Efficient and robust artificial nanomotors could provide a variety of exciting possibilities for applications in physics, biology and chemistry, including nanoelectromechanical systems, biochemical sensing, and drug delivery. However, the application of current man-made nanomotors is limited by their sophisticated fabrication techniques, low mechanical output power and severe environmental requirements, making their performance far below that of natural biomotors. Here we show that single-crystal gold nanorods can be rotated extremely fast in aqueous solutions through optical torques dominated by plasmonic resonant scattering of circularly polarized laser light with power as low as a few mW. The nanorods are trapped in 2D against a glass surface, and their rotational dynamics is highly dependent on their surface plasmon resonance properties. They can be kept continuously rotating for hours with limited photothermal side effects and they can be applied for detection of molecular binding with high sensitivity. Because of their biocompatibility, mechanical and thermal stability, and record rotation speeds reaching up to 42 kHz (2.5 million revolutions per minute), these rotary nanomotors could advance technologies to meet a wide range of future nanomechanical and biomedical needs in fields such as nanorobotics, nanosurgery, DNA manipulation and nano/microfluidic flow control.

The synthesis of large lattice mismatch metal-semiconductor core-shell hetero-nanostructures remains challenging, and thus the corresponding optical properties are seldom discussed. Here, we report the gold-nanorodseeded growth of Au-CdS core-shell hetero-nanorods by employing Ag 2 S as an interim layer that favors CdS shell formation through a cation-exchange process, and the subsequent CdS growth, which can form complete coreshell structures with controllable shell thickness. Exciton-plasmon interactions observed in the Au-CdS nanorods induce shell thickness-tailored and red-shifted longitudinal surface plasmon resonance and quenched CdS luminescence under ultraviolet light excitation. Furthermore, the Au-CdS nanorods demonstrate an enhanced and plasmon-governed two-photon luminescence under near-infrared pulsed laser excitation. The approach has potential for the preparation of other metal-semiconductor hetero-nanomaterials with complete core-shell structures, and these Au-CdS nanorods may open up intriguing new possibilities at the interface of optics and electronics.

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Though an excellent protection material, graphene possesses an unpleasant adverse side effect, which refers to the phenomenon that graphene can aggravate metal corrosion. This effect potentially impedes its applications in metal protection. This work aims to demonstrate a facile graphene encapsulation strategy to effectively inhibit the corrosion-promotion activity of graphene. We encapsulated reduced graphene oxide (rGO) with (3-aminopropyl)-triethoxysilane (APTES). The composite of encapsulated rGO (rGO@APTES) has a flake-like structure with high aspect-ratio. Embedding appropriate amounts of rGO@APTES in polyvinyl butyral coating effectively enhances the barrier properties of the coating by suppressing the penetration of aggressive species. Besides, scratch tests further reveal that the corrosion-promotion activity of the graphene incorporated into the coating is completely inhibited. The strategy of graphene encapsulation can be extended to develop new graphene-based materials with superior physical and chemical properties for the protection of metal components.