We review the development of carbon-sulfur composites and the application for Li-S batteries. Discussions are devoted to the synthesis approach of the various carbon-sulfur composites, the structural transformation of sulfur, the carbon-sulfur interaction and the impacts on electrochemical performances. Perspectives are summarized regarding the synthesis chemistry, electrochemistry and industrial production with particular emphasis on the structural optimization of carbon-sulfur composites.

No abstract

No abstract

Non-precious metal oxide/carbon hybrid electrocatalysts are of increasing importance for the oxygen reduction reaction (ORR). A synergistic effect is commonly used to explain the superior ORR activity exerted by metal oxide/nanocarbon hybrids, and this effect is attributed to covalently coupled interfaces between the two materials. However, the origin of the high activity, the structure, and the electrocatalytic nature of the interface remain unclear. By combining X-ray photoelectron spectroscopy with synchrotron far-infrared spectroscopy, we resolved the interface structure between spinel manganese oxide nanocrystals and graphene oxide nanoribbons, and the role of this interface in the promoted ORR. Moreover, we demonstrated the excellent ORR activity by a functional synergism of the hybrid constituents through a series of comparative electrochemical experiments.

Water-processable binders improved the electrode polarity and wettability. Li–S batteries consisting of such binders exhibited superior performance at high current densities.

Diatomite, a porous non-metal mineral, was used as support to prepare TiO 2 /diatomite composites by a modified sol-gel method. The as-prepared composites were calcined at temperatures ranging from 450 to 950 o C. The characterization tests included X-ray powder diffraction (XRD), scanning electron microscopy (SEM) with an energy-dispersive X-ray spectrometer (EDS), High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption/desorption measurements. The XRD analysis indicated that the binary mixtures of anatase and rutile exist in the composites. The morphology analysis confirmed the TiO 2 particles were uniformly immobilized on the surface of diatom with a strong interfacial anchoring strength, which leads to few drain of photocatalytic components during practical applications. In further XPS studies of hybrid catalyst, we found the evidence of the presence of Ti-O-Si bond and increased percentage of surface hydroxyl. In addition, the adsorption capacity and photocatalytic activity of synthesized TiO 2 /diatomite composites were evaluated by studying the degradation kinetics of aqueous Rhodamine B under UV-light irradiation.The photocatalytic degradation was found to follow pseudo-first order kinetics according to the Langmuir-Hinshelwood model. The preferable removal efficiency was observed in composites by 750 o C calcination, which is attributed to a relatively 2 appropriate anatase/rutile mixing ratio of 90/10.

A novel type of hierarchical porous carbon has been successfully prepared by constructing intra-and inter-sphere -COcrosslinking bridges of monodisperse styrene-divinylbenzene copolymer nanospheres. The -C 6 H 4 -crosslinking bridges ensure good stability of the nanospheres during swelling and crosslinking, and the -CO-crosslinking bridges play an important role in achieving good nanostructure inheritability during carbonization.Natural species provide several examples revealing that a considerable portion of complex functionalities of living systems rely on their hierarchical structures. 1 Compared to conventional porous materials consisting of uniform pore dimensions that can be adjusted over a wide range of length scales, hierarchical porous materials with well-defined pore dimensions and topologies can achieve minimized diffusive resistance to mass transport from macropores and high surface area for active site dispersion from micro-and/or mesopores. 2 Without doubt, such a novel type of nanostructured materials will have played a significant role in catalysis, energy storage, adsorption, separation, etc. 3 In materials science, there has been considerable interest in synthesis of such hierarchical structured materials, especially hierarchical porous carbons (HPCs). Constructing different nanoscaled pores and making them interconnected are very important in the synthesis of HPCs. To date, great achievements have been made in the preparation of well-defined HPCs by hard-/soft-templating approaches or templating and post-activation combination methods. 4 For example, Cheng and co-workers prepared a 3D aperiodic hierarchical porous graphitic carbon by using Ni(OH) 2 /NiO as a hard template, 3b and Lu and co-workers prepared a HPC by post-activation of Pluronic F127-templated mesoporous carbon. 4c However, most of the templates are expensive and the post-synthetic removal of the template to produce a carbon replica requires additional processing steps that are usually time-consuming, severe and harmful to the environment. These limitations impart to HPCs an uncompetitive price-to-performance ratio as compared with other materials for any given applications, and thus limit their commercial viability. Obviously, the problem would be completely eliminated if the hierarchical porosity could be introduced into carbon without any auxiliary templates. Therefore, building controllable hierarchical porous structure through a template-free method is a great challenge for materials science.Most recently, a template-free method to fabricate HPC has been developed by our group by constructing carbonyl (-CO-) crosslinking bridges between linear polystyrenes, where carbonyl crosslinking bridges simultaneously provided the resulting hierarchical porous polystyrene (HPP) with both a high crosslinking density and a proper amount of oxygen atoms, thus leading to good inheritability of hierarchical pore structure during carbonization. 2 However, the formation and growth of network nanoparticles from crosslinking of linear polystyr...

No abstract