Titanium dioxide has attracted considerable interest as a prototypical semiconductor photocatalyst. However, because of the relative large bandgap energy, further application of TiO2 photocatalyst is limited by its inefficient solar energy conversion. Various attempts have been made to broaden the light absorption window of the TiO2, such as growth of TiO2-based heterostructures. Herein, a novel three-component system, Ag2O/TiO2/V2O5 one-dimensional nanoheterostructures with enhanced solar light absorption, is prepared by depositing Ag2O nanoparticles onto the surface of TiO2/V2O5 nanofibers through a two-step synthetic process. This three-component system exhibits excellent solar-driven photocatalytic activity, far exceeding those of the single- and two-component systems, as a result of extended solar light absorption and efficient electron-hole separation. Furthermore, the photocatalytic performance of Ag2O/TiO2/V2O5 one-dimensional nanoheterostructures is very stable for recycling use.

Hierarchical nanostructures with much increased surface-to-volume ratio have been of significant interest for prototypical gas sensors. Herein we report a novel resistive gas sensor based on TiO2/V2O5 branched nanoheterostructures fabricated by a facile one-step synthetic process, in which well-matched energy levels induced by the formation of effective heterojunctions between TiO2 and V2O5, a large Brunauer-Emmett-Teller surface area and complete electron depletion for the V2O5 nanobranches induced by the branched-nanofiber structures are all beneficial to the change of resistance upon ethanol exposure. As a result, the ethanol sensing performance of this device shows a lower operating temperature, faster response/recovery behavior, better selectivity and about seven times higher sensitivity compared with pure TiO2 nanofibers. This study not only confirms the gas sensing mechanism for performing enhancement of branched nanoheterostructures, but also proposes a rational approach to the design of nanostructure-based chemical sensors with desirable performance.

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Much greater surface-to-volume ratio of hierarchical nanostructures renders them attract considerable interest as prototypical gas sensors. In this work, a novel resistive gas sensor based on TiO2/Ag0.35V2O5 branched nanoheterostructures is fabricated by a facile one-step synthetic process and the ethanol sensing performance of this device is characterized systematically, which shows faster response/recovery behavior, better selectivity, and higher sensitivity of about 9 times as compared to the pure TiO2 nanofibers. The enhanced sensitivity of the TiO2/Ag0.35V2O5 branched nanoheterostructures should be attributed to the extraordinary branched hierarchical structures and TiO2/Ag0.35V2O5 heterojunctions, which can eventually result in an obvious change of resistance upon ethanol exposure. This study not only indicates the gas sensing mechanism for performance enhancement of branched nanoheterostructures, but also proposes a rational approach to design nanostructure based chemical sensors with desirable performance.

Ceramics typically have very high hardness, but suffer from poor toughness. Here, we use graphene to enhance the toughness of bulk boron carbide ceramics. The reduced graphene oxide (rGO) platelets are homogenously dispersed with boron carbide particles after sintering at 1350°C, under high pressure of 4.5 GPa with a multi-anvil apparatus. Fracture toughness of the composites is increased~131% (from~3.79 tõ 8.76 MPaÁm 1/2 ) at 1.5 vol% rGO platelets as a result of a toughing effect of graphene along with a little sacrificing of the hardness and elastic modulus, compared with those of pure boron carbide. The remarkably enhanced fracture toughness in the boron carbide ceramics is associated with graphene sheets crack bridging and graphene interface sliding effect. This study holds much significance for the understanding and development of high-performance graphene reinforcing ceramics.