Jing Ning

Reduced Graphene Oxide‐Mediated Growth of Uniform Tin‐Core/Carbon‐Sheath Coaxial Nanocables with Enhanced Lithium Ion Storage Properties

Tin-core/carbon-sheath coaxial nanocables directly integrated into a reduced graphene oxide (RGO) surface are constructed by a new strategy involving a RGO-mediated procedure. The as-synthesized nanocables, with uniform diameter and high aspect ratio, are versatile and exhibit excellent lithium storage properties, as revealed by electrochemical evaluation.

Structural Evolution of 2D Microporous Covalent Triazine-Based Framework toward the Study of High-Performance Supercapacitors

A series of nitrogen-containing micropore-donimated materials, porous triazine-based frameworks (PTFs), are constructed through the structural evolution of a 2D microporous covalent triazine-based framework. The PTFs feature predictable and controllable nitrogen doping and pore structures, which serve as a model-like system to more deeply understand the heteroatom effect and micropore effect in ionic liquid-based supercapacitors. The experimental results reveal that the nitrogen doping can enhance the supercapacitor performance mainly through affecting the relative permittivity of the electrode materials. Although microspores contribution is not as obvious as the doped nitrogen, the great performances of the micropore-dominated PTF suggest that micropore-dominated materials still have great potential in ionic liquid-based supercapacitors.

High Volumetric Capacity Silicon-Based Lithium Battery Anodes by Nanoscale System Engineering

The nanostructuring of silicon (Si) has recently received great attention, as it holds potential to deal with the dramatic volume change of Si and thus improve lithium storage performance. Unfortunately, such transformative materials design principle has generally been plagued by the relatively low tap density of Si and hence mediocre volumetric capacity (and also volumetric energy density) of the battery. Here, we propose and demonstrate an electrode consisting of a textured silicon@graphitic carbon nanowire array. Such a unique electrode structure is designed based on a nanoscale system engineering strategy. The resultant electrode prototype exhibits unprecedented lithium storage performance, especially in terms of volumetric capacity, without the expense of compromising other components of the battery. The fabrication method is simple and scalable, providing new avenues for the rational engineering of Si-based electrodes simultaneously at the individual materials unit scale and the materials ensemble scale.

High-Performance Silicon Battery Anodes Enabled by Engineering Graphene Assemblies.

We propose a novel material/electrode design formula and develop an engineered self-supporting electrode configuration, namely, silicon nanoparticle impregnated assemblies of templated carbon-bridged oriented graphene. We have demonstrated their use as binder-free lithium-ion battery anodes with exceptional lithium storage performances, simultaneously attaining high gravimetric capacity (1390 mAh g(-1) at 2 A g(-1) with respect to the total electrode weight), high volumetric capacity (1807 mAh cm(-3) that is more than three times that of graphite anodes), remarkable rate capability (900 mAh g(-1) at 8 A g(-1)), excellent cyclic stability (0.025% decay per cycle over 200 cycles), and competing areal capacity (as high as 4 and 6 mAh cm(-2) at 15 and 3 mA cm(-2), respectively). Such combined level of performance is attributed to the templated carbon bridged oriented graphene assemblies involved. This engineered graphene bulk assemblies not only create a robust bicontinuous network for rapid transport of both electrons and lithium ions throughout the electrode even at high material mass loading but also allow achieving a substantially high material tap density (1.3 g cm(-3)). Coupled with a simple and flexible fabrication protocol as well as practically scalable raw materials (e.g., silicon nanoparticles and graphene oxide), the material/electrode design developed would propagate new and viable battery material/electrode design principles and opportunities for energy storage systems with high-energy and high-power characteristics.

Bottom-up construction of triazine-based frameworks as metal-free electrocatalysts for oxygen reduction reaction.

A bottom-up method is used to construct novel metal-free catalysts for deeper study of oxygen reduction reaction (ORR) catalysis. Through controlling the structural evolution of a 2D covalent triazine-based framework, the conductivity, nitrogen configurations, and multidoping structures of the as-prepared catalysts can be easily tuned, which makes a great platform for both studying the mechanisms of the ORR and optimizing the performances of the metal-free catalysts.

A graphene-oxide-based thin coating on the separator: an efficient barrier towards high-stable lithium–sulfur batteries

The electrochemical performance of lithium–sulfur (Li–S) batteries can be significantly improved by simply coating a thin barrier layer on the separator. The spray-coating of a mixture of graphene oxides (GO) and oxidized carbon nanotubes (o-CNT) can achieve a barrier coating of only 0.3 mg cm−2, which is much less than conventional interlayers and has no negative impact on the energy density but significantly enhances the electrochemical performances of the whole battery device. Due to the binding forces induced by functional groups on GO and the interconnected nanoscale channels provided by o-CNT, the thus fabricated Li–S batteries show dramatically improved specific discharge capacities of up to 750 mAh g−1 at 1 C even after 100 cycles, more than twice those of batteries without barrier coatings.

A Facile Reduction Method for Roll‐to‐Roll Production of High Performance Graphene‐Based Transparent Conductive Films

A facile roll-to-roll method is developed for fabricating reduced graphene oxide (rGO)-based flexible transparent conductive films. A Sn2+ /ethanol reduction system and a rationally designed fast coating-drying-washing technique are proven to be highly efficient for low-cost continuous production of large-area rGO films and patterned rGO films, extremely beneficial toward the manufacture of flexible photoelectronic devices.

A fast room-temperature strategy for direct reduction of graphene oxide films towards flexible transparent conductive films

Chemically reduced graphene oxide (rGO) is widely studied as a transparent electrode, as it can be cheaply prepared on a large scale, easily integrated into flexible devices, and contributes to excellent device performances. However, the commonly used reduction methods for converting graphene oxide (GO) films into rGO ones generally involve toxic reagents or complex transfer steps. In this report, we develop a simple short-term room-temperature strategy for the direct fabrication of rGO-based transparent conductive films on flexible substrates, where tin (Sn) is used to promote the conversion of pre-deposited GO films into rGO ones. The thus-prepared rGO films exhibit sheet resistances of 6.7–17.3 kΩ sq−1 and transparencies of 75–81% at 550 nm, indicating great potential of the here-developed methodology for the fabrication of graphene-based transparent conductive films, under conditions without any heating and transferring processes, as well as toxic agents.

Fabrication of the reduced preoxidized graphene-based nanofiltration membranes with tunable porosity and good performance

A series of reduced preoxidized graphene membranes (rPGMs) were prepared by reducing the preoxidized graphene membranes (PGMs) at different reduction times. The pore morphology of the membranes and the changes in the specific porosity values along with the water flux parameters were investigated. In addition, the membranes were able to maintain a high dye rejection (>97.5% for methyl orange (MO)) and a good rejection ratio for salt ions (71.2% for MgSO4). The preoxidized graphene-based nanofiltration membranes with tunable porosity exhibit great potential as high-precision molecular sieves for water purification and other applications.