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[Display omitted] Ce-based three-dimensional (3D) mesoporous microspheres with Mn homogeneous incorporation were synthesized. The CeMn-0.4, characterized by a Ce/Mn molar ratio of 6:4, demonstrated exceptional catalytic activity and stability. The formation of CeMn solid solution strengthened the Ce-Mn interaction, yielding higher concentrations of Ce3+ and Mn4+. Mn4+ initiated toluene preliminary activation owing to its robust oxidative properties, while Ce3+ contributed to oxygen vacancy generation, enhancing the activation of gaseous oxygen and lattice oxygen mobility. Integrating experiments and Density Functional Theory (DFT) calculations elucidated the oxygen reaction mechanisms. A portion of oxygen was converted into surface reactive oxygen species (O ads) that directly oxidized toluene. Additionally, the presence of oxygen vacancies promoted the participation of oxygen in toluene oxidation by converting it into lattice oxygen, which was crucial for the deep oxidation of toluene. Diffuse Reflectance Fourier Transform Infrared Spectroscopy (DRIFTS) indicated the accumulation of benzene-ring intermediates on the catalyst surface hindered continuous toluene oxidation. Thus, the abundant oxygen vacancies in CeMn-0.4 played a pivotal role in sustaining the oxidation process by bolstering the activation of gaseous oxygen and the mobility of lattice oxygen. [ABSTRACT FROM AUTHOR]

Thermal catalytic oxidation (TCO) technology is one of the effective methods to remove formaldehyde. CeO2, known for its oxygen storage capacity (OSC), is a promising rare earth material for the thermal catalytic oxidation of formaldehyde. The oxidation mechanism of formaldehyde on the CeO2(110) surface was investigated by density functional theory (DFT). Herein, formaldehyde and oxygen could not be stably adsorbed on a stoichiometric CeO2(110) surface, which was verified by charge-density difference and PDOS analysis. The defective CeO2(110) surface strengthened the adsorption of formaldehyde and oxygen by filling oxygen vacancies and evolved the free oxygen into chemisorbed oxygen. Formaldehyde was difficult to dehydrogenate on stoichiometric or defective CeO2(110) surfaces without oxygen. The water-forming capacity of chemisorbed oxygen promoted the dehydrooxidation of formaldehyde. It not only greatly reduced the energy barrier for the rate-determining step in the formaldehyde oxidation process but also helped formaldehyde to complete a complete oxidation cycle pathway. [ABSTRACT FROM AUTHOR]

Enhancing the resistance of SCR (Selective Catalytic Reduction) catalyst to K poisoning can be effectively achieved through modification. This study investigated the impact of transition metal modification on improving the ability of Ce/TiO 2 (CT) catalysts to resist K poisoning by DFT (Density functional theory) calculations. Mo-, Nb-, and W-doping could effectively suppress the adsorption of K. O v (oxygen vacancy) formation and hydrogenation reactions were both facilitated due to the modification of Cu, Co and Sb. The Cu-doping had a significant contribution to the adsorption of NH 3 and NO, and showed the best resistance to K poisoning in the adsorption of reactive species. Additionally, Cu-doping decreased the energy barriers for NH 3 dehydrogenation, NH 2 NO generation and decomposition, and NO 2 formation on CT catalyst, and weakened the inhibition effect of K on the above elementary reactions. Consequently, this provided an effective improvement in the k-poisoning tolerance of the CT catalysts. [Display omitted] • A method for screening modified elements based on DFT calculation was reported. • M-doping benefits hydrogenation, oxygen vacancy formation, and adsorption of NH 3 /NO. • M-doping mitigated the toxic effect of K in adsorption energy and energy barrier. • The modification effect of Cu was better than that of Co, Sb, Mo, Zr, Nb, W. • CCuT extremely weakened the inhibition of E-R and L-H mechanisms by K. [ABSTRACT FROM AUTHOR]

CeO 2 /TiO 2 catalyst is a promising material for realizing the integration of denitrification and mercury removal to reduce mercury emissions. Oxidation mechanism of Hg0 on CeO 2 /TiO 2 (001) surface in the presence of HCl and O 2 was studied by density functional theory (DFT). The results indicated that Hg0 was physically adsorbed on CeO 2 /TiO 2 (001) surface. As an important intermediate, HgCl was adsorbed on the surface of CeO 2 /TiO 2 (001) utilizing enhanced chemisorption, while the adsorption energy of HgCl 2 was only −57.05 kJ/mol. In the absence of HCl, mercury oxidation followed the Mars-Maessen mechanism with a relatively high energy barrier, and the product (HgO) was difficult to desorb, which hindered the reaction process. When HCl existed, reactive chlorine (Cl*) would be produced by the dissociation of HCl, and the mercury oxidation would follow the Langmuir-Hinshelwood mechanism. The co-existence of HCl and O 2 had no significant effect on the adsorption of Hg0, but reduced the reaction energy barrier and the final product (HgCl 2) was more easily desorbed from the catalyst surface. In addition, two complete cyclic reaction pathways for catalytic oxidation of Hg0 on CeO 2 /TiO 2 (001) surface were constructed to clarify the detailed reaction process. [Display omitted] • Hg0 oxidation mechanism on CeO 2 /TiO 2 (001) surface was studied by DFT calculation. • Difficult formation and desorption of HgO result in low oxidation efficiency. • HCl and O 2 could significantly reduce the reaction energy barrier. • Hg0 oxidation by HCl followed Langmuir-Hinshelwood mechanism. • Two complete catalytic cycles were constructed to understand the reaction pathway. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) is applied to investigate the stability and mechanical properties of NbxCy compounds. The structures of NbxCy compounds are optimized, and the results are in good agreement with previous work. The calculated results of the cohesive energy and the formation enthalpy of NbxCy show that they are thermodynamically stable structures, except for Pmc21-Nb2C. The mechanical properties such as the bulk modulus, Young's modulus, the shear modulus, and Poisson's ratio are obtained by Voigt—Reuss—Hill approximation. The results show that the Young's modulus and shear modulus of NbC are larger than other NbxCy compounds. The mechanical anisotropy is characterized by calculating several different anisotropic indexes and factors, such as universal anisotropic index (AU), shear anisotropic factors (A1, A2, A3), and percent anisotropy (AB and AG). The surface constructions of bulk and Young's moduli are illustrated to indicate the mechanical anisotropy. The hardness of NbxCy compounds is also discussed in this paper. The estimated hardness for all NbxCy compounds is less than 20 GPa. [ABSTRACT FROM AUTHOR]

[Display omitted] A dendrite-free and ultra-stable potassium metal composite anode has realized by infusing metallic potassium into a 3D potassiophilic α-MoC modified carbon cloth. Both the density functional theory (DFT) calculations and COMSOL Multiphysics demonstrate that the potassiophilic 3D host not only can facilitate fast molten potassium wetting and reduce nucleation overpotential but also homogenize the distribution of current density and inhibit potassium dendrite growth. • Dendrite-free K metal anode has realized by potassiophilic α-MoC modified host. • 3D potassiophilic host reduces nucleation overpotential and inhibits dendrite. • 3D potassiophilic host homogenizes the distribution of current density. • DFT and COMSOL demonstrate the effectiveness of 3D potassiophilic host. Potassium metal anodes are desirable for the advantages of low price, high abundance, and similar standard redox potential with metallic lithium. However, dendritic growth and large volume changes impede its practical application. Herein, a dendrite-free and stable potassium metal composite anode has realized by infusing metallic potassium into an α-MoC modified carbon cloth (α-MoC@CC). The prepared α-MoC@CC as a 3D host exhibits an intrinsic potassiophilicity based on experimental investigations and density functional theory (DFT) calculations, which not only facilitates fast molten potassium wetting but also reduces nucleation overpotential. In addition, the current density distribution of the composite anode carried out by COMSOL Multiphysics reveals that the 3D host can effectively reduce current density and inhibit dendrite growth. Consequently, the K@α-MoC@CC composite anode displays stable plating/stripping profiles for more than 2000 h with low polarization in symmetric batteries. As a practical device application, the K@α-MoC@CC composite anode demonstrates superior suitability when paired with Prussian blue cathode in a full battery. Significantly, this work represents an effective pathway to regulate potassium metal anode towards practical applications. [ABSTRACT FROM AUTHOR]

Abstract: DFT calculations were carried out to study the behavior of NO2 in the selective catalytic reduction of nitric oxides with ammonia on the surface of the V2O5 catalyst. The results showed that NO2 could readily reoxidize V4+–OH through two reaction routes: (1) NO2 directly reoxidizing V4+–OH to V5+ NO2 reacting with H2O or NH3 to produce HNO3, which subsequently reoxidizes V4+–OH to V5+ te-determining step of route 1 is the desorption of cis-HNO2 from the reoxidized V5+ endothermic by 9.91kcal/mol. Route 2 possesses an energy barrier of 7.44kcal/mol, less than route 1. This energetic comparison shows that route 2 is the predominant reaction mechanism at low temperature. Reactions of the by-product, HNO2, were also investigated. The results showed that both cis-HNO2 (route 1) and trans-HNO2 (route 2) can either react with NH3, producing H2O and N2, or react with themselves, producing H2O, NO and NO2. A systemic description of the behavior for NO2 in “fast” SCR on V2O5 surface, including the reaction routes and energy profiles, has been proposed in our work. [Copyright &y& Elsevier]

[Display omitted] • CeO 2 -TiO 2 catalyst followed both E-R and L-H mechanisms. • NH 2 NO was an important intermediate in E-R mechanism. • The reaction of adsorbed NO 2 with adsorbed NH 3 was the only form of L-H mechanism. • NH 2 formation from NH 3 dehydrogenation was the rate-limiting step of N 2 formation. The reaction mechanism over CeO 2 -TiO 2 catalyst was investigated using in-situ DRIFTS spectra and density functional theory (DFT) calculations. DRIFTS results revealed that the SCR reactions on CeO 2 -TiO 2 catalyst followed both E-R and L-H mechanisms. In the E-R mechanism, NH 2 NO species was considered as the reaction intermediate that decomposed into H 2 O and N 2. In the L-H mechanism, only adsorbed NO 2 species reacted with NH 3 to generate H 2 O and N 2. Based on the two mechanisms, the corresponding adsorption energy, activation energy barrier, and reaction heat in the process of NH 3 adsorption and activation, NH 2 NO formation and decomposition, O 2 dissociation, and NO oxidation were calculated by DFT. By combining the DRIFTS and DFT results, the detailed reaction pathways over CeO 2 -TiO 2 catalyst were obtained finally. [ABSTRACT FROM AUTHOR]