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Nanostructured Li 2 FeSiO 4 /C composites have been successfully synthesized by adopting polyethylene glycol (PEG) as the surfactant and L-ascorbic acid as the carbon additive, using a sol-gel method based on the acid-catalyzed hydrolysis/condensation of tetraethoxysilane (TEOS). The Li 2 FeSiO 4 /C nanocomposites possess dispersed spherical particles (∼50 nm) with narrow particle size distribution, embedded in a continuous carbon matrix. The Li 2 FeSiO 4 /C nanocomposites deliver first discharge capacity of 138.2 mAhg −1 at C/16 and maintain at about 130.4 mAhg −1 after 40 cycles at various rates at room temperature, which outperform those of Li 2 FeSiO 4 /C samples synthesized without PEG. The electrochemical performances of Li 2 FeSiO 4 /C were largely enhanced after the introduction of PEG due to the following two aspects. On one hand, the smaller particle size facilitated the shorter diffusion length for lithium ions; On the other hand, the more continuous carbon film coated on the particle surface enhanced the electronic conductivity of the nanocomposites and restrained the side reaction occurring at the electrode-electrolyte interface.

Abstract Over the past decade, the plasmonics of graphene and black phosphorus (BP) were widely recognized as promising media for establishing linear and nonlinear light-matter interactions. Compared to the conventional metals, they support significant light-matter interaction of high efficiency and show undispersed optical properties. Furthermore, in contrast to the conventional metals, the plasmonic properties of graphene and BP structure can be tuned by electrical and chemical doping. In this review, a deep attention was paid toward the second- and third-order nonlinear plasmonic modes of graphene and BP. We present a theoretical framework for calculating the lifetime for surface plasmons modes of graphene and BP assisted by the coupled mode theory. The effect of the Fermi energy on the second-order and third-order nonlinear response is studied in detail. We survey the recent advances in nonlinear optics and the applications of graphene and BP-based tunable plasmonic devices such as light modulation devices, switches, biosensors, and other nonlinear photonic devices. Finally, we highlight a few representative current applications of graphene and BP to photonic and optoelectronic devices.