1.3 C). When discharge/charge is carried out at a high current density of 10.5 A g − 1 (70 C), the thin fi lm electrodes retain a good discharge capacity of 120 mA h g − 1 , and the specifi c power density is over 28 kW kg − 1 .

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In this work, g-CN@GO gel-like hybrid is obtained by assembling intentionally exfoliated g-CN sheets on graphene oxide (GO) sheets under a hydrothermal condition. A specific N-doping process is first designed by heating the g-CN@GO interlaced hybrid in vacuum to form nitrogen-doped graphene nanosheets (NGS) with high level of pyridinic-N (56.0%) and edge-rich defect structure. The prepared NGS exhibited a great electrocatalysis for oxygen reduction reaction (ORR) in terms of the activity, durability, methanol tolerance, and the reaction kinetics. And the excellent electrocatalytic performance stems from the effective N-doped sites that the nitrogen atom is successfully doped at the defective edges of graphene, and the annealing temperature can play significant role of the doping pattern and location of N. The research provides a new insight into the enhancement of electrocatalysis for ORR based on nonmetal carbons by using the novel N-doping method.

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Using the density functional theory (DFT), first-principles computations were performed to investigate the intercalation site, phase transformation, electronic properties, and migration energy barrier of Li and Mg atoms in V2O5 to thoroughly illuminate the phase transformation and microscopic interaction as well as the migration mechanism of Li and Mg in V2O5. It is found that Li and Mg atoms prefer to locate at the site that is above, near the center of the quadrilateral composed of four V atoms. With the increase of the intercalation concentration (0 ≤ x ≤ 1), V2O5 undergoes a structural transformation from α-phase to ε-phase and δ-phase. Compared with ε-M0.5V2O5 (M = Li/Mg), the electronic conductivity of δ-MV2O5 (M = Li/Mg) is declined. On the basis of diffusion kinetics, Mg exhibits more difficulty in inserting and extracting in V2O5 than Li. This study can be useful for the further application of V2O5 in Mg ion batteries.

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High valence cobalt sites are considered as highly active centers for oxygen evolution reaction (OER) and their corresponding construction is thus of primary importance to pursue outstanding performance. Herein, we...