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Improving the low‐temperature water‐resistance of methane combustion catalysts is of importance for industrial applications and it is challenging. A stepwise strategy is presented for the preparation of atomically dispersed tungsten species at the catalytically active site (Pd nanoparticles). After an activation process, a Pd−O−W1‐like nanocompound is formed on the PdO surface with an atomic scale interface. The resulting supported catalyst has much better water resistance than the conventional catalysts for methane combustion. The integrated characterization results confirm that catalytic combustion of methane involves water, proceeding via a hydroperoxyl‐promoted reaction mechanism on the catalyst surface. The results of density functional theory calculations indicate an upshift of the d‐band center of palladium caused by electron transfer from atomically dispersed tungsten, which greatly facilitates the adsorption and activation of oxygen on the catalyst. [ABSTRACT FROM AUTHOR]

Improving the low‐temperature water‐resistance of methane combustion catalysts is of importance for industrial applications and it is challenging. A stepwise strategy is presented for the preparation of atomically dispersed tungsten species at the catalytically active site (Pd nanoparticles). After an activation process, a Pd−O−W1‐like nanocompound is formed on the PdO surface with an atomic scale interface. The resulting supported catalyst has much better water resistance than the conventional catalysts for methane combustion. The integrated characterization results confirm that catalytic combustion of methane involves water, proceeding via a hydroperoxyl‐promoted reaction mechanism on the catalyst surface. The results of density functional theory calculations indicate an upshift of the d‐band center of palladium caused by electron transfer from atomically dispersed tungsten, which greatly facilitates the adsorption and activation of oxygen on the catalyst. [ABSTRACT FROM AUTHOR]

Ethylene elimination can effectively inhibit the rapid aging of fruits and vegetables in storage and transportation. Improving the low-temperature activity, moisture resistance, and stability of Pt based catalysts is a challenge for catalytic oxidation of ethylene which is an effective elimination method. Herein, we constructed ultrasmall MnO x cluster (< 1 nm) on Pt particles via an alloy in situ transformation strategy, which created a large number of MnO x /Pt interfaces. Among all of the samples, 1.89Pt 2.20 Mn/TiO 2 showed the highest catalytic activity in the oxidation of ethylene at a space velocity of 20,000 mL/(g h): T 50% = 34 oC and T 90% = 43 oC, specific reaction rate at 35 oC = 33.0 µmol/(g Pt s), and turnover frequency at 35 oC = 6.5 × 10–3 s−1. In addition, Pt 2.20 Mn/TiO 2 also exhibited better water resistance and stability than Pt/TiO 2. The results of XPS, H 2 O-TPD, C 2 H 4 -TPD, in situ DRIFTS, and H 2 18O isotopic tracing characterization revealed that the MnO x /Pt interfacial sites accelerated desorption of CO 2 and enhanced the activation of surface active oxygen species (O 2 to O 2 2−). Meanwhile, the numerous interfaces provide more active sites for ethylene adsorption and activation, reducing the inhibitory effect of adsorbed water on ethylene adsorption. It was concluded that the prohibited CO 2 adsorption, and increased adsorbed oxygen species were responsible for the excellent catalytic performance and good stability of 1.89Pt 2.20 Mn/TiO 2 , while the more active sites for ethylene adsorption and activation were responsible for the good water resistance of 1.89Pt 2.20 Mn/TiO 2. [Display omitted] • The ultrasmall MnO x clusters (∼1 nm) are constructed on Pt particles by the alloy in situ transformation strategy. • Pt 2.20 Mn/TiO 2 shows the highest catalytic activity, eliminate ethylene at room temperature. • Pt 2.20 Mn/TiO 2 exhibits better water resistance and stability than Pt/TiO 2. • Prohibited CO 2 adsorption, increased active sites, and active oxygen species govern ethylene oxidation. • The introduced H 2 18O and oxygen undergo synergistic activation and participate in the oxidation of ethylene. [ABSTRACT FROM AUTHOR]

Catalytic combustion of methane is widely used in industrial and transportation activities. The commonly used Pd‐based catalysts, however, are easily deactivated under hydrothermal conditions. In this work, we adopted a novel strategy to prepare a GaOx‐doped Pd/Al2O3 catalyst via the oxidative transformation of intermetallic Pd5Ga3 nanocrystals supported on γ‐Al2O3. We observed a synergistic effect between palladium and gallium oxide via formation of a bi‐functional active Pd−O−Ga phase, resulting in a highly active and exceptionally stable catalyst that could markedly suppress the sintering of noble metals under harsh conditions (hydrothermal treatment at 750 °C). Moreover, the presence of a large amount of surface oxygen vacancies and the surface Pd−O−Ga phase could promote methane combustion over the catalysts. It is believed that such a novel dual‐metal catalyst is promising in practical applications for methane combustion. Effective synergy: The Pd−GaOx/Al2O3 catalysts are prepared via the oxidative transformation of intermetallic Pd5Ga3 nanocrystals supported on Al2O3. A synergistic effect between palladium and gallium oxide via formation of a bi‐functional active Pd−O−Ga phase is observed, resulting in a highly active and exceptionally stable catalyst that can markedly suppress the sintering of noble metals under harsh conditions. Surface oxygen vacancies and the surface Pd−O−Ga phase are the catalytically active sites. [ABSTRACT FROM AUTHOR]

The Pd Co single-atom catalyst is prepared via a novel strategy. The double effects of the palladium and cobalt oxide result in an enhanced performance for benzene oxidation. The catalyst also possesses enhanced sulfur resistance performance. The good regeneration ability of the active sites in the catalyst can be explained by the single-atom dispersion of Pd and Co. • The Pd and Co single atoms are highly dispersed on γ-Al 2 O 3. • The Pd-Co single atoms catalyst exhibits a good catalytic activity for benzene oxidation. • The supported single atom catalyst can significantly decrease the inhibitory effect of SO 2 for benzene oxidation. • VOCs activation on the PdO–CoO x interfaces is a beneficial factor in the oxidative removal of VOCs. • The reaction pathway of benzene oxidation on the single atom catalyst is well explored. Catalytic oxidation is one of the effective pathways for completely eliminating volatile organic compounds (VOCs) emitted from industrial and transportation activities. Meanwhile, single-atom catalysts have excellent application prospects in numerous reactions due to their high metal atomic utilization efficiency. In this work, we adopted a novel strategy to prepare an active Pd/Co single-atom catalyst (i.e., Pd 1 Co 1 /Al 2 O 3) for benzene oxidation. The successful formation of the atomically dispersed palladium and cobalt species on Al 2 O 3 was verified by the aberration-corrected high-angle annular dark-field scanning transmission electron microscopy and X-ray absorption fine structure. By the in situ temperature-programmed techniques and in situ diffuse reflectance Fourier transform infrared spectroscopy, we observed a double effect of the palladium and cobalt oxide active sites, resulting in an enhanced performance for benzene oxidation. A benzene conversion of 90 % was achieved over the Pd 1 Co 1 /Al 2 O 3 catalyst at 250 °C and a space velocity of 40,000 mL/(g h). Interestingly, the catalyst also possessed enhanced sulfur resistance performance. The good regeneration ability of the active sites in the catalyst was due to the single-atom dispersion of Pd and Co. In addition, we deduce that benzene oxidation might occur over Pd 1 Co 1 /Al 2 O 3 via a pathway of benzene → cyclohexadiene → phenol → quinone → maleate → acetate → CO 2 and H 2 O. We believe that the obtained results can provide a useful idea for rationally designing the double active site single-atom catalysts and understanding the mechanism of VOCs oxidation. [ABSTRACT FROM AUTHOR]

The painting and electronics industries simultaneously release aromatic compounds and chlorinated organics. The development of catalysts with synergistic control of these pollutants is of great significance to achieve air purification. However, developing active catalysts while maintaining good chlorine resistance remain a huge challenge due to the difficulty of the trade-off between the redox properties and acidity and the production of polychlorinated byproducts. Herein, we introduce a novel tandem PtSn/CeO 2 &Mn/ZSM-5 catalyst and investigate its catalytic performance for multicomponent volatile organic compounds (VOCs) oxidation. The two individual catalysts, PtSn/CeO 2 and Mn/ZSM-5, were used to catalyze two distinct sequential reactions. PtSn/CeO 2 catalyzed toluene oxidation to produce CO 2 and H 2 O. Meanwhile, the introduction of SnO x favored the adsorption of trichloroethylene (TCE) molecules that prevented Pt sites from chlorine poisoning and possibly converted adsorbed TCE into intermediates, which were subsequently oxidized deeply by the nearby Mn/ZSM-5. This approach resulted in a remarkable oxidation efficiency for toluene (T 90 = 296 °C) and TCE (T 90 = 384 °C), with fewer unexpected toxic byproducts (chlorobenzene and 4-chlorotoluene). Furthermore, the tandem catalyst possessed excellent chlorine and water resistances. In conclusion, the above findings provide new insights into the design and/or syntheses of advanced catalysts for widespread VOCs pollution control. [Display omitted] • The novel tandem catalyst (PtSn/CeO 2 &Mn/ZSM-5) with separated catalytic active sites are prepared. • The tandem catalyst shows good catalytic activities for toluene and trichloroethylene oxidation. • The chlorine-containing toxic by-products can be effectively inhibited to form over the tandem catalyst. • There is no visible change in catalytic performance of the tandem catalyst after the introduction of H 2 O. [ABSTRACT FROM AUTHOR]

The emission of methane leads to the increase in the methane concentration in the atmosphere, which not only wastes resources but also intensifies the greenhouse effect and brings about serious environmental problems. Catalytic combustion can completely convert methane into carbon dioxide and water at low temperatures. However, the catalytic activities of the conventional supported palladium catalysts (e.g., Pd/Al2O3 and Pd/ZrO2) are easy to decrease or the two catalysts can even be deactivated under actual harsh reaction conditions (high temperatures, steam- and sulfur dioxide-containing atmospheres, etc.). Recently, noble metal catalysts supported on zeolites with ordered pores and good thermal stability have attracted much attention. This review article summarizes the recent progress on the development and characteristics of zeolite-supported noble metal catalysts for the combustion of methane. The effects of framework structures, silica/alumina ratios, acidity, doping of alkali metals or transition metals, particle sizes and distributions, and their locations of/in the zeolites on methane combustion activity are discussed. The importance of developing high-performance catalysts under realistic operation conditions is highlighted. In addition, the related research work on catalytic methane combustion in the future is also envisioned. [ABSTRACT FROM AUTHOR]

1 ​wt% Ru/5 ​wt% Nb 2 O 5 /CeO 2 (RuNbCe) catalyst was synthesized via the incipient wetness impregnation method, and measured for the catalytic oxidation of dichloromethane (DCM). The physicochemical properties of catalysts were determined used various characterization techniques. Compared with 1 ​wt% Ru/CeO 2 , 5 ​wt% Nb 2 O 5 /CeO 2 , CeO 2 , 1 ​wt% Ru/ x Nb 2 O 5 /CeO 2 (x ​= ​1 ​wt%, 2 ​wt%, and 3 ​wt%) and 1 ​wt% Ru/ yM O n /CeO 2 (M ​= ​Co, Cr, Fe, Mg, Cu; y ​= ​5 ​wt%), the addition of 5 ​wt% Nb 2 O 5 obviously improved the catalytic performance of 1 ​wt% Ru/CeO 2 , with the T 90% and apparent activation energy (E a) being 287 oC and 43.5 ​kJ/mol, respectively, and less formation of polychlorinated byproducts at space velocity (SV) ​= ​15,000 ​mL ​g‒1 ​h‒1. The RuNbCe catalyst showed good thermal and hydrothermal stability, as well as HCl-resistance performance. We deduced that the higher oxidation performance of the RuNbCe catalyst may be attributed to the suitable acidic sites, good redox capacity, high surface adsorbed oxygen species concentration, and the strong interaction among Ru, Nb 2 O 5 and CeO 2. The RuNbCe catalyst has the potential to be applied for the elimination of chlorinated volatile organic compounds (CVOCs). [Display omitted] • Ru/Nb 2 O 5 /CeO 2 catalyst is prepared by an incipient wetness impregnation method. • Ru/Nb 2 O 5 /CeO 2 exhibits high catalytic activity for dichloromethane removal. • Ru/Nb 2 O 5 /CeO 2 shows high (hydro-)thermal stability and HCl-resistance. • High performance relates to acidity, redox capacity, O ads , and strong interaction. [ABSTRACT FROM AUTHOR]

Perovskite-type oxides, due to their structural stability and special physical and chemical properties, have become important topics in the field of catalytic materials research. This article focuses on the effect of γ-ray irradiation on the catalytic activity of LaCoO 3 and BaPbO 3. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction (TPR) were used to analyze the physical and chemical properties of LaCoO 3 and BaPbO 3. Finally, H 2 O 2 catalytic decomposition and toluene catalytic combustion experiments were performed to verify the activity of LaCoO 3 and BaPbO 3 before and after irradiation. The results show that after γ-ray irradiation, the activity of LaCoO 3 and BaPbO 3 on catalytic hydrogen peroxide decomposition was reduced, and the activity of catalytic toluene combustion was enhanced. • The effects of different radiation dose on lattice oxygen in LaCoO 3 and BaPbO 3 were analyzed by XPS. • The effects of different radiation dose on the oxidative capacity of LaCoO 3 and BaPbO 3 were analyzed by TPR. • It was found that γ-ray irradiation enhance the catalytic activity of LaCoO 3 and BaPbO 3 in toluene combustion. [ABSTRACT FROM AUTHOR]

Pt nanoparticles and a CeMnOx composite were loaded on the surface of the natural diatomite material to generate the Pt/CeMnOx/diatomite using the redox precipitation and impregnation methods. The physicochemical properties of the catalysts were characterized by means of various techniques. The catalytic properties and resistance to H2O and SO2 of the catalysts were measured for the oxidation of typical volatile organic compounds (i.e., toluene and ethyl acetate). Among all of the as-prepared samples, Pt/CeMnOx/diatomite exhibited the highest catalytic activity: the temperatures (T90%) at a toluene or ethyl acetate conversion of 90% were 230 and 210 °C at a space velocity (SV) of 20,000 mL g−1 h−1, respectively, and the turnover frequency (TOFPt) at 220 °C was 1.04 μmol/(gcat s) for ethyl acetate oxidation and 1.56 μmol/(gcat s) for toluene oxidation. In particular, this sample showed a superior catalytic activity for ethyl acetate oxidation at low temperatures, with its T50% being 185 °C at SV = 20,000 mL g−1 h−1. In addition, the Pt/CeMnOx/diatomite sample possessed good sulfur dioxide resistance during the toluene oxidation process. In the presence of SO2, some of the SO2 molecules were adsorbed on diatomite, which protected the active sites from being poisoned by SO2 to a certain extent. The pathways of ethyl acetate and toluene oxidation over Pt/CeMnOx/diatomite or Pt/CeMnOx were as follows: The C–C and C–O bonds in ethyl acetate are first broken to form the CH3CH2O* and CH3CO* species or toluene is first oxidized to benzaldehyde and benzoic acid, and all of these intermediates are then converted to CO2 and H2O. This work can provide a strategy to develop efficient catalysts with high catalytic activity, durability, low cost, and easy availability under actual working conditions. [ABSTRACT FROM AUTHOR]

The development of efficient and stable catalysts is of great importance for the elimination of volatile organic pollutants (VOCs). In this work, AuPdx nanoparticles (NPs) were loaded on TiO2 through the electrostatic adsorption approach to generate the yAuPdx/TiO2 (i.e., 0.35AuPd0.46/TiO2, 0.34AuPd2.09/TiO2, and 0.37AuPd2.72/TiO2; x and y are Pd/Au molar ratio and AuPdx loading, respectively; x = 0.46–2.72; and y = 0.34–0.37 wt%) catalysts, and their catalytic activities for the oxidation of ethyl acetate were determined. The results showed that the 0.37AuPd2.72/TiO2 sample exhibited the best activity (T50% = 217 °C and T90% = 239 °C at SV = 40,000 mL/(g h), Ea = 37 kJ/mol, specific reaction rate at 220 °C = 113.8 µmol/(gPd s), and turnover frequency (TOFNoble metal) at 220 °C = 109.7 × 10−3 s−1). The high catalytic performance of the 0.37AuPd2.72/TiO2 sample was attributed to the good dispersion of AuPd2.72 NPs, the strong redox ability, the large ethyl acetate adsorption capacity, and the strong interaction between AuPdx and TiO2. Acetaldehyde, ethanol, and acetic acid are the main intermediates in the oxidation of ethyl acetate, and the loading of AuPdx NPs effectively reduces the formation of the toxic by-product acetaldehyde. The oxidation of ethyl acetate over the 0.34AuPd2.09/TiO2 sample might occur via the pathway of ethyl acetate → ethanol → acetic acid → acetate → CO2 and H2O. We believe that the obtained results may provide a useful idea for the design of bimetallic catalysts under industrial conditions and for understanding the VOCs oxidation mechanisms. [ABSTRACT FROM AUTHOR]

Due to the expensive price and the low reserve of noble metals in nature, much attention has been paid to single-atom catalysts (SACs)—especially single-atom noble metal catalysts—owing to their maximum atomic utilization and dispersion. The emergence of SACs greatly decreases the amount of precious metals, improves the catalytic activity, and makes the catalytic process progressively economic and sustainable. However, the most remarkable challenge is the active sites and their stability against migration and aggregation under practical conditions. This review article summarizes the preparation strategies of SACs and their catalytic applications for the oxidation of methane, carbon monoxide, and volatile organic compounds (VOCs) and the reduction of nitrogen oxides. Furthermore, the perspectives and challenges of SACs in future research and practical applications are proposed. It is envisioned that the results summarized in this review will stimulate the interest of more researchers in developing SACs that are effective in catalyzing the reactions related to the environmental pollution control. [ABSTRACT FROM AUTHOR]

Three-dimensionally ordered macroporous (3DOM) Ce 0.7 Zr 0.3 O 2 -supported Pd (x Pd/3DOM Ce 0.7 Zr 0.3 O 2 , x = 0.97, 1.49, and 2.10 wt%) catalysts were fabricated using the polymethyl methacrylate (PMMA) microsphere-templating and polyvinyl alcohol (PVA)-protected reduction methods. It was found that the x Pd/3DOM Ce 0.7 Zr 0.3 O 2 samples with surface areas of 31.9−38.2 m2/g possessed a high-quality 3DOM architecture, with the Pd nanoparticles (NPs) being uniformly dispersed on the 3DOM Ce 0.7 Zr 0.3 O 2 surface. Among all of the samples, 1.49 Pd/3DOM Ce 0.7 Zr 0.3 O 2 showed the best CH 4 combustion activity: The T 10% , T 50% , and T 90% (the temperatures at CH 4 conversions = 10, 50, and 90%) were 269, 330, and 380 °C, respectively; specific reaction rate at 260 °C was 115.0 × 10−6 mol/(g Pd s), and turnover frequency at 260 °C (TOF Pd) was 28.8 × 10−3 s−1. The good catalytic performance of 1.49 Pd/3DOM Ce 0.7 Zr 0.3 O 2 was associated with the well-defined 3DOM structure, high Pd NP dispersion, rich adsorbed oxygen species, and strong interaction between Pd NPs and 3DOM Ce 0.7 Zr 0.3 O 2. Interestingly, the 1.49 Pd/3DOM Ce 0.7 Zr 0.3 O 2 sample also exhibited superior water-tolerant performance. The product analysis results after the in situ introduction of isotopic water demonstrated that the excellent water resistance of 1.49 Pd/3DOM Ce 0.7 Zr 0.3 O 2 was due to the interaction of oxygen and water to form the peroxy hydroxyl species on the sample surface after the water pretreatment, which was beneficial for the combustion of methane. [Display omitted] • x Pd/3DOM Ce 0.7 Zr 0.3 O 2 are prepared by PMMA-templating and PVA-protected reduction methods. • 1.49 Pd/3DOM Ce 0.7 Zr 0.3 O 2 performs the best in CH 4 combustion among x Pd/3DOM Ce 0.7 Zr 0.3 O 2. • A peroxy hydroxyl species is formed on 1.49 Pd/3DOM Ce 0.7 Zr 0.3 O 2 after O 2 and H 2 O treatment. • 1.49 Pd/3DOM Ce 0.7 Zr 0.3 O 2 possesses excellent water resistance in CH 4 combustion. [ABSTRACT FROM AUTHOR]

Chlorinated volatile organic compounds (CVOCs), even in small quantities, can cause Pt-based catalyst poisoning. Improving the low-temperature chlorine resistance of catalysts is of vital importance for industrial application, although it remains challenging. Considering actual industrial production, a TiO2-supported ternary metal catalyst was prepared in this work to study the catalytic oxidation of multicomponent VOCs (toluene and trichloroethylene (TCE)). Among all of the samples, PtWRu/TiO2 and PtWCr/TiO2 exhibited the best catalytic performance for toluene oxidation. In the mixed VOC oxidation, the PtWCr/TiO2 sample showed the best catalytic activity for toluene combustion (a toluene conversion of 90% was achieved at 258 °C and a space velocity of 40,000 mL g−1 h−1, and the specific reaction rate and turnover frequency at 215 °C were 44.9 × 10−6 mol gPt−1 s−1 and 26.2 × 10−5 s−1). The PtWRu/TiO2 sample showed the best catalytic activity for TCE combustion (a TCE conversion of 90% was achieved at 305 °C and a space velocity of 40,000 mL g−1 h−1, and the specific reaction rate and turnover frequency at 270 °C were 9.0 × 10−6 mol gPt−1 s−1 and 7.3 × 10–5 s−1). We concluded that the ternary metal catalysts could greatly improve chlorine desorption by increasing the active lattice oxygen mobility and surface acidity, thus reducing chlorinated byproducts and other serious environmental pollutants. This work may serve as a reasonable design reference for solving more practical industrial production emissions of multicomponent VOCs. [ABSTRACT FROM AUTHOR]

The results of experimental and DFT investigations reveal that among the Au x Mn y /meso-Fe 2 O 3 catalysts, Au 5 Mn 2 /meso-Fe 2 O 3 performs the best in benzene oxidation, which is related to its well dispersed Au 5 Mn 2 NPs, high O ads species concentration, good low-temperature reducibility, high benzene adsorption capacity, and strong benzene adsorption. [Display omitted] • Au x Mn y intermetallic compounds are synthesized using the oil-phase reduction strategy. • The Au x Mn y /meso-Fe 2 O 3 catalysts are prepared via an impregnation route. • Experimental and DFT investigations are made for typical aromatics oxidation over AuMn/meso-Fe 2 O 3. • The Au 5 Mn 2 /meso-Fe 2 O 3 catalyst performs the best in benzene oxidation. • Strong benzene adsorption on the Au surface is in the form of a π bond. Aromatic volatile organic compounds (VOCs) are usually pollutants to the atmosphere environment and human health. In the present work, we first adopted the co-reduction and KIT-6-templating strategies to prepare the Au x Mn y intermetallic compounds and mesoporous iron oxide (meso-Fe 2 O 3), respectively, and then used the impregnation method to generate the Au x Mn y /meso-Fe 2 O 3 catalysts. Catalytic performance of these materials was evaluated for benzene, toluene or o -xylene (typical aromatics) oxidation. It is found that the Au 5 Mn 2 /meso-Fe 2 O 3 catalyst exhibited the best activity: the temperatures at benzene conversions of 50 and 90 % were 237 and 254 °C at a space velocity of 20,000 mL/(g h), with the TOF Au values and specific reaction rates at 210 and 230 °C being 1.08 and 2.29 s−1, and 6.92 and 11.58 mmol/(g Au s), respectively. Such excellent performance of Au 5 Mn 2 /meso-Fe 2 O 3 was related to its well dispersed Au 5 Mn 2 nanoparticles, high adsorbed oxygen species concentration, good low-temperature reducibility, high benzene adsorption capacity, and strong benzene adsorption. The benzene chemisorption mechanism and adsorbed oxygen species could greatly influence the oxidation of benzene. According to the first-principles calculations, we find that benzene adsorption on the surface of Au in Au 5 Mn 2 /meso-Fe 2 O 3 was in the form of a π bond, in which the Au could obtain electrons from benzene ring in the presence of benzene adsorption, resulting in a stronger adsorption of benzene and thus increasing the catalytic activity for benzene oxidation. The mechanism of benzene oxidation might take place via the route of benzene → phenol → benzoquinone → maleate (acetate) → carbon dioxide and water. [ABSTRACT FROM AUTHOR]

Ir and IrFe x nanocrystals (NCs) are first synthesized using the butyllithium reduction method, and the 0.53−0.89IrFe x /meso-CeO 2 catalysts are then prepared via an adsorption route. The good catalytic performance of 0.59IrFe 0.90 /meso-CeO 2 is associated with its well dispersed IrFe 0.90 NCs, high adsorbed oxygen and acetylene concentrations, low-temperature reducibility, and strong interaction between IrFe 0.90 NCs and meso-CeO 2. [Display omitted] • IrFe x bimetallic nanocrystals are fabricated via the n -butyllithium reduction route. • IrFe x /meso-CeO 2 is prepared using the adsorption of IrFe x on meso-CeO 2. • 0.59IrFe 0.90 /meso-CeO 2 performs the best for acetylene combustion. • 0.59IrFe 0.90 /meso-CeO 2 exhibits good H 2 O-, CO 2 -, and SO 2 -resistant performance. • IrFe x dispersion, reactant adsorption, reducibility, and metal–support interaction govern catalytic activity. Bimetallic compounds are a kind of important catalytic materials in heterogeneous catalysis. In this work, we first employed n -butyllithium as reducing agent to synthesize Ir and IrFe x (x is the Fe/Ir molar ratio and equal to 0.49, 0.90, and 2.80) nanocrystals (NCs), and then used an adsorption strategy to load them on the surface of ordered mesoporous ceria (meso-CeO 2) derived from the KIT-6-templating route to obtain the 0.48 wt% Ir/meso-CeO 2 (denoted as 0.48Ir/meso-CeO 2) and 0.53–0.89 wt% IrFe x /meso-CeO 2 (denoted as 0.53IrFe 0.49 /meso-CeO 2 , 0.59IrFe 0.90 /meso-CeO 2 , and 0.89IrFe 2.80 /meso-CeO 2) samples. Physicochemical properties of the samples were characterized by means of various techniques. It is shown that all of the samples possessed a cubic crystal phase, an ordered mesoporous architecture, and a surface area of 84–124 m2/g, in which the IrFe x NCs with an average size of ca. 2 nm were highly dispersed on the meso-CeO 2 surface. Among all of the samples, 0.59IrFe 0.90 /meso-CeO 2 performed the best for acetylene combustion (T 10% =155 °C, T 50% =162 °C, and T 90% =165 °C at space velocity = 20,000 mL/(g h)). Furthermore, 0.59IrFe 0.90 /meso-CeO 2 showed good water- and carbon dioxide-resistant performance, and its partial deactivation due to the introduction of SO 2 was reversible. The possible reaction mechanisms over Ir/meso-CeO 2 or IrFe x /meso-CeO 2 were also discussed. We conclude that the well dispersed IrFe 0.90 NCs, high adsorbed oxygen and acetylene amounts, low-temperature reducibility, and strong interaction between IrFe 0.90 NCs and meso-CeO 2 were responsible for the good catalytic performance of 0.59IrFe 0.90 /meso-CeO 2. [ABSTRACT FROM AUTHOR]

x AuPd z / y Co 3 O 4 /3DOM MnCo 2 O 4 (x = 0.56–1.98 wt%, z = 1.9–2.1, and y = 4.80–24.36 wt%) samples are prepared using PMMA-templating, incipient wetness impregnation, and PVA-protected reduction methods. The good performance for methane combustion of 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 is related to its high O ads species concentration, good low-temperature reducibility, and strong interaction between Co 3 O 4 or AuPd 2.1 NPs and 3DOM MnCo 2 O 4. [Display omitted] • 3DOM MnCo 2 O 4 is fabricated using the PMMA-templating method. • 18.20Co 3 O 4 /3DOM MnCo 2 O 4 is obtained by the incipient wetness impregnation method. • 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 is prepared via the PVA-protected reduction route. • 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 perform the best for methane combustion. • O ads concentration, reducibility, and AuPd 2.1 or Co 3 O 4 and MnCo 2 O 4 interaction govern activity. Three-dimensionally ordered macroporous (3DOM) MnCo 2 O 4 -supported Co 3 O 4 and AuPd (x AuPd z / y Co 3 O 4 /3DOM MnCo 2 O 4 ; x = 0.56–1.98 wt%, z = 1.9–2.1, and y = 4.80–24.36 wt%) catalysts were prepared using polymethyl methacrylate (PMMA) microsphere-templating, incipient wetness impregnation, and polyvinyl alcohol (PVA)-protected reduction methods. Physicochemical properties of the materials were characterized by means of numerous techniques, and their catalytic activities were evaluated for methane combustion. It is found that the x AuPd z / y Co 3 O 4 /3DOM MnCo 2 O 4 samples with a surface area of 26.5–53.1 m2/g possessed a high-quality 3DOM architecture, in which the AuPd nanoparticles (NPs) with a size of 4.6–5.8 nm were highly dispersed on the surface of the macropore framework. Among all of the samples, 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 exhibited the highest catalytic activity: the T 10% , T 50% , and T 90% (temperatures required for achieving methane conversions of 10, 50, and 90 %, respectively) were 262, 340, and 408 °C at a space velocity of 40,000 mL/(g h). Partial deactivation of the 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 sample due to introduction of water vapor or carbon dioxide was reversible. It is concluded that the good catalytic performance of 1.98AuPd 2.1 /18.20Co 3 O 4 /3DOM MnCo 2 O 4 was associated with its high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Co 3 O 4 or AuPd 2.1 NPs and 3DOM MnCo 2 O 4. [ABSTRACT FROM AUTHOR]

The good catalytic activity, stability, and chlorine-resistance of 0.98 wt% Ru/3DOM SnO 2 for TCE oxidation is associated with its abundant hydroxyl groups adsorbed at oxygen vacancies, strong O 2 adsorption ability, good low-temperature reducibility, and strong interaction between Ru NPs and 3DOM SnO 2. CHCl 3 , CCl 4 , C 2 Cl 4 , and CCl 3 CH(OH) 2 are the main intermediates. [Display omitted] • Ru NPs with a size of 5.2–10.0 nm are dispersed on the surface of 3DOM SnO 2. • 0.98Ru/3DOM SnO 2 shows good catalytic activity, stability, and H 2 O-tolerant ability in trichloroethylene oxidation. • H 2 O addition produces the active HOO species, promotes chlorine species removal, and generates more HCl and less Cl 2. • CHCl 3 , CCl 4 , C 2 Cl 4 , and CCl 3 CH(OH) 2 are the main intermediates in TCE oxidation. • Toluene introduction decreases the catalytic activity of trichloroethylene oxidation. SnO 2 is widely used in catalysis owing to its oxygen vacancies, reducible oxygen species, and acidity. In this work, Ru nanoparticles (NPs) supported on three-dimensionally ordered macroporous (3DOM) SnO 2 (x Ru/3DOM SnO 2 , Ru loading (x) = 0.09–1.65 wt%) were fabricated via the polyvinyl alcohol-protected reduction routes, and their catalytic activities were determined for trichloroethylene (TCE) and/or toluene oxidation. It was shown that the 0.98Ru/3DOM SnO 2 sample exhibited the best activity and good thermal stability, with the temperature (T 90%) and apparent activation energy at a TCE (1000 ppmv) conversion of 90% being 300 °C and 44 kJ/mol at space velocity = 40,000 mL/(g h), respectively. Trichloromethane, carbon tetrachloride, tetrachloroethylene, and trichloroacetaldehyde hydrate were the main intermediates in TCE oxidation. The high catalytic performance of 0.98Ru/3DOM SnO 2 was attributed to the presence of hydroxyl groups adsorbed at the oxygen vacancies, strong O 2 adsorption ability, good low-temperature reducibility, and strong interaction between Ru NPs and 3DOM SnO 2. In addition, a catalytic mechanism over x Ru/3DOM SnO 2 was proposed under dry and humid conditions. The introduction of H 2 O could block some of the reaction pathways from inhibiting the production of C 2 Cl 4 , reduce formation of some by-products (e.g., CH 2 Cl 2 , CH 3 COOH, and C 2 H 2 Cl 2), promote removal of the chlorine species, and generate a greater amount of HCl and a smaller amount of Cl 2. Furthermore, introducing toluene into the TCE stream could generate smaller amounts of organic chlorine by-products and greater amounts of inorganic chlorine products (HCl and Cl 2). We are sure that this work can provide a guideline for the industrial application of supported Ru catalysts in the removal of Cl-containing volatile organic compounds. [ABSTRACT FROM AUTHOR]

The control of volatile organic compounds (VOCs) from cooking oil fumes via synergic photothermocatalytic oxidation not only saves energy, but also helps to reduce carbon emissions. Differences between the copper oxide−ceria (CC) supported atomically-dispersed (Pt 1 /CC) and particulate Pt (Pt NPs /CC) on photothermocatalytic heptane oxidation were investigated. The conversion efficiency at 170 oC of heptane oxidation over the Pt 1 /CC catalyst was 55% higher than that over the Pt NPs /CC catalyst. Pt NPs /CC showed a larger capacity of heptane adsorption, but limited amounts of the adsorbed oxygen and active surface lattice oxygen species were difficult to completely oxidize the over-adsorbed heptane. Heptane and its intermediates gradually accumulated at the active sites, resulting in poor catalytic activity and stability. However, Pt 1 /CC possessed a strong electron donating ability due to its unique coordination unsaturated sites and electron structure, which was conducive to oxygen activation. This allowed rapid conversion of heptane and intermediates, accelerating oxidation of the adsorbed heptane to CO 2 and H 2 O. The complete oxidation of 500 ppm heptane was basically achieved at 190 oC and an optical power density of 300 mW/cm2. [Display omitted] • Copper oxide−ceria (CC) supported atomically-dispersed (Pt 1 /CC) and particulate Pt (Pt NPs /CC) catalysts are prepared. • A synergistic photothermocatalytic oxidation method is proposed to eliminate typical VOCs from cooking oil fumes. • Pt 1 /CC outperforms Pt NPs /CC in the photothermocatalytic oxidation of heptane. • The difference in photothermocatalytic activity of Pt 1 /CC and Pt NPs /CC for VOCs oxidation is clarified. • The general pathways of photothermocatalytic heptane oxidation over the Pt 1 /CC catalyst is proposed. [ABSTRACT FROM AUTHOR]

The PtRu NPs partially embedded in the skeleton of 3DOM Ce 0.7 Zr 0.3 O 2 (CZO) are prepared using the PMMA-templating and EG reduction methods. The embedded structure facilitates formation of a more amount of Pt O Ce-like bonds via the strong interaction between PtRu NPs and 3DOM CZO, hence contributing to the good thermal stability in toluene combustion. • 1.98PtRu@3DOM CZO is prepared via the PMMA-templating and EG reduction routes. • PtRu nanoparticles (NPs) are partially embedded in the skeleton of 3DOM CZO. • Ru promotes enhancement in low-temperature reducibility and oxygen adsorption ability. • Good toluene and oxygen adsorption ability contribute to high activity of 1.98PtRu@3DOM CZO. • Formation of PtRu NPs–3DOM CZO interfaces and Pt O Ce-like bonds is responsible for good stability. We successfully prepared 1.98 wt% PtRu nanoparticles (NPs) partially embedded in the skeleton of three-dimensionally ordered macroporous Ce 0.7 Zr 0.3 O 2 (denoted as 1.98PtRu@3DOM CZO) using the polymethyl methacrylate-templating and ethylene glycol reduction methods. For comparison purposes, we also synthesized a 3DOM CZO-supported 2.03 wt% PtRu catalyst (denoted as 2.03PtRu/3DOM CZO) via a colloidal adsorption route. The 1.98PtRu@3DOM CZO sample exhibited better performance than the Pt or Ru NPs partially embedded in the skeleton of 3DOM CZO. Ru played an important role in promoting the low-temperature reducibility and oxygen adsorption ability of the sample. The catalytic activity of 2.03PtRu/3DOM CZO was better than that of 1.98PtRu@3DOM CZO (Δ T 90% = 23 °C) for toluene combustion, and the former showed lower apparent activation energy (45 kJ/mol). However, 1.98PtRu@3DOM CZO possessed excellent thermal stability, over which the activity did not change obviously, while that over 2.03PtRu/3DOM CZO decreased greatly; furthermore, the catalytic activity of the former was superior to that of the latter after calcination at 800 °C for 5 h. After high-temperature treatment, the average particle size of PtRu NPs in 1.98PtRu@3DOM CZO increased slightly from 4.2 to 6.7 nm, whereas that of PtRu NPs in 2.03PtRu/3DOM CZO increased significantly from 5.1 to 17.3 nm. It is concluded that the good performance of 1.98PtRu@3DOM CZO is associated with its highly dispersed partially embedded PtRu NPs and good toluene and oxygen adsorption ability, since the embedded structure facilitated formation of a larger amount of Pt O Ce-like bonds that possessed strong interaction between PtRu NPs and 3DOM CZO and hence contributed to its better thermal stability. [ABSTRACT FROM AUTHOR]

A novel nanocomposite containing CuAl-layered double hydroxide (CuAl-LDH) nanoflowers with ultrathin petals and cobalt tungstate nanostars (CuAl-LDH/CoWO4) was employed to devise a high-performance supercapacitor. In the proposed composite, a CoWO4 binary metal oxide was used to generate more electroactive sites, enhance the conductivity of the CuAl-LDH nanoflowers, and prevent their aggregation, therefore promoting the electrochemical activity of the resultant electrode. A three-electrode system was adopted to investigate the electrochemical performance of the nanocomposite and assess its potential for application as an electrode material in supercapacitor devices. The nanocomposite presented an outstanding specific capacitance at a current density of 5 A g−1 (i.e., 675 F g−1), exhibiting noticeable cycling stability over 5000 continuous cycles. Also, application of the nanocomposite in the fabrication of a two-electrode asymmetric supercapacitor provided 35.87 W h kg−1 maximum energy density, 10 188 W kg−1 power density and high cycling stability. So, the fabricated supercapacitor maintained 97.1% of its initial capacitance after 5000 cycles and powered a red light-emitting diode for a considerable period of time. Based on electrochemical measurements, it was found that the specific morphology of the CuAl-LDH/CoWO4 nanocomposite helps it to provide many ion/charge transportation paths, a high electrochemically active surface area and, therefore, a high level of supercapacitance. In general, the findings of this study show that the CuAl-LDH/CoWO4 nanocomposite is an appropriate electrode material for the practical storage of energy. [ABSTRACT FROM AUTHOR]

Among the single-atom catalysts (SACs), the bimetallic single-atom catalysts play an increasingly promising role in the oxidative removal of volatile organic compounds (VOCs) due to their high efficiency. However, it remains a significant challenge to resist SO 2 poisoning in industrial applications. In this work, we report (i) the synthesis of three-dimensionally ordered mesoporous Fe 2 O 3 -supported bimetallic AuPt single-atom (denote as Au 1 Pt 1 /meso-Fe 2 O 3) catalyst via a modified polyvinyl alcohol-protected reduction route; (ii) catalytic performance of the catalysts for methanol oxidation; and (iii) catalytic and SO 2 -resistant mechanism. It was found that compared with Pt 1 /meso-Fe 2 O 3 and Pt np /meso-Fe 2 O 3 , Au 1 Pt 1 /meso-Fe 2 O 3 exhibited better catalytic activity for methanol combustion, with the temperature at 90% methanol conversion, TOF noble metal at 120 °C, and apparent activation energy being 137 °C at a space velocity of 20 000 mL g–1 h–1, 6.51 × 10–2 s–1, and 36 kJ mol− 1, respectively. The enhanced activity was associated with the improved reducibility, methanol adsorption ability, and strong interaction between noble metal and support. The reaction pathway was deduced to follow a sequence of methanol → methoxy species → formaldehyde → formic acid → CO 2 and H 2 O. Furthermore, the order of SO 2 resistance was Au 1 Pt 1 /meso-Fe 2 O 3 > Pt 1 /meso-Fe 2 O 3 > Pt np /meso-Fe 2 O 3. The good SO 2 resistance of the Au 1 Pt 1 /meso-Fe 2 O 3 catalyst was attributed to the Au−Pt bimetallic single atoms uniformly dispersed on the meso-Fe 2 O 3 with the strong ability of sulfate decomposition and the protection of the active sites by meso-Fe 2 O 3 as a sacrificial site. This work presents a novel way for developing high-performance catalysts for VOCs elimination in the presence of SO 2. [Display omitted] • Au 1 Pt 1 /meso-Fe 2 O 3 is prepared via the PVA-protected reduction method. • Au 1 Pt 1 /meso-Fe 2 O 3 shows high activity and strong SO 2 tolerance. • The Au 1 Pt 1 bi-single-atom structure enhances the sulfates decomposition. • Meso-Fe 2 O 3 plays a sacrificial role in storing SO 2 to inhibit active sites poisoning. [ABSTRACT FROM AUTHOR]

[Display omitted] • The supported ternary metallic catalysts (PtSnM/CeO 2 ; M = Mn, W, Nb) with the closely coupled multi-catalytic active sites are prepared. • The ternary metallic catalysts show good catalytic activities for toluene and chlorobenzene (CB) oxidation and excellent chlorine resistance. • The chlorine-containing toxic by-products can be effectively inhibited to form over the ternary metallic catalysts. • H 2 O introduction promotes removal of the chlorine species. Pt-based commercial catalysts tend to be poisoned by chlorine species in the oxidation of chlorinated volatile organic compounds (CVOCs), which greatly limits their wide applications. It is vital to develop the active catalysts with good chlorine resistance. In the present work, the novel supported ternary metallic catalysts (PtSnM/CeO 2 ; M = Mn, W, Nb) with the closely coupled multi-active sites show good catalytic performance and excellent chlorine resistance for the oxidation of toluene and chlorobenzene (CB), and can effectively inhibit formation of the toxic chlorine-containing by-products. The catalytic activity for toluene oxidation in the mixed VOCs system follows the sequence: PtSnMn/CeO 2 > PtSnW/CeO 2 ≈ PtSnNb/CeO 2 > PtSn/CeO 2 > Pt/CeO 2. The change of the electron structure around Pt results in the difference in adsorption capacity of toluene and CB. The C−Cl bond is first dissociated at the Brønsted acid sites, and the non-chlorinated organic compounds are oxidized at the Pt sites that contact with the acid sites in the proximity. Additional water provides sufficient protons to react with Cl species, enhancing the desorption amount of HCl; furthermore, the water also reacts with the adsorbed oxygen to generate new oxygen species, which participates in the oxidation of VOCs, so as to accelerate the removal of Cl species on the catalyst surface and reduce the more toxic polychlorine by-products. This work is helpful for developing the supported noble metal catalysts with good chlorine-resistant performance in the oxidation of multicomponent VOCs under the actual industrial conditions. [ABSTRACT FROM AUTHOR]

Mesoporous manganese oxide (meso-MnO y) and its supported Co, Pt, and Pt x Co catalysts are prepared via the KIT-6-templating and PVA-protected reduction routes, respectively. The excellent catalytic activity of 0.70 wt% Pt 2.42 Co/meso-MnO y is associated with its highly dispersed Pt 2.42 Co alloy NPs, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Pt 2.42 Co NPs and meso-MnO y. • Pt x Co/meso-MnO y is prepared via the polyvinyl alcohol-protected reduction route. • Pt x Co alloy is formed in each of the Pt x Co/meso-MnO y samples. • 0.70 wt% Pt 2.42 Co/meso-MnO y performs the best for methanol combustion. • Pt x Co alloy, O ads content, reducibility, and metal-support interaction govern activity. The KIT-6-templating and polyvinyl alcohol-protected NaBH 4 reduction methods were adopted to prepare the mesoporous manganese oxide (meso-MnO y) and its supported Co, Pt, and Pt x Co catalysts, respectively. Numerous techniques were used to characterize the physicochemical properties of the materials. Catalytic performance of the samples was evaluated for methanol combustion. All of the samples possessed a three-dimensionally ordered mesoporous structure and a surface area of 94–110 m2/g. The Co, Pt, and Pt x Co nanoparticles (NPs) with an average size of 2.2–3.0 nm were uniformly dispersed on the surface of meso-MnO y. The 0.70 wt% Pt 2.42 Co/meso-MnO y sample performed the best: the T 50% and T 90% (temperatures required for achieving methanol conversions of 50 and 90%, respectively) were 50 and 86 °C at a space velocity of 80,000 mL/(g h). The partial deactivation of the 0.70Pt 2.42 Co/meso-MnO y sample due to water vapor or carbon dioxide introduction was reversible. It is concluded that the excellent catalytic activity of 0.70 wt% Pt 2.42 Co/meso-MnO y was associated with its highly dispersed Pt 2.42 Co alloy NPs, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Pt 2.42 Co alloy NPs and meso-MnO y. [ABSTRACT FROM AUTHOR]

Graphical abstract The 0.25 Pt 1 /meso-Fe 2 O 3 sample shows much better catalytic activity and water-resistant ability than the 0.25 Pt NP /meso-Fe 2 O 3 sample. The good performance of 0.25 Pt 1 /meso-Fe 2 O 3 is associated with the strong interaction between Pt and meso-Fe 2 O 3. Highlights • 3D ordered mesoporous Fe 2 O 3 (meso-Fe 2 O 3) is fabricated via the KIT-6-templaing route. • Single-atom Pt (x Pt 1 /meso-Fe 2 O 3) is prepared via the PVA-protected reduction route. • 0.25 Pt 1 /meso-Fe 2 O 3 performs much better than 0.25 Pt NP /meso-Fe 2 O 3 for benzene combustion. • 0.25 Pt 1 /meso-Fe 2 O 3 exhibits better water-resistant ability than 0.25 Pt NP /meso-Fe 2 O 3. • Good stability of 0.25 Pt 1 /meso-Fe 2 O 3 is related to the strong Pt-meso-Fe 2 O 3 interaction. Abstract Single-atom catalysts are a kind of promising catalytic materials that can use the precious metal more efficiently. The KIT-6-templaing method was adopted to obtain three-dimensionally ordered mesoporous iron oxide (meso-Fe 2 O 3). The meso-Fe 2 O 3 -supported single-atom Pt with a loading of x wt% (x Pt 1 /meso-Fe 2 O 3 , x = 0.08, 0.15, and 0.25) catalysts were synthesized via a polyvinyl alcohol-protected reduction route. The 0.25 Pt 1 /meso-Fe 2 O 3 sample showed much better catalytic activity than the meso-Fe 2 O 3 -supported Pt nanoparticle (0.25 Pt NP /meso-Fe 2 O 3) sample for benzene combustion, with the temperatures T 10% , T 50% , and T 90% (corresponding to benzene conversions of 10, 50, and 90%) were 164, 186, and 198 °C at a space velocity of 20,000 mL/(g h), respectively. The TOF Pt (2.69 s−1) obtained over 0.25 Pt 1 /meso-Fe 2 O 3 at 160 °C was much higher than that (1.16 s−1) obtained over the 0.25 Pt NP /meso-Fe 2 O 3 sample at 160 °C. Furthermore, the 0.25 Pt 1 /meso-Fe 2 O 3 and 0.15Pt 1 /meso-Fe 2 O 3 samples exhibited better water-resistant ability than the 0.25 Pt NP /meso-Fe 2 O 3 sample, which was possibly due to formation of the active radicals and decomposition of carbonates in the presence of moisture. In situ DRIFTS results demonstrate that the phenolate and benzoquinone as well as cyclohexanone and maleate were the main intermediates in the oxidation of benzene. The good stability of the 0.15Pt 1 /meso-Fe 2 O 3 and 0.25 Pt 1 /meso-Fe 2 O 3 samples was associated with the strong interaction between Pt and meso-Fe 2 O 3. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 3DOM La 0.6 Sr 0.4 Mn 1– x Pd x O 3 (LSMPd x O) was fabricated using the PMMA-templating method. • Pd/3DOM La 0.6 Sr 0.4 MnO 3 (LSMO) is derived from in-situ reduction of 3DOM LSMPd x O. • 1.18 wt% Pd/3DOM LSMO shows good activity and stability for methane combustion. • 1.18 wt% Pd/3DOM LSMO shows good resistance to the poisoning of SO 2. • The strong Pd NPs―3DOM LSMO interaction is the main reason for the good stability. Abstract To improve the stability of Pd-based catalysts at high temperatures, we herein report a novel strategy of first incorporating Pd to the lattice of three-dimensionally ordered macroporous La 0.6 Sr 0.4 MnO 3 (3DOM LSMO) and then depositing Pd nanoparticles (NPs) on the surface of 3DOM LSMO directly by in-situ reducing 3DOM La 0.6 Sr 0.4 Mn 1 –x Pd x O 3 (3DOM LSMPd x O). Physicochemical properties of the materials were characterized by means of numerous techniques, and their catalytic activities were evaluated for the combustion of methane. Compared to the Pd-free sample, the doping of Pd was beneficial for improvement in catalytic activity, and the 3DOM LSMPd 0.04 O sample performed the best (T 50% = 458 °C and T 90% = 550 °C at a space velocity of 40,000 mL/(g h)). The in-situ reduction of the Pd-doped samples could generate the y Pd/3DOM LSMO (y = 1.18–2.57 wt%) catalysts that exhibited good thermal stability and SO 2 -tolerant ability although their catalytic activities slightly decreased as compared to that prepared by the traditional impregnation method. The slight drop in activity of y Pd/3DOM LSMO was due to the partial destroy of the LSMO perovskite after reduction at 500 °C. Among the Pd/3DOM LSMO samples, 1.18Pd/3DOM LSMO showed the best thermal stability and SO 2 -tolerant ability, which was attributed to the strong interaction between Pd NPs and 3DOM LSMO. [ABSTRACT FROM AUTHOR]

Three-dimensionally ordered macroporus LaMnAl 11 O 19 (3DOM LMAO) and its supported Pd, Pd–Pt, and Pt nanoparticles were prepared using the polymethyl methacrylate-templating and polyvinyl alcohol-protected reduction methods, respectively. The 1100 °C-calcined 3DOM LMAO support possessed a hexaaluminate phase, and its supported noble metal samples displayed a high surface area of 26–29 m 2 /g. A Pd–Pt alloy was generated in the PdPt/3DOM LMAO samples, and the particle sizes of the noble metal nanoparticles (NPs) were 3–5 nm. The 0.97 wt% Pd/3DOM LMAO (0.97 P d/3DOM LMAO) sample possessed the highest surface adsorbed oxygen concentration and the best low-temperature reducibility, showing the highest catalytic activity ( T 10%  = 259 °C, T 50%  = 308 °C, and T 90%  = 343 °C at SV = 20,000 mL/(g h)) for methane combustion. The 1.14 wt% Pd 2.8 Pt/3DOM LMAO (1.14Pd 2.8 Pt/3DOM LMAO) sample performed the best ( T 10%  = 284 °C, T 50%  = 372 °C, and T 90%  = 456 °C at SV = 20,000 mL/(g h)) among the PdPt/3DOM LMAO samples. Doping of Pt to the Pd-based catalyst could improve the H 2 O-, CO 2 -, and SO 2 -resistant ability without significant influence on thermal stability, although 1.14Pd 2.8 Pt/3DOM LMAO was less active than 0.97 P d/3DOM LMAO for methane combustion. The ex situ X-ray photoelectron spectroscopy was used to explore the formation of active PdO species during the oxidation processes of Pd in 1.14Pd 2.8 Pt/3DOM LMAO and 0.97Pd/3DOM LaMnAl 11 O 19 at different temperatures. [ABSTRACT FROM AUTHOR]

The supported palladium catalysts perform well in the oxidative removal of hazardous aromatic hydrocarbons. However, water vapor can seriously deactivate the catalysts especially in the low-temperature regime. Hence, improving moisture resistance of the Pd-based catalysts is full of challenge in the removal of aromatics. Herein, we report a new type of Pd@NC/BN catalysts featured with nitrogen-doped carbon layers modified Pd supported on hexagonal boron nitride (h -BN), and the relationship between structure and water resistance of the catalysts. The results show that in the presence of 10 vol% H 2 O in the feedstock, the Pd@NC/BN catalyst could effectively oxidize o -xylene (with an almost 87% removal efficiency), whereas o -xylene conversion declined from 69% to 20% over the conventional Pd/Al 2 O 3 at a reaction temperature of 210 °C and a space velocity of 40,000 mL/(g h). The adsorption of H 2 O was significantly inhibited on the nitrogen-doped carbon layers due to the hydrophobic nature. Meanwhile, the oxygen species active for o -xylene oxidation were not only from the adsorbed gas-phase oxygen but also from the new active oxygen (*OOH and *OH) species that were generated via the interaction of O 2 and H 2 O in the presence of water in the feedstock. It is concluded that the reactive oxygen species that accelerated the activation and cleavage of C−H bonds significantly facilitated the conversion of key intermediate species (from benzaldehyde to benzoic acid), thus playing a decisive role in o -xylene oxidation. The present work provides a direction for developing the superior water resistance catalysts with hydrophobic nature and good water activation ability in the oxidative removal of volatile organic compounds. [Display omitted] • The Pd@NC/BN catalysts, featuring nitrogen-doped carbon layers, are synthesized using the pyrolysis strategy. • The Pd@NC/BN catalysts exhibit good catalytic activity and hydrothermal stability in o -xylene oxidation. • The main reason for the Pd@NC/BN catalysts to possess the super hydrothermal stability is well explored. • The reaction pathway of o -xylene oxidation over Pd@NC/BN is explored. • The role of water in o -xylene oxidation is investigated. [ABSTRACT FROM AUTHOR]

Electron paramagnetic resonance, in situ diffuse reflection infrared Fourier transform spectroscopy, and temperature-programmed techniques by means of the isotopic trace strategies were used to investigate the effects of water vapor on oxygen species, reaction pathways, byproducts distributions, and accumulation of the chlorine and carbon species on the catalyst surface for 1,2-dichloroethane oxidation over Ru/WO 3 or Ru/TiO 2 catalyst. The introduction of water vapor produced the OOH species that were converted into more active oxygen (O 2 – and O−) species. The mulliken population analysis indicates that β C and α C in VC are bonded with H and nucleophilic oxygen of −OH in sequence, respectively, which proved that water directly promoted the transformation of vinyl chloride to CH 3 COOH. Besides, water could be partially adsorbed at the hydroxyl groups on the Ru/WO 3 sample surface, which were provided the adsorption sites for 1,2-dichloroethane molecules. However, the severe competitive adsorption on the surface of Ru/TiO 2 resulted in insufficient oxygen adsorption to supplement the oxygen vacancy. The isotopic trace strategy is used to deeply investigate the effects of water vapor on oxygen species, reaction pathways, by-products distributions, and accumulation of the chlorine and carbon species on the Ru/WO 3 or Ru/TiO 2 catalyst for 1,2-dichloroethane (1,2-DCE) oxidation. It is found that water vapor promotes 1,2-DCE oxidation over Ru/WO 3 but inhibits 1,2-DCE oxidation over Ru/TiO 2. [Display omitted] • The isotopic trace strategy is used to investigate the effects of water vapor on 1,2-DCE oxidation over Ru/WO 3 or Ru/TiO 2. • The oxygen in water directly promotes the conversion of vinyl chloride to CH 3 COOH and improves HCl and CO 2 selectivities. • The Mulliken atomic charge calculations reveal the H and nucleophilic O of −OH attack C1 and C2 of vinyl chloride in sequence. • There are synergistic Langmuir−Hinshelwood and Mars-van Krevelen mechanisms over Ru/WO 3. • Water vapor promotes 1,2-DCE oxidation over Ru/WO 3 but inhibits 1,2-DCE oxidation over Ru/TiO 2. [ABSTRACT FROM AUTHOR]

A series of three-dimensionally ordered macroporous (3DOM) nickel−copper mixed oxides (with the NiO/CuO molar ratios of 3 : 3, 3 : 2, and 3 : 1) calcined at various temperatures (450, 550, and 650 ​°C) were prepared using the dual-templating (Pluronic P123 and polymethyl methacrylate (PMMA)) method in a mixed solution of ethylene glycol and methanol with different volumetric ratios (1 : 2, 1 : 1.5, and 1 : 1). The sample obtained after the use of P123 and PMMA exhibited a much higher catalytic activity for CO oxidation, over which a complete CO conversion was achieved at 138 ​°C, CO/O 2 volumetric ratio ​= ​2 : 5, and space velocity ​= ​60,000 mL/(g h), and this catalyst possessed good stability in the presence of water vapor in the feed stream. The large surface area, high oxygen adspecies concentration, good low-temperature reducibility, and unique nanovoid 3DOM structure were accountable for the superior catalytic performance of the sample prepared by the dual P123- and PMMA-templating method. [Display omitted] • The 3DOM NiO–CuO catalysts are prepared using the PMMA-P123 dual templating method. • Annealing temperatures and solvent molar ratios are examined in 3DOM NiO–CuO preparation. • 3DOM NiO–CuO derived from the dual-templating method performs excellently in CO oxidation. • The different NiO/CuO molar ratio can significantly influence the catalytic activity. [ABSTRACT FROM AUTHOR]

The Pt- M O x /Al 2 O 3 samples performed excellent for benzene oxidation. The high catalytic efficiency could be explained by the good ability to adsorb and activate benzene on the small M O x ensembles in the proximity contact with Pt. • Pt M (M = W, Mo) NPs are prepared via solvothermal synthesis. • Pt M (M = W, Mo) NPs with narrow particle size distributions and uniform morphologies are highly dispersed on γ-Al 2 O 3. • The Pt–WO x /Al 2 O 3 -2 sample perform the best for benzene oxidation • The bimetallic samples possess better endurance in the oxidation of the benzene and DCE mixture. • VOCs activation on the W/Mo-containing phase and Pt–MO x interfaces are beneficial factors for the oxidative removal of VOCs. Since the Pt-based catalysts often suffer severe deactivation by chlorine, development of a catalyst with good activity and chlorine-resistant ability is of importance in effectively controlling emissions of (chlorinated) volatile organic compounds ((C)VOCs). In this work, we prepared the Al 2 O 3 -supported bimetallic catalysts with narrow metal particle size distributions and their application in benzene oxidation. It is found that PtW/Al 2 O 3 showed the highest catalytic activity and the lowest activation energy. The characterization results were well correlated with the catalytic activities, and a Pt– M O x (M = W, Mo) bimetallic synergistic effect was proposed. In situ FTIR studies reveal that the transformation from phenol to benzoquinone was the key step in benzene oxidation process. The influence of 1,2-dichloroethane (DCE) on catalytic activity for benzene oxidation of the as-obtained samples was also examined. It is demonstrated that there was a competitive adsorption between benzene and DCE molecules, and the DCE exerted an inhibitive effect on benzene oxidation. We conclude that excellent catalytic performance of the bimetallic sample was associated with its good abilities to adsorb and activate benzene on small ensembles of the M O x in proximity contact with Pt as well as the strong interaction between the highly dispersed metallic Pt species and the M O x clusters (which led to enhancement in anti-deactivation of the Pt species under the oxygen-rich and Cl-containing reaction conditions). We are sure that the present work can provide an idea for understanding the nature of bimetallic active sites and rationally designing the efficient bimetallic catalysts for the oxidative removal of VOCs. [ABSTRACT FROM AUTHOR]

The Pt nanoparticles (NPs) partially embedded in the skeleton of 3DOM Mn 2 O 3 (x wt% Pt/3DOM Mn 2 O 3 ; x = 0.2–2.3) are prepared using the PMMA-templating and ethylene glycol reduction methods. The good stability of 2.3 Pt/3DOM Mn 2 O 3 is associated with the strong interaction between Pt NPs and 3DOM Mn 2 O 3. • Pt/3DOM Mn 2 O 3 is prepared using the PMMA-templating and glycol reduction methods. • Pt nanoparticles (NPs) are partially embedded in the skeleton of 3DOM Mn 2 O 3. • 2.3 wt% Pt/3DOM Mn 2 O 3 shows the best activity and lowest apparent activation energy. • 2.3 wt% Pt/3DOM Mn 2 O 3 exhibits good catalytic and thermal stability. • The strong Pt NPs–3DOM Mn 2 O 3 interaction is responsible for the good stability. Polymethyl methacrylate-templating and ethylene glycol reduction methods were adopted to prepare the nanosized Pt catalysts (x wt% Pt/3DOM Mn 2 O 3 ; x = 0.2–2.3) that were partially embedded in the skeleton of three-dimensionally ordered macroporous (3DOM) Mn 2 O 3. These materials possessed a surface area of 33–36 m2/g, with the Pt NPs (3.6–4.4 nm in size) being well embedded in the skeleton of 3DOM Mn 2 O 3. The 2.3 wt% Pt/3DOM Mn 2 O 3 sample showed the best activity and the lowest apparent activation energy (41 kJ/mol) for toluene combustion, which was related to its high adsorbed oxygen species concentration and good low-temperature reducibility. Compared with 2.0 wt% Pt/3DOM Mn 2 O 3 -imp derived from the colloid adsorption method, 2.3 wt% Pt/3DOM Mn 2 O 3 exhibited a better catalytic stability within 60 h of toluene combustion. After calcination at 650 °C for 3 h, the average particle size of Pt nanoparticles (NPs) in 2.3 wt% Pt/3DOM Mn 2 O 3 grew up slightly from 4.3 to 4.9 nm and toluene conversions decreased slightly, while that of Pt NPs in 2.0 wt% Pt/3DOM Mn 2 O 3 -imp increased greatly from 4.4 to 13.7 nm and toluene conversions dropped significantly. Effects of H 2 O, CO 2 , and SO 2 on activity of 2.3 wt% Pt/3DOM Mn 2 O 3 and 2.0 wt% Pt/3DOM Mn 2 O 3 -imp were also examined. Partial deactivation induced by H 2 O or CO 2 addition was reversible, whereas that due to SO 2 introduction was irreversible. It is concluded that the strong interaction between Pt NPs and 3DOM Mn 2 O 3 was responsible for excellent stability of the partially Pt-embedded 3DOM Mn 2 O 3 sample in toluene combustion. [ABSTRACT FROM AUTHOR]

The titanium dioxide/ZnAl-layered double hydroxide (TiO 2 /ZnAl-LDH) nanocomposite was first prepared using the co-precipitation method, and the TiO 2 /metal mixed oxide (TiO 2 /MMO) was then fabricated by annealing the TiO 2 /ZnAl-LDH nanocomposite at 430 °C. The obtained materials were characterized by means of techniques, such as field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV–visible diffuse reflectance spectroscopy (DRS), and N 2 adsorption-desorption (BET). Photocatalytic activities of the TiO 2 /MMO nanocomposite was evaluated for O 2 generation from aqueous solutions in the presence of AgNO 3 (1 mmol) as the sacrificial agent at neutral pH and room temperature under visible-light irradiation. It is found that photocatalytic activity of the TiO 2 /MMO sample was better than that of the TiO 2 /ZnAl-LDH sample, which could be attributed to the reduction in bandgap energy, low electron-hole recombination, and high surface area. An O 2 generation rate of 371 μmol/(g h) was achieved over 20 mg of the TiO 2 /MMO nanocomposite photocatalyst, and the quantum efficiency for O 2 generation was 84% at 400 nm. Such a quantum efficiency was the highest value obtained over the TiO 2 /MMO sample under visible-light illumination. This study presents a novel approach for water oxidation using the visible-light-responsive TiO 2 /MMO nanocomposite photocatalyst, which might be applied as a promising candidate in solar energy conversion and environmental science for highly efficient O 2 generation. Unlabelled Image • TiO 2 / ZnAl-LDH was synthesized using the co-precipitation method and TiO 2 /MMO obtained from annealing of nanocomposite at 430 °C. • TiO 2 /MMO products O 2 with high rate 371 μmolh-1g-1 and the quantum efficiency of O 2 generation is 80 % at 415 nm. • High O 2 production over the TiO 2 /MMO catalysts is due to the small bandgap and the larger surface area in comparison with TiO 2 /ZnAl –LDH. • The quantum yield is the highest value ever determined with visible light for TiO 2 /MMOs and layered double hydroxide materials. [ABSTRACT FROM AUTHOR]