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Electrocatalysts for anode or cathode reactions are at the heart of electrochemical energy conversion and storage devices. Molecular design of carbon based nanomaterials may create the next generation electrochemical catalysts for broad applications. Herein, we present the synthesis of a three-dimensional (3D) nanostructure with a large surface area (784 m(2) g(-1)) composed of nitrogen doped (up to 8.6 at.%) holey graphene. The holey structure of graphene sheets (~25% of surface area is attributed to pores) engenders more exposed catalytic active edge sites. Nitrogen doping further improves catalytic activity, while the formation of the 3D porous nanostructure significantly reduces graphene nanosheet stacking and facilitates the diffusion of reactants/electrolytes. The three factors work together, leading to superb electrochemical catalytic activities for both hydrazine oxidation (its current generation ability is comparable to that of 10 wt% Pt-C catalyst) and oxygen reduction (its limiting current is comparable to that of 20 wt% Pt-C catalyst) with four-electron transfer processes and excellent durability.

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Selective polymer wrapping is a promising approach to obtain high-chiral-purity single-walled carbon nanotubes (SWCNTs) needed in technical applications and scientific studies. We showed that among three fluorene-based polymers with different side-chain lengths and backbones, poly[(9,9-dihexylfluorenyl-2,7-diyl)-co-(9,10-anthracene)] (PFH-A) can selectively extract SWCNTs synthesized from the CoSO4 /SiO2 catalyst, which results in enrichment of 78.3 % (9,8) and 12.2 % (9,7) nanotubes among all semiconducting species. These high-chiral-purity SWCNTs may find potential applications in electronics, optoelectronics, and photovoltaics. Furthermore, molecular dynamics simulations suggest that the extraction selectivity of PFH-A relates to the bending and alignment of its alkyl chains and the twisting of its two aromatic backbone units (biphenyl and anthracene) relative to SWCNTs. The strong π-π interaction between polymers and SWCNTs would increase the extraction yield, but it is not beneficial for chiral selectivity. Our findings suggest that the matching between the curvature of SWCNTs and the flexibility of the polymer side chains and the aromatic backbone units is essential in designing novel polymers for selective extraction of (n,m) species.

Novel porous carbon materials with excellent electronic, chemical and structural properties and high nitrogen content are desirable for many applications. Here, we show the design and synthesis of a new multifunctional porous carbon material with a unique architecture through a simple but effective activation-free procedure. Porous carbon derived from a copolymer poly(vinylidene chloride-coacrylonitrile) serves as the nitrogen-rich "mortar". Reduced graphene oxide layers work as "bricks" with an aim to provide an open nanoscale scaffold and connect porous carbon, as well as modulate the ratio between mesopores and micropores. This new material has a large surface area (957 m 2 g À1 ), high nitrogen content (6.6 at%), excellent conductivity (up to 5.1 S cm À1 ), and favorable hierarchical mesoand microporosity. Benefiting from these intriguing features, this material shows an ultrahigh specific capacitance of 361 F g À1 in an aqueous electrolyte. The as-assembled asymmetric supercapacitors with the designed carbon materials as negative electrodes and porous cobalt oxide nanorods as positive electrodes deliver a high-energy of 50.1 W h kg À1 with a cell voltage of up to 1.6 V. Further, this material shows high electrocatalytic activity for the oxygen reduction reaction in alkaline medium comparable with that of 20 wt% platinum-carbon electrodes, with better methanol tolerance and longterm durability. We expect that this uniquely designed nitrogen-rich porous carbon material with its simple and scalable synthesis method will have great potential for various applications in energy storage, energy conversion and catalysis.