Metal oxide-based materials with yolk-shell morphology have been intensively investigated as important anodes for Li-ion batteries due to their large ion storage ability, high safety, and excellent cycling stability. In this work, in situ carbon-coated yolk-shell V2O3 microspheres were synthesized via a template-free polyol solvothermal method. The growth of yolk-shell microspheres underwent coordination and polymerization, followed by an inside-out Ostwald-ripening process and further calcination in N2 atmosphere. The thin amorphous carbon layers coating on the microspheres' surface came from polyol frameworks which could protect V2O3 during the charge-discharge process and led to a better stability in Li-ion batteries. The in situ carbon-coated yolk-shell V2O3 microspheres showed a capacity of 437.5 mAh·g(-1) after 100 cycles at a current density of 0.1 A·g(-1), which was 92.6% of its initial capability (472.5 mAh·g(-1)). They were regarded as excellent electrode materials for lithium-ion batteries and exhibit good electrochemistry performance and stability.

B,N-codoped carbon nanostructures (BNCS) can serve as alternative low-cost metal-free electrocatalysts for oxygen reduction reactions (ORR). However, the compensation effect between the p- (B atoms) and n-type (N atoms) dopants would make the covalent boron-nitride (BN) easily formed during the synthesis of BNCS, leading to a unsatisfactory ORR activity. Therefore, it has been challenging to develop facile and rapid synthetic strategies for highly active BNCS without forming the direct covalent BN. Here, a facile method is developed to prepare B and N isolate-doped graphitic nanosheets (BNGS) by using iron species for saving N element and simultaneous doping the B element from nitrogen-containing ion-exchanged resins (NR). The resulting BNGS exhibits much more onset potential (Eonset) compared with the B-doped graphitic carbon nanosheets (BGS), N-doped graphitic carbon nanosheets (NGS), as well as B,N-codoped disorder carbon (BNC). Moreover, the BNGS shows well methanol tolerance propery and excellent stability (a minimal loss of activity after 5,000 potential cycles) compared to that of commercial Pt/C catalyst. The goog performance for BNGS towards ORR is attributed to the synergistic effect between B and N, and the well electrons transport property of graphitic carbon in BNGS.

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Alien elemental segregation can pronouncedly change the grain boundary properties. Systematic firstprinciples calculations were performed to investigate the Mg and Cu segregation behavior at 5 (210)[001] symmetrical tilt grain boundary (STGB) in Al. The mechanical properties of Mg or Cu containing 5 (210)[001] STGBs were probed by combining a canonical Griffith fracture model with an ab-initio tensile test method. It is found that both Mg and Cu have a large driving force to segregate to Al grain boundaries, with Mg preferentially segregating at symmetric substitutional core sites and Cu at interstitial hollow sites at the grain boundary. Interestingly, Al 5 (210)[001] is shown to possess a stronger sink strength of Cu impurities than Mg. Both Mg and Cu segregation leads to a grain boundary expansion and a significant decrease of the grain boundary energy. Calculations show that Mg segregation leads to embrittlement of the STGB, contrary to the cohesion enhancing effect of Cu solutes on Al grain boundaries. The Mg induced embrittlement is due to a combination of "structural effect" -(grain boundary expansion) and "chemical effect" -(charge density depletion).The strengthening effect of Cu solutes lies in the creation of new Cu-Al bonds across the grain boundary, which is considered as a strong contribution to the grain boundary cohesion, thereby increasing its resistance against intergranular cleavage. This work demonstrates how a fundamental 2 theoretical understanding on the atomic and electronic level can rationalize mechanical properties of alloys at the macroscopic scale.

Graphene nanosheets possess a promising potential as electrodes in Li-ion batteries (LIBs); consequently, the development of low-cost and high-productivity synthetic approaches is crucial. Herein, porous graphene-like nanosheets (PGSs) have been synthesized from expandable graphite (EG) by initially intercalating phosphoric acid, and then performing annealing to enlarge the interlayer distance of EG, thus facilitating the successive intercalation of zinc chloride. Subsequently, the following pyrolysis of zinc chloride in the EG interlayer promoted the formation of the porous PGS structure; meanwhile, the gas produced during the formation of the porous structure could exfoliate the EG to graphene-like nanosheets. The synthetic PGS material used as LIB anode exhibited superior Li + storage performance, showing a remarkable discharge capacity of 830.4 mAh·g −1 at 100 mA·g −1 , excellent rate capacity of 211.6 mAh·g −1 at 20,000 mA·g −1 , and excellent cycle performance (near 100% capacity retention after 10,000 cycles). The excellent rate performance is attributed to the Li + ion rapid transport in porous structures and the high electrical conductivity of graphene-like nanosheets. It is expected that PGS may be widely used as anode material for high-rate LIBs via this facile and low-cost route by employing EG as the raw material.

High surface area, hierarchical porous carbon materials were obtained by carbonization and activation process of the loofah sponge. The porous carbon materials with good conductivity exhibit high energy density and power density.

The interactions between substitutional carbon atoms and Σ3 {111}, Σ9 {221}, and Σ27 {552} twin boundaries (TB) in silicon were investigated by first-principles calculations. The preferential segregation sites and segregation energy for carbon at different TBs were determined. It shows that segregation of carbon atoms at Σ3 {111} TB is energetically unfavorable while Σ9 {221} and Σ27 {552} TBs are efficient gettering centers for carbon. A linear relationship between the atomic-site specific segregation energy for carbon at TBs and the average bond length (ABL) of the atomic site is deduced.

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