Graphene oxide

/Tag: Graphene oxide

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".

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

2018-11-10T00:32:34+00:00November 9th, 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".

Synthesis of novel cyclodextrin-modified reduced graphene oxide composites by a simple hydrothermal method

2018-11-08T14:32:34+00:00November 8th, 2018|Categories: Publications|Tags: , |

RSC Adv., 2018, 8,37623-37630DOI: 10.1039/C8RA07807F, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Qingli Huang, MingYan Li, LiLi Wang, Honghua Yuan, Meng Wang, Yongping Wu, Ting LiThe [email protected]@[email protected] nanocomposite showed the stimulative effect of heat, pH

Published in: "RSC Advances".

Efficient Room-Temperature Production of High-Quality Graphene by Introducing Removable Oxygen Functional Groups to Precursor

2018-11-08T04:31:52+00:00November 8th, 2018|Categories: Publications|Tags: , |

Chem. Sci., 2019, Accepted ManuscriptDOI: 10.1039/C8SC03695K, Edge Article Open Access &nbsp This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Hongwu Chen, Wencheng Du, Jing Liu, Liangti Qu, Chun LiExcellent solution-processability of graphene oxide (GO) have provided a collection of strategies for the construction of functional graphene assemblies. To improve the performance of graphene-based materials, structurally intact GO should…The content of this RSS Feed (c) The Royal Society of Chemistry

Published in: "Chemical Science".

Exploring Indium‐Based Ternary Thiospinel as Conceivable High‐Potential Air‐Cathode for Rechargeable Zn–Air Batteries

2018-11-07T14:33:10+00:00November 7th, 2018|Categories: Publications|Tags: , , |

A novel and promising bifunctional oxygen electrocatalyst (CoIn2S4) is demonstrated, with S‐doped reduced graphene oxide as an electronic conductor. Both experimental and theoretical investigations demonstrate that the introduction of indium can effectively promote the reversible oxygen electrode reactions. A rechargeable Zn–air battery with this catalyst exhibits a high voltaic efficiency and long cycling life, outperforming the costlier Pt/C+RuO2 mixture catalyst. Abstract Reversible oxygen reactions in Zn–air batteries require cost‐effective and highly‐active bifunctional electrocatalysts to substitute traditional noble‐metal based catalysts. Herein, a new and promising electrocatalytic material, ternary CoIn2S4 thiospinel, is demonstrated for effectively catalyzing oxygen reduction and oxygen evolution reactions (ORR and OER) with S‐doped reduced graphene oxide (S‐rGO) as an electronic conductor. Compared with Co9S8/S‐rGO (without In doping), the newly developed CoIn2S4/S‐rGO reveals superior electrocatalytic properties for the ORR (half‐wave potential of 0.83 V) and OER (overpotential of 0.37 V at 10 mA cm−2), demonstrating that the introduction of In can promote the reversible oxygen electrode reactions of CoIn2S4. The superior experimentally‐observed electrocatalytic properties are corroborated via density function theory investigations. Meanwhile, the synergistic improvements in the bifunctional activities resulting from the combination of CoIn2S4 and S‐rGO are also confirmed. As a proof of concept, home‐made Zn–air cells are assembled with CoIn2S4/S‐rGO as an air‐cathode. The developed Zn–air cells exhibit a high peak power density (133 mW cm−2) with an energy density of 951 Wh kgZn−1 and robust cycling stability over 150 cycles for 50 h, exceeding of those commercial Pt/C+RuO2 which highlights the practical viability of CoIn2S4/S‐rGO

Published in: "Advanced Energy Materials".

Fast Na‐Ion Intercalation in Zinc Vanadate for High‐Performance Na‐Ion Hybrid Capacitor

2018-11-07T14:33:02+00:00November 7th, 2018|Categories: Publications|Tags: , , |

A composite of reduced graphene oxide and Zn0.25V2O5·nH2O nanobelts is reported as a new type of Na+ intercalation material with high pseudocapacitance, enabling fast sodium storage. Combination of this material as an anode with a capacitive cathode composed of an ordered mesoporous carbon gives access to a high‐performance Na‐ion hybrid capacitor. Abstract Na‐ion hybrid capacitors are an emerging class of inexpensive and sustainable devices that combine the high energy of batteries with the high power of capacitors. However, their development is strongly impeded by a limited choice of electrode materials that display good electrochemical kinetics and long‐term cyclability. Here, a reduced graphene oxide–Zn0.25V2O5·nH2O nanobelt composite is introduced as a high power anode for Na‐ion batteries and Na‐ion hybrid capacitors. The composite material possesses fast Na‐ion intercalation kinetics, high electronic conductivity, and small volume change during Na‐ion storage, which lead to outstanding rate capability and cycling stability in half‐cell tests. Pairing it with a hard salt–templated, highly ordered mesoporous carbon as a high‐performance capacitive cathode results in a Na‐ion hybrid capacitor, which delivers a high energy density (88.7 Wh kg−1 at 223 W kg−1), a high power density (12552 W kg−1 with 13.2 Wh kg−1 retained), and an impressive cycling performance (31.7 Wh kg−1 (i.e., 87%) retained after 2000 cycles at 1 A g−1). This work explores zinc vanadate, a typical example of a layered metal vanadate, as an intercalation anode material with high pseudocapacitance for Na‐ion hybrid capacitors, which may open a promising direction for high‐rate Na‐ion storage.

Published in: "Advanced Energy Materials".

Physicochemical characterisation of reduced graphene oxide for conductive thin films

2018-11-07T12:32:38+00:00November 7th, 2018|Categories: Publications|Tags: , |

RSC Adv., 2018, 8,37540-37549DOI: 10.1039/C8RA08849G, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.Elizabeth J. Legge, Muhammad Ahmad, Christopher T. G. Smith, Barry Brennan, Christopher A. Mills, Vlad Stolojan, Andrew J. Pollard, S. Ravi P. SilvaWe

Published in: "RSC Advances".

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

2018-11-07T08:35:43+00:00November 7th, 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".

Glass‐Fabric Reinforced Ag Nanowire/Siloxane Composite Heater Substrate: Sub‐10 nm [email protected] Oxide Nanosheet for Sensitive Flexible Sensing Platform

2018-11-07T08:35:38+00:00November 7th, 2018|Categories: Publications|Tags: , |

A highly sensitive flexible sensing platform is successfully achieved by integrating ultrathin Pt‐loaded SnO2 nanosheets and Ag nanowires embedded flexible hybrimer heater. As a result, via tailored combination of Pt‐SnO2 NSs with AgNW‐GFRVPH film substrate, not only improved bendability with high thermal stability but also extremely sensitive and selective DMS sensing properties are obtained. Abstract The development of flexible chemiresistors is imperative for real‐time monitoring of air quality and/or human physical conditions without space constraints. However, critical challenges such as poor sensing characteristics, vulnerability under toxic chemicals, and weak reliability hinder their practical use. In this work, for the first time, an ultrasensitive flexible sensing platform is reported by assembling Pt loaded thin‐layered (≈10 nm) SnO2 nanosheets (Pt‐SnO2 NSs) based 2D sensing layers on Ag nanowires embedded glass‐fabric reinforced vinyl–phenyl siloxane hybrid composite substrate (AgNW‐GFRVPH film) as a heater. The thermally stable AgNW‐GFRVPH film based heater is fabricated by free radical polymerization of vinyl groups in vinyl–phenyl oligosiloxane and phenyltris(dimethylvinylsiloxy)silane with Ag NW and glass‐fabric, showing outstanding heat generation (≈200 °C), high dimensional stability (13 ppm °C−1), and good thermal stability (≈350 °C). The Pt‐SnO2 NSs, which are synthesized by calcination of Sn precursor coated graphene oxide (GO) sheets and subsequent Pt functionalization, exhibit high mechanical flexibility and superior response (R air/R gas = 4.84) to 1 ppm level dimethyl sulfide. Taking these advantages, GO‐templated oxide NSs combined with a highly stable AgNW‐GFRVPH film heater exhibits the best dimethyl sulfide sensing performance compared to state‐of‐the‐art flexible chemiresistors, enabling them

Published in: "Small".

Sphere‐to‐Multipod Transmorphic Change of Nanoconfined Pt Electrocatalyst during Oxygen Reduction Reaction

2018-11-07T08:35:31+00:00November 7th, 2018|Categories: Publications|Tags: , |

Pt nanoconfined within holes of graphene exhibits excellent durability along repeated oxygen reduction. The Ostwald ripening dominant over the surface migration in the nanoconfined situation evolves spherical multifaceted Pt particles to the {110}‐dominant dendritic multipods. Abstract An oxygen reduction reaction (ORR) catalyst/support system is designed to have Pt nanoparticles nanoconfined in a nanodimensionally limited space. Holey crumpled reduced graphene oxide plates (hCR‐rGO) are used as a carbon support for Pt loading. As expected from interparticular Pt‐to‐Pt distance of Pt‐loaded hCR‐rGO longer than that of Pt/C (Pt‐loaded carbon black as a practical Pt catalyst), the durability of ORR electroactivity along cycles is improved by replacing the widely used carbon black with hCR‐rGO. Unexpected morphological changes of Pt are electrochemically induced during repeated ORR processes. Spherical multifaceted Pt particles are evolved to {110}‐dominant dendritic multipods. Nanoconfinement of a limited number of Pt within a nanodimensionally limited space is responsible for the morphological changes. The improved durability observed from Pt‐loaded hCR‐rGO originates from 1) dendritic pod structure of Pt exposing more active sites to reactants and 2) highly ORR‐active Pt {110} planes dominant on the surface.

Published in: "Small".

“Non‐Naked” Gold with Glucose Oxidase‐Like Activity: A Nanozyme for Tandem Catalysis

2018-11-07T08:35:15+00:00November 7th, 2018|Categories: Publications|Tags: , |

“Non‐naked” gold nanoparticles (Au NPs) with the glucose oxidase (GOx)‐like activity are synthesized by using protein as protector. “Non‐naked” Au NPs show tandem enzyme‐like characteristics, which simultaneously have dual enzyme‐like activities. Moreover, the covalent modification of Au NPs with graphene oxide cannot affect their GOx‐like activity. Furthermore, a one‐pot enzyme‐free strategy is developed for the fast colorimetric detection of glucose. Abstract It has been widely reported that “naked” gold nanoparticles (Au NPs) without protectors have glucose oxidase (GOx)‐like activity, and the use of protectors can inhibit the GOx‐like activity. Here, “non‐naked” Au NPs with GOx‐like activity are synthesized by using protein as protector. Although “naked” Au NPs have peroxidase‐like activity and GOx‐like activity, the optimal pH ranges of the both activities are obviously different. Fortunately, as‐synthesized “non‐naked” Au NPs show the dual enzyme‐like activities at the same pH. So, “non‐naked” Au NPs can be described as “tandem nanozyme.” As another bonus, the participation of protein protector can stabilize the GOx‐like activity and make Au NPs modifiable. Even though Au NPs are connected with graphene oxide (GO), the GOx‐like activity is still not changed. Further, Au NPs‐GO nanocomposites are applied on the one‐pot nonenzymatic glucose colorimetric detection. The “non‐naked” gold not only broadens the species of tandem nanozymes, but also facilitates the functionalization of nanozymes, which is promising for immunoassay, biosensor, and medical treatment.

Published in: "Small".

Mesoporous Reduced Graphene Oxide as a High Capacity Cathode for Aluminum Batteries

2018-11-07T08:35:04+00:00November 7th, 2018|Categories: Publications|Tags: , , |

Tailoring the pore size distribution of carbon‐based cathodes is a decisive factor for the electrochemical performance of aluminum batteries. Here, the mesopores in a reduced graphene oxide powder facilitate the movement of large chloroaluminate ions, effectively minimizing the inactive mass content of the electrode and compensating for an ordinary micropore volume. Abstract Research in the field of aluminum batteries has focused heavily on electrodes made of carbonaceous materials. Still, the capacities reported for these multivalent systems remain stubbornly low. It is believed that a high structural quality of graphitic carbons and/or specific surface areas of >1000 m2 g‐1 are key factors to obtain optimal performance and cycling stability. Here an aluminum chloride battery is presented in which reduced graphene oxide (RGO) powder, dried under supercritical conditions, is used as the active cathode material and niobium foil as the current collector. With a specific surface area of just 364 m2 g‐1, the RGO enables a gravimetric capacity of 171 mAh g‐1 at 100 mA g‐1 and remarkable stability over a wide range of current densities (<15% decrease over 100 cycles in the interval 100–20000 mA g‐1). These properties, up to now achieved only with much larger surface area materials, result from the cathode’s tailored mesoporosity. The 20 nm wide mesopores facilitate the movement of the chloroaluminate ions through the RGO, effectively minimizing the inactive mass content of the electrode. This more than compensates for the ordinary micropore volume of the graphene powder.

Published in: "Small".

Exploring Indium‐Based Ternary Thiospinel as Conceivable High‐Potential Air‐Cathode for Rechargeable Zn–Air Batteries

2018-11-07T02:37:40+00:00November 7th, 2018|Categories: Publications|Tags: , , |

A novel and promising bifunctional oxygen electrocatalyst (CoIn2S4) is demonstrated, with S‐doped reduced graphene oxide as an electronic conductor. Both experimental and theoretical investigations demonstrate that the introduction of indium can effectively promote the reversible oxygen electrode reactions. A rechargeable Zn–air battery with this catalyst exhibits a high voltaic efficiency and long cycling life, outperforming the costlier Pt/C+RuO2 mixture catalyst. Abstract Reversible oxygen reactions in Zn–air batteries require cost‐effective and highly‐active bifunctional electrocatalysts to substitute traditional noble‐metal based catalysts. Herein, a new and promising electrocatalytic material, ternary CoIn2S4 thiospinel, is demonstrated for effectively catalyzing oxygen reduction and oxygen evolution reactions (ORR and OER) with S‐doped reduced graphene oxide (S‐rGO) as an electronic conductor. Compared with Co9S8/S‐rGO (without In doping), the newly developed CoIn2S4/S‐rGO reveals superior electrocatalytic properties for the ORR (half‐wave potential of 0.83 V) and OER (overpotential of 0.37 V at 10 mA cm−2), demonstrating that the introduction of In can promote the reversible oxygen electrode reactions of CoIn2S4. The superior experimentally‐observed electrocatalytic properties are corroborated via density function theory investigations. Meanwhile, the synergistic improvements in the bifunctional activities resulting from the combination of CoIn2S4 and S‐rGO are also confirmed. As a proof of concept, home‐made Zn–air cells are assembled with CoIn2S4/S‐rGO as an air‐cathode. The developed Zn–air cells exhibit a high peak power density (133 mW cm−2) with an energy density of 951 Wh kgZn−1 and robust cycling stability over 150 cycles for 50 h, exceeding of those commercial Pt/C+RuO2 which highlights the practical viability of CoIn2S4/S‐rGO

Published in: "Advanced Energy Materials".

Fast Na‐Ion Intercalation in Zinc Vanadate for High‐Performance Na‐Ion Hybrid Capacitor

2018-11-07T02:37:21+00:00November 7th, 2018|Categories: Publications|Tags: , , |

A composite of reduced graphene oxide and Zn0.25V2O5·nH2O nanobelts is reported as a new type of Na+ intercalation material with high pseudocapacitance, enabling fast sodium storage. Combination of this material as an anode with a capacitive cathode composed of an ordered mesoporous carbon gives access to a high‐performance Na‐ion hybrid capacitor. Abstract Na‐ion hybrid capacitors are an emerging class of inexpensive and sustainable devices that combine the high energy of batteries with the high power of capacitors. However, their development is strongly impeded by a limited choice of electrode materials that display good electrochemical kinetics and long‐term cyclability. Here, a reduced graphene oxide–Zn0.25V2O5·nH2O nanobelt composite is introduced as a high power anode for Na‐ion batteries and Na‐ion hybrid capacitors. The composite material possesses fast Na‐ion intercalation kinetics, high electronic conductivity, and small volume change during Na‐ion storage, which lead to outstanding rate capability and cycling stability in half‐cell tests. Pairing it with a hard salt–templated, highly ordered mesoporous carbon as a high‐performance capacitive cathode results in a Na‐ion hybrid capacitor, which delivers a high energy density (88.7 Wh kg−1 at 223 W kg−1), a high power density (12552 W kg−1 with 13.2 Wh kg−1 retained), and an impressive cycling performance (31.7 Wh kg−1 (i.e., 87%) retained after 2000 cycles at 1 A g−1). This work explores zinc vanadate, a typical example of a layered metal vanadate, as an intercalation anode material with high pseudocapacitance for Na‐ion hybrid capacitors, which may open a promising direction for high‐rate Na‐ion storage.

Published in: "Advanced Energy Materials".

Fast Na‐Ion Intercalation in Zinc Vanadate for High‐Performance Na‐Ion Hybrid Capacitor

2018-11-07T02:37:20+00:00November 7th, 2018|Categories: Publications|Tags: , , |

A composite of reduced graphene oxide and Zn0.25V2O5·nH2O nanobelts is reported as a new type of Na+ intercalation material with high pseudocapacitance, enabling fast sodium storage. Combination of this material as an anode with a capacitive cathode composed of an ordered mesoporous carbon gives access to a high‐performance Na‐ion hybrid capacitor. Abstract Na‐ion hybrid capacitors are an emerging class of inexpensive and sustainable devices that combine the high energy of batteries with the high power of capacitors. However, their development is strongly impeded by a limited choice of electrode materials that display good electrochemical kinetics and long‐term cyclability. Here, a reduced graphene oxide–Zn0.25V2O5·nH2O nanobelt composite is introduced as a high power anode for Na‐ion batteries and Na‐ion hybrid capacitors. The composite material possesses fast Na‐ion intercalation kinetics, high electronic conductivity, and small volume change during Na‐ion storage, which lead to outstanding rate capability and cycling stability in half‐cell tests. Pairing it with a hard salt–templated, highly ordered mesoporous carbon as a high‐performance capacitive cathode results in a Na‐ion hybrid capacitor, which delivers a high energy density (88.7 Wh kg−1 at 223 W kg−1), a high power density (12552 W kg−1 with 13.2 Wh kg−1 retained), and an impressive cycling performance (31.7 Wh kg−1 (i.e., 87%) retained after 2000 cycles at 1 A g−1). This work explores zinc vanadate, a typical example of a layered metal vanadate, as an intercalation anode material with high pseudocapacitance for Na‐ion hybrid capacitors, which may open a promising direction for high‐rate Na‐ion storage.

Published in: "Advanced Energy Materials".

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

2018-11-07T02:33:04+00:00November 7th, 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".

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