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[Display omitted] • The catalytic ozonation performances for seven CeO 2 catalysts with different morphologies and exposed facets are disclosed. • CeO 2 nanorods with (1 1 0) and (1 0 0) facets exposed show the best performance. • A linear relationship between Frenkel-type OV density and O 3 decomposition rate is revealed regardless of morphology and exposed facet. • DFT calculation and experimental data reveal OV boosts O 3 activation on both the Ce and hydroxyl sites of CeO 2. Morphology and facet effects of metal oxides in heterogeneous catalytic ozonation (HCO) are attracting increasing interests. In this paper, the different HCO performances for degradation and mineralization of phenol of seven ceria (CeO 2) catalysts, including four with different morphologies (nanorod, nanocube, nanooctahedron and nanopolyhedron) and three with the same nanorod morphology but different exposed facets, are comparatively studied. CeO 2 nanorods with (1 1 0) and (1 0 0) facets exposed show the best performance, much better than that of single ozonation, while CeO 2 nanocubes and nanooctahedra show performances close to single ozonation. The underlying reason for their different HCO performances is revealed using various experimental and density functional theory (DFT) calculation results and the possible catalytic reaction mechanism is proposed. The oxygen vacancy (OV) is found to be pivotal for the HCO performance of the different CeO 2 catalysts regardless of their morphology or exposed facet. A linear correlation is discerned between the rate of catalytic decomposition of dissolved ozone (O 3) and the density of Frenkel-type OV. DFT calculations and in-situ spectroscopic studies ascertain that the existence of OV can boost O 3 activation on both the hydroxyl (OH) and Ce sites of CeO 2. Conversely, various facets without OV exhibit similar O 3 adsorption energies. The OH group plays an important role in activating O 3 to produce hydroxyl radical (∙OH) for improved mineralization. This work may offer valuable insights for designing Facet- and OV-regulated catalysts in HCO for the abatement of refractory organic pollutants. [ABSTRACT FROM AUTHOR]

Oxygen vacancies and heteroatom doping play important role in oxygen reduction activity of metal oxides. Developing efficient modification method is one of the key issues in catalysts research. Room temperature plasma treatment, with the advantages of mild working conditions, no emissions and high efficiency, is a new catalyst modification method developed in recent years. In this work, hydrothermal synthesized α -MnO2 nanorods are treated in NH3 plasma at room temperature. In the reducing atmosphere, oxygen vacancies and N doping are achieved simultaneously on the surface. The NH3 plasma etched MnO2 demonstrate a significant enhanced oxygen reduction activity with half-wave potential of 0.84 V, limiting current density of 6.32 mA cm−2 and transferred electrons number of 3.9. The Mg–air battery with N-MnO2 display a maximum power density of 76.3 mW cm−2 as well as stable discharge performance. This work provides new ideas for preparing efficient and cost-effective method to boost the catalysts activity. [ABSTRACT FROM AUTHOR]

The conversion of CO2 into fuels and value-added chemicals over heterogeneous catalysts may help realize a carbon-neutral or carbon-negative society. Recently, the direct conversion of CO2 to aromatics has been extensively explored. However, the requirement of multifunctional active sites, complexity of tandem cascade reactions, and difficulty in understanding reaction mechanisms present significant challenges to the design of effective heterogeneous catalysts. In this review, catalytic systems used for the direct production of aromatics from CO2 via the methanol-mediated and modified Fischer–Tropsch synthesis pathways are critically discussed. The initial section discusses the role of acid sites in HZSM-5 for the formation of aromatics. This is followed by a thorough review of recent progress on aromatic syntheses in terms of their catalytic performance, Si/Al ratios of zeolites, proximity between metal oxide and zeolite, and reaction conditions. The reaction mechanisms and the stability of existing catalysts are also discussed. Finally, the current challenges and future prospects of the catalytic conversion of CO2 to aromatics are highlighted. [ABSTRACT FROM AUTHOR]

Catalytic conversion of CO2 to CO via the reverse water gas shift (RWGS) reaction has been identified as a promising approach for CO2 utilization and mitigation of CO2 emissions. Bare Pt shows low activity for the RWGS reaction due to its low oxophilicity, with few research works having concentrated on the inverse metal oxide/Pt catalyst for the RWGS reaction. In this work, MnOx was deposited on the Pt surface over a SiO2 support to prepare the MnOx/Pt inverse catalyst via a co-impregnation method. Addition of 0.5 wt% Mn to 1 wt% Pt/SiO2 improved the intrinsic reaction rate and turnover frequency at 400 °C by two and twelve times, respectively. Characterizations indicate that MnOx partially encapsulates the surface of the Pt particles and the coverage increases with increasing Mn content, which resembles the concept of strong metal–support interaction (SMSI). Although the surface accessible Pt sites are reduced, new MnOx/Pt interfacial perimeter sites are created, which provide both hydrogenation and C-O activation functionalities synergistically due to the close proximity between Pt and MnOx at the interface, and therefore improve the activity. Moreover, the stability is also significantly improved due to the coverage of Pt by MnOx. This work demonstrates a simple method to tune the oxide/metal interfacial sites of inverse Pt-based catalyst for the RWGS reaction. [ABSTRACT FROM AUTHOR]

Catalysts containing supported metal oxides are very versatile materials used in liquid phase oxidation reactions. The present study aimed to determine the influence of niobium supported on a silica matrix (SiO2) for the oxidation of thioanisole to methyl phenyl sulfoxide and methyl phenyl sulfone. Characterization of the synthesized Nb5SiO2 and Nb10SiO2 catalysts revealed that although they are not completely crystalline, these microporous materials displayed even niobium dispersion on the SiO2 support whilst containing Lewis and Brönsted acidic sites on their surface. Nb5SiO2 and Nb10SiO2 catalysts showed higher activities compared to pure SiO2 catalyst. Niobium-containing catalysts promoted the subsequent oxidation reaction that converted methyl phenyl sulfoxide to methyl phenyl sulfone. The formation of methyl phenyl sulfone was observed in the presence of niobium-containing catalysts even when using a deficiency of H2O2 (0.44 equivalents), whereas the same result could not be achieved for the SiO2 catalyst. The formation of methyl phenyl sulfone occurred in a significantly shorter time in the presence of Nb10SiO2, demonstrating the effectiveness of niobium in producing active oxygen species that promote the subsequent reactions. Under the optimized conditions, methyl phenyl sulfoxide could be obtained with 100% conversion and selectivity at room temperature (25 °C) in either acetonitrile or methanol as solvent. Finally, theoretical calculations showed, through energy values, that the niobium-containing catalysts have a lower relative surface energy compared to the pure silica catalyst. The results presented in this research show the potential of the synthesized materials to promote thioanisole catalytic oxidation reactions using hydrogen peroxide as an oxidant. [ABSTRACT FROM AUTHOR]

To elucidate the synergistic effect of dual-atom catalysts (DACs) at the microscopic level, we propose and construct a prototype heteronuclear system, CuNi/TiO2, in which the two elements of a pair have significantly different d electron-donating abilities, as a piece in the puzzle. Using density functional theory calculations, we investigate charge-dependent configurations of Cu-Ni dimers anchored on TiO2 by the mixing of individual constituent atoms. The d electron-donating ability determines deposition sequence and position of transition metal atoms on oxides, establishing dimer pattern and metal–support interactions. The interaction between Cu and Ni, beyond the coordination environment, predominately contributes to the synergistic effect. A complex adsorption–reduction behavior of H species on CuNi/TiO2 is observed. The reaction mechanism and catalytic activity of CuNi/TiO2 for hydrogen production are explored. At room temperature and high H coverages, CuNi/TiO2 shows better performance and efficiency than Ni1/TiO2. Our findings provide a new understanding of the synergistic effect on structure–activity relationships of supported dimers, which would be beneficial in the future design of various DACs or even atomically dispersed metal catalysts. [ABSTRACT FROM AUTHOR]

Heterogeneous catalysts are the crucial element for many catalytic processes. In most of the cases, the pivotal structure consists of catalytic metals/alloy particles supported by oxides. Knowledge of the interaction between metal and oxide is central to understand the structure–performance relationship of such systems. X‐ray photoelectron spectroscopy provides access to the chemical–physical properties of metal and oxide interface as well as polarization effects. The results are usually derived from changes of the measured binding energies based on initial state analysis. We propose to extend the analysis using photoelectron as well as Auger transition to include final state effects (Wagner/Hohlneichner plots). This gives additional information on the specific chemical neighborhood of the excited atom. Three archetypal systems are investigated by hard X‐ray photoelectron spectroscopy (HAXPES) to introduce two approaches to this analysis for the most common support elements Al and Si. [ABSTRACT FROM AUTHOR]

A new synthetic strategy to produce porous ceramic particles with well-defined polyhedral particle morphology and three-dimensionally interconnected mesoporous structure has been developed by means of the combination of topotactic conversion of polyhedral crystal precursors and pyrolysis-induced phase separation. The crystal morphology of precursors is controlled by the liquid-phase synthesis, while the mesoporous structure in each polyhedral particle is tailored by the selective removal of a phase-separated phase preserving the other phase. In this review, two examples of porous polyhedral metal oxides prepared from hydrogarnet precursors: mesoporous and mesocrystalline 12CaO • 7Al2O3 mayenite microcubes and porous SrFeO3-δ perovskite polyhedral particles. The synthesis and characterization of these porous materials as well as their applications in catalysis are overviewed. [ABSTRACT FROM AUTHOR]

The strong metal–support interaction (SMSI) is a phenomenon observed in supported metal catalyst systems in which reducible metal oxide supports can form overlayers over the surface of active metal nanoparticles (NPs) under a hydrogen (H2) environment at elevated temperatures. SMSI has been shown to affect catalyst performance in many reactions by changing the type and number of active sites on the catalyst surface. Laboratory methods for the analysis of SMSI at the nanoparticle‐ensemble level are lacking and mostly based on indirect evidence, such as gas chemisorption. Here, we demonstrate the possibility to detect and characterize SMSIs in Co/TiOx model catalysts using the laboratory X‐ray standing wave (XSW) technique for a large ensemble of NPs at the bulk scale. We designed a thermally stable MoNx/SiNx periodic multilayer to retain XSW generation after reduction with H2 gas at 600°C. The model catalyst system was synthesized here by deposition of a thin TiOx layer on top of the periodic multilayer, followed by Co NP deposition via spare ablation. A partial encapsulation of Co NPs by TiOx was identified by analyzing the change in Ti atomic distribution. This novel methodological approach can be extended to observe surface restructuring of model catalysts in situ at high temperature (up to 1000°C) and pressure (≤3 mbar), and can also be relevant for fundamental studies in the thermal stability of membranes, as well as metallurgy. [ABSTRACT FROM AUTHOR]

Improving the selectivity in the oxidative coupling of methane to ethane/ethylene poses a significant challenge for commercialization. The required improvements are hampered by the uncertainties associated with the reaction mechanism due to its complexity. Herein, we report about 90 % selectivity to the target products at 11 % methane conversion over Gd2O3‐based catalysts at 700 °C using N2O as the oxidant. Sophisticated kinetic studies have suggested the nature of adsorbed oxygen species and their binding strength as key parameters for undesired methane oxidation to carbon oxides. These descriptors can be controlled by a metal oxide promoter for Gd2O3. [ABSTRACT FROM AUTHOR]

A systematic study of the hydrogenation of individual aromatic hydrocarbons (benzene, toluene, xylene) and their mixtures was carried out at 1800C, H2/Ar=7, WHSV = 2h-1 and atmospheric pressure on a composite catalyst 0.4%Co/HZSM-5/SO4 2-(2.0%)-ZrO2. It has been established that the developed catalyst has a high hydrogenating ability with respect to aromatic hydrocarbons at low hydrogen pressures. Alkyl-substituted benzenes turned out to be more active. It was found that alkyl substituents increase the activity of hydrogenation of the benzene ring of an aromatic hydrocarbon. According to their conversion, benzene, toluene and xylene form the following sequence: benzene

Metal oxide supported metal catalysts show promising catalytic performance in many industry-relevant reactions. However, the enhancement of performance is often limited by the insufficient metal/metal oxide interface. In this work, we demonstrate a general synthesis of Pt-early transition metal oxide (Pt-MOx, M = Ti, Zr, V, and Y) catalysts with rich interfacial sites, which is based on the air-induced surface segregation and oxidation of M in the supported Pt-M alloy catalysts. Systematic characterizations verify the dynamic structural response of Pt-M alloy catalysts to air and the formation of Pt-MOx catalysts with abundant interfacial sites. The prepared Pt-TiOx interfacial catalysts exhibit improved performance in hydrogenation reactions of benzaldehyde, nitrobenzene, styrene, and furfural, as a result of the heterolytic dissociation of H2 at Pt-metal oxide interfacial sites. [ABSTRACT FROM AUTHOR]

In this work, Ni-based mixed metal oxide (MMOs) materials were synthesized by coprecipitation, and then ceria (CeO 2) was incorporated. The obtained structures were characterized by XRD, TEM, BET, H 2 -TPR, and CO 2 -TPD techniques. The synthesized materials were evaluated in the CO 2 methanation process (250–400 °C range). Firstly, the effects of space velocity and Ni loading on the catalyst were tested, and 36000 h−1 and 5 % of Ni were found to be suitable conditions for CO 2 conversion. The addition of Co or Fe to the Ni-based MMO was then assessed. Co improved the catalytic activity, meanwhile, the Fe addition did not have an enhancing effect. Afterward, the role of CeO 2 as support on Ni-, NiFe- and NiCo-based MMOs was evaluated, evidencing that selectivity and space-time yields were enhanced in the materials by the CeO 2 presence. Furthermore, due to the characteristics of CeO 2 , the MMO containing nickel, cobalt, and ceria was more stable, showing ∼85% conversion of CO 2 after 1400 min of continuous use. • Adding Co to Ni-based MMO improved catalysis but Fe presence had negative effects. • Ceria is successfully incorporated into Ni-based MMOs by the reconstruction method. • CeO 2 incorporation enhanced selectivity and space-time yield for CO 2 methanation. • High catalyst stability for CO 2 conversion after a long time of continuous use. [ABSTRACT FROM AUTHOR]

Developing highly effective cheap metal oxides is of great value for the 5-hydroxymethylfurfural (HMF) aerobic oxidation to 2,5-furandicarboxylic acid (FDCA) under environmentally friendly conditions. Herein, we synthesized a non-precious cobalt–bismuth binary oxide with rich oxygen vacancies by a facile malic-acid-assisted method and then employed it as a superior catalyst for the HMF aerobic oxidation to FDCA in water. Given the characterization results, the accession of Bi2O3 made the (311) facet become the preferential orientation plane for Co3O4 in the cobalt–bismuth binary oxide. Then, the oxygen vacancies from Co3O4 will be increased due to the greater exposure of Co2+ on the dominant exposed (311) facet, which in turn will facilitate the aerobic oxidation of HMF to FDCA. Evaluating the performance of cobalt–bismuth binary oxide in HMF oxidation reactions, an outstandingly high FDCA yield of 98.23% with nearly 100% HMF conversion could be found over CoBi-12 (Co/Bi molar ratio of 12 : 1) under 0.6 MPa O2 pressure and 110 °C in water for 3 h. The findings of this study can contribute to the development of efficient non-precious metal-based catalysts for the aqueous-phase aerobic oxidation of biomass-derived HMF. [ABSTRACT FROM AUTHOR]

The oxidative C-C cleavage of a C18 substrate is an important transformation in synthetic organic chemistry, facilitating the synthesis of valuable C8-C9 acids widely used in many industries. Through a comparative analysis of the catalytic and physicochemical properties of catalysts, comprising mono- (Pd or Au) and bimetallic (PdAu) nanoparticles deposited on oxides, oxyhydroxides and graphite-like carbon material Sibunit (Cp), it was shown that the efficiency of the catalyst in the oxidative cleavage of 9,10-dihydroxystearic acid relies on the nature of the active component, the support and the average size of metal nanoparticles (NPs). The dependency of 9,10-DSA conversion on the average size of metal NPs shows the structural sensitivity of the oxidative cleavage reaction. Notably, catalysts with an average size of gold particles less than 3 nm exhibit the highest activity. The nature of the active component and the support material are crucial factors determining the process selectivity. Among the catalysts studied, the most effective for the oxidative cleavage of 9,10-DSA is a material based on Au NPs deposited on Cp. [ABSTRACT FROM AUTHOR]

The absorption of CO2 gas into aqueous alkanolamine solutions is the most advanced CO2 separation technology and a key challenge in this technique is the energy‐intensive process of solvent regeneration. The tertiary amine N,N′‐diethylethanolamine (or DEEA) is a candidate CO2‐capturing solvent with potential. To improve the energy efficiency of regeneration of DEEA, several catalysts were used for desorbing CO2 from loaded solutions of DEEA (2.5 M) at T = 363 K. Desorption trials were conducted in batch mode. The initial CO2 loading varied in the 0.3–0.35 mol CO2/mol DEEA range. The performance was analyzed by calculating the rate of CO2 desorption, cyclic capacity, and reduction in sensible energy. The amount of thermal energy needed for amine regeneration was significantly lowered by using nine transition metal oxide catalysts and the hierarchy was as follows: Al2O3 < MoO3 < V2O5 < TiO2 < MnO2 < ZnO < Cr2O3 < SiO2 < ZrO2. Among the metal oxides, Al2O3 increased desorption efficiency compared to blank runs by 89%. A clay‐based powder bentonite was also used as catalyst and its efficacy was compared with the metal oxides. This cheap and easily available bentonite catalyst was tuned through simple ion‐exchange with four acids (HCl, H3PO4, HNO3, and H2SO4). Upon treatment with H2SO4, bentonite remarkably increased desorption efficiency by 100%. Furthermore, bentonite catalyst treated with sulphuric acid (denoted here as Bt/H2SO4) was characterized by Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), Fourier transform infrared spectrometery (FTIR), X‐ray diffraction (XRD), and ammonia temperature‐programmed desorption (NH3‐TPD). In this way, a comprehensive study on catalytic desorption of DEEA was performed. [ABSTRACT FROM AUTHOR]

The objectives of this study were to prepare a high-purity hydroxylammonium nitrate (HAN) solution and evaluate the performance of various types of metal oxide/honeycomb catalysts during the catalytic decomposition of the HAN solution. Hydroxylammonium nitrate was prepared via a neutralization reaction of hydroxylamine and nitric acid. FT-IR was used to analyze the chemical composition, chemical structure, and functional groups of the HAN. The aqueous HAN solution obtained from pH 7.06 showed the highest concentration of HAN of 60% and a density of 1.39 g/mL. The concentration of HAN solution that could be obtained when the solvent was evaporated to the maximum level could not exceed 80%. In this study, catalysts were prepared using a honeycomb structure made of cordierite (5SiO2-2MgO-2Al2O3) as a support, with Mn, Co, Cu, Pt, or Ir impregnated as active metals. The pore structure of the metal oxide/honeycomb catalysts did not significantly depend on the type of metal loaded. The Cu/honeycomb catalyst showed the strongest effect of lowering the decomposition onset temperature in the decomposition of the HAN solution likely due to the intrinsic activity of the Cu metal being superior to that of the other metals. It was confirmed that the effect of the catalyst on the decomposition mechanism of the aqueous HAN solution was negligible. Through a repetitive cycle of HAN decomposition, it was confirmed that the Cu/honeycomb catalyst could be recovered and reused as a catalyst for the decomposition of an aqueous HAN solution. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) is the key reaction in the water splitting and CO 2 electrochemical reduction. However, the current catalysts for OER still suffer from high potentials and poor stability. Herein, hierarchical self-supporting Ni-based oxides (NiMO x)/Ni–V/Ni foam (NF) (M = Fe, Co, Cu, Mo) catalysts are directly grown on NF by in-situ hydrothermal roasting method. The OER activity of a series of Ni-based oxide catalysts doped with different metal are investigated. The results demonstrate that the NiFeO x /Ni–V/NF exhibits the best OER activity. At the current density of 10 mA cm−2, a smaller overpotential for OER of 270 mV is achieved in 1.0 M KOH electrolyte. No obvious decay in performances is observed after constant electrolysis of about 25 h, demonstrating its outstanding stability. The formation of new oxides compounds and the structure changes due to the addition of Fe, Co, Cu, Mo to the NiO x contribute to the improvements in activity. A hierarchical NiMOx/Ni–V/NF (M = Fe, Co, Cu, Mo) array was grown directly on Ni foam by in-situ hydrothermal roasting method. A series of Ni-based oxide catalysts doped with different metal were investigated as highly efficient electrocatalyst for oxygen evolution reaction. [Display omitted] • Hierarchical NiMOx/Ni–V/NF are prepared by in-Situ hydrothermal roasting method. • The performances of Ni-based oxide for oxygen evolution reaction are investigated. • The NiFeOx/Ni–V/NF shows the best catalytic activity toward OER in 1.0 M KOH. • The NiFeOx/Ni–V/NF also shows high stability. • The 3D electrocatalysts is promising for practical application of water splitting. [ABSTRACT FROM AUTHOR]

We report the development of Ru/Mg–Al oxide coated metal-structured catalysts with excellent heat and mass transfer characteristics for efficient clean H 2 production from ammonia decomposition. Ammonia is a promising carrier for the mass transport of hydrogen and facilitates the production of COx-free hydrogen by decomposing into nitrogen and hydrogen. Ru nanoparticles are uniformly dispersed on the Mg–Al oxide layer of the FeCralloy monoliths and foams via precipitation. The catalytic activities depend on the surface area and loading of the catalysts and the metal dispersion in the oxide layer. At temperatures <650 °C, and a gas hourly space velocity (GHSV) of 3,000 h−1, monolithic catalysts with a large surface area and evenly distributed active metals perform excellently. Foam catalysts with excellent heat transfer performance better at temperatures >650 °C and GHSV >6,000 h−1. Foam catalyst stability is verified for 100 h in a 20 Nm3/h high-purity hydrogen production system. [Display omitted] • COx-free H 2 production via NH 3 decomposition on Ru-coated metal-structured catalysts. • Nano-sized Ru uniformly dispersed in plate-like Mg–Al oxide layers by precipitation. • Amount of Ru in the structured catalyst was <∼1/10 of that in the pellet catalyst. • Foams performed better catalytically than monoliths at higher GHSV (6,000 h−1). • Foam catalyst stability was verified in a 20 Nm3/h-H 2 production system for 100 h. [ABSTRACT FROM AUTHOR]

Recently, interest in converting bio‐derived fatty acid methyl esters (FAMEs) into added‐value products has significantly increased. The selectivity of ketonization reaction in the conversion of the FAMEs has significantly hampered the efficiency of this process. Herein, this work reports the preparation of catalysts with different levels of oxygen vacancies while the crystal phase remained unchanged. The catalyst with the highest level of oxygen vacancy exhibited the maximum selectivity. The density functional theory (DFT) simulation showed an increase in interatomic distances leading to the formation of frustrated Lewis pairs (FLPs) upon the creation of oxygen vacancies. The surface measurements, type and density of acid sites of the catalysts, showed that the Lewis acid sites enhanced the selectivity for ketone production; while Bronsted acid sites increased the formation of by‐products. Moreover, the ketone formation rate was directly proportional to acid density. The findings of this research provide a different approach for catalyst design, based on defects engineering and their effect on the surface activity, which could be used for enhancing the catalytic performance of novel metal oxides. [ABSTRACT FROM AUTHOR]

The hydrogenation of biomass‐derived furan compounds provides a sustainable pathway for the production of various valuable chemicals; product selectivity among multiple reaction pathways of furan compound hydrogenation is crucially dependent on catalytic sites; however controlling reaction pathways remains challenging due to the lack of identification and understanding of active sites. In this work we reveal the role of base sites in furfural selective hydrogenation through deliberately designed and synthesized reversed catalysts, basic metal oxides and hydroxide on Cu. It is demonstrated that base species greatly enhanced the selectivity of 1, 2‐pentanediol (1, 2‐PeD) from furfural, presenting a nearly fourfold increase of 1, 2‐PeD: methyl furan ratio over the Cu based reverse catalysts. A combination of infrared spectroscopy and DFT calculations demonstrates the strong interaction between the C−O−C bond in furan ring and the catalyst surface in preferentially parallel adsorption mode in the presence of base species on Cu, thus facilitating the activation of C−O−C bond to produce 1, 2‐PeD. This work provides a strategy of designing reversed catalyst to study the effect of promoters and reveals the role of base sites in the hydrogenation of biomass‐derived furan compounds to diols. [ABSTRACT FROM AUTHOR]

Strain engineering is an effective strategy in modulating activity of electrocatalysts, but the effect of strain on electrochemical stability of catalysts remains poorly understood. In this work, we combine ab initio thermodynamics and molecular dynamics simulations to examine the role of compressive and tensile strain in the interplay between activity and stability of metal oxides considering RuO2 ${{}_{2}}$ and IrO2 ${{}_{2}}$ as exemplary catalysts. We reveal that although compressive strain leads to improved activity via the adsorbate‐evolving mechanism of the oxygen evolution reaction, even small strains should substantially destabilize these catalysts promoting dissolution of transition metals. In contrast, our results show that the metal oxides requiring tensile strain to promote their catalytic activity may also benefit from enhanced stability. Importantly, we also find that the detrimental effect of strain on electrochemical stability of atomically flat surfaces could be even greater than that of surface defects. [ABSTRACT FROM AUTHOR]

Dry reforming of methane (DRM) is an effective method for achieving carbon reduction and carbon neutrality by directly converting two greenhouse gases, CH 4 and CO 2 , into value-added products. However, catalysts used in this process are prone to metal sintering and carbon deposition, which are major obstacles. Thus, the design of high-performance catalysts is crucial for the success of dry reforming technology. In this paper, a series of Co-based catalysts modified with different rare earth metals (Y, Tb, Gd) and γ-Al 2 O 3 as the support were prepared using the conventional co-impregnation method. The effects of the introduction of rare earth metals additives on the activity and resistance to carbon build-up of the catalysts were investigated. The catalysts were analyzed using various characterization techniques. The results showed that Y and Tb as additives could effectively improve the activity and stability of the catalyst. However, the Gd modified Co-based catalyst had a large specific surface area but was less favorable for the DRM reaction. The best performance catalyst was achieved with the 10Co–5Y/γ-Al 2 O 3 under 750 °C with CH 4 and CO 2 conversions of 91.79% and 98.33%, respectively. This is mainly due to the fact that the introduction of Y enhances the electron transfer between Co and metal oxides, generating more oxygen vacancies and base vacancies on the surface, thus enhancing the adsorption and activation of CO 2. The 10Co–5Y/γ-Al 2 O 3 catalyst demonstrated excellent DRM performance even after 20 h at 750 °C. Moreover, we proposed a hypothesis regarding the mechanism of resistance to carbon build-up. This study provides a reasonable idea to design Co-based catalysts with resistance to sintering and carbon accumulation to improve the performance of reforming catalysts. [Display omitted] • The introduction of Y and Tb enhances the electron transfer ability of Co species. • The introduction of Y improves the cobalt dispersibility and oxygen vacancies. • 30% enhancement in CH 4 and CO 2 conversion was achieved with 10Co–5Y/γ-Al 2 O 3. • The mechanism of resistance to carbon build-up was proposed. [ABSTRACT FROM AUTHOR]

Knowing the structure of catalytically active species/phases and providing methods for their purposeful generation are two prerequisites for the design of catalysts with desired performance. Herein, we introduce a simple method for precise preparation of supported/bulk catalysts. It utilizes the ability of metal oxides to dissolve and to simultaneously precipitate during their treatment in an aqueous ammonia solution. Applying this method for a conventional VOx−Al2O3 catalyst, the concentration of coordinatively unsaturated Al sites was tuned simply by changing the pH value of the solution. These sites affect the strength of V−O−Al bonds of isolated VOx species and thus the reducibility of the latter. This method is also applicable for controlling the reducibility of bulk catalysts as demonstrated for a CeO2−ZrO2−Al2O3 system. The application potential of the developed catalysts was confirmed in the oxidative dehydrogenation of ethylbenzene to styrene with CO2 and in the non‐oxidative propane dehydrogenation to propene. Our approach is extendable to the preparation of any metal oxide catalysts dissolvable in an ammonia solution. [ABSTRACT FROM AUTHOR]

Ground-level ozone is harmful to human beings and ecosystems, while room-temperature catalytic decomposition is the most effective technology for ozone abatement. However, solving the deactivation of existing metal oxide catalysts was caused by oxygen-containing intermediates is challenging. Here, we successfully prepared a two-dimensional NiFe layered double hydroxide (NiFe-LDH) catalyst via a facile co-precipitation method, which exhibited stable and highly efficient performance of ozone decomposition under harsh operating conditions (high space velocity and humidity). The NiFe-LDH catalyst with Ni/Fe = 3 and crystallization time over 5 hr (named Ni 3 Fe-5) exhibited the best catalytic performance, which was well beyond that of most existing manganese-based oxide catalysts. Specifically, under relative humidity of 65% and space velocity of 840 L/(g·hr), Ni 3 Fe-5 showed ozone conversion of 89% and 76% for 40 ppmV of O 3 within 6 and 168 hr at room-temperature, respectively. We demonstrated that the layered structure of NiFe-LDH played a decisive role in its outstanding catalytic performance in terms of both activity and water resistance. The LDH catalysts fundamentally avoids the deactivation caused by the occupancy of oxygen vacancies by oxygen-containing species (H 2 O, O−, and O2−) in manganese-based oxide. This study indicated the promising application potential of LDHs than manganese-based oxide catalysts in removal of gaseous ozone. [Display omitted] [ABSTRACT FROM AUTHOR]

To obtain insight into the effect of promoter-support interactions in CO2 reforming of CH4, a series of Ni and Ni-Co (3:1) catalysts were prepared over modified-MgAl2O4 and MgAl2O4. The prepared samples were characterised and investigated for dry reforming of methane reactions at 873 K and 1 atm. From XRD, it appears that CaO, in a specified amount, is an appropriate modifier to retain the active metallic phase of catalyst and also prevents the formation of a solid solution of itself with the metal oxides during catalyst synthesis. From activity results, enhancement in catalytic activity was observed for Ni and Ni-Co catalysts supported over modified-MgAl2O4 support due to the presence of new and more number of active metal sites. For 100Ni-2.5CaO/MgAl2O4 catalyst, initial CH4 conversion was 1.3 times greater than 100Ni/MgAl2O4. For Ni-Co catalysts comparable results were observed over modified-MgAl2O4 and MgAl2O4 supports. Moderately active carbon species were formed during dry reforming of methane reaction and the presence of new and more number of basic sites helped to minimise carbon deposition. [ABSTRACT FROM AUTHOR]

The integration of metal oxide nanomaterials with mesoporous silica is a promising approach to exploiting the advantages of both types of materials. Traditional synthesis methods typically require multiple steps. This work instead presents a fast, one-step, template-free method for the synthesis of metal oxides homogeneously dispersed within mesoporous silica, including oxides of W, Ti, Nb, Ta, Sn, and Mo. These composites have tunable metal oxide contents, large surface areas, and wide mesopores. The combination of Nb2O5 nanoparticles (NPs) with SiO2 results in an increased surface area and a larger number of acid sites compared to pure Nb2O5 NPs. The surface texture and acidity of the silica–niobia composites can be tuned by adjusting the Nb/Si molar ratio. Moreover, the silica provides protection to the niobia NPs, preventing sintering during thermal treatment at 400 °C. The silica–niobia materials exhibit superior performance as catalysts in the aldol condensation of furfural (Fur) with acetone compared to pure niobia, leading to an up to 62% in product yield. Additionally, these catalysts show remarkable stability, retaining their performance over multiple runs. This work demonstrates the potential of the proposed synthesis approach for preparing more sustainable, high-performance, durable, and stable nanoscale metal oxide-based catalysts with a tunable composition, surface area, and active site density. [ABSTRACT FROM AUTHOR]

To obtain insight into the effect of promoter-support interactions in CO2 reforming of CH4, a series of Ni and Ni-Co (3:1) catalysts were prepared over modified-MgAl2O4 and MgAl2O4. The prepared samples were characterised and investigated for dry reforming of methane reactions at 873 K and 1 atm. From XRD, it appears that CaO, in a specified amount, is an appropriate modifier to retain the active metallic phase of catalyst and also prevents the formation of a solid solution of itself with the metal oxides during catalyst synthesis. From activity results, enhancement in catalytic activity was observed for Ni and Ni-Co catalysts supported over modified-MgAl2O4 support due to the presence of new and more number of active metal sites. For 100Ni-2.5CaO/MgAl2O4 catalyst, initial CH4 conversion was 1.3 times greater than 100Ni/MgAl2O4. For Ni-Co catalysts comparable results were observed over modified-MgAl2O4 and MgAl2O4 supports. Moderately active carbon species were formed during dry reforming of methane reaction and the presence of new and more number of basic sites helped to minimise carbon deposition. [ABSTRACT FROM AUTHOR]

The conventional Haber-Bosch (HB) process is the mainstream route to manufacture ammonia (NH 3); the latter being one of the most significant compounds and a carbon-free energy carrier; HB operates at high pressure and temperature, resulting in significant energy consumption and CO 2 emissions. An alternative method that has lately received a lot of attention is the electrocatalytic nitrogen reduction reaction (NRR), which produces NH 3 in ambient settings using renewable energy. The rate of NH 3 synthesis and faradaic efficiency (FE) are both used as catalytic activity descriptors; their values decreased when the competing hydrogen evolution reaction (HER) is picking up. The design of high-performance NRR catalysts, operating under ambient settings, while suppressing HER, is a major research field in the energy sector. This review discusses recent progress on catalyst design, as well as challenges and opportunities on the catalytic NH 3 synthesis pathways focusing on different classes of materials, such as Ru-based catalysts, inorganic metal oxides, organic covalent-organic frameworks (COFs), and metal-organic frameworks (MOFs). Experimental validation studies on the NRR, through isotopic studies, are presented as well as future directions for the most prominent catalytic substrates. • NH3 synthesis can follow associative, dissociative, and Mars Van Krevelen mechanism. • Defects engineering and structure manipulation are considered game changers. • Design of single-atom catalysts can tailor the rate of NH 3 synthesis reaction. • DFT tools guide the electrochemical and thermochemical catalysts design. • Both inorganic and organic materials are subjected into shape and structure tuning. [ABSTRACT FROM AUTHOR]

The incorporation of the metal phase into cellulose hydrogels, resulting in the formation of metallogels, greatly expands their application potential by introducing new functionalities and improving their performance in various fields. The unique antiviral, antibacterial, antifungal, and anticancer properties of metal and metal oxide nanoparticles (Ag, Au, Cu, CuxOy, ZnO, Al2O3, TiO2, etc.), coupled with the biocompatibility of cellulose, allow the development of composite hydrogels with multifunctional therapeutic potential. These materials can serve as efficient carriers for controlled drug delivery, targeting specific cells or pathogens, as well as for the design of artificial tissues or wound and burn dressings. Cellulose-based metallogels can be used in the food packaging industry to provide biodegradable and biocidal materials to extend the shelf life of the goods. Metal and bimetallic nanoparticles (Au, Cu, Ni, AuAg, and AuPt) can catalyze chemical reactions, enabling composite cellulose hydrogels to be used as efficient catalysts in organic synthesis. In addition, metal-loaded hydrogels (with ZnO, TiO2, Ag, and Fe3O4 nanoparticles) can exhibit enhanced adsorption capacities for pollutants, such as dyes, heavy metal ions, and pharmaceuticals, making them valuable materials for water purification and environmental remediation. Magnetic properties imparted to metallogels by iron oxides (Fe2O3 and Fe3O4) simplify the wastewater treatment process, making it more cost-effective and environmentally friendly. The conductivity of metallogels due to Ag, TiO2, ZnO, and Al2O3 is useful for the design of various sensors. The integration of metal nanoparticles also allows the development of responsive materials, where changes in metal properties can be exploited for stimuli-responsive applications, such as controlled release systems. Overall, the introduction of metal phases augments the functionality of cellulose hydrogels, expanding their versatility for diverse applications across a broad spectrum of industries not envisaged during the initial research stages. [ABSTRACT FROM AUTHOR]

Single‐atom catalysts (SACs) often show exceptionally high performance per metal loading. Besides benefiting from a better atom utilisation, the metal‐support interaction is more pronounced in SACs compared to traditional nanoparticle catalysts. Thus, using SACs in photochemical conversions is of great advantage where the rapid reactions often depend on the synergistic interaction of the active site with the photoactive support. Here we show the importance of this interaction by maximizing the active site/support interface using SACs. As an example, we examine the oxidation reaction of anthracene to anthracene‐9,10‐endoperoxide (EPO) in the presence of 0.1 wt% Pt/TiO2. Our SACs give a six‐fold improvement compared to dense packed nanoparticle catalysts (TOF=113 mMol Anthracene gPt−1 min‐−1 for the SAC). We attribute this to the synergy between the active site and the support. Moreover, we show that photocatalytic conversion is possible with photons of lower energy (2.7 eV) than the bandgap of pristine TiO2 (Eg=3.0–3.2 eV) thanks to organic doping of the metal oxide. [ABSTRACT FROM AUTHOR]

Non-thermal plasma (NTP) has been demonstrated as one of the promising technologies that can degrade volatile organic compounds (VOCs) under ambient condition. However, one of the key challenges of VOCs degradation in NTP is its relatively low mineralization rate, which needs to be addressed by introducing catalysts. Therefore, the design and optimization of catalysts have become the focus of NTP coupling catalysis research. In this work, a series of two-dimensional nanosheet Co-Ni metal oxides were synthesized by microwave method and investigated for the catalytic oxidation of benzene in an NTP-catalysis coupling system. Among them, Co 2 Ni 1 O x achieves 60% carbon dioxide (CO 2) selectivity (S CO2) when the benzene removal efficiency (RE benzene) reaches more than 99%, which is a significant enhancement compared with the CO 2 selectivity obtained without any catalysts (38%) under the same input power. More intriguingly, this S CO2 is also significantly higher than that of single metal oxides, NiO or Co 3 O 4 , which is only around 40%. Such improved performance of this binary metal oxide catalyst is uniquely attributed to the synergistic effects of Co and Ni in Co 2 Ni 1 O x catalyst. The introduction of Co 2 Ni 1 O x was found to promote the generation of acrolein significantly, one of the key intermediates found in NTP alone system reported previously, suggest the benzene ring open reaction is promoted. Compared with monometallic oxides NiO and Co 3 O 4 , Co 2 Ni 1 O x also shows higher active oxygen proportion, better oxygen mobility, and stronger low-temperature redox capability. The above factors result in the improved catalytic performance of Co 2 Ni 1 O x in the NTP coupling removal of benzene. [Display omitted] [ABSTRACT FROM AUTHOR]

BACKGROUND: Selective catalytic reduction (SCR) of nitrous oxides (NOx) with ammonia (NH3) as reductant is used worldwide in mobile and stationary sources to reach strict emission standards. It is a feasible strategy to modify support with acidic metal oxides to improve the alkali metal potassium (K) tolerance of SCR catalysts. Herein, a comparative investigation was conducted based on iron/zirconium dioxide (Fe/ZrO2)and Fe/ZrO2‐tungsten (W) catalysts to reveal the correlation of support modification with W and K‐tolerance performance. RESULTS: The NOx conversion for K‐Fe/ZrO2 catalyst was <80% across the whole temperature range, and the catalyst was completely deactivated at ≈400 °C. As expected, the Fe/ZrO2‐W catalyst exhibited a much superior anti‐K‐performance in comparison to the Fe/ZrO2 catalyst. The active temperature window for K‐Fe/ZrO2‐W catalyst was 285–485 °C (NOx conversion of >80%). CONCLUSION: According to the characterization results, it was found that K‐species impose a negative impact on NH3 adsorption on the surface of the Fe/ZrO2 catalyst, especially drastically preventing the adsorption of NH3 species on Brønsted acid sites, thus inhibiting the occurrence of SCR reactions via the Langmuir–Hinshelwood (L‐H) mechanism. By contrast, W modification resulted in more chemisorbed oxygen, stronger redox capacity and an increased Fe3+/(Fe3++Fe2+) ratio on the surface of the Fe/ZrO2‐W catalyst. More importantly, W modification brought about abundant Brønsted acid sites, significantly promoting NH3 adsorption and activation. W modification also weakened the adsorption stability of NOx species to a certain extent. As a result, SCR reactions over the Fe/ZrO2‐W catalyst could proceed via both Eley–Rideal (E‐R) and L‐H pathways. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Herein, a facile, controllable, and versatile method is reported to prepare monodisperse yolk‐shell and yolk‐multishell silica nanoparticles (NPs) with mesoporous shells by a novel selective etching strategy. The mechanism of selective etching based on fluoride‐silica chemistry is investigated in detail and thus provides a fundamentally novel principle for the fabrication of yolk‐shell NPs. Specifically, this unprecedented and versatile synthesis strategy can be used to encapsulate essentially any silica‐based, carbon‐based, metal, metal oxide, or other possible NPs. Noteworthy is that most of the yolk‐shell mesoporous silica (mSiO2) NPs are prepared for the first time. To demonstrate the major structural and compositional advantages of the designed yolk‐shell NPs, their applications in the fields of ultralow‐dielectric constant (k) materials, drug delivery systems, and catalysts were explored. In detail, the lowest k value of the prepared yolk‐shellordered mesoporous silica@mSiO2/fluorinated polybenzoxazole composite films is 2.02; The obtained yolk‐shell mSiO2/C@mSiO2/C NPs possess high hydrophilicity and pH‐responsive sensitivity; The conversion of the catalytic reaction of the designed magnetic yolk‐shell hollow Fe3O4@SiO2/Au@mSiO2 NPs at 20 min is 97% with a high conversion rate (92%) and recyclability even after 10 reuses. This innovative work lays a solid foundation for freely tailorable yolk‐shell encapsulation and will greatly stimulate more efforts devoted to relevant research and development. [ABSTRACT FROM AUTHOR]

Catalytic pyrolysis of lipids is an alternative pathway for alternative aviation fuel production with advantages of H 2 -free and mild reaction conditions. However, it is still hindered by coking of catalysts and low selectivity of kerosene. In this research, composite catalysts were synthesized via postsynthesis method (alkali treatment) followed by doping of metal oxides (ZnO, La 2 O 3 , and CeO 2). Catalytic performance of as-synthesized catalysts was evaluated during catalytic pyrolysis of microalgal lipids. The characterization of BET, XRD, SEM, NH 3 -TPD for catalysts indicated that alkaline treatment increased the mesoporous structure (5.28–5.91 nm) of microporous zeolite HZSM-5 to form a hierarchically porous structure without apparent disruption of crystal structure of zeolite, while doping of metal oxides (about 10 wt%) enhanced the performance of hetero-atoms (oxygen and nitrogen) removal. The acidity of as-synthesized catalysts significantly decreased from 1175.61 μmol/g (HZSM-5) to 406.77 μmol/g (Ce-MHZ). After catalytic pyrolysis carbon number distribution and compound type of produced liquid fuels tended to high kerosene components (above 40%) and increased hydrocarbon content with reduced content of oxygen-containing compounds. The hierarchically porous zeolite also presented aromatization for aromatic hydrocarbons in alternative aviation fuels. Catalytic mechanism was also elucidated including complex reactions of decarboxylation, decarbonylation, carbon chain cracking, and aromatization. [Display omitted] [ABSTRACT FROM AUTHOR]

Transition metal oxide (TMO) active centers on the TiO2 surface actuate NHPI molecule producing PINO• radical, which initiates/propagates homogeneous oxidation. Surface acidity and redox properties of the metal oxide catalyst influence activation of NHPI. [Display omitted] • NHPI yields PINO□ radical upon reaction with transition metal oxide (TMO). • Activation of NHPI is influenced by surface acidity and redox properties of the metal oxide. • Free radical PINO□, activated at the surface, initiates/propagates homogeneous oxidation. • Synergy between NHPI and TMO promotes oxidation rate. • Calculated ΔH f can be used as a descriptor of thermodynamic favorability of a catalytic reaction. The activities of transition metal oxide (TMO) heterogeneous catalysts based on individual components such as VO X , and MnO X supported on TiO 2 and TiO 2 -SiO 2 as cocatalysts in catalytic systems complemented with N-hydroxyphthalimide (NHPI) in the processes of aerobic liquid-phase radical chain oxidation of alkylarenes (RH) was investigated. The mechanisms of catalysis by NHPI in a liquid phase and participation of TMO in the chain initiation stage were discussed. Catalytic activities of Mn- and V-oxide catalysts were compared with the results of molecular hydrogen temperature programmed reduction profiles (H 2 -TPR) of the catalysts, revealing correlation between them. Reaction enthalpies calculated via a semi-empirical method for model structures of catalytic centers explained the obtained experimental results. Finally, catalytic cumene oxidation was presented using a reactions scheme identifying the concomitant role of heterogeneous initiation and homogeneous propagation and termination steps for the oxidation process proceeding via a free-radical mechanism. [ABSTRACT FROM AUTHOR]

The low-temperature water-gas-shift (LT-WGS) reaction has shown remarkable activity for Au single-atom supported on reducible oxide catalysts. The water dissociation step of the WGS reaction is calculated using density functional theory (DFT) over four single Au atom (Au 1)-pristine reversible oxides support systems Au 1 /M a O b -O v (Au 1 /TiO 2- x , Au 1 /ZrO 2- x , Au 1 /CeO 2- x and Au 1 /Co 3 O 4- x) system and four Au 1 -supports with O vacancy (O v) systems Au 1 /M a O b (Au 1 /TiO 2 , Au 1 /ZrO 2 , Au 1 /CeO 2 and Au 1 /Co 3 O 4). According to its greatest H 2 O adsorption energy, lowest water dissociation barrier, and slightest structural distortion, Au 1 /CeO 2- x is chosen as the most beneficial catalyst for the WGS process. Afterwards, for Au 1 /CeO 2- x , three reaction pathways (redox path, formate path and carboxyl path) are calculated. The predominant reaction pathway is the carboxyl pathway, and hydrogen production is the rate-determining step (RDS). For the purpose of designing single metal-support catalysts for the LT-WGS reaction, this paper gives information on the strong metal-support interaction (SMSI). [Display omitted] • LT-WGS reaction on Au 1 single atom supported on four metal oxides is carried out. • The oxygen vacancy (O v) of oxide support plays a key role in Au 1 stabilization. • H 2 O dissociates on O v and Au 1 /CeO 2- x has the lowest H 2 O dissociation energy. • Au 1 /CeO 2- x takes carboxyl path, H 2 generation is the rate limiting step. [ABSTRACT FROM AUTHOR]

Mesoporous multicomponent materials with uniform pore sizes and well-defined network geometries are viewed as highly attractive candidates in the catalysis field. However, their synthesis at a high homogeneity level is considered quite challenging. Herein, alumina based mixed oxides (Al/Ce/Cu or Fe) are produced through a facile evaporation-induced-self-assembly route and tested towards preferential oxidation of CO in H 2 -rich gas. The effect of several synthetic parameters is investigated, with citric acid addition identified as a key factor in view of obtaining high mesoscopic order and notable homogeneity, particularly at high dopant amounts. Following thermal aging at 900 °C, metal oxides distribution and nanoporous nature are well-preserved with a parallel nucleation of ceria nanoparticles into the semi-crystalline inorganic framework. CO-PROX assessment of the aged samples reveals a drastic enhancement in catalytic activity, especially for the ternary Cu–Ce–Al system, associated with material's structural reconstruction strongly affecting metal–support interaction. [Display omitted] • Multicomponent alumina based mesoporous oxide catalysts. • Coupling high dopants' amount with homogeneity in distribution and pore arrangement. • Notable thermal stability after aging at 900 °C. • Drastic enhancement in CO-PROX activity after thermal aging. • CeO 2 structural evolution upon aging affords easily reducible/highly reactive sites. [ABSTRACT FROM AUTHOR]

The properties of Pt-based catalysts could be modified by the addition of second metal and formation of an alloy or metal-oxide interface. In the present work we studied the effect of Cr, Mo and W doping on the Pt performance in CO TOX and PROX reactions. [Pt(NH 3) 4 ]MO 4 (M = Mo, W) salts and solid solutions [Pt(NH 3) 4 ](M'O 4) x (M″O 4) 1-x (M' = Cr,Mo,W; M'' = Cr,Mo,W) were used as a single-source catalyst precursors. They were synthesized and characterized by a number of physicochemical methods of analysis. The thermal properties of obtained salts were studied in an oxidative atmosphere. The process of the decomposition is multistage and ends with a formation of platinum and the corresponding oxides of base metals (Cr/Mo/W). [ [Display omitted] ] • Novel complex salts [Pt(NH3)4]MO4 (M = Mo, W) were synthesized. • The thermal properties of synthesized salts were studied in an oxidative atmosphere. • The catalytic properties of metal-oxide catalysts were compared with the monometallic Pt in CO TOX and PROX processes. [ABSTRACT FROM AUTHOR]

Converting CO2 to valuable chemicals through a variety of thermal, photo-, and electro-catalytic reaction processes will reduce the net CO2 emission and contribute positively to the "net-zero" goal. C1 and C2 products are important chemical feedstocks and can be produced from the effective catalytic conversion of CO2. The key to developing effective CO2 conversion catalysts is an understanding of CO2 interaction and the elementary bond-breaking and formation steps on the active catalysts. Over the past two decades, density functional theory-based approaches have enabled both mechanistic understanding and catalyst design for CO2 activation and conversion. In this article, we review our recent effort in understanding the mechanism of CO2 activation and conversion, focusing on the unique role of the metal/metal oxide interfaces in both thermal and electrochemical catalytic CO2 reduction. We showed that In2O3-based catalysts exhibited a uniquely high methanol selectivity while suppressing CO formation from the reverse water–gas shift reaction. We have also demonstrated that the metal/metal-oxide interfaces can be tuned by selecting an appropriate metal and metal oxide to optimize its activity and selectivity for both thermal- and electro-catalytic reduction of CO2. The oxophilicity of the metal in the metal oxide can be used as a qualitative measure for determining the selectivity towards CH3OH or CH4 in the electro-catalytic reduction of CO2. The studies demonstrated the impact of the density functional theory-based atomic-level approaches in unravelling the reaction mechanism and predicting highly efficient catalysts and catalytic systems. [ABSTRACT FROM AUTHOR]

Metal-supported solid oxide electrolysis cells (MS-SOECs) are being developed for steam-to-hydrogen electrolysis, especially for utilization of dynamic or intermittent electrical power from renewable sources. Various aspects of the electrocatalyst processing and composition, and metal support structure were explored. Catalyst materials, infiltration temperature and infiltration cycles were optimized for high performance and durability. Numerous catalyst materials were screened for both oxygen and steam electrodes. The oxygen catalyst had moderate impact on both initial cell performance and durability. Reducing Ni content in the steam electrode had little effect on durability, but reduced initial performance. Ex-situ XRD analysis and cell assessment of catalyst infiltration temperature revealed that the optimal range is 750–850 °C. The best cell performance and durability was achieved with LSCF-SDC oxygen electrocatalyst and SDC-Ni (60:40 vol%) steam electrocatalyst infiltrated 11 times at 800 °C and operated at 700 °C. At low steam content, a significant mass transport limitation on the steam side results in limiting current behavior. Thinner and more porous metal supports were implemented, and found to improve steam mass transport at low steam content, relevant for SOECs operating under high H 2 recycle rate or high steam utilization. • MS-SOECs are optimized for performance and initial durability. • Performance is sensitive to infiltrated catalyst calcining temperature, and Ni content. • Thinner and more porous metal support improves performance at low steam content. [ABSTRACT FROM AUTHOR]

In the present research, we report on an innovative and quick procedure for the synthesis of metal oxides: a sol-gel procedure which is followed by two steps that are assisted by microwaves (MW) heating. First, MW heating promotes gel drying and successively permits the calcination of the xerogel in a few minutes, using a susceptor that rapidly reaches high temperatures. The procedure was employed for the synthesis of zirconium dioxide (ZrO2), and MW-assisted calcination enables the collection of tetragonal ZrO2, as confirmed by different experimental techniques (PXRD, HR-TEM and Raman spectroscopy). Using this MW-assisted sol-gel procedure, a promoted sulphated zirconia (SZ) has been obtained. Both the nature and strength of SZ surface acidity have been investigated with FTIR spectroscopy using CO and 2,6-dimethylpyridine (2,6-DMP) as probe molecules. The obtained materials were tested as catalysts in acid hydrolysis of glucose to give 5-(hydroxymethyl)furfural (5-HMF). One of the obtained catalysts exhibited a better selectivity towards 5-HMF with respect to SZ material prepared by a classical precipitation route, suggesting that this procedure could be employed to obtain a well-known catalyst with a less energy-consuming procedure. Catalytic results also suggest that good selectivity to 5-HMF can be achieved in aqueous media in the presence of weak Lewis and Brønsted sites. [ABSTRACT FROM AUTHOR]

Nitrogen oxides emitted from diesel vehicle exhaust seriously endanger the atmospheric environment and human health, which have attracted people's attention. Among numerous nitrogen oxide (NOx) removal technologies, photocatalytic removal of NOx and SCR have received widespread attention. The photocatalytic treatment of NOx technology is a good choice due to its mild reaction conditions and low costs. Moreover, NH3-SCR has been widely used in denitration technology and plays an important role in controlling NOx emissions. In NH3-SCR technology, the development of high-efficiency catalysts is an important part. This paper summarizes the research progress of metal oxide catalysts for NH3-SCR reactions, including V-based catalysts, Mn-based catalysts, Fe-based catalysts, Ce-based catalysts, and Cu-based catalysts. Meanwhile, the detailed process of the NH3-SCR reaction was also introduced. In addition, this paper also describes a possible SO2 poisoning mechanism and the stability of the catalysts. Finally, the problems and prospects of metal oxide catalysts for NOx removal were also proposed. [ABSTRACT FROM AUTHOR]

The abundant C1 source CO2 can be utilized to produce value-added chemicals through hydrogenation technology. A bifunctional catalyst consisting of reducible metal oxide Cr2O3 and acidic zeolite ZSM-5 was designed for the direct conversion of CO2 + H2 into valuable aromatics, especially para-xylene (PX), via the methanol-mediated pathway. The twin structure of ZSM-5 (ZSM-5T), with sinusoidal channels that are predominantly exposed to the external surface, enhances the possibility of the transformation of methanol into PX due to the favorable diffusion dynamic of PX in the sinusoidal channels. Via the bifunctional catalyst Cr2O3&ZSM-5T, a PX selectivity of 28.7% and PX space-time yield (STY) of 2.5 gCH2 h−1 kgcat−1 are achieved at a CO2 conversion rate of 16.5%. Furthermore, we rationally modify the ZSM-5T zeolite via Cu species doping and amorphous SiO2 shell coating (Cu-ZSM-5T@SiO2). After combining with the Cr2O3 catalytic component, the CO2 conversion (18.4%) and PX selectivity (33.8%) are increased to some extent, which systematically increases the STY of PX to 3.0 gCH2 h−1 kgcat−1. The physicochemical property of the acidic zeolite and the corresponding structure-function relationship in enhancing the PX productivity are discovered. Our work provides a novel catalyst design idea to boost PX synthesis performance from CO2 hydrogenation. [ABSTRACT FROM AUTHOR]

The one-pot production of a relevant chemical such as 1,5-pentanediol (1,5-PDO) from sustainable sources (furfural) is a key reaction to compete with existing fossil sources. This work provides new evidence on the influence of the starting reagent, the features of layered double hydrotalcite (LDH)-derived catalysts in the form of mixed metal oxides (MMO) and of reaction conditions on the productivity of 1,5-PDO under batch conditions. Unlike reported studies, these results suggest the direct pathway through furfuryl alcohol intermediates, allowing the one-pot production from furfural at lower temperature than analogous systems. Productivity is maximized when Co2+ species partially substitute Mg2+ species in parent LDH, yielding promising pentanediol yields under mild reaction conditions. MMOs containing Co2+ sites show marked differences compared to analogous bivalent metals, which is here attributed to the position in which reaction intermediates such as furfuryl alcohol are adsorbed onto surface specie. This is consistent with characterized surface species by XRD, temperature programmed reduction under H2, and chemisorption experiments using CO or CO2 as probe molecules, indicative of a proper balance between metal and basic sites onto MMOs. The reported data aim to provide new reaction evidence to contribute into the search of sustainable 1,5-PDO sources. [ABSTRACT FROM AUTHOR]

Catalysts (metaloxide/carbon support) for carbon monoxide methanation were prepared with two different preparation methods using three different metals and three different carbon supports. While nickel (Ni), iron (Fe), and cobalt (Co) were used as metals, graphene oxide, activated carbon and mesoporous carbon were used as carbon support. Two traditional preparation methods, impregnation and co-precipitation, were used in order to prepare the catalysts. The X-ray diffraction, N2 physisorption, high-resolution transmission electron microscopy, and scanning electron microscopy analysis were used to characterize the catalysts. The CO methanation studies were conducted on all catalysts. The highest surface area results were obtained over the iron oxide composed catalysts. It was found that the impregnation method is the most suitable method for obtaining a high surface area. The average pore diameters of the catalysts entered to the mesopore diameter scale in the Dubinin classification. Except for active carbon-supported iron and cobalt catalysts, other catalysts have crystal phases due to the NiO, Fe2O3, and Co3O4, according to the composition of catalysts. Activated carbon-supported iron and cobalt catalysts showed an amorphous phase structure. The catalysts prepared by the impregnation method had higher activity. Higher activities were obtained from the graphene oxide supported catalysts. When activities were evaluated in terms of active component (metal oxide) type, cobalt oxide active component provided better results. Co3O4/graphene oxide catalyst prepared by the impregnation method leads to 100% CO conversion and 85% CH4 formation at 275 °C. [ABSTRACT FROM AUTHOR]

Highly efficient catalysts play an important role in the effective use of biomass oil to produce clean fuel. In this work, pure‐phase Ni−Mo bimetallic nitrides (Ni2Mo3N and Ni3Mo3N) with different stoichiometric ratios are prepared by temperature‐programmed nitridation of the metal oxide precursors in ammonia, which are investigated in the hydrodeoxygenation of methyl palmitate in the fixed‐bed reactor at moderate conditions. The physical and chemical properties of catalysts were evaluated by H2‐TPR, XRD, SEM, TEM, XPS, and CO chemisorption. The Ni2Mo3N catalyst presents the best methyl palmitate hydrogenation activity (con.%=95.4 %) and the maximum hexadecane selectivity (95.0 %), which is obviously higher than those of Ni3Mo3N and Mo2N catalysts. By introducing transition metal Ni into the Mo2N lattice to form nickel‐molybdenum bimetallic nitride, the lattice structure and electronic structure of the Mo active center have been changed, which greatly enhances the hydrodeoxygenation performances for the transformation of biomass oil to clean fuel. [ABSTRACT FROM AUTHOR]