Graphene oxide

/Tag: Graphene oxide

Graphene‐Based Actuator with Integrated‐Sensing Function

2018-11-17T22:32:10+00:00November 17th, 2018|Categories: Publications|Tags: , |

A graphene‐based actuator with integrated‐sensing function is developed. It realizes real‐time measurements of the shape deformation of the actuator. A smart gripper based on the actuator demonstrates perfect integration of actuating and sensing functions. It can not only grasp and release an object, but also sense every actuation state of the actuator. Abstract Flexible actuators have important applications in artificial muscles, robotics, optical devices, and so on. However, most of the conventional actuators have only actuation function, lacking in real‐time sensing signal feedbacks. Here, to break the limitation and add functionality in conventional actuators, a graphene‐based actuator with integrated‐sensing function is reported, which avoids the dependence on image post‐processing for actuation detection and realizes real‐time measurement of the shape‐deformation amplitudes of the actuator. The actuator is able to show a large bending actuation (curvature of 1.1 cm−1) based on a dual‐mode actuation mechanism when it is driven by near infrared light. Meanwhile, the relative resistance change of the actuator is −17.5%. The sensing function is attributed to piezoresistivity and thermoresistivity of the reduced graphene oxide and paper composite. This actuator can be used as a strain sensor to monitor human motions. A smart gripper based on the actuators demonstrates perfect integration of the actuating and sensing functions, which can not only grasp and release an object, but also sense every actuation state of the actuator. The developed integrated‐sensing actuator is hopeful to open new application fields in soft robotics, artificial muscles, flexible wearable devices, and other integrated‐multifunctional devices.

Published in: "Advanced Functional Materials".

Synergistic effect of functionalized graphene oxide and carbon nanotube hybrids on mechanical properties of epoxy composites

2018-11-16T14:32:37+00:00November 16th, 2018|Categories: Publications|Tags: , |

RSC Adv., 2018, 8,38689-38700DOI: 10.1039/C8RA08312F, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Zehao Qi, Yefa Tan, Zhongwei Zhang, Li Gao, Cuiping Zhang, Jin TianThe 3D structure hybrids obtained by combining CNT and epoxy functionalized GO

Published in: "RSC Advances".

Ultrafine MnO2 nanowires grown on RGO-coated carbon cloth as a binder-free and flexible supercapacitor electrode with high performance

2018-11-16T12:33:28+00:00November 16th, 2018|Categories: Publications|Tags: , , |

RSC Adv., 2018, 8,38631-38640DOI: 10.1039/C8RA05890C, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Zhihui Xu, Shishuai Sun, Wen Cui, Dan Yu, Jiachun DengReduced graphene oxide coated carbon cloth has been used as a substrate for the

Published in: "RSC Advances".

Graphene‐Based Actuator with Integrated‐Sensing Function

2018-11-16T04:34:05+00:00November 16th, 2018|Categories: Publications|Tags: , |

A graphene‐based actuator with integrated‐sensing function is developed. It realizes real‐time measurements of the shape deformation of the actuator. A smart gripper based on the actuator demonstrates perfect integration of actuating and sensing functions. It can not only grasp and release an object, but also sense every actuation state of the actuator. Abstract Flexible actuators have important applications in artificial muscles, robotics, optical devices, and so on. However, most of the conventional actuators have only actuation function, lacking in real‐time sensing signal feedbacks. Here, to break the limitation and add functionality in conventional actuators, a graphene‐based actuator with integrated‐sensing function is reported, which avoids the dependence on image post‐processing for actuation detection and realizes real‐time measurement of the shape‐deformation amplitudes of the actuator. The actuator is able to show a large bending actuation (curvature of 1.1 cm−1) based on a dual‐mode actuation mechanism when it is driven by near infrared light. Meanwhile, the relative resistance change of the actuator is −17.5%. The sensing function is attributed to piezoresistivity and thermoresistivity of the reduced graphene oxide and paper composite. This actuator can be used as a strain sensor to monitor human motions. A smart gripper based on the actuators demonstrates perfect integration of the actuating and sensing functions, which can not only grasp and release an object, but also sense every actuation state of the actuator. The developed integrated‐sensing actuator is hopeful to open new application fields in soft robotics, artificial muscles, flexible wearable devices, and other integrated‐multifunctional devices.

Published in: "Advanced Functional Materials".

Computational insights and the observation of SiC nanograin assembly: towards 2D silicon carbide. (arXiv:1701.07387v2 [cond-mat.mtrl-sci] UPDATED)

2018-11-16T02:29:21+00:00November 16th, 2018|Categories: Publications|Tags: , , , , |

While an increasing number of two-dimensional (2D) materials, including graphene and silicene, have already been realized, others have only been predicted. An interesting example is the two-dimensional form of silicon carbide (2D-SiC). Here, we present an observation of atomically thin and hexagonally bonded nanosized grains of SiC assembling temporarily in graphene oxide pores during an atomic resolution scanning transmission electron microscopy experiment. Even though these small grains do not fully represent the bulk crystal, simulations indicate that their electronic structure already approaches that of 2D-SiC. This is predicted to be flat, but some doubts have remained regarding the preference of Si for sp$^{3}$ hybridization. Exploring a number of corrugated morphologies, we find completely flat 2D-SiC to have the lowest energy. We further compute its phonon dispersion, with a Raman-active transverse optical mode, and estimate the core level binding energies. Finally, we study the chemical reactivity of 2D-SiC, suggesting it is like silicene unstable against molecular absorption or interlayer linking. Nonetheless, it can form stable van der Waals-bonded bilayers with either graphene or hexagonal boron nitride, promising to further enrich the family of two-dimensional materials once bulk synthesis is achieved.

Published in: "arXiv Material Science".

Preparation, characterization and reusability efficacy of amine-functionalized graphene oxide-polyphenol oxidase complex for removal of phenol from aqueous phase

2018-11-14T14:32:32+00:00November 14th, 2018|Categories: Publications|Tags: , |

RSC Adv., 2018, 8,38416-38424DOI: 10.1039/C8RA06364H, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.Pravin M. D., Chris Felshia S., A. GnanamaniSchematic representation of the present study describing amine functionalization followed by enzyme immobilization and degradation of

Published in: "RSC Advances".

Selective Nitrogen Doping Graphene Oxide by Laser Irradiation for Enhanced Hydrogen Evolution Activity

2018-11-13T20:33:09+00:00November 13th, 2018|Categories: Publications|Tags: , |

Chem. Commun., 2018, Accepted ManuscriptDOI: 10.1039/C8CC07725H, CommunicationWenjing Zheng, Yan Zhang, Kaiyang Niu, Tao Liu, Karen Bustillo, Peter Ercius, Dennis Nordlund, Junqiao Wu, Haimei Zheng, Xiwen DuSelective nitrogen-doping graphene oxide with high pyridinic N ratio (51%; L-GO) was achieved by laser irradiation of graphene oxide with ammonia. The resulting L-GO exhibited the enhanced electrocatalytic properties, specifically,…The content of this RSS Feed (c) The Royal Society of Chemistry

Published in: "Chemical Communications".

A facile synthesis methodology for preparation of Ag–Ni-reduced graphene oxide: a magnetically separable versatile nanocatalyst for multiple organic reactions and density functional study of its electronic structures

2018-11-12T08:32:33+00:00November 12th, 2018|Categories: Publications|Tags: , |

RSC Adv., 2018, 8,37774-37788DOI: 10.1039/C8RA08235A, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Madhurya Chandel, Priyanka Makkar, Barun Kumar Ghosh, Debabrata Moitra, Narendra Nath GhoshHere, we report a simple ‘in situ’ co-precipitation reduction synthesis method for

Published in: "RSC Advances".

Graphene‐Sensitized Perovskite Oxide Monolayer Nanosheets for Efficient Photocatalytic Reaction

2018-11-11T04:32:54+00:00November 11th, 2018|Categories: Publications|Tags: , , |

Ca2Nb3O10 monolayer nanosheet/reduced graphene oxide (RGO) (CNOMS/RGO) 2D–2D nanohybrids with much enhanced photocatalytic H2 production and tetracycline hydrochloride degradation activities are successfully synthesized. Integrating the experiment data with density functional theory calculation, it is demonstrated that RGO acts as an excellent photosensitizer to boost the visible‐light–harvesting of monolayer CNO nanosheets in solar‐energy conversion. Abstract Efficient visible light harvesting and fast charge transfer are of high importance for solar‐energy conversion over semiconducting metal oxide photocatalysts. Here, a proof‐of‐concept strategy is developed to enable visible‐light photocatalytic activity of wide bandgap Ca2Nb3O10 monolayer nanosheet by incorporation of reduced graphene oxide (RGO) nanosheet as a photosensitizer. The Ca2Nb3O10 monolayer nanosheet/RGO 2D–2D nanohybrids exhibit largely elevated performance in photocatalytic H2 evolution with a H2 production rate of 820.76 µmol h−1 g−1 and tetracycline hydrochloride degradation reactions under the visible light irradiation. The combined experimental and theoretical results demonstrate that the electrons generated from the photoexcited RGO transfer to the Ca2Nb3O10 monolayer nanosheet and then participate in the photocatalytic reactions. The constructed RGO sensitized monolayer perovskite photocatalyst nanohybrids are demonstrated as an efficient photosensitizer for enhancing visible light harvesting of wide bandgap semiconductor in solar‐energy conversion, and elaborated in details of the charge transfer process of this type of nanohybrid photocatalyst.

Published in: "Advanced Functional Materials".

Bioinspired Micro/Nanofluidic Ion Transport Channels for Organic Cathodes in High‐Rate and Ultrastable Lithium/Sodium‐Ion Batteries

2018-11-11T04:32:52+00:00November 11th, 2018|Categories: Publications|Tags: , , |

Inspired by the fast permeation of ions within the protein ion channels on cell membranes, a flexible sandwich‐structured 3,4,9,10‐perylenetetracarboxylic dianhydride (PTCDA)/reduced graphene oxide (RGO)/carbon nanotube (CNT) (PTCDA/RGO/CNT) film with bioinspired three‐dimensional multilayered micro/nanochannels is designed for lithium and sodium ion batteries. Because of the unique structural features, the PTCDA/RGO/CNT electrode exhibits particularly excellent lithium/sodium storage performance and cyclic stability. Abstract Conjugated carbonyl compounds are considered as ideal substitutes for traditional inorganic electrodes in lithium/sodium ion batteries (LIBs/SIBs) due to their excellent redox reversibility and structural tunability. Here, a flexible sandwich‐structured 3,4,9,10‐perylenetetracarboxylic dianhydride (PTCDA)/reduced graphene oxide (RGO)/carbon nanotube (CNT) (PTCDA/RGO/CNT) composite film with bioinspired micro/nanofluidic ion transport channels and interconnected porous conductive frameworks is designed and obtained by vacuum‐filtration and heating methods for LIB/SIB applications. The PTCDA/RGO/CNT electrode with robust mechanical deformability exhibits high diffusion coefficients of Li+/Na+ and low Warburg coefficients. Thus, desirable electrochemical performances with high capacities of 131 and 126 mA h g−1 at 10 mA g−1, and ultralong cycling stability with over 99% capacity retention after 500 cycles at 200 mA g−1 are achieved for LIBs and SIBs, respectively. In particular, Li/Na‐ion full cells consisting of lithiated or sodiated electrospun carbon nanofiber anode and PTCDA/RGO/CNT‐based cathode are developed to exhibit high energy densities of 132.6 and 104.4 W h kg−1 at the power densities of 340 and 288 W kg−1 for LIBs and SIBs, respectively. The advantageous features demonstrated by constructing bioinspired micro/nanofluidic channels may provide a new pathway toward the design of next‐generation wearable energy

Published in: "Advanced Functional Materials".

A Multifunctional Silly‐Putty Nanocomposite Spontaneously Repairs Cathode Composite for Advanced Li−S Batteries

2018-11-11T04:32:44+00:00November 11th, 2018|Categories: Publications|Tags: , , |

Self‐healing conductive polymer reduced graphene oxide–Silly Putty enables effective suppression of “shuttle effects” while spontaneously forming all‐around conductive protecting layer on the surface of the cathode and repairs the mechanical/structure damages of the cathode in Li−S batteries during cycling is reported. As a result, the G‐SP added cell delivers a capacity of 586 mAh g−1 after 1000 cycles. Abstract Although lithium–sulfur batteries have been regarded as one of the most promising candidates for high efficient energy storage devices, however, their practical application are still hindered by the notorious “shuttle effect” and instability of cathode structure during cycling. In this work, conductive reduced graphene oxides nanosheets added–putty (rGO–putty ) adaptive functional interlayer is designed to effectively suppress the diffusion of polysulfides while simultaneously promoted the dynamic protection of the whole cathode structure during cycling. Consequently, largely suppressed polysulfides diffusion combined with the greatly enhanced cathode stability is achieved while the all‐around conductive protecting layer is formed benefited from the viscoelasticity property of rGO–putty. As a result, a capacity of 586 mAh g−1 is demonstrated after long‐cycling term of 1000 cycles and high cycling stability of only 0.03% capacity decay per cycle is exhibited. The largely enhanced electrochemical performance suggests the important role of the rGO–putty in suppressing the “shuttle effect” and maintaining the integrity of the cathode material.

Published in: "Advanced Functional Materials".

3D‐Printed Graphene Oxide Framework with Thermal Shock Synthesized Nanoparticles for Li‐CO2 Batteries

2018-11-11T04:32:30+00:00November 11th, 2018|Categories: Publications|Tags: , , |

An ultrathick electrode (≈0.4 mm) with ultrafine Ni nanoparticles (≈5 nm) anchored on a 3D reduced graphene oxide framework is designed as cathode for Li‐CO2 batteries via 3D printing technique and thermal shock treatment (1900 K for 54 ms). The electrode exhibits low overpotential, long cycling life, good rate capability, and high areal capacity for Li‐CO2 batteries. Abstract Li‐CO2 batteries have emerged as a promising energy storage technology due to their high theoretical energy density. A thick electrode design is an effective approach for further increasing the energy density on device level by decreasing the weight and volume ratios of inactive materials. Exploring and designing novel thick electrodes with high catalytic activity toward reversible reaction between lithium and carbon dioxide are key challenges to achieve a low charge overpotential, long cycling stability, and high rate performance. Herein, an ultrathick electrode (≈0.4 mm) design for Li‐CO2 batteries by anchoring ultrafine Ni nanoparticles (≈5 nm) on a 3D‐printed reduced graphene oxide framework via thermal shock (1900 K for 54 ms) is demonstrated. The cathode displays low overpotential of 1.05 V at 100 mA g−1, high cycling stability of over 100 cycles, and good rate capability (up to 1000 mA g−1). In particular, a high areal capacity of 14.6 mA h cm−2 can be achieved due to the thick electrode design and uniform distribution of ultrafine catalyst nanoparticles. The strategy of combining an advanced 3D printing technique with fast thermal shock represents a promising direction toward thick electrode design in energy storage

Published in: "Advanced Functional Materials".

Thermally Conductive Phase Change Composites Featuring Anisotropic Graphene Aerogels for Real‐Time and Fast‐Charging Solar‐Thermal Energy Conversion

2018-11-11T04:32:21+00:00November 11th, 2018|Categories: Publications|Tags: , , |

Anisotropic and high‐quality graphene aerogels are fabricated by directional‐freezing of polyamic acid salt/graphene oxide slurries, followed by freeze‐drying, imidization, and graphitization. A phase change composite derived from the aerogel exhibits both high longitudinal thermal conductivity of ≈8.87 W m−1 K−1 and excellent latent heat retention of 98.7% with satisfactory stability, and is suitable for real‐time and fast solar‐thermal energy conversion. Abstract Phase change materials (PCMs) have triggered considerable attention as candidates for solar‐thermal energy conversion. However, their intrinsic low thermal conductivity prevents the rapid spreading of heat into the interior of the PCM, causing low efficiencies in energy storage/release. Herein, anisotropic and lightweight high‐quality graphene aerogels are developed by directionally freezing aqueous suspensions of polyamic acid salt and graphene oxide to form vertically aligned monoliths, followed by freeze‐drying, imidization at 300 °C and graphitization at 2800 °C. After impregnating with paraffin wax, the resultant phase change composite (PCC) exhibits a high transversal thermal conductivity of 2.68 W m−1 K−1 and an even higher longitudinal thermal conductivity of 8.87 W m−1 K−1 with an exceptional latent heat retention of 98.7%. When subjected to solar radiation, solar energy is converted to heat at the exposed surface of the PCC. As a result of the PCC’s high thermal conductivity in the thickness direction, heat can spread readily into the interior of the PCC enabling a small temperature gradient of <3.0 K cm−1 and a fast charging feature. These results demonstrate the potential for real‐time and fast‐charging solar‐thermal energy conversion using phase change

Published in: "Advanced Functional Materials".

Architectured Leaf‐Inspired Ni0.33Co0.66S2/Graphene Aerogels via 3D Printing for High‐Performance Energy Storage

2018-11-11T04:32:14+00:00November 11th, 2018|Categories: Publications|Tags: , , |

A shape‐programmable Ni0.33Co0.66S2/graphene aerogel is 3D printed (3DP‐NCS/G) to mimic the mass transfer process of natural leaves. A hybrid ink is developed for components regulation and shape design. The interconnected networks and massive exposed edge sites of the 3DP‐NCS/G aerogels contribute to enhanced electrochemical performances. The device delivers competitive areal energy/power densities at practical levels of mass loading. Abstract The construction of high‐performance electrodes with sufficient active sites and interconnected networks for rapid electron/ions transport is challengeable for energy storage devices. Inspired by natural leaves, a facile 3D‐printing strategy for constructing architected Ni0.33Co0.66S2/graphene (3DP‐NCS/G) aerogels to mimic the analogous mass transfer process toward superior electrochemical performances is demonstrated. The key step is to develop hybrid inks with printability and homogeneity by introducing sodium alginate into graphene oxide solutions to boost viscoelastic responses and adopting a new developed precursor Ni0.33Co0.66(OH)2·xH2O with ultrafine and high stable features. Benefiting from high‐speed channels for electron/ion transport provided by the interconnected graphene frameworks and massive exposed edge sites provided by the uniformly dispersed Ni0.33Co0.66S2 nanoparticles, the 3DP‐NCS/G electrode exhibits capacities of 217.6 mAh g−1 at 1 A g−1 and 164.6 mAh g−1 at 10 A g−1. Furthermore, a hybrid device is demonstrated for the first time with both electrodes manufactured by 3D‐printing technique, which delivers excellent areal energy/power densities with values comparable to those of commercial devices, even at a practical level of electrode mass loading (17.86 mg cm−2). This work offers a versatile strategy for integrating various functional nanomaterials with programmable architectures toward

Published in: "Advanced Functional Materials".

Molecule–Graphene Hybrid Materials with Tunable Mechanoresponse: Highly Sensitive Pressure Sensors for Health Monitoring

2018-11-10T22:34:43+00:00November 10th, 2018|Categories: Publications|Tags: , |

Toward highly performing piezoresistive pressure sensors, a radically new type of sensor based on reduced graphene oxide is demonstrated. Functionalization of graphene oxide with flexible molecular springs allows generation of devices featuring high sensitivity, short response time, and ultralow detection limit, which can be applied to health monitoring and 3D mapping of the pressure. Abstract The development of pressure sensors is crucial for the implementation of electronic skins and for health monitoring integrated into novel wearable devices. Tremendous effort is devoted toward improving their sensitivity, e.g., by employing microstructured electrodes or active materials through cumbersome processes. Here, a radically new type of piezoresistive pressure sensor based on a millefeuille‐like architecture of reduced graphene oxide (rGO) intercalated by covalently tethered molecular pillars holding on‐demand mechanical properties are fabricated. By applying a tiny pressure to the multilayer structure, the electron tunnelling ruling the charge transport between successive rGO sheets yields a colossal decrease in the material’s electrical resistance. Significantly, the intrinsic rigidity of the molecular pillars employed enables the fine‐tuning of the sensor’s sensitivity, reaching sensitivities as high as 0.82 kPa−1 in the low pressure region (0–0.6 kPa), with short response times (≈24 ms) and detection limit (7 Pa). The pressure sensors enable efficient heartbeat monitoring and can be easily transformed into a matrix capable of providing a 3D map of the pressure exerted by different objects.

Published in: "Advanced Materials".

Graphene‐Sensitized Perovskite Oxide Monolayer Nanosheets for Efficient Photocatalytic Reaction

2018-11-10T00:32:36+00:00November 9th, 2018|Categories: Publications|Tags: , , |

Ca2Nb3O10 monolayer nanosheet/reduced graphene oxide (RGO) (CNOMS/RGO) 2D–2D nanohybrids with much enhanced photocatalytic H2 production and tetracycline hydrochloride degradation activities are successfully synthesized. Integrating the experiment data with density functional theory calculation, it is demonstrated that RGO acts as an excellent photosensitizer to boost the visible‐light–harvesting of monolayer CNO nanosheets in solar‐energy conversion. Abstract Efficient visible light harvesting and fast charge transfer are of high importance for solar‐energy conversion over semiconducting metal oxide photocatalysts. Here, a proof‐of‐concept strategy is developed to enable visible‐light photocatalytic activity of wide bandgap Ca2Nb3O10 monolayer nanosheet by incorporation of reduced graphene oxide (RGO) nanosheet as a photosensitizer. The Ca2Nb3O10 monolayer nanosheet/RGO 2D–2D nanohybrids exhibit largely elevated performance in photocatalytic H2 evolution with a H2 production rate of 820.76 µmol h−1 g−1 and tetracycline hydrochloride degradation reactions under the visible light irradiation. The combined experimental and theoretical results demonstrate that the electrons generated from the photoexcited RGO transfer to the Ca2Nb3O10 monolayer nanosheet and then participate in the photocatalytic reactions. The constructed RGO sensitized monolayer perovskite photocatalyst nanohybrids are demonstrated as an efficient photosensitizer for enhancing visible light harvesting of wide bandgap semiconductor in solar‐energy conversion, and elaborated in details of the charge transfer process of this type of nanohybrid photocatalyst.

Published in: "Advanced Functional Materials".

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