N-Doped Carbon Nanotube Shell Encapsulating the NiFe Metal Core for Enhanced Catalytic Stability in Methanol Oxidation Reaction by the Structural Cooperation Mechanism.

Exploitation of high-efficiency catalysts toward methanol oxidation is a pivotal step to promote the commercialization of direct methanol fuel cells. Herein, a strategy is demonstrated to prepare nitrogen-doped carbon nanotubes with NiFe metal particles (NiFe@N-CNT) as the carrier material of Pt nanoparticles. Combining SEM and TEM, NiFe metal particles are fully encapsulated in N-CNTs, and they form the metal core and carbon nanotube shell structure based on the structural cooperation mechanism. Surprisingly, the as-prepared Pt/NiFe@N-CNT catalyst shows superior catalytic activity (1023 mA mg-1Pt) compared to commercial Pt/C (392 mA mg-1Pt), Pt/Ni@N-CNT (331 mA mg-1Pt), and Pt/Fe@N-CNT (592 mA mg-1Pt). After 1000 cycles, Pt/NiFe@N-CNT maintains the optimal catalytic activity (588 mA mg-1Pt), and its mass activity loss is 42.5%, which is better than those of commercial Pt/C (64.0%), Pt/Ni@N-CNT (67.7%), and Pt/Fe@N-CNT (59.6%) catalysts, indicating that the Pt/NiFe@N-CNT catalyst achieves excellent catalytic activity and stability, which stems chiefly from the homodispersed Pt nanoparticles and the generation of the metal core-carbon nanotube shell based on the structural cooperation mechanism. This study reports the facile construction of a metal core-carbon nanotube shell structure, which intrinsically ameliorates structural collapse of carrier material, thereby improving the catalytic stability of the Pt-based catalyst and broadening the view for design of other desire catalysts in methanol oxidation.

Accurately manipulating hierarchical flower-like Fe2P@CoP@nitrogen-doped carbon spheres as an efficient carrier material of Pt-based catalyst.

Fabrication of hierarchical porous catalysts with a large specific surface area and tunable architecture provides an effective strategy to promote the catalytic performance of Pt-based catalysts. Herein, we design and construct hierarchical flower-like Fe2P@CoP@nitrogen-doped carbon (Fe2P@CoP@NDC) through a facile method, and synthesize Pt/Fe2P@CoP@NDC porous spheres via acid pickling and depositing of Pt NPs. The morphology of Fe2P@CoP@NDC is precisely manipulated by controlling the synthesis conditions, including the reaction time and the addition of a protective agent, and the protective growth mechanism of the hierarchical flower-like Fe2P@CoP@NDC spheres is mentioned. Significantly, the Pt/Fe2P@CoP@NDC catalyst exhibits 3.29 and 2.36 times higher mass activity and specific activity than those of commercial Pt/C for methanol oxidation, respectively. Furthermore, its residual mass activity after 1000 cycles is 5.77 times as much as that of the commercial Pt/C catalyst in acidic electrolytes. Based on exploration of the reaction kinetics of the Pt/Fe2P@CoP@NDC catalyst, the excellent catalytic activity and durability are attributed to the unique porous structure with relatively open area and enlarged specific surface area, which can promote fast electron transport and charge transfer, resulting in quick reaction kinetics. Moreover, metal phosphides can effectively accelerate the oxidative removal of intermediates, accordingly improving the catalytic activity. Therefore, the Pt/Fe2P@CoP@NDC material with these compositional and structural features is expected to be a promising electrochemical catalyst.

Engineering intermetallic-metal oxide interface with low platinum loading for efficient methanol electrooxidation.

Constructing a distinctive electrochemical interface with low platinum content to boost the sluggish methanol electrooxidation kinetics is critical for commercializing the direct methanol fuel cells. Herein, we have synthesized highly active electrocatalysts with unique intermetallic-metal oxide interfaces through a facile pyrolysis method. Physical characterizations demonstrate that the obtained PtFe(1:2)@a-FeOx/NC-C catalyst with low platinum content of 7.2 wt% possesses an interfacial structure composed of face-centered tetragonal (L10) PtFe intermetallic nanoparticles accompanied with amorphous iron oxide. Electrochemical measurements show that the synthesized PtFe(1:2)@a-FeOx/NC-C catalyst not only exhibits excellent methanol electrooxidation activities with a mass activity of 1.48 A mg-1Pt and a specific activity of 2.34 mA cm-2Pt in acid medium, but also possesses better CO-tolerant performance and faster methanol oxidation kinetics compared with commercial Pt/C. The improved electrochemical performances may ascribe to the modified electronic structure by alloying platinum with iron and the special PtFe@a-FeOx interface, which render strong synergistic interactions between bimetallic PtFe nanoparticles and amorphous iron oxide. Consequently, the presented strategy offers new prospects into the construction of low-cost electrocatalysts with unique electrochemical interface for enhancing catalytic performances.

Recognition for avian influenza virus proteins based on support vector machine and linear discriminant analysis.

Total 200 properties related to structural characteristics were employed to represent structures of 400 HA coded proteins of influenza virus as training samples. Some recognition models for HA proteins of avian influenza virus (AIV) were developed using support vector machine (SVM) and linear discriminant analysis (LDA). The results obtained from LDA are as follows: the identification accuracy (R ia) for training samples is 99.8% and R ia by leave one out cross validation is 99.5%. Both R ia of 99.8% for training samples and R ia of 99.3% by leave one out cross validation are obtained using SVM model, respectively. External 200 HA proteins of influenza virus were used to validate the external predictive power of the resulting model. The external R ia for them is 95.5% by LDA and 96.5% by SVM, respectively, which shows that HA proteins of AIVs are preferably recognized by SVM and LDA, and the performances by SVM are superior to those by LDA.