A Facile Way To Improve Pt Atom Efficiency for CO Oxidation at Low Temperature: Modification by Transition Metal Oxides

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.

Recent advances in noble metal-based catalysts for CO oxidation

Carbon monoxide, one of the major pollutants in the air, is mainly produced due to the incomplete combustion of fossil fuels such as coal and oil. Among all the techniques developed for removing CO, catalytic oxidation has been considered one of the most effective approaches, and the commonly used catalysts include metal oxides and noble metals. Noble metal attracted extensive attention due to its good catalytic performance at low temperatures and high resistance to poisoning. The review summarizes the recent advances of noble metals including Pt, Pd, Au, Ru, Rh, and Ir in CO oxidation. The effect of support, metal doping, the particle size of noble metals, and the hydroxyl groups on CO oxidation is discussed. Besides, the metal-support interaction on the stability and activity is also involved in this review. Finally, the challenges and opportunities of supported noble metal catalysts in practical CO oxidation are proposed.

Structured Catalysts and Catalytic Processes: Transport and Reaction Perspectives

The structure of catalysts determines the performance of catalytic processes. Intrinsically, the electronic and geometric structures influence the interaction between active species and the surface of the catalyst, which subsequently regulates the adsorption, reaction, and desorption behaviors. In recent decades, the development of catalysts with complex structures, including bulk, interfacial, encapsulated, and atomically dispersed structures, can potentially affect the electronic and geometric structures of catalysts and lead to further control of the transport and reaction of molecules. This review describes comprehensive understandings on the influence of electronic and geometric properties and complex catalyst structures on the performance of relevant heterogeneous catalytic processes, especially for the transport and reaction over structured catalysts for the conversions of light alkanes and small molecules. The recent research progress of the electronic and geometric properties over the active sites, specifically for theoretical descriptors developed in the recent decades, is discussed at the atomic level. The designs and properties of catalysts with specific structures are summarized. The transport phenomena and reactions over structured catalysts for the conversions of light alkanes and small molecules are analyzed. At the end of this review, we present our perspectives on the challenges for the further development of structured catalysts and heterogeneous catalytic processes.

Investigation into the roles of interfacial H2O structure in catalytic oxidation of HCHO and CO over CuMnO2 catalysts

The rapid deactivation of cost-effective MnO2-based catalysts in humid air limits their application in practice, and the identification of the role of water in an oxidation process is significant for developing water-resistant MnO2-based catalysts. Here, CuMnO2 showed a 20.3% HCHO conversion in 10 hr at room temperature in humid air with relative humidity of 40%, but deactivated in 3 hr in dry air. The excellent activity and stability of HCHO oxidation in humid air were attributed to the positive effect of H2O on HCHO oxidation to the H2O-HOCH2OH supermolecule assemblies via hydrogen bonds formed on CuMnO2. H2O-HOCH2OH supermolecule assemblies tend to be oxidized to carbonate, which is further oxidized to CO2. Furthermore, CuMnO2 exhibited a much poorer activity of CO oxidation in humid air, but the CO conversion was still 100% in 10 hr in dry air. H2O showed a competitive adsorption effect to CO on CuMnO2. CuMnO2 could be applied in HCHO elimination in humid air and CO elimination in dry air.

FeOx-Modified Ultrafine Platinum Particles Supported on MgFe2O4 with High Catalytic Activity and Promising Stability toward Low-Temperature Oxidation of CO

Catalytic oxidation is widely recognized as a highly effective approach for eliminating highly toxic CO. The current challenge lies in designing catalysts that possess exceptional low-temperature activity and stability. In this work, we have prepared ultrafine platinum particles of ~1 nm diameter dispersed on a MgFe2O4 support and found that the addition of 3 wt.% FeOx into the 3Pt/MgFe2O4 significantly improves its activity and stability. At an ultra-low temperature of 30 °C, the CO can be totally converted to CO2 over 3FeOx-3Pt/MgFe2O4. High and stable performances of CO-catalytic oxidation can be obtained at 60 °C on 3FeOx-3Pt/MgFe2O4 over 35 min on-stream at WHSV = 30,000 mL/(g·h). Based on a series of characterizations including BET, XRD, ICP, STEM, H2-TPR, XPS, CO-DRIFT, O2-TPD and CO-TPD, it was disclosed that the relatively high activity and stability of 3FeOx-3Pt/MgFe2O4 is due to the fact that the addition of FeOx could facilitate the antioxidant capacity of Pt and oxygen mobility and increase the proportion of adsorbed oxygen species and the amounts of adsorbed CO. These results are helpful in designing Pt-based catalysts exhibiting higher activity and stability at low temperatures for the catalytic oxidation of CO.

Enhancing oxidation reaction over Pt-MnO2 catalyst by activation of surface oxygen

Formaldehyde (HCHO) and carbon monoxide (CO) are both common air pollutants and hazardous to human body. It is imperative to develop the catalyst that is able to efficiently remove these pollutants. In this work, we activated Pt-MnO2 under different conditions for highly active oxidation of HCHO and CO, and the catalyst activated under CO displayed superior performance. A suite of complementary characterizations revealed that the catalyst activated with CO created the highly dispersed Pt nanoparticles to maintain a more positively charged state of Pt, which appropriately weakens the Mn-O bonding strength in the adjacent region of Pt for efficient supply of active oxygen during the reaction. Compared with other catalysts activated under different conditions, the CO-activated Pt-MnO2 displays much higher activity for oxidation of HCHO and CO. This research contributes to elucidating the mechanism for regulating the oxidation activity of Pt-based catalyst.

Synthesis of Inexpensive Ternary Metal Oxides by a Co-Precipitation Method for Catalytic Oxidation of Carbon Monoxide

By using a simple co-precipitation method, new Fe2 O3 -based nanocatalysts (samples) were synthesized. The samples were composites of two or three transition metal oxides, MOx (M=Fe, Mn, Co, Ni, and Cu). The average size of CuO crystallites in the composites composed of two oxide components (CuO-Fe2 O3 ) was about 14.3 nm, while in those composed of three (CuO-MnOx -Fe2 O3 ), the composite's phase compositions were almost in the amorphous form when annealing the sample at 300 °C. The latter sample had a specific surface area higher than that of the former, 207.9 and 142.1 g/m2 , respectively, explaining its higher catalytic CO oxidation. The CO conversion over the CuO-MnOx -Fe2 O3 -300 catalyst (1 g of catalyst, 2600 ppm of CO concentration in air, and 1.0 L/min of gas flow rate) begins at about 40 °C; the temperature for 50 % CO conversion (t50 ) is near 82 °C; and CO removal is almost complete at t99 ≈110 °C. The activity of the optimal sample was tested in different catalytic conditions, thereby observing a high durability of 99-100 % CO conversion at 130 °C. The obtained results were derived from XRD, FTIR, BET, SEM, elemental analysis and mapping, as well as catalytic experiments.

Preformed Pt Nanoparticles Supported on Nanoshaped CeO2 for Total Propane Oxidation

Pt-based catalysts have been widely used for the removal of short-chain volatile organic compounds (VOCs), such as propane. In this study, we synthesized Pt nanoparticles with a size of ca. 2.4 nm and loaded them on various fine-shaped CeO2 with different facets to investigate the effect of CeO2 morphology on the complete oxidation of propane. The Pt/CeO2-o catalyst with {111} facets exhibited superior catalytic activity compared to the Pt/CeO2-r catalyst with {110} and {100} facets. Specifically, the turnover frequency (TOF) value of Pt/CeO2-o was 1.8 times higher than that of Pt/CeO2-r. Moreover, Pt/CeO2-o showed outstanding long-term stability during 50 h. X-ray photoelectron spectroscopy (XPS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) revealed that the excellent performance of Pt/CeO2-o is due to the prevalence of metallic Pt species, which promotes C-C bond cleavage and facilitates the rapid removal of surface formate species. In contrast, a stronger metal-support interaction in Pt/CeO2-r leads to easier oxidation of Pt species and the accumulation of intermediates, which is detrimental to the catalytic activity. Our work provides insight into the oxidation of propane on different nanoshaped Pt/CeO2 catalysts.

Single-atom Pt-CeO2/Co3O4 catalyst with ultra-low Pt loading and high performance for toluene removal

The design and manufacture of high activity and thermal stability catalysts with minimal precious metal loading is essential for deep degradation of volatile organic compounds (VOCs). In this paper, a novel single-atom Pt-CeO₂/Co₃O₄ catalyst with ultra-low Pt loading capacity (0.06 wt%, denoted as 0.06Pt-SA) was fabricated via one-step co-precipitation method. The 0.06Pt-SA exhibited excellent toluene degradation activity of T₉₀ = 169 °C, matched with the nanoparticle Pt-supported CeO₂/Co₃O₄ catalyst with more than six times higher Pt loading (0.41 wt%, denoted as 0.41Pt-NP). Moreover, the ultra-long durability (toluene conversion remains 99% after 120 h stability test) and excellent toluene degradation ability in a wide space speed range of 0.06Pt-SA were superior to that of 0.41Pt-NP catalyst. The excellent performance was derived from the strong metal-support interaction (SMSI) between the single atomic Pt and the carrier, which induced more Pt⁰ and Ce³⁺ for oxygen activation and more Co³⁺ for toluene removal. The in situdiffuse reflectance infrared spectroscopy (DRIFTS) experiments confirmed that the conversion of intermediates was accelerated in the reaction process, thereby promoting the toluene degradation. Our results should inspire the exploitation of noble single-atomic modification strategy for developing the low cost and high performance VOCs catalyst.

Fabrication of supported Pt/CeO2 nanocatalysts doped with different elements for CO oxidation: theoretical and experimental studies

Supported Pt/CeO₂ catalysts have been widely used in carbon monoxide (CO) oxidation; however, the high oxygen vacancy formation energy (E_vac) in the process leads to the poor performance of these catalysts. Herein, we explored different element (Pr, Cu, or N) doped CeO₂ supports using Ce-based metal-organic frameworks (MOFs) as precursors via calcination treatment. The obtained CeO₂ supports were used to load Pt nanoparticles. These catalysts were systematically characterized by various techniques, and they showed superior catalytic activity for CO oxidation compared to undoped catalysts which could be attributed to the formation of Ce³⁺, and high amounts of O_ads/(O_ads + O_lat) and Pt^δ+/Pt_total. Moreover, density functional theory calculations with on-site Coulomb interaction correction (DFT+U) were performed to provide atomic-scale insights into the reaction process by the Mars-van Krevelen (M-vK) mechanism, which revealed that the element-doped catalysts could simultaneously reduce the adsorption energies of CO and lower reaction energy barriers in the *OOCO associative pathway.

Regulating Pt-based noble metal catalysts for the catalytic oxidation of volatile organic compounds: a mini review

Volatile organic compounds (VOCs) are an important class of environmental pollutants, and there is much interest in China to eliminate such pollutants. Noble metal catalysts have long been a family of catalysts with high efficiency and good low-temperature catalytic activity. As a representative of the noble metals, Pt has been widely used. This paper reviews the research trend of Pt-based catalysts for the catalytic oxidation of VOCs, and it compares several important components of Pt-based catalysts. The size of Pt particles, supported carriers, and reaction mechanism are reviewed. Toluene in VOCs is the main research subject. The activity, stability, water resistance, and selectivity of a series of Pt-based catalysts are summarized.

Electronic Modification by Transitional Metal Dopants to Tune the Oxidation Activity of Pt-CeO2-Based Catalysts

While utilization of transitional metals as a promoter has been extensively studied to enhance the activity of Pt-based catalysts for the oxidation of formaldehyde (HCHO), there is still a lack of well elucidated property-function relationship for the rational selection of a promoter in catalyst design. Herein, we modified a Pt/CeO₂ catalyst with two transitional metal dopants (i.e., Mn and Cu) that showed negligible influence on the physical structure of the Pt-CeO₂ matrix but distinct effects on the activity of the catalyst. Complementary characterizations combined with density functional theory modeling revealed that the transitional metal dopants significantly modified the electronic structure of the catalyst and shifted the d-band of Pt to higher energy with different extents, which may tune the bonding strength of HCHO/intermediates with the Pt-CeO₂ interface domain. The catalyst with moderate bonding strength (i.e., Pt-Mn/CeO₂) displayed the highest reactivity under the ambient condition, while Pt-Cu/CeO₂ with the highest bonding strength showed a dramatically decreased activity. No correlation was observed between the abundancy of the active oxygen and catalytic activity, likely due to the oxygen supply having a much higher rate than the rate-determining step. This work contributes to the elucidation about the property-function relationship of a transitional metal dopant in Pt-based catalysts for the oxidation of HCHO.

Vinyl chloride catalytic combustion on Pt/CeO2: Tuning Pt chemical state to promote Cl removing

Supported Pt catalysts usually produce chlorinated byproducts during chlorinated volatile organic compounds (CVOCs) combustion, the removal of formed surface chlorine species is the key to improve the activity, selectivity and stability. In this paper, the Pt chemical state is adjusted by the interaction between Pt and CeO₂ through controlling the morphology of CeO₂, which further affects the catalytic performance of VC combustion. For Pt/CeO₂-octahedron, the weak interaction between Pt and CeO₂ results in the formation of PtO₂, facilities VC adsorption and C-Cl bonds cleavage and becomes a key active site to accommodate the dissociated Cl species. While the strong interaction leads to the formation of Pt_xCe_1-xO_2-σ solid solution on Pt/CeO₂-rod has relative lower ability in Cl species removal compared with PtO₂. Density functional theory (DFT) calculations also confirms that the introduced Pt species reduces the concentration of Cl species on the surface as well as the chlorinated-byproducts. Hence, Pt/CeO₂-octahedron outperformed Pt/CeO₂-rod and Pt/CeO₂-cube with 90% VC conversion at 280 °C. Furthermore, under the same VC conversion (90%), the concentration of chlorinated byproducts on Pt/CeO₂-octahedron was only 4% than that of Pt/CeO₂-rod.

Optimizing the synergy between alloy and alloy-oxide interface for CO oxidation in bimetallic catalysts

Creating synergetic metal-oxide interfaces is a promising strategy to promote the catalytic performance of heterogeneous catalysts. However, this strategy has been mainly applied to monometallic catalysts, while scarcely applied to alloy catalysts. In this work, we present a comprehensive study on the synergetic alloy-oxide interfaces in the bimetallic Pt-Co/Al₂O₃ catalysts for CO oxidation. A series of Pt₁Co_x/Al₂O₃ catalysts with various Co/Pt molar ratios with x ranging from 0.5 to 3.8 was synthesized via a facile wet-chemistry strategy. Among them, the Pt₁Co_0.5/Al₂O₃ catalyst exhibits the best catalytic performance for CO oxidation, with the lowest CO complete conversion temperature of -10 °C and the highest mass specific rate of 2.61 (mol CO) h^-1 (g Pt)^-1. From in situ X-ray absorption fine structure and diffuse reflectance infrared Fourier-transform spectroscopy studies, the superior catalytic performance of Pt₁Co_0.5/Al₂O₃ originates from the optimal length of the three-dimensional alloy-oxide perimeter sites. We further extended this strategy to other bimetallic systems of Pt-Fe and Pt-Ni, which also show similar structural properties and remarkable promotional effects on the catalytic activity.

Modeling surface spin polarization on ceria-supported Pt nanoparticles

In this work, we employ density functional theory simulations to investigate possible spin polarization of CeO₂-(111) surface and its impact on the interactions between a ceria support and Pt nanoparticles. With a Gaussian type orbital basis, our simulations suggest that the CeO₂-(111) surface exhibits a robust surface spin polarization due to the internal charge transfer between atomic Ce and O layers. In turn, it can lower the surface oxygen vacancy formation energy and enhance the oxide reducibility. We show that the inclusion of spin polarization can significantly reduce the major activation barrier in the proposed reaction pathway of CO oxidation on ceria-supported Pt nanoparticles. For metal-support interactions, surface spin polarization enhances the bonding between Pt nanoparticles and ceria surface oxygen, while CO adsorption on Pt nanoparticles weakens the interfacial interaction regardless of spin polarization. However, the stable surface spin polarization can only be found in the simulations based on the Gaussian type orbital basis. Given the potential importance in the design of future high-performance catalysts, our present study suggests a pressing need to examine the surface ferromagnetism of transition metal oxides in both experiment and theory.

Modulate the metal support interactions to optimize the surface-interface features of Pt/CeO2 catalysts for enhancing the toluene oxidation

Metal support interactions modulation is one of the effective strategies to enhance the catalytic performance. Herein, we reported that modulating metal support interactions by switching the strength (CO, H₂, NH₃) and temperature (200, 300, 400 °C) of reducing gases is a facile way to improve the catalytic performance of Pt/CeO₂ for toluene oxidation. The distinct reduction treatments will stepwise enhance the reducibility, ratio of Pt⁰ and oxygen vacancy concentration, which dominated the activity. The metal support interactions modulation can significantly affect toluene deep oxidation (from benzoate to formate or monodentate carbonate) via enhancing the mobility of surface/lattice oxygen and activation ability towards O₂ molecules, since the main activation sites for O₂ molecules expand from Pt⁰ sites to oxygen vacancies and Pt⁰ sites with temperature increasing.

Highly efficient Au/Fe2O3 for CO oxidation: The vital role of spongy Fe2O3 toward high catalytic activity and stability

Supported gold catalysts have drawn great attention for many decades due to their outstanding performance in remedying the environment from carbon monoxide (CO) pollution. In this study, due to the large surface area of spongy Fe₂O₃, fabricated by salt-assisted ultrasonic spray pyrolysis, a considerable amount of Au was loaded on spongy Fe₂O₃ compared to low-surface-area non-spongy Fe₂O₃. It is seen that the spongy Fe₂O₃ catalyst loaded with Au has an interface that can be extremely active for CO desorption and O₂ activation. That means it has high catalytic activity in CO oxidation than non-spongy and low surface area Fe₂O₃ loaded with Au. Also, the incorporation of Au in low alkaline condition further enhances the interaction between Au and Fe₂O₃, providing more active sites. This made the catalyst to have better activity, good stability over 60 hrs, and there was no carbonate on its surface. It had full conversion at 30 °C on 120 L g^-1h^-1 with high TOF (2.2 s^-1).

Pt-Co nanoparticles supported on hollow multi-shelled CeO2 as a catalyst for highly efficient toluene oxidation: Morphology control and the role of bimetal synergism

A series of hollow multi-shelled CeO₂ (HoMS-CeO₂) support materials with tunable shell numbers were fabricated and applied to the catalytic oxidation of toluene. HoMS-CeO₂ possess much higher catalytic activity (T₉₀ = 236 ℃) than hollow CeO₂ with only a single shell (h-CeO₂) (T₉₀ = 275℃). The porous multiple-shelled structure has a higher S_BET, which strongly promotes gas distribution and provides more active sites. The superiority of this kind of structure was also verified by comparing h-Co₃O₄ and HoMS-Co₃O₄. Furthermore, Pt-Co bimetallic nanoparticles were loaded onto HoMS-CeO₂. The synergistic effect between Pt and Co was verified by XPS and O₂-TPD, which was observed to allow electron transfer between Pt and Co and thus regulate the electronic state of the Pt. Compared with Pt alone, Pt-Co bimetallic nanoparticles could stronglypromotethe activation of O₂and oxygen mobility, as revealed by a much higher O_ads content and a lower oxygen desorption temperature. Of the catalysts prepared in this study, the 1 wt% PtCo₃/CeO₂ catalyst was found to be the most suitable for toluene oxidation owing to its excellent activity (T₉₀ = 158 ℃), long-term stability, and water resistance. Finally, in situ DRIFTS was employed to investigate mechanism during toluene oxidation and the possible reaction pathway was proposed.

Tailoring the activity and selectivity of Rh/SiO2 in the selective hydrogenation of phenol by CoOx promotion

Although supported Rh nanoparticles (NPs) are one of the best catalysts for the selectivity hydrogenation of phenol to cyclohexanol, they still suffer from poor selectivity problems. In this study, we...

Mechanistic insights into CoOx–Ag/CeO2 catalysts for the aerobic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxylic acid

CoOx–Ag/CeO2 catalysts achieve satisfactory FDCA yield from HMF, and a fundamental understanding about the reaction mechanism is provided.

Boosting the catalytic performance of single-atom catalysts by tuning surface lattice expanding confinement

We report that Pt single atoms embedded on a disordered TiO2 surface have a weaker affinity for CO than those supported on a perfect TiO2 surface, thus generating much better CO oxidation activity.

Tuning Metal-Support Interaction of Pt-CeO2 Catalysts for Enhanced Oxidation Reactivity

Metal-support interaction (MSI) has been widely recognized to be playing a pivotal role in regulating the catalytic activity of various reactions. In this work, the degree of MSI between Pt and CeO₂ support was finely tuned by adjusting the activation condition, and the obtained catalysts were tested for the oxidative abatement of CO and HCHO under ambient conditions. The characterization of catalysts shows that activation of strongly interacting Pt-CeO₂ at higher temperatures by H₂ leads to a weaker MSI with increased electron density of Pt, and this modification of local electronic properties is demonstrated to result in enhanced O₂ adsorption/activation to prevent the CO self-poisoning effect, while it abates the activity of CO adsorption/activation and oxidation of adsorbed CO. The Pt-CeO₂ catalyst with a moderate MSI, which is able to balance each step in the catalytic cycle over Pt and Pt-CeO₂ interface domains, displays the highest activity for CO/HCHO oxidation under ambient conditions.

Highly dispersed Cr oxygenated species on Pt nanowire assemblies for enhanced electrocatalytic methanol oxidation

In this paper, Cr oxygenated species dispersed on Pt nanowire assemblies (PtCrO_X NWs) were successfully prepared for the methanol oxidation reaction by a metal precursor dilution strategy. Notably, the PtCrO_X NWs catalyst exhibits excellent performance for electrocatalytic methanol oxidation. Density functional theory results revealed that the doped Cr oxygenated species, which moderated the electronic structure of the Pt atoms, can significantly decrease the free energy of COOH* formation, thus leading to superior methanol oxidation performance.

Facilitating Catalytic Purification of Auto-Exhaust Carbon Particles via the Fe2O3{113} Facet-dependent Effect in Pt/Fe2O3 Catalysts

The purification efficiency of auto-exhaust carbon particles in the catalytic aftertreatment system of vehicle exhaust is strongly dependent on the interface nanostructure between the noble metal component and oxide supports. Herein, we have elaborately synthesized the catalysts (Pt/Fe₂O₃-R) of Pt nanoparticles decorated on the hexagonal bipyramid α-Fe₂O₃ nanocrystals with co-exposed twelve {113} and six {104} facets. The area ratios (R) of co-exposed {113} to {104} facets in α-Fe₂O₃ nanocrystals were adjusted by the fluoride ion concentration in the hydrothermal method. The strong Pt-Fe₂O₃{113} facet interaction boosts the formation of coordination unsaturated ferric sites for enhancing adsorption/activation of O₂ and NO. Pt/Fe₂O₃-R catalysts exhibited the Fe₂O₃{113} facet-dependent performance during catalytic purification of soot particles in the presence of H₂O. Among the catalysts, the Pt/Fe₂O₃-19 catalyst exhibits the highest catalytic activities (T₅₀ = 365 °C, TOF = 0.13 h^-1), the lowest apparent activation energy (69 kJ mol^-1), and excellent catalytic stability during soot purification. Combined with the results of characterizations and density functional theory calculations, the catalytic mechanism is proposed: the active sites located at the Pt-Fe₂O₃{113} interface can boost the key step of NO oxidation to NO₂. The crystal facet engineering is an effective strategy to obtain efficient catalysts for soot purification in practical applications.

Hollow and mesoporous aluminosilica-encapsulated Pt-CoOx for the selective hydrogenation of substituted nitroaromatics

Hollow and mesoporous aluminosilica nanoreactors (HMANs) with Pt-CoO_x cores (∼4.7 nm) and hollow aluminosilica shells (∼50 nm) were designed by a selective etching method. The Pt-CoO_x@HMANs demonstrate a greatly enhanced activity and selectivity for the hydrogenation of various substituted nitroaromatics compared to Pt@HMANs and Pt-CoO_x@SiO₂.

Potassium-incorporated manganese oxide enhances the activity and durability of platinum catalysts for low-temperature CO oxidation

Potassium-incorporated manganese oxide is demonstrated as an efficient support for fabricating highly active and stable Pt catalysts for low-temperature CO oxidation.

Enhanced strong metal–support interactions between Pt and WO3–x nanowires for the selective hydrogenation of p-chloronitrobenzene

Pt/WO3–x nanocatalysts demonstrate significantly enhanced catalytic performance due to the strong interaction between Pt and WO3–x nanowires.

Efficient and stable low-temperature CO oxidation over Pt/In–SnO2 composite triggered by abundant oxygen vacancies and adsorption sites

In ion doping can greatly improve the active oxygen migration ability in the Pt/In–SnO₂ catalyst, which is beneficial to CO oxidation at low temperature.

Topological transformation of LDH nanosheets to highly dispersed PtNiFe nanoalloys enhancing CO oxidation performance

Highly dispersed nanoalloys with a tailored metal-oxide interface are pivotal in developing advanced catalysts with superior performance for applications. Herein, a series of highly dispersed Pt/NiFeAl nanoalloys on amorphous supports were successfully fabricated by a topological transformation of layered-double-hydroxide nanosheets. With increasing reduction temperature, samples Pt/NiFeAl-x (x = reduction temperature) showed a progressive transformation from Pt/NiFeAl-LDH to a mixture (Pt, NiFe alloys, FeOy, and NiOy) supported on amorphous Al2O3, which eventually transformed to atomically dispersed PtNiFe alloys supported on amorphous Al2O3. Systematic sample characterization demonstrates that amorphous alumina-supported PtNiFe nanoalloys are merited by excellent redox ability, outstanding O2 activation ability, and moderate CO adsorption strength. When tested as catalysts for CO oxidation, all samples have demonstrated an apparent interfacial effect on catalytic performance, among which Pt/NiFeAl-600 shows a strikingly high CO oxidation activity at low-temperatures coupled with a broader operation temperature window (i.e. CO conversion >99.0%, 100-400 °C). Such a topological transformation strategy has proven applicable for generating atomically dispersed nanoalloys on amorphous supports for catalytic applications.

Synergism of Iron and Platinum Species for Low-Temperature CO Oxidation: From Two-Dimensional Surface to Nanoparticle and Single-Atom Catalysts

CO oxidation is one of the most studied reactions in heterogeneous catalysis. It is present in air cleaning and automotive emission control. It also participates in the removal of CO from streams of hydrogen used in fuel cells. Because of the competitive adsorption of CO and O₂ over active sites, the use of Pt-based catalysts for low-temperature CO oxidation remains a challenge. Recently, great progress has been made with catalysts containing Pt-Fe species because of the contribution of Fe species to O₂ activation. The structure-activity relationship and reaction mechanisms have been investigated with various Pt-Fe catalysts. In this Perspective, we give a summary of the recent advances of low-temperature CO oxidation over Pt-Fe catalysts with a focus on the synergistic effect of Pt and Fe species in the CO and O₂ activation of catalytic reactions. Future prospects for the preparation of highly effective Pt-Fe catalysts are also proposed.

Oxygen mobility and microstructure properties-redox performance relationship of Rh/(Ce,Zr,La)O2 catalysts

Rh/(Ce,Zr,La)O₂ (CZL) catalysts with different Ce/Zr molar ratios of 1:0, 8:1, 4:1, 2:1, 1:1, 1:2, 1:4, 1:8 and 0:1 were prepared. The relationship of microstructure, dynamic oxygen mobility and the redox properties with catalytic activity for HC, CO and NO_x eliminations were investigated. The results demonstrate that CZL mixed oxide with Ce/Zr ratio of 1:1 exhibits the largest OSC values as 904.3 umol·g^-1 and structural defects. The increase of oxygen vacancies and structural defects would promote the interaction between Rh species and CZL mixed oxides, which further promotes the stabilization of RhO_x particles and enhances the oxygen storage/release ability. Rh/CZLx catalysts with Ce/Zr molar ratio of 1:1-1:4 exhibit better catalytic activity and wider dynamic operation window due to their higher DOSC.

The highly efficient and selective dicarbonylation of acetylene catalysed by palladium nanosheets supported on activated carbon

An ultrathin Pd nanosheet-supported heterogeneous catalyst, Pd_CO/AC, with exposed (111) crystal plane was synthesized, and it shows superior catalytic reactivity (∼43.8%) and selectivity (∼99.0%) for the dicarbonylation of acetylene and CO.

Strong metal–support interactions between palladium nanoclusters and hematite toward enhanced acetylene dicarbonylation at low temperature

A four-fold increase in palladium-based acetylene dicarbonylation activity was obtained at low temperature due to the strong metal–support interaction between Pd and the earth-abundant α-Fe₂O₃ material.

Novel metallic electrically heated monolithic catalysts towards VOC combustion

Metallic electrically heated monolithic catalysts with dual-function, high activity, fast response, small volume, changeable shape and energy conservation properties.