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We performed a systematic study of carbon monoxide oxidation on the nitrogen-doped penta-graphene by utilizing spin-polarized density functional theory calculations. The possible reaction pathways via both Eley–Rideal (ER) and Langmuir–Hinshelwood (LH) mechanisms were illustrated. The results manifest that the nitrogen-doped penta-graphene displays very high catalytic activity and is more competitive with many metal-based and carbon-based catalysts for low-temperature CO oxidation by reason of the very small energy barrier of the rate-limiting step (there is no activation energy for the ER mechanism and only 0.33 eV for the LH mechanism). This study opens a new avenue for the design of 2-D graphene-based materials and provides valuable clues for developing catalytic activity carbon materials for low-temperature CO oxidations. [ABSTRACT FROM AUTHOR]

In this work, we perform density functional theory (DFT) calculations to investigate the hydrogen adsorption on Pt 4 cluster supported on pristine, B-, and N-doped graphene sheets. It is found that the doping B or N atom in the graphene could enhance the interaction between the Pt 4 cluster and the supporting substrate. The first H 2 molecule is found to be dissociative chemisorption on the three substrates. Further, dissociative and molecular adsorption of multiple H 2 molecules are co-adsorbed on the three substrates. In addition, the interaction between Pt 4 (H 2 ) x and the substrate is illustrated for the stability of Pt 4 (H 2 ) x on the substrate. AIMD simulation is also performed to verify the stability and hydrogen storage. Accordingly, the B-graphene is predicted to be the most potential materials for hydrogen storage among these three materials. [ABSTRACT FROM AUTHOR]

We have performed a spin-polarized density functional theory (DFT) study for understanding the detailed reaction mechanism of CO and H 2 O on WC (0001) surface. The adsorption properties and vibrational frequencies of H 2 O, OH, O, H, CO and CO 2 on the WC (0001) surface were illustrated. These results are well in consistent with the experimental observations studied by temperature-programmed desorption (TPD) and high-resolution electron energy loss spectroscopy (HREELS). Based on the adsorption results, potential energy profiles of H 2 O and OH dehydrogenation and HCO, COH, COOH, and CO 2 formation on the WC (0001) surface were predicted. The calculation results demonstrated that the WC (0001) surface as Fe (110) surface exhibits significantly reaction activity toward the dehydrogenation of H 2 O and OH but less activity toward the formation of HCO, COH, COOH and CO 2 compared to the Cu (111) and Pt (111) surfaces. [ABSTRACT FROM AUTHOR]

We systematically investigate electrocatalytic activity and NH 3 selectivity of a single-atom catalyst supported on graphitic carbon nitride for nitrate reduction reaction (NO 3 RR) using first-principles calculations. Our results reveal Ti/g-C 3 N 4 , V/g-C 3 N 4 , and Nb/g-C 3 N 4 serve as the most promising NO 3 RR catalysts, as they exhibit excellent activity, high selectivity, and low limiting potential. [Display omitted] • Electrocatalytic activity and NH 3 selectivity of single-atom catalysts for nitrate reduction reaction has been explained. • This work reveals the structure dependence of NO 3 RR reaction pathways in single-atom catalysts. • Ti/g-C 3 N 4 , V/g-C 3 N 4 , and Nb/g-C 3 N 4 serve as the most promising NO 3 RR catalysts with excellent activity, high selectivity and low limiting potential. Electroreduction of water-pollutant nitrate to valuable ammonia provides a green and efficient route for low-temperature NH 3 production instead of the convention Haber-Bosch process. However, finding robust catalysts for achieving nitrate to ammonia conversion remains a challenge due to the lack of a mechanistic view on the highly complex nitrate reduction and NH 3 selectivity. Herein, we systematically investigate electrocatalytic activity and NH 3 selectivity of a single-atom catalyst supported on graphitic carbon nitride (TM/g-C 3 N 4) for nitrate reduction reaction (NO 3 RR) using first-principles calculations. Our results reveal that Ti/g-C 3 N 4 , V/g-C 3 N 4 , and Nb/g-C 3 N 4 serve as the most promising NO 3 RR catalysts, as they exhibit stability, excellent activity, high selectivity (Faradaic efficiency of ∼ 100%), and low limiting potential (−0.42, −0.25, and −0.40 V for Ti/g-C 3 N 4 , V/g-C 3 N 4 , and Nb/g-C 3 N 4, respectively). In addition, considerable potential energy barriers are found in the formation of byproducts NO 2 , NO, and N 2 O, validating their high selectivity. Nitrate to ammonia conversion is more competitive than hydrogen evolution reaction on TM/g-C 3 N 4 owning to a lower limiting potential. This work reveals the structure dependence of NO 3 RR reaction pathways in single-atom catalysts and opens a new avenue for designing more efficient catalysts for NO 3 RR under ambient conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Discovery of electrocatalytic materials for CO 2 reduction is essential to mitigate greenhouse effect. • Chemical reduction of CO 2 by reverse water-gas shift reaction on the Ru(0001) surface has illustrated. • We explore the role of water solvation on the CO 2 conversion path by assessing the H-shuttled (O-H bond formation) and water solvated (C-H bond formation). In this work, we systematically illustrate CO 2 reduction by H 2 on the Ru(0001) surface using periodic DFT calculations with micro-kinetic modeling to explore adsorbate-substrate, adsorbate-solvent, solvent-substrate interactions as well as reaction mechanisms. The effects of adsorbate-substrate interactions, water-mediated protonation kinetics, thermodynamics, and transient potential sweeps on reaction rate and selectivity are also studied. We propose three simple thermodynamic descriptors (CO + O, HCOO, and COOH) that represent the effectiveness of CO selectivity on Ru catalysts. More importantly, we explore the role of water solvation on the CO 2 conversion by assessing the H-shuttled (O-H bond formation) and water solvated (C-H bond formation) with various solvation models. To examine the solvation effect, a 6H 2 O/Ru(0001) water bilayer model is constructed by optimizing six H 2 O molecules close to the Ru surface, and multiple H-bonds are observed as local-minimum solvation structures among water molecules. Finally, the efficiency of the ruthenium catalyst is expressed by turnover frequencies (TOFs). We hope that these insights will deliver useful guidelines for designing more efficient, earth-abundant electrocatalysts in the future. [ABSTRACT FROM AUTHOR]

Abstract: We have used spin-polarized density functional theory to investigate the adsorption and dissociation of N2O molecule on Fe(111) surface. Several adsorption geometries and sites were examined in detail. In our computational results, the Fe–N2O–η 2-[Nt(1,2), Ot(1)] exhibited the greatest adsorption energy, 1.16eV, on Fe(111) surface, whereas the other binding modes still have effective adsorption and dissociation behaviors. For the N2O dissociation mechanisms, our calculated results indicate that the most favorable pathway is the production of N2 +O fragments on the Fe(111) surface. Formation of NO+N is also possible, although this pathway involves a higher energy barrier. [Copyright &y& Elsevier]

Abstract: The rate-determining step of βC–H bond scission of ethanol dehydrogenation on Ru/ZrO2 and clean ZrO2 surfaces are investigated. This barrier is greater by 48.40kcal/mol on ZrO2 surface than that on Ru/ZrO2 counterpart. Deposition of Ru atoms on the ZrO2 surface greatly increases the catalytic performance. We calculate density of states and deformation energies of adsorbates and find out that the relative stability depends not only on the surface restructuring, but also on the interaction between surface and adsorbates. The catalytic role of deposited Ru is analyzed. [ABSTRACT FROM AUTHOR]