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Wonsik Eom Ayoung Kim Hun Park Hansu Kim Tae Hee Han 《Advanced functional materials》2016,26(42):7605-7613
2D nanoscale oxides have attracted a large amount of research interest due to their unique properties. Here, a facile synthetic approach to prepare graphene‐mimicking, porous 2D Co3O4 nanofoils using graphene oxide (GO) as a sacrificial template is reported. The thermal instability of graphene, as well as the catalytic ability of Co3O4 particles to degrade carbon backbones, allow the fabrication of porous 2D Co3O4 nanofoils without the loss of the 2D nature of GO. Based on these results, a graphene mimicking as a route for large‐area 2D transition metal oxides for applications in electrochemical energy storage devices is proposed. As a proof of concept, it is demonstrated that graphene‐like, porous 2D Co3O4 nanofoils exhibit a high reversible capacity (1279.2 mAh g?1), even after 50 cycles. This capacity is far beyond the theoretical capacity of Co3O4 based on the conversion mechanism from Co3O4 to Li2O and metallic Co. 相似文献
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Mohammad Razaul Karim Hideaki Shinoda Mina Nakai Kazuto Hatakeyama Hidenobu Kamihata Takeshi Matsui Takaaki Taniguchi Michio Koinuma Keita Kuroiwa Mohamedally Kurmoo Yasumichi Matsumoto Shinya Hayami 《Advanced functional materials》2013,23(3):323-332
The rare coexistence of ferromagnetism and electrical conductivity is observed in the reduced graphene oxide–metal oxide hybrids, rGO‐Co, rGO‐Ni, and rGO‐Fe, using chemical reduction with hydrazine or ultraviolet photoirradiation of the graphene oxide–metal complexes, GO‐Co, GO‐Ni, and GO‐Fe. The starting and final materials are characterized by X‐ray photoelectron spectroscopy, transmission electron microscopy (TEM), elemental analysis, Mössbauer spectroscopy, and Raman spectroscopy. In contrast to graphene, where the electrical conductivity and magnetic properties are controlled by carrier (electron or hole) doping, those of graphene oxide can be controlled by complexation with Co2+, Ni2+, and Fe3+ cations through the strong electrostatic affinity of negatively charged graphene oxide towards metal cations. The presence of ferromagnetism and electrical conductivity in these hybrids can promote significant applications including magnetic switching and data storage. 相似文献
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Jin‐Yong Hong Bo Mee Bak Jeong Jae Wie Jing Kong Ho Seok Park 《Advanced functional materials》2015,25(7):1053-1062
High porosity combined with mechanical durability in conductive materials is in high demand for special applications in energy storage under limiting conditions, and it is fundamentally important for establishing a relationship between the structure/chemistry of these materials and their properties. Herein, polymer‐assisted self‐assembly and cross‐linking are combined for reduced graphene oxide (rGO)‐based aerogels with reversible compressibility, high elasticity, and extreme durability. The strong interplay of cross‐linked rGO (x‐rGO) aerogels results in high porosity and low density due to the re‐stacking inhibition and steric hinderance of the polymer chains, yet it makes mechanical durability and structural bicontinuity possible even under compressive strains because of the coupling of directional x‐rGO networks with polymer viscoelasticity. The x‐rGO aerogels retain >140% and >1400% increases in the gravimetric and volumetric capacitances, respectively, at 90% compressive strain, showing reversible change and stability of the volumetric capacitance under both static and dynamic compressions; this makes them applicable to energy storage devices whose volume and mass must be limited. 相似文献
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One of the biggest challenges in graphene applications is how one can fabricate 3D architectures comprising graphene sheets in which the resulting architectures have inherited graphene's excellent intrinsic properties but have overcome its shortcomings. Two series of 3D graphene monoliths (GMs) using zigzag or armchair graphene nanoribbons as building blocks and sp3 carbon chains as junction nodes are constructued, and calculations based on first principles are performed in order to predict their mechanical and electronic properties. The perfect match between sp2 nanoribbons and sp3 linkers results in favorable energy and mechanical/dynamic stability. Owing to their tailored motifs, wine‐rack‐like pores, and rigid sp3 linkers, these GMs possess high surface areas, appreciable mechanical strength, and tunable band gaps. Negative linear compressibilities in a wide range are found for the zigzag GMs. By solving the problems of zero gap and dimensionality of graphene sheets simultaneously, these GMs offer a viable strategy towards many applications, e.g., microelectronic devices, energy storage, molecular sieves, sensitive pressure detectors, and telecommunication line systems. 相似文献
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Huhu Cheng Yaxin Huang Qilong Cheng Gaoquan Shi Lan Jiang Liangti Qu 《Advanced functional materials》2017,27(42)
Self‐healing materials are capable of spontaneously repairing themselves at damaging sites without additional adhesives. They are important functional materials with wide applications in actuators, shape memorizing materials, smart coatings, and medical treatments, etc. Herein, this study reports the self‐healing of graphene oxide (GO) functional architectures and devices with the assistance of moisture. These GO architectures can completely restore their mechanical‐performance (e.g., compressibility, flexibility, and strength) after healing their broken sites using a little amount of water moisture. On the basis of this effective moisture‐triggered self‐healing process, this study develops GO smart actuators (e.g., bendable actuator, biomimetic walker, rotatable fiber motor) and sensors with self‐healing ability. This work provides a new pathway for the development of self‐healing materials for their applications in multidimensional spaces and functional devices. 相似文献
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Kiran Kumar Manga Yong Zhou Yongli Yan Kian Ping Loh 《Advanced functional materials》2009,19(22):3638-3643
Alternating graphene (G) and titania (Ti0.91O2) multilayered nanosheets are fabricated using layer‐by‐layer electrostatic deposition followed by UV irradiation. Successful assemblies of graphene oxide (GO) and titania nanosheets in sequence with polyethylenimine as a linker is confirmed by UV–vis absorption and X‐ray diffraction. Photocatalytic reduction of GO into G can be achieved upon UV irradiation. Ultrafast photocatalytic electron transfer between the titania and graphene is demonstrated using femtosecond transient absorption spectroscopy. Efficient exciton dissociation at the interfaces coupled with cross‐surface charge percolation allows efficient photocurrent conversion in the multilayered Ti0.91O2/G films. 相似文献
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In Kyu Moon Seonno Yoon Kyoung‐Yong Chun Jungwoo Oh 《Advanced functional materials》2015,25(45):6976-6984
The simple synthesis of ultralow‐density (≈2.32 mg cm?3) 3D reduced graphene oxide (rGO) aerogels that exhibit high electrical conductivity and excellent compressibility are described herein. Aerogels are synthesized using a combined hydrothermal and thermal annealing method in which hexamethylenetetramine is employed as a reducer, nitrogen source, and graphene dispersion stabilizer. The N‐binding configurations of rGO aerogels increase dramatically, as evidenced by the change in pyridinic‐N/quaternary‐N ratio. The conductivity of this graphene aerogel is ≈11.74 S m?1 at zero strain, whereas the conductivity at a compressive strain of ≈80% is ≈704.23 S m?1, which is the largest electrical conductivity reported so far in any 3D sponge‐like low‐density carbon material. In addition, the aerogel has excellent hydrophobicity (with a water contact angle of 137.4°) as well as selective absorption for organic solvents and oils. The compressive modulus (94.5 kPa; ρ ≈ 2.32 mg cm?3) of the rGO aerogel is higher than that of other carbon‐based aerogels. The physical and chemical properties (such as high conductivity, elasticity, high surface area, open pore structure, and chemical stability) of the aerogel suggest that it is a viable candidate for the use in energy storage, electrodes for fuel cells, photocatalysis, environmental protection, energy absorption, and sensing applications. 相似文献
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傅里叶变换红外光谱（Fourier Transform Infrared Spectrometry, FTIR）分析技术凭借其在红外波段中高灵敏度和高分辨率的表征能力,已经成为药物开发、材料研究、化学分析等领域最重要的光谱学表征手段之一。随着综合探测技术的不断进步,FTIR面临着进一步提升光谱分析能力以及轻量化、集成化的发展需求。基于石墨烯的光电探测器具有超宽谱的光电响应范围、超快的光电响应速度、微米级的探测器特征尺寸以及与其他材料耦合的高兼容性,在高性能集成化FTIR光谱仪技术开发中表现出极大的应用潜力。利用高精度纳米位移台取代复杂的参考光路,结合石墨烯光电探测器,实现了基于石墨烯光电探测的无参考光束FTIR光谱仪。通过实验进一步验证了无参考光束FTIR光谱仪的宽波段表征能力,实现了0.6 cm−1的光谱分辨率和40 dB的信噪比,并准确表征了聚二甲基硅氧烷（PDMS）的特征吸收峰。研究结果证明了基于石墨烯光电探测的无参考光束FTIR光谱仪在提高光谱分析能力以及实现设备轻量化方面的优势,为FTIR分析技术提供了更具优势的开发与优化途径。 相似文献
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Shi Wun Tong Nimai Mishra Chen Liang Su Venkatram Nalla Wenya Wu Wei Ji Jie Zhang Yinthai Chan Kian Ping Loh 《Advanced functional materials》2014,24(13):1904-1910
Core/shell tetrapods synthesized from CdSe and CdTe exhibit a type II band offset that induces separation of charge upon photoexcitation and localizes carriers to different regions of the tetrahedral geometry. CdSe/CdTe nanocrystals immobilized on oleylamine‐functionalized reduced graphene oxide (rGO) sheets can be homogeneously mixed with an organic dye (PCDTBT) to form donor–acceptor dispersed heterojunctions and exhibit a high power conversion efficiency of ～3.3% in solar cell devices. The near‐IR light absorbing type II nanocrystals complement the absorption spectrum of the visible light‐absorbing organics. The high efficiency is attributed to the amine‐functionalized rGO sheets, which allow intimate contact with the nanocrystals and efficient dispersal in the organic matrix, contributing to highly efficient charge separation and transfer at the nanocrystal, rGO, and polymer interfaces. 相似文献
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Min Gyu Kang Seul‐Yi Lee Deepam Maurya Christopher Winkler Hyun‐Cheol Song Robert B. Moore Mohan Sanghadasa Shashank Priya 《Advanced functional materials》2017,27(29)
1D ferroelectric nanostructures are promising for enhanced ferroelectric and piezoelectric performance on the nanoscale, however, their synthesis at the wafer scale using industrially compatible processes is challenging. In order to advance the nanostructure‐based electronics, it is imperative to develop a silicon‐compatible growth technique yielding high volumetric density and an ordered arrangement. Here, a major breakthrough is provided in addressing this need and ordered and close‐packed single crystalline ferroelectric nanorod arrays, of composition PbZr0.52Ti0.48O3 (PZT), grown on commercial grade 3 in. silicon wafer are demonstrated. PZT nanorods exhibit enhanced piezoelectric and ferroelectric performance compared to thin films of similar dimensions. Sandwich structured architecture utilizing 1D PZT nanorod arrays and 2D reduced graphene oxide thin film electrodes is fabricated to provide electrical connection. Combined, these results offer a clear pathway toward integration of ferroelectric nanodevices with commercial silicon electronics. 相似文献
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Sn‐based materials have triggered significant research efforts as anodes for lithium‐storage because of their high theoretical capacity. However, the practical applications of Sn‐based materials are hindered by low capacity release and poor cycle life, which are mainly caused by structural pulverization and large volume changes on cycling. Herein, a surfactant‐assisted assembly method is developed to fabricate 3D nanoarchitectures in which Sn‐based nanoparticles are encapsulated by a porous graphene network. More precisely, the graphene forms a 3D cellular network, the interstices of which only partially filled by the electroactive masses, thus establishing a high concentration of interconnected nanosized pores. While the graphene‐network itself guarantees fast electron transfer, it is the characteristic presence of nanosized pores in our network that leads to the favorable rate capability and cycling stability by i) accommodating the large volume expansion of Sn‐based nanoparticles to ensure integrity of the 3D framework upon cycling and ii) enabling rapid access of Li‐ions into Sn‐based nanoparticles, which are in addition prevented from agglomerating. As a result, the 3D Sn‐based nanoarchitectures deliver excellent electrochemical properties including high rate capability and stable cycle performance. Importantly, this strategy provides a new pathway for the rational engineering of anode materials with large volume changes to achieve improved electrochemical performances. 相似文献
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Shaoxiong Liu Lingxia Zheng Pingping Yu Sancan Han Xiaosheng Fang 《Advanced functional materials》2016,26(19):3331-3339
Novel composites composed of α‐Fe2O3 tetrakaidecahedrons and graphene oxide have been easily fabricated and demonstrated to be efficient photoelectrodes for photoelectrochemical water splitting reaction with superior photocurrent response. α‐Fe2O3 tetrakaidecahedrons are facilely synthesized in a green manner without any organic additives and then modified with graphene oxide. The morphological and structural properties of α‐Fe2O3/graphene composite are intensively investigated by several means, such as X‐ray diffraction, field‐emission scanning electron microscope, transmission electron microscope, X‐ray photoelectron spectroscopy, Fourier Transform infrared spectroscopy, and Raman spectroscopy. The tetrakaidecahedronal hematite particles have been indicated to be successfully coupled with graphene oxide. Systematical photoelectrochemical and impedance spectroscopy measurements have been carried out to investigate the favorable performance of α‐Fe2O3/graphene composites, which are found to be effective photoanodes with rapid, steady, and reproducible feature. The coupling of graphene with α‐Fe2O3 particles has greatly enhanced the photoelectrochemical performance, resulting in higher photocurrent and lower onset potential than that of pure α‐Fe2O3. This investigation has provided a feasible method to synthesize α‐Fe2O3 tetrakaidecahedron and fabricate an efficient α‐Fe2O3/graphene photoelectrode for photoelectrochemical water oxidation, suggesting a promising route to design noble metal free semiconductor/graphene photocatalysts. 相似文献
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Jincheng Liu Hongwei Bai Yinjie Wang Zhaoyang Liu Xiwang Zhang Darren Delai Sun 《Advanced functional materials》2010,20(23):4175-4181
TiO2 nanorods are self‐assembled on the graphene oxide (GO) sheets at the water/toluene interface. The self‐assembled GO–TiO2 nanorod composites (GO–TiO2 NRCs) can be dispersed in water. The effective anchoring of TiO2 nanorods on the whole GO sheets is confirmed by transmission electron microscopy (TEM), X‐ray diffraction (XRD), Fourier transform IR spectroscopy (FTIR), and thermogravimetric analysis (TGA). The significant increase of photocatalytic activity is confirmed by the degradation of methylene blue (MB) under UV light irridiation. The large enhancement of photocatalytic activity is caused by the effective charge anti‐recombination and the effective absorption of MB on GO. The effective charge transfer from TiO2 to GO sheets is confirmed by the significant photoluminescence quenching of TiO2 nanorods, which can effectively prevent the charge recombination during photocatalytic process. The effective absorption of MB on GO is confirmed by the UV‐vis spectra. The degradation rate of MB in the second cycle is faster than that in the first cycle because of the reduction of GO under UV light irradiation. 相似文献
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Shuxia Ren Zhenhua Li Lingzhi Tang Xiao Su He Zhang Guanglei Zhang Han Zhang Guozhong Cao Jinjin Zhao 《Advanced Electronic Materials》2020,6(5)
Resistive random access memories (RRAMs) are promising candidates for future nonvolatile memories. Here, a flexible nonvolatile resistive switching (RS) device is constructed by spin coating an RS film of graphene oxide (GO) incorporating with TiO2 nanoparticles, denoted as TGO, on an indium‐doped tin oxide electrode. The TGO film is highly flexible and optically transparent (92–98%), and the device demonstrates excellent RS characteristics (centralized SET and RESET voltages and large RS ratio) at a low voltage of 0.5 V. The RS behavior is found to originate from the migration and distribution of oxygen anions in the TGO film under an electric field. The oxygen anions extracted from TiO2 nanoparticle provide good chemical linkage for the development of sp2 filaments in the GO film, promoting the RS behavior. The findings of this study may also be very useful for researchers working on controlling magnetism in RRAM devices. 相似文献