Yunhong Jiang

A green approach to the synthesis of reduced graphene oxide nanosheets under UV irradiation

We present a totally green approach towards the synthesis and stabilization of aqueous graphene dispersions through UV-irradiated reduction of exfoliated graphene oxide (GO). Polyvinyl pyrrolidone (PVP) is used to enhance the dispersibility of reduced graphene oxide (RGO) by one-step functionalization. The proposed method is low cost and easy without using any photocatalysts or reducing agents, which can open up a new possibility for green preparation of stable RGO dispersions in large-scale production.

Facile preparation of exposed {001} facet TiO2 nanobelts coated by monolayer carbon and its high-performance photocatalytic activity

The photocatalytic property of TiO2-based nanomaterials can be markedly enhanced by hybridizing conjugated materials at the surface. In this paper, we first utilized a silane coupling agent as carbon source and grafting reagent to prepare a graphite-like carbon coating on the surface of {001} crystal facets that were exposed on TiO2 nanobelts. The thickness of this carbon layer could be controlled to a thickness of a few molecules by adjusting the addition of silane. Due to the synergistic effects between the monolayer carbon coating (~1xa0nm) and the exposed {001} crystal facets, the as-prepared TiO2 nanobelts enhanced the photocatalytic activity by approximately 2.5 times that of pure TiO2 (Degussa, P–25), to photodegrade methylene blue under UV light. Additionally, the photodegradation of rhodamine B (RHB) was better (approximately 2.1 times) than that of P–25. Further, we discuss the proper mechanism of the enhanced performance, which is attributed to the faster transfer of photogenerated electrons by d-π interaction and the decreased possibility of recombination of e−/h+ pairs.

Nanoscale mechanical characterization of PMMA by AFM nanoindentation: a theoretical study on the time-dependent viscoelastic recovery

Temperature-dependent indent recovery of polymethyl methacrylate is depicted by atomic force microscopy. The viscoelastic indent recovery is predicted by a numerical model based on the Boussinesq elastic theory. From the perspective of an elastic solution, viscoelastic solution for stress and displacement field is constructed through the analysis of the elasticity–viscoelasticity corresponding theory. The findings also illustrate the effect of loading condition, elastic modulus, and viscosity on the viscoelastic recovery rate.

Mechanical properties of a single SnO 2 fiber prepared from the electrospinning method

Uniform SnO2 fibers were prepared from the electrospinning method in this paper. The mechanical properties of a single SnO2 fiber were characterized by three-point bending experiments with atomic force microscopy. Finite element method was employed to simulate the shape of the SnO2 fiber during the bending process. The elastic modulus of SnO2 fibers increased with the calcined temperature. A high elastic modulus of 72.59u2009GPa was obtained with a diameter of 160u2009nm. The results indicate that atomic force microscopy tips penetrated the surfaces under maximum loading.Graphical abstractThe force-displacement curve from simulation is in accordance with the results from experiments by using AFM and theoretical calculation. The equivalent strain nephogram indicates that the maximal strain is about 0.0143 at the midpoint of the fiber.

Natural assembly of a ternary Ag–SnS–TiO2 photocatalyst and its photocatalytic performance under simulated sunlight

Natural assembly method was utilized to prepare a novel ternary Ag–SnS–TiO2 nanocomposite, in which TiO2 nanobelts were used as templates. The co-loading of Ag and SnS nanoparticles endows TiO2 nanobelts with enhanced photocatalytic capability, resulting from the broadened light absorption spectra and decreased band gaps. Comparing with raw TiO2 nanobelts and commercial Degussa P25, an improvement in photodegradation of simulated organic pollutants was successfully demonstrated due to the decreasing recombination of photogenerated electron–hole pairs. Our work presents a new strategy for the preparation of ternary TiO2-based photocatalysts in the practical application of wastewater treatment.

Hierarchical C/SiO x /TiO2 ultrathin nanobelts as anode materials for advanced lithium ion batteries

TiO2-based nanomaterials are demonstrated to be a promising candidate for next generation lithium ion batteries due to their stable performance and easy preparation. However, their inherent low capacity impedes their wide application compared to commercial carbon nanomaterials. Here we present a unique in situ grafting-graphitization method to achieve a ternary nanocomposite of C/SiO x /TiO2 ultrathin nanobelts with a core-shell heterostructure. The obtained ternary nanocomposite integrates the merits of high specific capacity of SiO x , the excellent mechanical stability of graphite-like carbon and the high reactivity of TiO2. Cyclic voltammetric curves and cycling performance manifest the optimal ternary nanocomposite and deliver a very high initial specific capacity of ∼1196 mA h g-1 with both good rate capability (∼200 mA h g-1 up to 10 C) and especially enhanced cycle stability. Our work demonstrates that building hierarchical core-shell heterostructures is an effective strategy to improve capacity and cycling performance in other composite anodes for electrochemical energy storage materials.

Effect of oxygen vacancies on Li-storage of anatase \(\hbox {TiO}_{2}\) (001) facets: a first principles study

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Preparation of nano-structured LiFePO4/graphene composites by co-precipitation method

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