Tianjiao Hu

Water-soluble ribbon-like graphitic carbon nitride (g-C3N4): green synthesis, self-assembly and unique optical properties

Ribbon-like g-C3N4 was obtained from dicyandiamide using NaCl crystals as the template. Modification of the texture led to an increase of the band gap to 3.0 eV, with much stronger photoluminescence. Hydrogen bonding produces an exceptionally stable dispersion in water. Upon adding different alcohols, various special assemblies were observed to precipitate from the dispersion.

Simple synthesis of g-C3N4/rGO hybrid catalyst for the photocatalytic degradation of rhodamine B

Abstract A hybrid catalyst of g-C3N4 (graphitic carbon nitride)/rGO (reduced graphene oxide) was prepared by directly heating a mixture of melamine and GO in air. g-C3N4 in the hybrid retained the structure of pristine g-C3N4, and the heterojunction between g-C3N4 and rGO was formed by π-π interaction. The highest photocatalytic efficiency for the degradation of rhodamine B (RhB) was with the melamine/GO mass ratio of 800/1, with a first order rate constant 2.6 times that of pristine g-C3N4. The enhanced photocatalytic activity was assigned to the rGO-promoted separation of photo-generated electron (e−)-hole (h+) pairs. In addition, the photocatalytic activity of g-C3N4/rGO was pH sensitive with a much increased photodegrading rate at low pH values. The first order rate constant was 8.6 times that of pristine g-C3N4 at pH = 1.98. The pH sensitive behavior resulted from the promoted oxidation of h+ with RhB by the consumption of e− with the reaction of proton (H+) in which rGO acted as a good platform for transferring e− through its atomic sheets.

Graphene oxide based BCNO hybrid nanostructures: tunable band gaps for full colour white emission

The emission of BCNO phosphors has been easily tuned from the violet to the near red regions by varying the carbon content. Here we report the optimal conversion of graphene oxide (GO) into BCNO hybrid nanostructures by one-step air oxidation with boric acid and urea. White lighting phosphor was obtained in which the doped porous graphene acts as an interconnecting framework generating and transferring electrons under excitation light. Various carbon-related levels in the BN band structures play an essential role in emitting full colour white light. The quantum confinement in the various kinds of GQDs and GO are also beneficial to widen the emission spectrum.

Gyrification-Inspired Highly Convoluted Graphene Oxide Patterns for Ultralarge Deforming Actuators

Gyrification in the human brain is driven by the compressive stress induced by the tangential expansion of the cortical layer, while similar topographies can also be induced by the tangential shrinkage of the spherical substrate. Herein we introduce a simple three-dimensional (3D) shrinking method to generate the cortex-like patterns using two-dimensional (2D) graphene oxide (GO) as the building blocks. By rotation-dip-coating a GO film on an air-charged latex balloon and then releasing the air slowly, a highly folded hydrophobic GO surface can be induced. Wrinkling-to-folding transition was observed and the folding state can be easily regulated by varying the prestrain of the substrate and the thickness of the GO film. Driven by the residue stresses stored in the system, sheet-to-tube actuating occurs rapidly once the bilayer system is cut into slices. In response to some organic solvents, however, the square bilayer actuator exhibits excellent reversible, bidirectional, large-deformational curling properties on wetting and drying. An ultralarge curvature of 2.75 mm-1 was observed within 18 s from the original negative bending to the final positive bending in response to tetrahydrofuran (THF). In addition to a mechanical hand, a swimming worm, a smart package, a bionic mimosa, and two bionic flowers, a crude oil collector has been designed and demonstrated, aided by the superhydrophobic and superoleophilic modified GO surface and the solvent-responsive bilayer system.

Predispersed Carbocatalyst: Vertically Aligned Nitrogen-Doped Graphene Rooted on SiC Microspheres for Selective Oxidation

Vertically aligned N‐doped graphene rooted on SiC microspheres (NG on SiC) is prepared by precursor pyrolysis. One of the raw materials, acetonitrile, has three important effects that could facilitate the N‐doping process effectively, promote the lateral dimensions and improve the graphitization degree of NG on SiC significantly. The metal‐free carbocatalyst NG on SiC is an effective and selective oxidation catalyst towards targeted C−H bond activation of ethylbenzene. The unique nanostructure of NG on SiC is composed of predispersed graphene, which is expected to avoid harmful agglomeration during preparation, storage, transportation, and applications.

Preparation of highly efficient antibacterial polymeric films via the modulation of charge density and hydrophobicity

Highly efficient antibacterial polymeric films were prepared in a facile manner via a thiol–ene reaction assisted by ultraviolet radiation. The influence of the positive charge density and hydrophobicity on the antimicrobial activity was evaluated with Escherichia coli and Staphylococcus aureus. There was a synergetic enhancement in sterilization in the presence of a positive charge density and hydrophobicity, which provided a convenient way to design and synthesize highly effective antimicrobial polymers. The prepared films, with abundant cations and sufficient hydrophobicity, exhibited robust antibacterial effects against E. coli and S. aureus. Their excellent thermostability makes these films suitable for practical applications.

Chapter 7 – Synthesis and Properties of Silicon Carbide Nanopapers

Abstract It has been generally accepted that the band gap width of crystallized silicon carbide (SiC) is about two to three times more than silicon. This feature of SiC results in higher activation energy demand during the electron transition, which is vital for maintaining the semiconducting electron transfer. Although this feature used to be considered as a drawback of SiC electronic devices under mild circumstances, now the SiC-based electronics are expected to serve in harsh environments of higher temperature, higher power, and higher frequency conditions. The theoretical design seems practical since SiC nanopapers were discovered. This chapter starts with the review of the preparation of one-dimensional SiC nanostructures (1D SiC) since the 1D SiC are the most ideal building blocks of SiC nanopaper. Especially to the centimeters-long SiC nanowires, the as-prepared SiC nanopapers could be a strong “bridge” between microworld and macroworld due to their unique fabric morphology. Based on practical and potential strategies of organizing 1D SiC into SiC nanopaper, the novel nanopaper has been proved could be practically applied. SiC nanopapers exhibit electrical resistance that linearly increases with increasing environmental relative humidity in a very short time, and high photoelectrocatalytic activity under UV irradiation, which are potentially applied to high performance sensors and new energy transfer devices.