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After stepping into the pandemic, it has been entirely not bizarre to wear facial masks to diminish the spreading of viruses in human daily outings. Due to the low expense and stable protection capability, disposable masks are the most widely used types of medical masks. By functionalities and medical standards, disposable masks mainly consist of surgical masks and N95/KN95 respirators in the market. In the assembling scheme, there are typically three or more polymeric layers (i.e., mainly polypropylene) in disposable masks; in addition, the ear loops in masks are usually made from textile constituents, such as polyamides. Therefore, the vast utilization and rapid accumulation of disposal mask waste can directly bring an emerging crisis of foreseeable environmental pollution. To minimize and prevent such mask-led microplastic pollution, chemical pyrolysis of mask waste is one of the most feasible and promising strategies. Via the direct and selective pyrolysis of disposable masks, it can effectively convert the mask waste into high-value fuel-range chemicals, e.g., liquid hydrocarbon blends, aromatics, C1–5 gas alkanes/alkenes, hydrogen, etc. In this way, it can not only tackle environmental challenges from plastic waste but also afford sustainable fuels with low carbon emission and circular economy. [ABSTRACT FROM AUTHOR]

The density functional theory (DFT) method was used to investigate the mechanism of N-arylation of nitrogen heterocycles with aryl halides catalyzed by CoCl 2 ·6H 2 O in the presence of different chelating ligands. Cobalt complexes of N, Nˊ -dimethylethenediamine ligand were selected as model catalytic system. Calculations were carried out for single electron transfer, oxidative addition/reductive elimination, iodine atom transfer and σ-bond metathesis mechanism for different possible intermediate cobalt complexes in the reaction solution. According to calculation results, the single electron transfer mechanism has the lowest activation energy (23.3 kcal/mol) for the C-N coupling reaction. Iodine atom transfer mechanism shows 25.6 kcal/mol activation energy for the reaction. Activation energy for oxidative addition/reductive elimination (49.2 kcal/mol) and σ-bond metathesis mechanism (45.5 kcal/mol) is very high under the given experimental conditions. [ABSTRACT FROM AUTHOR]

The density functional theory (DFT) method was used to investigate the mechanism of ligand-free copper-catalyzed arylation of nitrogen heterocycles from benzenediazonium acetate. Two possible mechanisms, single electron transfer and oxidative addition/reductive elimination reaction mechanism were investigated for two possible Cu(I) complexes in the reaction solution. Complex 1 has an acetate and a pyrazole ligand coordinated to Cu(I), and complex 2 has two pyrazole ligands coordinated to Cu(I). Both Cu(I) complexes have sufficiently low activation energy barriers for oxidative addition/reductive elimination reactions. Activation energy barrier for single electron transfer reaction is significantly higher than oxidative addition/reductive elimination reaction. [ABSTRACT FROM AUTHOR]

Direct coupling of alkanes via C−H activation of terminal methyl groups has acquired tremendous interests both scientifically and technically. Herein we present the results of linear alkane-coupling at the step edges of Cu surfaces at modulated temperatures. Combining the observations of scanning tunneling microscopy (STM) with density functional theory plus dispersion (DFT-D) calculations, we elucidate the mechanism of the reaction and demonstrate that the low activation barrier relies on heterogeneous catalysis at the upper step edges, where low-coordinated surface atoms are present. We further reveal the generality of the reaction, so that it can be applied on the step edges of different facets of surfaces. [ABSTRACT FROM AUTHOR]

• Supported bimetallic catalysts typically possess superior performances than monometal catalysts and the impregnation method has been widely applied for the bimetallic catalyst preparations. • Impregnation sequences could play their significant roles on the physical and chemical properties of supported bimetallic catalysts. • A host of characterizations from impregnation sequential effects were briefly evaluated by reviewing the recent representative literatures. • The investigation of the nature of active sites and the structural dynamics on bimetallic catalysts are prospected accordingly to enhance the fundamental understanding of sequential influences. • The appropriate measurement of reaction rates is much required to compare the bimetallic catalysts that are prepared by different sequences of impregnations. Supported bimetallic catalysts have been paid great attention regarding their excellent catalytic performances in chemical process. Notably, comparing to monometallic catalysts, the synergetic properties of dual-metal-based materials demonstrate unique physiochemical functionalities that single metal materials do not possess. The preparation of supported bimetallic materials is widely conducted with applying the impregnation method because of the straightforward and inexpensive technique. Wherein, the impregnation of dual metals on support could either undergo co-impregnation or sequential impregnations. It has been frequently reported that there are substantial differences in physiochemical properties and catalyst performances by impregnation sequences. Specifically, during the investigation of various sequential impregnated bimetallic catalysts, a host of characterization strategies are employed to compare the physical and chemical properties that play vital role to impact the catalyst activity/selectivity/stability. However, it is still not well understood regarding the impregnation sequential effects, such as the nature of bimetallic active sites and the dynamics of bimetallic surface structures along with reaction progress. This presenting perspective article is devoted to take a succinct review regarding the general sequential impacts on the physiochemical properties and further profoundly address the research outlook in this topic. [Display omitted]. [ABSTRACT FROM AUTHOR]

Highlights: [•] We explore that the remarkably catalytic role in which nitric acid plays in the hydrolysis of SO3. [•] We elucidate the reaction mechanisms of the SO3 with H2O in the presence of nitric acid. [•] Of great importance is estimated for the formation of sulfuric acid with the assistance of nitric acid in the atmosphere. [ABSTRACT FROM AUTHOR]

The alkylation of ketones or secondary alcohols using alcohols as alkylating agents via hydrogen borrowing strategy presents a powerful method for the synthesis of ɑ‐alkylated ketones. In this review, we summarize the progress catalyzed by Ir, Pd, Rh, Ru, Mn, Fe, Co, Ni, and Cu catalysts for the α‐alkylation of ketones with alcohols and cross‐coupling of secondary alcohols with alcohols from 2017 to 2021. A wide range of ketones (aromatic and aliphatic ketones) and alcohols (benzylic and aliphatic primary alcohols, aromatic and aliphatic secondary alcohols, alkenyl alcohols, and diols) are well tolerated. Furthermore, we also discuss current challenges and propose perspectives on the coming development in this filed. The objective of the present review is to give an overview on recent advances for α‐alkylation of ketones with alcohols and β‐alkylation of secondary alcohols with alcohols. Finally, we hope that this review will give inspirations on alkylation of ketones or secondary alcohols with alcohols. [ABSTRACT FROM AUTHOR]

The surface frustrated Lewis pairs (SFLPs) open up new opportunities for substituting noble metals in the activation and conversion of stable molecules. However, the applications of SFLPs on a larger scale are impeded by the complex construction process, low surface density, and sensitivity to the reaction environment. Herein, wurtzite‐structured crystals such as GaN, ZnO, and AlP are found for developing natural, dense, and stable SFLPs. It is revealed that the SFLPs can naturally exist on the (100) and (110) surfaces of wurtzite‐structured crystals. All the surface cations and anions serve as the Lewis acid and Lewis base in SFLPs, respectively, contributing to the surface density of SFLPs as high as 7.26×1014 cm−2. Ab initio molecular dynamics simulations indicate that the SFLPs can keep stable under high temperatures and the reaction atmospheres of CO and H2O. Moreover, outstanding performance for activating the given small molecules is achieved on these natural SFLPs, which originates from the optimal orbital overlap between SFLPs and small molecules. Overall, these findings not only provide a simple method to obtain dense and stable SFLPs but also unfold the nature of SFLPs toward the facile activation of small molecules. [ABSTRACT FROM AUTHOR]

The surface frustrated Lewis pairs (SFLPs) open up new opportunities for substituting noble metals in the activation and conversion of stable molecules. However, the applications of SFLPs on a larger scale are impeded by the complex construction process, low surface density, and sensitivity to the reaction environment. Herein, wurtzite‐structured crystals such as GaN, ZnO, and AlP are found for developing natural, dense, and stable SFLPs. It is revealed that the SFLPs can naturally exist on the (100) and (110) surfaces of wurtzite‐structured crystals. All the surface cations and anions serve as the Lewis acid and Lewis base in SFLPs, respectively, contributing to the surface density of SFLPs as high as 7.26×1014 cm−2. Ab initio molecular dynamics simulations indicate that the SFLPs can keep stable under high temperatures and the reaction atmospheres of CO and H2O. Moreover, outstanding performance for activating the given small molecules is achieved on these natural SFLPs, which originates from the optimal orbital overlap between SFLPs and small molecules. Overall, these findings not only provide a simple method to obtain dense and stable SFLPs but also unfold the nature of SFLPs toward the facile activation of small molecules. [ABSTRACT FROM AUTHOR]

• DBU-2EG multimer absorbent with double H-bonds was designed by intermolecular self-assembly using DBU and EG. • The concentrated electron density around O in EG of DBU-2EG is in favor of the absorption of H 2 S by DBU-2EG. • A method for developing a high-efficiency absorbent for H 2 S was constructed by designing H-bonds in an absorbent molecule. • DBU-2EG multimer absorbent has a high absorption solubility of 5.8 mol/kg (25 °C, 1 atm) for H 2 S. A double H-bonds multimer absorbent for hydrogen sulfide (H 2 S) absorption was designed via intermolecular self-assembly using 1,8-Diazabicyclo-[5.4.0]-undec-7-ene (DBU) and ethylene glycol (EG) under the guidance of quantum chemical calculation (QCC). The formation mechanisms of multimer absorbents and the absorption mechanisms between those absorbents and H 2 S were explored by QCC and experiments. It was found that the formed multimer absorbent at the DBU/EG molar ratio of 1:2 has two intermolecular H-bonds with different strengths between DBU and EG, which can combine with H 2 S via strong intermolecular forces. Furthermore, the characteristics analysis of multimer absorbents and complexes confirmed the above mechanisms. Experimental results indicated that the DBU-2EG has a higher H 2 S solubility of 5.8 mol/kg multimer absorbent with a low viscosity value of 15.12 mPa·s at 25 °C and better regeneration performance. The multimer absorbent exhibits great potential in the H 2 S capture process. [ABSTRACT FROM AUTHOR]

Direct methane conversion (DMC) to oxygenates at low temperature is of great value but remains challenging due to the high energy barrier for C−H bond activation. Here, we report that in situ decoration of Pd1‐ZSM‐5 single atom catalyst (SAC) by CO molecules significantly promoted the DMC reaction, giving the highest turnover frequency of 207 h−1 ever reported at room temperature and ~100 % oxygenates selectivity with H2O2 as oxidant. Combined characterizations and DFT calculations illustrate that the C‐atom of CO prefers to coordinate with Pd1, which donates electrons to the Pd1−O active center (L−Pd1−O, L=CO) generated by H2O2 oxidation. The correspondingly improved electron density over Pd−O pair renders a favorable heterolytic dissociation of C−H bond with low energy barrier of 0.48 eV. Applying CO decoration strategy to M1‐ZSM‐5 (M=Pd, Rh, Ru, Fe) enables improvement of oxygenates productivity by 3.2–11.3 times, highlighting the generalizability of this method in tuning metal‐oxo electronic structure of SACs for efficient DMC process. [ABSTRACT FROM AUTHOR]

Direct methane conversion (DMC) to oxygenates at low temperature is of great value but remains challenging due to the high energy barrier for C−H bond activation. Here, we report that in situ decoration of Pd1‐ZSM‐5 single atom catalyst (SAC) by CO molecules significantly promoted the DMC reaction, giving the highest turnover frequency of 207 h−1 ever reported at room temperature and ~100 % oxygenates selectivity with H2O2 as oxidant. Combined characterizations and DFT calculations illustrate that the C‐atom of CO prefers to coordinate with Pd1, which donates electrons to the Pd1−O active center (L−Pd1−O, L=CO) generated by H2O2 oxidation. The correspondingly improved electron density over Pd−O pair renders a favorable heterolytic dissociation of C−H bond with low energy barrier of 0.48 eV. Applying CO decoration strategy to M1‐ZSM‐5 (M=Pd, Rh, Ru, Fe) enables improvement of oxygenates productivity by 3.2–11.3 times, highlighting the generalizability of this method in tuning metal‐oxo electronic structure of SACs for efficient DMC process. [ABSTRACT FROM AUTHOR]

The development of a single-atom iron catalyst (Fe©SiO2) for the direct conversion of methane to olefins, aromatics, and hydrogen is a breakthrough in the field of nonoxidative conversion of methane (NCM). However, the optimization of the catalyst remains desirable for industrial applications. Herein, 25 transition metals, including Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt, and Au, are selected to replace the central Fe atom for screening out better single-atom catalysts for the NCM. Using the performance on the activation of methane, such as the adsorption energy of methane, the dissociation energy, and the barrier of methane as the screening descriptors, Mn©SiO2, Fe©SiO2, W©SiO2, and Re©SiO2 are first screened out. The remarkable performance of the four catalysts on methane activation is attributed to the unique geometric structure and the d z 2 orbitals of the central metal crossing over the Fermi level, which can benefit the interaction between methane and the catalysts. By considering the catalytic performance on the whole pathway of methane to ethylene, W©SiO2 is finally selected as the most active catalyst for the NCM, which has the lowest rate-determining barrier of 1.62 eV and the smallest free energy span (1.06 eV) of the overall catalytic cycle. [ABSTRACT FROM AUTHOR]

Recently discovered homogeneous frustrated Lewis pairs (FLPs) have attracted much attention for metal-free catalysis due to their promising potential for the activation of small molecules (e.g., H2, CO, CO2, NOx and many others). Hence, a wide range of these homogeneous FLPs have been extensively explored for many advanced organic syntheses, radical chemistry and polymerizations. In particular, these FLPs are efficiently utilized for the hydrogenation of various unsaturated substrates (e.g., olefins, alkynes, esters and ketones). Inspired by the substantial progress in these homogeneous catalytic systems, heterogeneous FLP catalysts, including semi-solid and all-solid catalysts, have also emerged as an exciting and evolving field. In this review, we highlight the recent advances made in heterogeneous FLP-like catalysts and the strategies to construct tailorable interfacial FLP-like active sites on semi-solid and all-solid FLP catalysts. Challenges and outlook for the further development of these catalysts in synthetic chemistry will be discussed. [ABSTRACT FROM AUTHOR]

The standard thermite reaction enthalpies (Δ r H m θ ) for seven metal oxides were theoretically analyzed using density functional theory (DFT) under five different functional levels, and the results were compared with experimental values. Through the comparison of the linear fitting constants, mean error and root mean square error, the Perdew-Wang functional within the framework of local density approximation (LDA-PWC) and Perdew-Burke-Ernzerhof exchange-correlation functional within the framework of generalized gradient approximation (GGA-PBE) were selected to further calculate the thermite reaction enthalpies for metal composite oxides (MCOs). According to the Kirchhoff formula, the standard molar reaction enthalpies for these MCOs were obtained and their standard molar enthalpies of formation (Δ f H m θ ) were finally calculated. The results indicated that GGA-PBE is the most suitable one out of the total five methods to calculate these oxides. Tungstate crystals present the maximum deviation of the enthalpies of thermite reactions for MCOs and these of their physical metal oxide mixtures, but ferrite crystals are the minimum. The correlation coefficients are all above 0.95, meaning linear fitting results are very precise. And the molar enthalpies of formation for NiMoO 4 , CuMoO 4 , PbZrO 3 ( Pm/3m ), PbZrO 3 ( PBA2 ), PbZrO 3 ( PBam ), MgZrO 3 , CdZrO 3 , MnZrO 3 , CuWO 4 and Fe 2 WO 6 were first obtained as −1078.75, −1058.45, −1343.87, −1266.54, −1342.29, −1333.03, −1210.43, −1388.05, −1131.07 and − 1860.11 kJ·mol −1 , respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • The effect of Mn doping size over Al 2 O 3 on NO oxidation activity were elucidated. • Mn SACs/Cs -Al 2 O 3 exhibits a superior NO-NO 2 capacity compared with Mn NPs -Al 2 O 3. • The coordination environment of Mn species significantly affects the mobility of O sur. • Reducing Mn size from NPs to SACs/Cs promotes labile nitrate species formation. The exploitation of transitional metal catalysts for high-efficient conversion of NO to NO 2 still persists as an imperative issue due to the high cost of currently used Pt–based catalysts. Herein, we report a TEA-modification strategy to anchor Mn single atoms/clusters on Al 2 O 3 (Mn/Al 2 O 3 -T) for NO oxidation. Activity tests show that Mn/Al 2 O 3 -T (T 83 = 275 °C) displays a superior NO-to-NO 2 capacity compared with the unmodified Mn nanoparticle on Al 2 O 3 (Mn/Al 2 O 3 -B, T 66 = 300 °C) and Pt/Al 2 O 3 (T 43 = 350 °C) counterparts. Comprehensive characterization and DFT calculations discover that the effective adjustment of TEA can promote the generation of coordination unsaturated Mn sites with elongated Mn-O bonds, which can improve the mobility of surface lattice oxygen and facilitate the activation of molecular oxygen. Additionally, reducing Mn size from nanoparticles to single atoms/clusters favors the formation of labile nitrate species and facile desorption of NO 2 , thereby regenerating active sites and accelerating overall NO oxidation reaction. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of SA-FLP dual-active-site catalysts are designed for the conversion of CH 4 and CO 2 to acetic acid. • The SA-FLP dual active sites can concurrently adsorb and activate CH 4 and CO 2. • Ag 1 -FLP catalyst exhibits the best performance in the reaction of CH 4 and CO 2 to acetic acid. Direct conversion of CH 4 and CO 2 into acetic acid is an emerging attractive process but remains a significant challenge due to the inherent stability of both molecules. Hence, developing active and stable catalysts is crucial for the simultaneous activation of CO 2 and CH 4. Herein, we designed the "Single-Atom" - "Frustrated-Lewis-Pair" (SA-FLP) dual-active-site catalysts for the co-conversion of CH 4 and CO 2 to acetic acid based on density functional theory (DFT) calculations. The SA sites were introduced by doping the transition-metal (TM) atoms (TM = Fe, Co, Ni, Cu; Ru, Rh, Pd, Ag; Os, Ir, Pt, Au) into CeO 2 (1 1 0) surface, and the FLP sites were constructed by the regulation of surface oxygen vacancies. Our results demonstrate the introduction of SA into CeO 2 surface could facilitate the formation of oxygen vacancies, and thus promotes the formation of FLP sites. The SA-FLP dual active sites can concurrently activate CH 4 and CO 2 with CH 4 preferentially activated at SA sites and CO 2 preferentially activated at FLP sites. Among the twelve SA-FLP catalysts, Ag 1 -FLP catalyst exhibits the best performance in the reaction of CH 4 and CO 2 to acetic acid with a rate-determining barrier of 1.12 eV and a turnover frequency of 2.52 × 10–3 s−1 at 573 K and 2 bar. This work not only offers a novel catalyst prototype for the co-conversion of CH 4 and CO 2 to acetic acid but also provides insights into developing dual-active-site catalysts on earth-abundant metal oxide materials. [ABSTRACT FROM AUTHOR]

• A microkinetic model combining oxygen supply and catalysis was established for Fe 2 O 3. • The influence of TMs-doping in Fe 2 O 3 on oxygen carriers was systematically studied. • Ni-doping in Fe 2 O 3 has been confirmed to enhance the formation rate and the selectivity of CO. The rate-matching between oxygen migration and surface catalytic reaction of oxygen carrier (OC) is a critical determinant for the reaction selectivity of the chemical looping reforming (CLR) of methane. However, the theoretical mechanism behind this rate-matching relationship is still unclear. Herein, we propose to use density functional theory (DFT) combined with microkinetic simulations to establish a model integrating the methane oxidation reactions with oxygen migration kinetics on α-Fe 2 O 3 oxygen carrier. Our calculated results reveal that the transition metals (TMs)-doping such as Co, Ni, and Cu after Fe element in the periodic table can accelerate the oxygen migration rate as it promotes the upshift of the O p -band center. Moreover, a suitable oxygen migration energy barrier of about 1.0 eV is helpful to enhance the harmonization of α-Fe 2 O 3 oxygen migration and surface catalytic reactions. Based on this, Ni-doping in α-Fe 2 O 3 is predicted to be able to enhance the oxygen migration rate to match the rate of first-step methane dissociation, thereby simultaneously improving the reaction rate and the selectivity in the CLR of methane to syngas. These results could help to understand the relationship between oxygen migration and surface catalytic reaction rates and pave the way for the rational design of metal oxide oxygen carriers. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ionic liquid was chemically bonded to mesoporous HAP. • High utilization of hydroxyl binding (90 %) produced high ILs loading (0.468 mmol/g). • High yield (98.7%) and high selectivity (100%) of propylene carbonate (PC). • Autocatalysis was found in the CO 2 fixed reaction. In this study, hydroxyapatite (HAP) with abundant surface hydroxyl and large pores was used as the ionic liquid ([DMCA]X) immobilization carrier, where the surface hydroxyl groups of HAP were used as binding sites and the n-halogen-acids were used as bonding agents. The supported ionic liquid catalysts [DMCA]X-n-HAP were characterized by XRD, TEM, TG and FTIR, proving that the ionic liquids were successfully bonded onto the surface of HAP. The utilization of hydroxyl sites on the surface of HAP was as high as 90%. The above catalysts were used to catalyze the cycloaddition reaction of CO 2 and propylene oxide (PO), and the yield and selectivity of propylene carbonate (PC) were up to 98.7% and 100%, respectively. The length effect of the bonding agents on the catalyst performance was also studied, and found that n-chlorine-butyric acid was the most suitable chemical for channel structure of HAP and spatial freedom of ionic liquid. In addition, the effects of halogen anion and hydroxyl hydrogen on the performance of the reaction were also studied. Importantly, autocatalysis was discovered in the reaction. Finally, the reaction intermediates and reaction mechanism of CO 2 cycloaddition were investigated by in situ -DRIFTS, revealing that ring-open of PO is rate-determining step. [ABSTRACT FROM AUTHOR]

The gas-phase reactions of sulfuricacid catalyzed hydrolysis offormaldehyde and formaldehyde with sulfuric acid and H2SO4···H2O complex are investigatedemploying the high-level quantum chemical calculations with M06-2Xand CCSD(T) theoretical methods and the conventional transition statetheory (CTST) with Eckart tunneling correction. The calculated resultsshow that the energy barrier of hydrolysis of formaldehyde in gasphase is lowered to 6.09 kcal/mol from 38.04 kcal/mol, when the sulfuricacid is acted as a catalyst at the CCSD(T)/aug-cc-pv(T+d)z//M06-2X/6-311++G(3df,3pd)level of theory. Furthermore, the rate constant of the sulfuric acidcatalyzed hydrolysis of formaldehyde combined with the concentrationsof the species in the atmosphere demonstrates that the gas-phase hydrolysisof formaldehyde of sulfuric acid catalyst is feasible and could beof great importance for the sink of formaldehyde, which is in previouslyforbidden hydrolysis reaction. However, it is shown that the gas-phasereactions of formaldehyde with sulfuric acid and H2SO4···H2O complex lead to the formationof H2C(OH)OSO3H, which is of minor importancein the atmosphere. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mechanism of NH 3 catalytic combustion at low O 2 /NH 3 ratios is revealed. • The NH 3 consumption rate is mainly limited by NH coupling and the O*-assisted NH 3 dehydrogenation. • Altering the adsorption energies of NH and O can be used as the design method of alloy catalyst. • Two alloys, CuAg 3 and CuAu 3 , were predicated to have superior catalytic performance than Cu. Copper and its oxides possess excellent performance for ammonia catalytic combustion, but further improving the catalytic performance is still impeded by the limited understanding of the reaction mechanism. Herein, a density functional theory-based microkinetic study by considering the adsorbate-adsorbate interactions was performed to uncover the reaction mechanism under experimental conditions and further design the superior Cu-based bimetal catalysts. Our calculations demonstrate that the partially oxidized Cu(1 1 1) covered by oxygen atoms is the active phase. The ammonia consumption rate is not only constrained by strong adsorption of NH and O species but also suppressed by elementary reactions of NH coupling and O-assisted NH 3 dehydrogenation from 400 to 800 K. Subsequently, two Cu-based bimetal catalysts, CuAg 3 and CuAu 3 , cautiously designed by weakening the adsorption of NH and O species and reducing the activation barriers of the two rate-determining steps, possess superior catalytic performance than the copper in ammonia catalytic combustion. Overall, our studies not only reveal the reaction mechanism of ammonia catalytic combustion on Cu(1 1 1) but also provide important insights for the design of optimal catalysts including two predicted Cu-based bimetal catalysts. [ABSTRACT FROM AUTHOR]

The effect of ZrO 2 crystalline phases on Pd/ZrO 2 for catalytic combustion of toluene was investigated. It was found that Pd/t-ZrO 2 showed superior activity when the toluene concentration was lower than 2000 ppm, while Pd/m-ZrO 2 performed better with toluene concentration higher than 3000 ppm. Kinetic studies showed that the reaction order of toluene on Pd/t-ZrO 2 and Pd/m-ZrO 2 is 0 and 2, respectively. The catalytic activity was controlled by combined effect of PdO activity and quantity, which was correlated with the interaction between palladium and zirconia. The t-ZrO 2 increased PdO species activity, while m-ZrO 2 could enhance the amount of PdO. DFT results showed that the p-band center of the O of PdO on t-ZrO 2 was higher, suggesting that PdO was more active. In situ -DRIFTS revealed that the reaction pathway of catalytic oxidation of toluene on Pd/ZrO 2 was as follows: toluene was oxidized stepwise to benzyl alcohol, benzaldehyde, benzoic acid, CO 2 and H 2 O. [Display omitted] • Effect of Pd/ZrO 2 with different ZrO 2 crystal types for toluene combustion. • Catalytic activity was controlled by the comprehensive effect between PdO activity and PdO quantity. • The reaction order of toluene on Pd/t-ZrO 2 and Pd/m-ZrO 2 is 0 and 2, respectively. • Desorption energies of O atoms in O-Pd/m-ZrO 2 and O-P/t-ZrO 2. • The reaction pathway of catalytic combustion of toluene on Pd/ZrO 2 catalysts. [ABSTRACT FROM AUTHOR]

The direct, nonoxidative conversion of methane on a silica‐confined single‐atom iron catalyst is a landmark discovery in catalysis, but the proposed gas‐phase reaction mechanism is still open to discussion. Here, we report a surface reaction mechanism by computational modeling and simulations. The activation of methane occurs at the single iron site, whereas the dissociated methyl disfavors desorption into gas phase under the reactive conditions. In contrast, the dissociated methyl prefers transferring to adjacent carbon sites of the active center (Fe1©SiC2), followed by C−C coupling and hydrogen transfer to produce the main product (ethylene) via a key −CH−CH2 intermediate. We find a quasi Mars–van Krevelen (quasi‐MvK) surface reaction mechanism involving extracting and refilling the surface carbon atoms for the nonoxidative conversion of methane on Fe1©SiO2 and this surface process is identified to be more plausible than the alternative gas‐phase reaction mechanism. [ABSTRACT FROM AUTHOR]

The direct, nonoxidative conversion of methane on a silica‐confined single‐atom iron catalyst is a landmark discovery in catalysis, but the proposed gas‐phase reaction mechanism is still open to discussion. Here, we report a surface reaction mechanism by computational modeling and simulations. The activation of methane occurs at the single iron site, whereas the dissociated methyl disfavors desorption into gas phase under the reactive conditions. In contrast, the dissociated methyl prefers transferring to adjacent carbon sites of the active center (Fe1©SiC2), followed by C−C coupling and hydrogen transfer to produce the main product (ethylene) via a key −CH−CH2 intermediate. We find a quasi Mars–van Krevelen (quasi‐MvK) surface reaction mechanism involving extracting and refilling the surface carbon atoms for the nonoxidative conversion of methane on Fe1©SiO2 and this surface process is identified to be more plausible than the alternative gas‐phase reaction mechanism. [ABSTRACT FROM AUTHOR]

• Construction of frustrated Lewis pair (FLP) sites on cobalt borate (CoBO x). • FLP composed of interfacial independent metal ion as acidic site and hydroxyl on top of Co as basic site. • High concentration of surface hydroxyl group increases the possibility to form FLP. • FLP sites deliver high capability for H 2 activation and thereof hydrogenation of alkenes. Precisely controlling the surface physicochemical properties of a solid is critical to construct novel catalytic sites for various heterogeneous catalytic reactions. Herein, the interfacial frustrated Lewis pairs on cobalt borate (CoBO x) nanosheets are constructed by the surface hydroxyl on the top of one surface Co atom as the independent Lewis basic site and adjacent interfacial cobalt ion as the independent Lewis acidic site, enabling the efficient hydrogen activation as well as subsequent hydrogenation activity. Theoretical calculations and isotope experiments show that such a FLP site triggers the heterolytic hydrogen dissociation with a low activation energy of 0.37 eV. The catalytic performance, computational results, kinetic analysis and in-situ Fourier transform infrared spectroscopy profiles indicate the abundance of the surface hydroxyl on the top of the surface Co atom is the key for the construction of the interfacial FLP sites and subsequent hydrogen activation on those sites. Such a strategy provides a feasible approach to design the heterogenized FLP catalysts by controlling the interfacial physicochemical properties in term of the surface hydroxyl groups. [ABSTRACT FROM AUTHOR]

Searching the high-efficient, stable, and earth-abundant electrocatalysts to replace the precious noble metals holds the promise for practical utilizations of hydrogen and oxygen evolution reactions (HER and OER). Here, a series of highly active and robust Co-doped nickel phosphides (Ni2− xCo xP) catalysts and their hybrids with reduced graphene oxide (rGO) are developed as bifunctional catalysts for both HER and OER. The Co-doping in Ni2P and their hybridization with rGO effectively regulate the catalytic activity of the surface active sites, accelerate the charge transfer, and boost their superior catalytic activity. Density functional theory calculations show that the Co-doped catalysts deliver the moderate trapping of atomic hydrogen and facile desorption of the generated H2 due to the H-poisoned surface active sites of Ni2− xCo xP under the real catalytic process. Electrochemical measurements reveal the high HER efficiency and durability of the NiCoP/rGO hybrids in electrolytes with pH 0-14. Coupled with the remarkable and robust OER activity of the NiCoP/rGO hybrids, the practical utilization of the NiCoP/rGO|NiCoP/rGO for overall water splitting yields a catalytic current density of 10 mA cm−2 at 1.59 V over 75 h without an obvious degradation and Faradic efficiency of ≈100% in a two-electrode configuration and 1.0 m KOH. [ABSTRACT FROM AUTHOR]

[Display omitted] • The oxygen migration properties of Fe 2 O 3 (oxygen carrier) were systematically investigated. • The matching problem of oxygen migration rate with the surface catalytic reaction rate was studied. • A suitable concentration of oxygen vacancies is found to be beneficial for the chemical looping reforming of methane to syngas. The chemical looping reforming of methane to syngas is of great significance to the sustainable development of energy and environment, where the oxygen carrier (OC) is the core element of this technology. To study the oxygen migration properties of OCs and the matching problem of oxygen migration rate with the surface catalytic reaction rate, we present a theoretical study by taking the abundant and cheap α-Fe 2 O 3 as the model OC. It is found that the migration rate of lattice oxygen and the dissociation of methane will be enhanced as the concentration of surface oxygen vacancy increases. By comparing the oxygen migration rate with the methane dissociation rate, we reveal that the two rates can match well at a low surface oxygen vacancy concentration, which is the key to the selective production of syngas. Lower or higher surface oxygen vacancy concentration will lead to the products towards carbon dioxide or coke. [ABSTRACT FROM AUTHOR]

Relevant parameters for the leaching of palladium atoms from small Pd clusters during Heck reactions of bromobenzene and styrene have been explored computationally and experimentally. With density functional theory calculations, we modeled reaction free energies for removing a Pd atom from a Pd 6 model cluster and for forming Pd-ligand complexes. Oxidative addition of bromobenzene decreases the dissolution energy. Additional parameters and mechanisms, especially bromide ions render the leaching process notably exergonic. Model results exhibit the same trends as the targeted experiments where Pd leaching from supported catalysts (Pd/C, Pd/SiO 2) was monitored as function of reaction temperature, time and components. [Display omitted] • Direct correlation of palladium leaching with reaction rate of Heck coupling. • Quantification of Pd dissolution as function of temperature, time and composition. • Aryl halide, alkene and bromide favor leaching singly and in combination. • Qualitative agreement of DFT model simulations with closely targeted experiments. [ABSTRACT FROM AUTHOR]

Confining Ag single atom sites over antimony-doped tin oxide via atom trapping provides a rational strategy for designing thermally stable Ag single-atom catalyst for catalysis. • Ag single-atom species survive under high-temperature calcination at 800 °C. • Commercially available antimony-doped tin oxide stabilizes the Ag single atoms via atom trapping. • Structural assignment is supported by X-ray absorption spectra and theory calculations. • Mars-van Krevelen mechanism is proposed to be of relevance for mechanism of CO oxidation. Catalysts based on single atoms of noble metals have attracted much research interest. However, single atoms are mobile and prone to sintering (forming large clusters) under reaction conditions, especially at elevated temperatures. Driven by the long-standing interest in the development of thermally stable catalysts, there is an urgent demand for synthesizing sintering-resistant single-atom catalysts. Here, we report a high-temperature self-assembly route to fabricate thermally stable silver (Ag) single-atom catalysts by confining Ag single atom sites over antimony-doped tin oxide (ATO) via atom trapping at 800 °C in air. Unique self-dispersion of Ag species takes place over the ATO support after high-temperature aging, contrary to a tendency of sintering or coalescence. Extended X-ray absorption fine structure (EXAFS) analysis confirms the presence of predominantly high dispersed isolated Ag species in Ag/ATO-800 °C aged sample. CO oxidation tests reveal that the stable single-atom Ag-on-ATO catalyst shows negligible decay and even a slight increase in experimentally observed activity after 800 °C aging. In contrast, the high temperature aging treatment causes serious catalyst deactivation, as expected for conventional Al 2 O 3 supported noble metal catalyst. Our finding paves the way for using commercially available support to disperse and stabilize noble metal single atoms via atom trapping for the automotive CO oxidation reaction. [ABSTRACT FROM AUTHOR]

• Pd nanoparticles enclosed by {100}, {110} and {111} facets were successfully synthesized in-situ on rGO. • Facet effect in the dehydrogenation of LOHC was proposed for the first time. • Restriction mechanism of the macrokinetic and thermodynamic rate-determining step was preliminarily discussed. Facet structure plays an important role in many reactions. Generally, dehydrogenation reactions with only C H bond cleavage are often considered as structure insensitive reactions and therefore, there is no report on facet effect in reactions of LOHC for now. Herein, we report a facile synthesis of Pd nanoparticles enclosed by {100}, {110} and {111} facets supported on reduced graphene oxide. Combined with catalyst characterization, dehydrogenation performance study and DFT calculations, we found that the conversion rate and selectivity were strongly correlated with the facet structure of Pd, and {100} facet exhibited superior activity. We also identified the rate-determining step in the dehydrogenation of tetrahydro-N-ethylcarbazole to N-ethylcarbazole on Pd {100} facet. This work provides a basis for research requiring template Pd catalysts on rGO and broaden design methods for LOHC catalysts. [ABSTRACT FROM AUTHOR]

Methane-to-syngas conversion plays an important role in industrial gas-to-liquid technologies, which is commercially fulfilled by energy-intensive reforming methods. Here we present a highly selective and durable iron-based La0.6Sr0.4Fe0.8Al0.2O3-δ oxygen carrier for syngas production via a solar-driven thermochemical process. It is found that a dynamic structural transformation between the perovskite phase and a Fe0@oxides core–shell composite occurs during redox cycling. The oxide shell, acting like a micro-membrane, avoids direct contact between methane and fresh iron(0), and prevents coke deposition. This core–shell intermediate is regenerated to the original perovskite structure either in oxygen or more importantly in H2O–CO2 oxidant with simultaneous generation of another source of syngas. Doping with aluminium cations reduces the surface oxygen species, avoiding overoxidation of methane by decreasing oxygen vacancies in perovskite matrix. As a result, this material exhibits high stability with carbon monoxide selectivity above 95% and yielding an ideal syngas of H2/CO ratio of 2/1. Iron-based oxides are promising oxygen carriers for thermochemical syngas production, but can be prone to deactivation during the reaction. Here an iron-based catalyst is shown to transform reversibly between perovskite and core–shell structures during methane-to-syngas conversion, accounting for its high stability toward coke deposition. [ABSTRACT FROM AUTHOR]