Wangjun Cui

Highly ordered mesoporous carbon nanofiber arrays from a crab shell biological template and its application in supercapacitors and fuel cells

Mesoporous carbons with large uniform pore sizes and high surface areas are of great interest due to their potential applications in electrochemical double layer capacitors (EDLCs), hydrogen storage, separation and catalysis. Here, we report a facile synthesis approach to highly ordered mesoporous carbon nanofiber arrays (MCNAs) by combining surfactant-templating self-assembly of organic resols with a natural crab shell hard-templating process. The obtained materials consist of a mesoporous carbon nanofiber (70 nm in mean diameter and 11 nm in mesopore), an interspacing void of 70 nm between nanofibers, and 1 micrometre of pores between nanofiber arrays. The unique structure (ordered mesopores, macroporous voids and partially graphitic framework) provides a more favorable path for electrolyte penetration and transportation, good electronic conductivity, as well as possess a large specific surface area (1270 m2 g−1) and more vacancies or defects in a graphite plane, which facilitate uniform distribution of metal nanoparticles and a synergistic effect between the nanoparticles and MCNAs, and give rise to promising electrocatalytic activity as a supporting medium for Pt in direct methanol fuel cells. The resultant materials also have excellent capacitive performance for supercapacitor application.

Preparation of three-dimensional ordered mesoporous carbon sphere arrays by a two-step templating route and their application for supercapacitors

A two-step template approach was demonstrated for preparation of the three-dimensional ordered mesoporous carbon sphere arrays. The ordered macroporous silica skeleton was formed from silicon alkoxide precursor templating around polystyrene (latex) spheres, and removal of the polystyrene spheres. These preforms as hard templates were infiltrated with a solution mixture of amphiphilic triblock copolymer PEO-PPO-PEO and soluble resol. By combining evaporation-induced surfactant-templating organic resol self-assembly with thermosetting, carbonization and hydrofluoric acid extraction of silica, the obtained mesoporous carbon has a pore size of 10.4 nm, interconnected window size of about 60 nm, surface area of 601 m2/g and pore volume of 1.70 cm3/g. The electrochemical properties as an electrode material for supercapacitor applications were investigated in nonaqueous electrolyte. They show rectangular-shaped cyclic voltammetry curves over a wide range of scan rates even up to 200 mV/s between 0 and 3 V, and deliver a large capacitance of 14 µF/cm2 (84 F/g), and good cycling stability with capacitance retention of 93% over 5000 cycles.

Core–shell carbon-coated Cu6Sn5 prepared by in situpolymerization as a high-performance anode material for lithium-ion batteries

A core–shell-structure carbon-coated nanoscale Cu6Sn5 is prepared by using an in situpolymerization method integrated with a surface modification technology. The composite combines the merits of intermetallic compounds and nano-sized anode materials, and exhibits an excellent cycling stability. The improvement in the cycling stability could be attributed to the fact that the well-coated carbon layer can effectively prevent the encapsulated low melting point alloy from out-flowing in a high-temperature treatment process, as well as preventing aggregation and pulverization of nano-sized Cu6Sn5 alloy particles during charge/discharge cycling.

Anomalous lithium storage in a novel nanonet composed by SnO2 nanoparticles and poly(ethylene glycol) chains

A series of PEG–SnO2 nanocomposites has been investigated as anode materials for lithium batteries. They exhibited an unexpectedly high lithium storage over the theoretical capacity of SnO2. The origin of such extra capacity cannot be interpreted by the conventional lithium storage mechanisms of anode materials.