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Summary: The extension of low‐expense and stable electrocatalysts for oxygen reduction reaction (ORR) is of importance to improve the performance of metal‐air batteries and fuel cells. In this work, we unravel the ORR electrocatalytical mechanisms on a series of transition metal atom‐doped on the defect graphene (TM@sv‐graphene) by carrying out spin‐polarized first‐principles computations. The formation energy of the TM@sv‐graphene, which is related to its stability, along with the binding energy of O2, OOH, 2OH, OH, and O species are evaluated. The calculations of Gibbs free energy show that two different pathways, O* mechanism and 2OH* mechanism, of ORR compete with each other based on the structures of intermediates (OOH, 2OH, OH and O). It is found that Co, Rh, Ir, Pt, and Mn@sv‐graphene favor the O* mechanism while Ag, Au, Cd, Cu, Zn, Fe, Ni, Pd, Sc, Cr, Ti, Zr, and V@sv‐graphene strongly promote the 2OH* mechanism. The overpotential (η) of the ORR is predicted and can be a valid descriptor that manifests the catalytic activity of different TM@sv‐graphene. Among these catalysts, the Pd@sv‐graphene (η = 1.20 V) exhibits the best activity for the ORR. The results provide new insight into electrochemical mechanism of ORR for novel single‐atom electrocatalyst. [ABSTRACT FROM AUTHOR]

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]

[Display omitted] • Electrocatalytic formic acid oxidation on graphene supported Pd-Ni catalysts has been explained. • The role of Ni content in different Pd-Ni atomic ratio and the hydrogen coverage effect are elucidated. • The selectivity of HCOO*/COOH* is enhancing in Pd-Ni cluster as compared to pure Pd catalyst. By means of periodic density functional theory calculations, we have investigated the electrocatalytic formic acid oxidation (FAO) on graphene supported Pd-Ni catalysts and elucidate the detail about the role of Ni content in different Pd-Ni atomic ratio and the hydrogen coverage effect. The FAO reaction often onsets at low oxidation potential range, where deposition of hydrogen is alive and affect the catalytic performance of Pd-Ni clusters, accordingly, the FAO reaction on varied H* ratio Pd-Ni clusters accompanying with enhanced external potential is also considered. In our calculation, the H* saturated situation would suppress the formation of COOH* much more than that of HCOO*, even controlling the reaction energy of HCOO* from HCOOH become moderate in FAO reaction. In addition, the potential requirements to proceed the FAO reaction on Pd 10 -gra and Pd 8 Ni 2 -graphene are similar but Ni content could also suppress formation of COOH* and enhance the interaction between Pd 8 Ni 2 -graphene and HCOO* species. Pd 6 Ni 4 -grahene model is another choice for FAO reaction, in which the HCOO* species on clean Pd 6 Ni 4 -graphene model has lowest onset potential of 0.18 V for HCOO* deprotonation to CO 2 in all of our models. However, excess Ni content would cause Ni exposed on Pd 2 Ni 8 - grahene, where the HCOO* is downhill in energy with a larger onset potential of 0.59 V for the deprotonation of HCOO*, but the hydride formation of 8H* and 9H* Pd 2 Ni 8 - graphene could overcome the question. [ABSTRACT FROM AUTHOR]