Yanping Tang

Nitrogen-Doped Porous Carbon Superstructures Derived from Hierarchical Assembly of Polyimide Nanosheets

3D carbon superstructures are fabricated through the hierarchical assembly of polyimide nanosheets and thermal treatment. Benefiting from the ultrahigh surface area and the hierarchically porous structure, along with the well-distributed highly electroactive sites, the flower-like carbon material exhibits outstanding catalytic activity toward the oxygen reduction reaction and also serves as a highly stable electrode material in supercapacitors.

Titania Nanosheet-Mediated Construction of a Two-Dimensional Titania/Cadmium Sulfide Heterostructure for High Hydrogen Evolution Activity

Two-dimensional titania nanosheets have been utilized to fabricate 2D titania-based mesoporous silica through a controlled sol-gel method, which can further serve as a robust and versatile template to construct various 2D heterostructures via a nanocasting technology. 2D titania-based CdS has been fabricated. This heterostructure manifests an excellent H2 -production rate of 285 μmol·h(-1) under visible-light irradiation and an apparent quantum yield of 6.9% at 420 nm.

Highly Crumpled Hybrids of Nitrogen/Sulfur Dual-Doped Graphene and Co9S8 Nanoplates as Efficient Bifunctional Oxygen Electrocatalysts

A bifunctional electrocatalyst for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is highly attractive for the manufacture of clean energy conversion devices. In this work, highly crumpled hybrid of nitrogen and sulfur dual-doped graphene and quasi-hexagonal Co9S8 nanoplates (Co9S8/NSGg-C3N4) is fabricated via a facile ionic assembly approach. The unique structure of Co9S8/NSGg-C3N4 renders it high specific surface area (288.3 m2 g-1) and large pore volume (1.32 cm3 g-1). As the electrocatalyst for ORR, Co9S8/NSGg-C3N4 demonstrates excellent performance with the onset potential of -0.02 V vs Ag/AgCl and the limited current density of 6.05 mA cm-2 at -0.9 V vs Ag/AgCl. Co9S8/NSGg-C3N4 also presents outstanding catalytic activity toward OER by delivering a limited current density of 48 mA cm-2 at 1 V vs Ag/AgCl. The bifunctional catalytic behaviors of Co9S8/NSGg-C3N4 enable the assembly of a rechargeable Zn-air battery with it as the cathode catalyst, which exhibits stable discharge/charge voltage plateaus upon long time cycling over 50 h.

Boron‐Doped, Carbon‐Coated SnO2/Graphene Nanosheets for Enhanced Lithium Storage

Heteroatom doping is an effective method to adjust the electrochemical behavior of carbonaceous materials. In this work, boron-doped, carbon-coated SnO2 /graphene hybrids (BCTGs) were fabricated by hydrothermal carbonization of sucrose in the presence of SnO2/graphene nanosheets and phenylboronic acid or boric acid as dopant source and subsequent thermal treatment. Owing to their unique 2D core-shell architecture and B-doped carbon shells, BCTGs have enhanced conductivity and extra active sites for lithium storage. With phenylboronic acid as B source, the resulting hybrid shows outstanding electrochemical performance as the anode in lithium-ion batteries with a highly stable capacity of 1165 mA h g(-1) at 0.1 A g(-1) after 360 cycles and an excellent rate capability of 600 mA h g(-1) at 3.2 A g(-1), and thus outperforms most of the previously reported SnO2-based anode materials.

Carbonized polyaniline coupled molybdenum disulfide/graphene nanosheets for high performance lithium ion battery anodes

Two-dimensional molybdenum disulfide/graphene hybrids wrapped in carbonized polyaniline (MCGs) have been constructed by the in situ growth of molybdenum trisulfide nanoparticles on polyaniline decorated graphene oxide nanosheets and the following carbonization. When the resulting hybrids were used as anode materials in lithium ion batteries, the carbonized polyaniline can effectively prevent the pulverization of MoS2 caused by the inner-plane volume expansion. It turns out that MCG-600, the sample thermally treated at 600 °C, manifests a capacity of 785 mA h g−1 after 300 cycles at the current density of 200 mA g−1 and a capacity of 724 mA h g−1 even at a high current density of 1 A g−1.

Using a layer-by-layer assembly method to fabricate a uniform and conductive nitrogen-doped graphene anode for indium-tin oxide-free organic light-emitting diodes.

Highly conductive, uniform, and transparent nitrogen-doped graphene multilayer films were produced by a layer-by-layer (LbL) assembly method. Such a technique was realized by alternate deposition of graphene oxide modified with the cationic surfactant N,N,N-trimethyl-1-dodecanaminium bromide (CTAB) and the anionic surfactant sodium dodecylbenzenesulfonate. In this way, we can achieve a highly conductive (900 S/cm), uniform, and controllable graphene film in terms of thickness, transmittance, and sheet resistance after high-temperature reduction. The improved conductivity is attributed to better graphitization and nitrogen-doping introduced by CTAB. The organic light-emitting diode using such a multilayer graphene film fabricated by the LbL method as an anode obtains higher current density and luminance at low voltage compared to that with an indium-tin oxide (ITO) anode. Moreover, the current efficiency of graphene-based device is comparable to that of an ITO-based device. It is proved that such a nitrogen-doped multilayer graphene film developed by the LbL assembly technique is a promising candidate for a transparent electrode in organic electronics.

A facile self-assembly strategy towards naphthalene diimide/graphene hybrids as high performance organic cathodes for lithium-ion batteries

A two-dimensional hybrid of naphthalene diimide and reduced graphene oxide (NDI–RGO) has been constructed by a facile self-assembly strategy. In the resulting hybrid, the non-covalent interactions between NDI and RGO enable the uniform distribution of NDI on the surface of RGO. As the cathode material in lithium ion batteries, NDI–RGO shows excellent revisable capacity and rate capability.

Carbon encapsulated Fe3O4/graphene framework with oriented macropores for lithium ion battery anode with enhanced cycling stability

Carbon encapsulated Fe3O4/graphene frameworks with highly oriented macroporous structures have been constructed by an ice-segregation-induced self-assembly process. Serving as the anode materials in lithium-ion batteries, the oriented macropores can reduce the polarization of electrode and the loss of capacity, and the carbon shells can effectively prevent the pulverization of Fe3O4 caused by the inner-plane volume expansion. C-Fe3O4/G with 60 wt% of Fe3O4 delivers a high capacity of 1065 mA h g−1 at a current density of 0.2 A g−1 after 200 cycles. Even at a high current density of 8 A g−1, the electrode still achieves a high capacity of 470 mA h g−1.

Bottom-up fabrication of nitrogen-doped mesoporous carbon nanosheets as high performance oxygen reduction catalysts

Nitrogen-doped mesoporous carbon nanosheets (NMCNs) with uniform hexagonal structures are fabricated via the thermal treatment of polyaniline enwrapped cobalt hydroxide (Co(OH)2) nanosheets and the subsequent acid etching of the resulting composites. It is found that the morphologies, poroisties and compositions of the NMCNs are greatly dependent on the ratio of the added aniline and Co(OH)2 nanosheets, which can in turn affect the electrochemical behavior of the NMCNs. As the electrocatalyst for oxygen reduction reaction in alkaline media, the NMCNs obtained with the aniline/Co(OH)2 ratio of ∼1.2 manifest excellent perfromance with the onset potential of -0.119V, the half-wave potential of -0.182V and the limiting current density of 5.06mAcm-2, which are superior to most of the previously reported N-doped porous carbon nanosheets.

Template Conversion of Covalent Organic Frameworks into 2D Conducting Nanocarbons for Catalyzing Oxygen Reduction Reaction

Progress over the past decades in porous materials has exerted great effect on the design of metal-free carbon electrochemical catalysts in fuel cells. The carbon material must combine three functions, i.e., electrical conductivity for electron transport, optimal pores for ion motion, and abundant heteroatom sites for catalysis. Here, an ideal carbon catalyst is achieved by combining two strategies-the use of a 2D covalent organic framework (COF) and the development of a suitable template to guide the pyrolysis. The COF produces nanosized carbon sheets that combine high conductivity, hierarchical porosity, and abundant heteroatom catalytic edges. The catalysts achieve superior performance to authentic Pt/C with exceptional onset potential (0 V vs -0.03 V), half-wave potentials (-0.11 V vs -0.16 V), high limit current density (7.2 mA cm-2 vs 6.0 mA cm-2 ), low Tafel slope (110 mV decade-1 vs 121 mV decade-1 ), long-time stability, and methanol tolerance. These results reveal a novel material platform based on 2D COFs for designing novel 2D carbon materials.