Construction of SnO2-Graphene Composite with Half-Supported Cluster Structure as Anode toward Superior Lithium Storage Properties

Inspired by nature, herein we designed a novel construction of SnO2 anodes with an extremely high lithium storage performance. By utilizing small sheets of graphene oxide, the partitioned-pomegranate-like structure was constructed (SnO2@C@half-rGO), in which the porous clusters of SnO2 nanoparticles are partially supported by reduced graphene oxide sheets while the rest part is exposed (half-supported), like partitioned pomegranates. When served as anode for lithium-ion batteries, SnO2@C@half-rGO exhibited considerably high specific capacity (1034.5 mAh g−1 after 200 cycles at 100 mA g−1), superior rate performance and remarkable durability (370.3 mAh g−1 after 10000 cycles at 5 A g−1). When coupled with graphitized porous carbon cathode for lithium-ion hybrid capacitors, the fabricated devices delivered a high energy density of 257 Wh kg−1 at ∼200 W kg−1 and maintained 79 Wh kg−1 at a super-high power density of ∼20 kW kg−1 within a wide voltage window up to 4 V. This facile and scalable approach demonstrates a new architecture for graphene-based composite for practical use in energy storage with high performance

Confined SnO2 quantum-dot clusters in graphene sheets as high-performance anodes for lithium-ion batteries

Construction of metal oxide nanoparticles as anodes is of special interest for next-generation lithium-ion batteries. The main challenge lies in their rapid capacity fading caused by the structural degradation and instability of solid-electrolyte interphase (SEI) layer during charge/discharge process. Herein, we address these problems by constructing a novel-structured SnO2-based anode. The novel structure consists of mesoporous clusters of SnO2 quantum dots (SnO2 QDs), which are wrapped with reduced graphene oxide (RGO) sheets. The mesopores inside the clusters provide enough room for the expansion and contraction of SnO2 QDs during charge/discharge process while the integral structure of the clusters can be maintained. The wrapping RGO sheets act as electrolyte barrier and conductive reinforcement. When used as an anode, the resultant composite (MQDC-SnO2/RGO) shows an extremely high reversible capacity of 924 mAh g−1 after 200 cycles at 100 mA g−1, superior capacity retention (96%), and outstanding rate performance (505 mAh g−1 after 1000 cycles at 1000 mA g−1). Importantly, the materials can be easily scaled up under mild conditions. Our findings pave a new way for the development of metal oxide towards enhanced lithium storage performance

A Fe/Fe3O4/N-carbon composite with hierarchical porous structure and in situ formed N-doped graphene-like layers for high-performance lithium ion batteries

Fe/Fe3O4/N-carbon composite consisting of a porous carbon matrix containing a highly conductive N-doped graphene-like network and Fe/Fe3O4 nanoparticles was prepared. The porous carbon has a hierarchical structure which is inherited from rice husk and the N-doped graphene-like network formed in situ. When used as an anode material for lithium batteries, the composite delivered a reversible capacity of approximately 610 mA h g(-1) at a current density of 200 mA g(-1) even after 100 cycles, due to the synergism between the unique hierarchical porous structures, highly electrically conductive N-doped graphene- like networks and nanosized particles of Fe/Fe3O4. This work provides a simple approach to prepare N-doped porous carbon activated nanoparticle composites which could be used to improve the electrochemical performance of lithium ion batteries

Fabrication of AgBr/boron-doped reduced graphene oxide aerogels for photocatalytic removal of Cr(VI) in water

AgBr nanoparticles on boron-doped reduced graphene oxide aerogels (AgBr/B-RGO) are synthesized by a facile hydrothermal method, which shows a superior performance in the photoreduction of toxic hexavalent chromium (CrVI) in aqueous media under visible light irradiation. The composition and structure of the samples have been characterized by using XPS, Raman, XRD, TEM and SEM measurements. As compared with that of AgBr on none-doped reduced graphene oxide aerogels (AgBr/RGO), the improved photocatalytic properties, can be attributed to the introduction of boron atoms in reduced graphene oxide (RGO), bringing in the improvement of electron transfer efficiency, and the depression of the recombination of photo-excited electrons and holes. Further tests in the photoreduction of CrVI reveal that the obtained AgBr/B-RGO presents excellent cycling performance with an interesting increase in the photocatalytic efficiency upon cycling number. This observation can be explained by the fact that the gradual emergence of Ag0 formed from the photo-induced decomposition of AgBr, introduces a Surface Plasmon Resonance (SPR) effect to the system. The approach herein reported could be extended to the design and fabrication of other photocatalysts with high performance that combine the boron-doped graphene and SPR effect

Synthesis of porous LiFe0.2Mn1.8O4 with high performance for lithium-ion battery

A facile and effective route was developed for the fabrication of LiFe0.2Mn1.8O4 with porous structures by using Pluronic P-123 as a soft template, based on a nitrate decomposition method. The resultant LiFe0.2Mn1.8O4 was characterized by XRD, SEM, as well as N2 adsorption/desorption measurements which showed a porous structure with a pore size centered at 20 nm. When used as cathode materials in lithium battery, the as-synthesized LiFe0.2Mn1.8O4 exhibited a discharge capacity of 122 mAh g-1 at 1 C and 102 mAh g-1 at 5 C. Moreover, after 500 cycles, the capacity retention (108 mAh g-1) reached 88% of the initial capacity at 1 C. As compared with conventional cathode LiMn2O4, the high performance is believed to originate from the combined effects of porous structure, iron doping and highly crystalline nature of the obtained LiFe0.2Mn1.8O4. This strategy is expected to allow the fabrication of other multiple metal oxides with porous structures for high performance cathode materials

Controlled fabrication of Si nanoparticles on graphene sheets for Li-ion batteries

A new route is presented for the synthesis of Si nanoparticle/Graphene (Si-Gr) composite by a sonochemical method and then magnesiothermic reduction process. During the process, silica particles were firstly synthesized and deposited on the surface of graphene oxide (SiO2-GO) by ultrasonic waves, subsequent low-temperature magnesiothermic reduction transformed SiO 2 to Si nanoparticles in situ on graphene sheets. The phase of the obtained materials was influenced by the weight ratio of Mg to SiO 2-GO. With the optimized ratio of 1 : 1, we can get Si nanoparticles on Gr sheets, with the average particle size of Si around 30 nm. Accordingly, the resultant Si-Gr with 78 wt% Si inside delivered a reversible capacity of 1100 mA h g-1, with very little fading when the charge rates change from 100 mA g-1 to 2000 mA g-1 and then back to 100 mA g-1. Thus, this strategy offers an efficient method for the controlled synthesis of Si nanoparticles on Gr sheets with a high rate performance, attributing to combination of the nanosized Si particles and the graphene. 2013 The Royal Society of Chemistry

Design and fabrication of Ag-CuO nanoparticles on reduced graphene oxide for nonenzymatic detection of glucose

In this study, a nano Ag-CuO/rGO (reduced graphene oxide) composite was designed and constructed as a novel nonenzymatic glucose sensor. The composite was fabricated through a one-step synthesis process. In the process, Ag-CuO with an average particle size of 10 nm formed and dispersed homogeneously on the surface of rGO sheets. When used for nonenzymatic glucose sensing, the resultant Ag-CuO/rGO composite showed a high sensitivity of 214.37 μA mM −1 cm −2 and an extremely wide linear response from 0.01 to 28 mM with a 0.76 μM detection limit (S/N = 3) at +0.6 V. The excellent sensing properties of the composite are probably due to the synergistic effect of the combination of Ag, CuO nanoparticles and rGO. The electron transfer is improved by the addition of Ag nanoparticles, and the composite electrode possesses larger surface area due to the rGO. The Ag-CuO/rGO composite doe not only show the good catalytic activity, excellent selectivity but also outstanding long term stability, good reproducibility, which makes it a novel type of composite for nonenzymatic glucose sensing

Simple fabrication of a Fe2O3/carbon composite for use in a high-performance lithium ion battery

A simple approach was developed for the fabrication of a Fe 2O 3/carbon composite by impregnating activated carbon with a ferric nitrate solution and calcinating it. The composite contains graphitic layers and 10 wt.% Fe 2O 3 particles of 20-50 nm in diameter. The composite has a high specific surface area of ∼828 m 2 g -1 and when used as the anode in a lithium ion battery (LIB), it showed a reversible capacity of 623 mAh g -1 for the first 100 cycles at 50 mA g -1. A discharge capacity higher than 450 mAh g -1 at 1000 mA g -1 was recorded in rate performance testing. This highly improved reversible capacity and rate performance is attributed to the combination of (i) the formation of graphitic layers in the composite, which possibly improves the matrix electrical conductivity, (ii) the interconnected porous channels whose diameters ranges from the macro- to meso- pore, which increases lithium-ion mobility, and (iii) the Fe 2O 3 nanoparticles that facilitate the transport of electrons and shorten the distance for Li + diffusion. This study provides a cost-effective, highly efficient means to fabricate materials which combine conducting carbon with nanoparticles of metal or metal oxide for the development of a high-performance LIB. © 2012 Elsevier Ltd. All rights reserved