structure with abundant architecture and excellent thermal stability through polymerization. Imidazole ionic liquid with varying carbon chain lengths was immobilized on the surface, resulting in the preparation of metal-free, halogen-free core-shell catalysts with different carbon chain lengths via HCO3- exchange. Characterization using FT-IR, XPS, and various techniques revealed the exceptional performance of our synthetic catalyst in terms of its internal structure. After extensive experimentation, we discovered that the synthesized catalyst exhibits dual functionality for epoxidation and CO2 cycloaddition reactions without requiring solvents or co-catalysts. The epoxidation system demonstrated remarkable conversion rates and selectivity while also exhibiting strong recyclability in heterogeneous reactions, according to kinetic parameters, the reaction order of styrene, TBHP and catalyst during epoxidation is approximately 1, the reference factor for this reaction was calculated to be 6.7×109 (L2·mol−2·min−1), with an activation energy of 48.9 kJ/mol obtained from analyzing reaction rates at different temperatures. In the CO2 cycloaddition reaction, our catalyst exhibited an advantage in catalyzing ring-opening reactions, achieving a conversion rate of 95 % for styrene oxide within six hours along with over 99 % selectivity towards cyclic carbonate formation. It is suggested that the epoxide reaction is carried out in steps, and it is inferred that the catalyst PS-ImC4HCO3 and TBHP are produced into peroxy intermediate active species TBA and HCO4, and the reaction between HCO4- and styrene is the determination step of the total reaction. The reaction rate constant k=0.009 of the absolute step is calculated based on the global optimization algorithm

Construction of multifunctional interface engineering on Cu‐SSZ‐13@Ce‐MnOx/Mesoporous-silica catalyst for boosting activity, SO2 tolerance and hydrothermal stability

Although small pore Cu-SSZ-13 catalysts have been successful as commercial catalysts for controlling NOx emissions from mobile sources, the challenges of high light-off temperature, SO2 tolerance and hydrothermal stability still need to be addressed. Here, we synthesized a multifunctional core-shell catalyst with Cu-SSZ-13 as the core phase and Ce-MnOx supported Mesoporous-silica (Meso-SiO2) as the shell phase via self-assembly and impregnation. The core-shell catalyst exhibited excellent low-temperature activity, SO2 tolerance and hydrothermal stability compared to the Cu-SSZ-13. The Ce-MnOx species dispersed in the shell are found to enhance both the acidic and oxidative properties of the core-shell catalyst. More critically, these species can rapidly activate NO and oxidize it to NO2, which allows the NH3-SCR reaction on the core-shell catalyst to be initiated in the shell phase. Meanwhile, Ce-MnOx species can react preferentially with SO2 as sacrifice components, effectively avoiding the sulfur inactivation of the copper active sites. Furthermore, the hydrophobic Meso-SiO2 shell provides an important barrier for the core phase, which reduces the loss of active species, acid sites and framework Al of the aged core-shell catalyst and mitigates the collapse of the zeolite framework. This work provides a new strategy for the design of novel and efficient NH3-SCR catalysts.

Electrochemical Oxidation of Ethanol and Methanol at Rh@Pt Catalysts at 80 °C in Proton Exchange Membrane (PEM) Cells

Efficient oxidation of ethanol to carbon dioxide is crucial for the development of sustainable electrochemical generation of power and hydrogen from bioethanol. However, high anode overpotentials and partial oxidation to acetaldehyde and acetic acid result in low efficiencies and waste management issues. Bimetallic Rh-Pt catalysts have shown enhanced activities and CO2 production in aqueous electrolytes, but not in proton exchange membrane (PEM) cells. In this work Rh@Pt core–shell catalysts, prepared from commercial carbon-supported Rh, have been evaluated in both aqueous H2SO4 and PEM cells. Cyclic voltammetry of aqueous methanol and ethanol has shown that the catalytic activity of the Pt shell is increased by the compressive strain induced by the Rh core, and that there is also a significant bifunctional effect at low Pt coverages. In PEM cells, these effects also increase selectivity for cleavage of the C–C bond of ethanol to produce CO2, which will enhance the efficiencies of ethanol fuel and electrolysis cells for producing power and hydrogen, respectively. Deposition of 0.5 monolayers of Pt onto the Rh core produced the highest CO2 yields at the lowest anode overpotentials, while higher coverages of Pt increased performances and CO2 yields at higher potentials.

Evaluation of photocatalytic properties of TiO2/g-C3N4 core-shell hybrid catalyst supported on Sr4Al14O25:eu,dy phosphor

TiO2/g-C3N4 hybrid compounds were supported as core-shell catalyst on Sr4Al14O25:Eu,Dy phosphor powder by a 2-step hydrothermal and solvothermal self-assembly method. Surface and chemical characterizations confirmed that the phosphor substrate and the hybrid catalysts co-existed as a multi-composite material. Where nano spherical TiO2 particles were dominant as core/shell catalyst. Diffuse reflectance spectra were shifted toward the visible light region (400 nm to 600 nm) in composites with g-C3N4 as shell-catalyst. X-ray photon spectroscopy (XPS) confirmed the chemical integrity and binding of g-C3N4 on phosphor/TiO2 material. When g-C3N4 was coated as shell-catalyst on phosphor/TiO2, superior photocatalytic performances of above 90% efficiency were obtained in comparison to where TiO2 was coated as shell-catalyst under both ultraviolet and visible light illumination. Thus, g-C3N4 is more active as shell-catalyst owing to its lower band gap of 2.7 eV than core TiO2 (3.2 eV).

Enhanced coke resistant Ni/SiO2@SiO2 core–shell nanostructured catalysts for dry reforming of methane: Effect of metal-support interaction and SiO2 shell

Suppressing coke formation on nickel-based catalysts used in methane-dry reforming is one of the most important issues. We investigate the effect of nickel metal-support interaction and outer porous silica shells on the coke formation in methane dry reforming over Ni/SiO2@SiO2 core–shell catalysts. Using a simple ammonia evaporation method, the Ni/SiO2_AE catalyst, which has highly dispersed nickel nanoparticles with ca. 7 nm, was synthesized and coated with an outer porous silica shell to produce a Ni/SiO2_AE/SiO2 core shell catalyst. Based on the TEM and N2 isotherm results, a 20 nm thick SiO2 shell having pores with a size of about 2 nm was uniformly coated on the Ni/SiO2_AE catalyst. H2-TPR, and XPS analysis results suggest that the Ni/SiO2_AE and Ni/SiO2_AE@SiO2 catalysts have high nickel dispersion. This high dispersion is due to strong metal-support interactions and the formation of Ni phyllosilicate species. On the other hand, the ones synthesized by wet impregnation method have low nickel dispersion due to weaker metal-support interactions. The Ni/SiO2_AE@SiO2 core–shell catalyst showed stable catalytic activity under methane dry reforming conditions at 600 °C. On the other hand, the Ni/SiO2_WI and Ni/SiO2_AE catalysts showed rapid deactivation due to severe coke formation. It can be concluded that the strong metal-support interaction and the silica shell can suppress catalyst deactivation caused by coke formation very effectively.

A confined catalysis strategy: Lewis acid-base (B/Br) and hydrogen bond donor (-OH) multi-functionalized core-shell catalyst for CO2 cycloaddition

In recent years, a significant number of metal-based catalysts were synthesized for the CO2 cycloaddition reaction. However, the leaking of active metal elements resulted in various environmental issues. To prevent the loss of active components and enhance the catalyst lifespan, a confined catalysis strategy involving a multi-functionalized core-shell catalyst with Lewis acid-base (B/Br) and hydrogen bond donor (-OH) was designed. It was noteworthy that B-mSiO2@MCM-IMOH featured multifunctional catalytic active sites, including Lewis acid-base (B/Br) and hydrogen bond donor (-OH), and the cooperative effect of B, Br and -OH significantly improved the catalytic activity. Therefore, B-mSiO2@MCM-IMOH demonstrated outstanding catalytic performance for the CO2 cycloaddition reaction. In addition, the core-shell molecular sieve, serving as a confined catalytic carrier, effectively enhanced the stability and recyclability of the catalyst. Utilizing DFT calculations, a cooperative catalytic mechanism was proposed involving Lewis acid-base (B/Br) and hydrogen bond donor (-OH). The synergistic interaction between B/Br and -OH markedly reduced the energy barrier for the ring-opening of propylene oxide from 58.6 kcal·mol−1 to 21.5 kcal·mol−1, thus facilitating the PO-CO2 cycloaddition reaction.

Insights into the role of Mo in boosting CHx* oxidation for CO2 methane reforming

CHx* oxidation is one of the most vital routes to alleviate the carbon deposition problem of CO2 reforming of methane (DRM) reaction. Whereas, little experimental evidence has been observed on NiMo catalysts where the CHx* oxidation was dominant over its dissociation reaction. Herein, to experimentally unveil the CHx* oxidation route of NiMo catalysts, we design three catalysts with different particle sizes and structures. Among them, Mo/Niphy@SiO2 core shell catalyst demonstrated the dominant CHx* oxidation route over its dissociation based on in-situ diffuse reflectance infrared Fourier transform spectroscopy experiments. This was attributed to the confinement effect of SiO2 and the formation of Ni–Mo alloy, inhibiting the CHx* dissociation reaction. It exhibited relatively stable CH4 and CO2 conversions (77 % and 75 % respectively) within 180 h. By contrast, on Mo/Niphy catalyst which has a big Ni size, CHx* was mainly dissociated to C* and oxidized to CO which further underwent a disproportion reaction to produce CO2 and C*, leading to the severe carbon deposition and unstable DRM performance. The strategy to unveil the dominant role of CHx* oxidation via design catalysts with different sizes and structures sheds light on the study of reaction mechanism of other reactions.