/Tag: Graphene

Self‐Powered Chemical Sensing Driven by Graphene‐Based Photovoltaic Heterojunctions with Chemically Tunable Built‐In Potentials

2018-12-16T00:33:48+00:00December 15th, 2018|Categories: Publications|Tags: , |

Graphene (Gr)‐based photovoltaic heterojunctions capable of self‐powered chemical sensing are presented. Owing to the chemically tunable electrochemical potential of Gr, the built‐in electric field at the junction is effectively modulated by absorbed gas molecules, enabling photovoltaic‐driven sensing without electric power consumption. An innovative strategy to realize extremely energy‐efficient sensors provides an important advancement for future ubiquitous sensing. Abstract Ultralow power chemical sensing is essential toward realizing the Internet of Things. However, electrically driven sensors must consume power to generate an electrical readout. Here, a different class of self‐powered chemical sensing platform based on unconventional photovoltaic heterojunctions consisting of a top graphene (Gr) layer in contact with underlying photoactive semiconductors including bulk silicon and layered transition metal dichalcogenides is proposed. Owing to the chemically tunable electrochemical potential of Gr, the built‐in potential at the junction is effectively modulated by absorbed gas molecules in a predictable manner depending on their redox characteristics. Such ability distinctive from bulk photovoltaic counterparts enables photovoltaic‐driven chemical sensing without electric power consumption. Furthermore, it is demonstrated that the hydrogen (H2) sensing properties are independent of the light intensity, but sensitive to the gas concentration down to the 1 ppm level at room temperature. These results present an innovative strategy to realize extremely energy‐efficient sensors, providing an important advancement for future ubiquitous sensing.

Published in: "Small".

Recent Advances in 3D Graphene Architectures and Their Composites for Energy Storage Applications

2018-12-16T00:33:47+00:00December 15th, 2018|Categories: Publications|Tags: , |

Here, recent advances in synthesizing 3D graphene architectures and their composites as well as their application in different energy storage devices are reviewed, including various battery systems and supercapacitors. In addition, their challenges for application at the current stage are discussed, and future development prospects are indicated. Abstract Graphene is widely applied as an electrode material in energy storage fields. However, the strong π–π interaction between graphene layers and the stacking issues lead to a great loss of electrochemically active surface area, damaging the performance of graphene electrodes. Developing 3D graphene architectures that are constructed of graphene sheet subunits is an effective strategy to solve this problem. The graphene architectures can be directly utilized as binder‐free electrodes for energy storage devices. Furthermore, they can be used as a matrix to support active materials and further improve their electrochemical performance. Here, recent advances in synthesizing 3D graphene architectures and their composites as well as their application in different energy storage devices, including various battery systems and supercapacitors are reviewed. In addition, their challenges for application at the current stage are discussed and future development prospects are indicated.

Published in: "Small".

Site‐Selective and van der Waals Epitaxial Growth of Rhenium Disulfide on Graphene

2018-12-16T00:33:45+00:00December 15th, 2018|Categories: Publications|Tags: , , , |

Vertical van der Waals heterostructure of graphene/rhenium disulfide (ReS2) is synthesized by chemical vapor deposition. The rhenium disulfide is successfully grown along the in‐plane direction on an atomically smooth and chemically inert graphene surface without developing any structural defects, resulting in the high‐quality graphene/rhenium disulfide heterostructure. In addition, the patterning of vertical heterostructure is achieved through the site‐specific growth of ReS2. Abstract The surface property of growth substrate imposes significant influence in the growth behaviors of 2D materials. Rhenium disulfide (ReS2) is a new family of 2D transition metal dichalcogenides with unique distorted 1T crystal structure and thickness‐independent direct bandgap. The role of growth substrate is more critical for ReS2 owing to its weak interlayer coupling property, which leads to preferred growth along the out‐of‐plane direction while suppressing the uniform in‐plane growth. Herein, graphene is introduced as the growth substrate for ReS2 and the synthesis of graphene/ReS2 vertical heterostructure is demonstrated via chemical vapor deposition. Compared with the rough surface of SiO2/Si substrate with dangling bonds which hinders the uniform growth of ReS2, the inert and smooth surface nature of graphene sheet provides a lower energy barrier for migration of the adatoms, thereby promoting the growth of ReS2 on the graphene surface along the in‐plane direction. Furthermore, patterning of the graphene/ReS2 heterostructure is achieved by the selective growth of ReS2, which is attributed to the strong binding energy between sulfur atoms and graphene surface. The fundamental studies in the role of graphene as the growth template in the formation of

Published in: "Small".

3D Gold‐Modified Cerium and Cobalt Oxide Catalyst on a Graphene Aerogel for Highly Efficient Catalytic Formaldehyde Oxidation

2018-12-16T00:33:41+00:00December 15th, 2018|Categories: Publications|Tags: , |

Au‐Ce xCo y catalyst and graphene oxide are well formed to aerogel through a diamine cross‐linker for formaldehyde catalytic oxidation. The porous structure of graphene aerogels provides pathways to allow the access of reactants to the catalyst particles. The interaction between CeO2 and Co3O4 supports effectively promotes the migration of oxygen species and activation of gold catalysts. Abstract A hard template method is used to prepare porous gold‐doped cerium and cobalt oxide (Au‐Ce xCo y) materials. A series of 3D Au‐Ce xCo y/graphene aerogel (GA) composites is then fabricated by a facile heating method. The obtained catalysts possess a well‐defined structure of ordered arrays of nanotubes and good performance in formaldehyde (HCHO) oxidation. The composition and surface elemental valence states of the catalysts are modulated by the Ce/Co molar ratio. The Au‐Ce xCo y catalyst and graphene oxide sheets are well compounded within 60 s through a diamine cross‐linker to form 3D Au‐Ce xCo y/GA composites. In addition, the resulting catalyst of 3 wt% Au‐Ce3Co/GA achieves ≈55% conversion at room temperature and 100% conversion when the reaction temperature is raised at 60 °C. The synergistic effect between CeO2 and Co3O4 promotes the migration of oxygen species and the activation of Au, which facilitates HCHO oxidation. The method used to prepare the 3D catalyst could be used to produce other catalytic materials with good replication of the template. In addition, these findings provide a simple method for rapid fabrication of catalyst/GA composites. The superior activity and stability of the 3D Au‐Ce3Co/GA

Published in: "Small".

Synthesis of P‐Doped and NiCo‐Hybridized Graphene‐Based Fibers for Flexible Asymmetrical Solid‐State Micro‐Energy Storage Device

2018-12-16T00:33:25+00:00December 15th, 2018|Categories: Publications|Tags: , , |

An all‐solid‐state P‐doped graphene oxide/carbon fiber (PGO/CF)//NiCo2O4‐based graphene oxide/carbon fiber (NCGO/CF) flexible asymmetric fiber supercapacitor (AFSC) with favorable flexibility and electrochemical properties is successfully assembled based on the PGO/CF and NCGO/CF electrodes. Interestingly, the introduction of the double reference electrode system provides a promising method for the study of the electrochemical performances of two‐electrode systems. Abstract Fiber supercapacitors (FSCs) are promising energy storage devices in portable and wearable smart electronics. Currently, a major challenge for FSCs is simultaneously achieving high volumetric energy and power densities. Herein, the microscale fiber electrode is designed by using carbon fibers as substrates and capillary channels as microreactors to space‐confined hydrothermal assembling. As P‐doped graphene oxide/carbon fiber (PGO/CF) and NiCo2O4‐based graphene oxide/carbon fiber (NCGO/CF) electrodes are successfully prepared, their unique hybrid structures exhibit a satisfactory electrochemical performance. An all‐solid‐state PGO/CF//NCGO/CF flexible asymmetric fiber supercapacitor (AFSC) based on the PGO/CF as the negative electrode, NCGO/CF hybrid electrode as the positive electrode, and poly(vinyl alcohol)/potassium hydroxide as the electrolyte is successfully assembled. The AFSC device delivers a higher volumetric energy density of 36.77 mW h cm−3 at a power density of 142.5 mW cm−3. In addition, a double reference electrode system is adopted to analyze and reduce the IR drop, as well as effectively matching negative and positive electrodes, which is conducive for the optimization and improvement of energy density. For the AFSC device, its better flexibility and electrochemical properties create a promising potential for high‐performance micro‐supercapacitors. Furthermore, the introduction of the double reference electrode system provides

Published in: "Small".

Superior Compatibility of C2N with Human Red Blood Cell Membranes and the Underlying Mechanism

2018-12-16T00:33:20+00:00December 15th, 2018|Categories: Publications|Tags: , , |

A combined experimental and theoretical study reveals that C2N exerts a negligible hemolysis effect on the blood cells with a superior biocompatibility. This arises from the unique electrostatic potential of the nanosheets, which enables it to exhibit neither phospholipid extraction nor a penetration effect on lipid membranes. Abstract The widespread use of nanomaterials, such as carbon based 2D nanomaterials, in biomedical applications, has been accompanied by a growing concern on their biocompatibility, and in particular, on how they may affect the integrity of cell membranes. Herein, the interactions between C2N, a novel 2D nanomaterial, and human red blood cell membranes are explored using a combined experimental and theoretical approach. The experimental microscopies show that C2N exerts a negligible hemolysis effect on the blood cells with a superior compatibility to their cell membranes, when compared with the control system, reduced graphene oxide (rGO), which is found to be highly hemolytic. The molecular dynamics simulations further reveal the underlying molecular mechanisms, which indicate that C2N prefers to be adsorbed flat on the water–membrane interface. Interaction energy analyses demonstrate the crucial role of Coulombic contributions, originating from the unique electrostatic potential surface of C2N, in preventing C2N from penetrating into cell membranes. These findings indicate a high compatibility of C2N with cell membranes, which may provide useful foundation for the future exploration of this 2D nanomaterial in related biomedical applications.

Published in: "Small".

Bioinspired Photonic Barcodes with Graphene Oxide Encapsulation for Multiplexed MicroRNA Quantification

2018-12-16T00:33:13+00:00December 15th, 2018|Categories: Publications|Tags: , |

A novel mussel‐inspired photonic crystal (PhC) barcode with graphene oxide (GO) encapsulation are presented for the multiplex miRNAs detection. The GO‐based hybridization chain reaction (HCR) strategy can realize low abundance and high sensitivity miRNA quantification. At the same time, multiplex detection can be achieved by employing different GO‐decorated PhC barcodes with high accuracy and reproducibility. Abstract Multiplexed microRNA (miRNA) quantification has a demonstrated value in clinical diagnosis. In this paper, novel mussel‐inspired photonic crystal (PhC) barcodes with graphene oxide (GO) encapsulation for multiplexed miRNA detection are presented. Using the excellent adhesion capability of polydopamine, the dispersed GO particles can be immobilized on the surfaces of the PhC barcodes to form an additional functional layer. The GO‐decorated PhC barcodes have constant characteristic reflection peaks because the GO immobilization process not only maintains their periodic microstructure but also enhances their stability and anti‐incoherent light‐scattering capability. The immobilized GO particles are shown to enable high‐sensitivity miRNA screening on the surface of the PhC barcodes by integration with a hybridization chain reaction amplification strategy. Because the PhC barcodes have stable encoding reflection peaks, multiplexed low‐abundance miRNA quantification can also be achieved rapidly, accurately, and reproducibly by employing different GO‐decorated PhC barcodes. These features should make GO‐encapsulated PhC barcodes ideal for many practical applications.

Published in: "Small".

Tension‐Induced Raman Enhancement of Graphene Membranes in the Stretched State

2018-12-16T00:33:07+00:00December 15th, 2018|Categories: Publications|Tags: |

An interesting tension‐induced Raman enhancement phenomenon, where the intensity ratios I 2D/I G are significantly enhanced up to 16.74 and increased by more than 670%, is observed in substrate‐supported graphene membranes near the wells. The microscopic mechanism of this phenomenon is the depression effect of built‐in stresses on the intensity of the G band. Abstract The intensity ratio of the 2D band to the G band, I 2D/I G, is a good criterion in selecting high quality monolayer graphene samples; however, the evaluation of the ultimate value of I 2D/I G for intrinsic monolayer graphene is a challenging yet interesting issue. Here, an interesting tension‐induced Raman enhancement phenomenon is reported in supported graphene membranes, which show a transition from the corrugated state to the stretched state in the vicinity of wells. The I 2D/I G of substrate‐supported graphene membranes near wells are significantly enhanced up to 16.74, which is the highest experimental value to the best of knowledge, increasing by more than 600% when the testing points approach the well edges.The macroscopic origin of this phenomenon is that corrugated graphene membranes are stretched by built‐in tensions. A lattice dynamic model is proposed to successfully reveal the microscopic mechanism of this phenomenon. The theoretical results agree well with the experimental data, demonstrating that tensile stresses can depress the amplitude of in‐plane vibration of sp2‐bonded carbon atoms and result in the decrease in the G band intensity. This work can be helpful in furthering the development of the method of suppressing small

Published in: "Small".

Facile Fabrication of Large‐Area Atomically Thin Membranes by Direct Synthesis of Graphene with Nanoscale Porosity

2018-12-15T22:34:17+00:00December 15th, 2018|Categories: Publications|Tags: |

Facile fabrication of large‐area atomically thin membranes by bottom‐up synthesis of nanoporous monolayer graphene is reported. A simple reduction in graphene growth temperature enables facile synthesis of nanoporous graphene. By solution‐casting a hierarchically porous support on the as‐grown nanoporous graphene, large‐area (>5 cm2) nanoporous atomically thin membranes for dialysis applications are demonstrated. Abstract Direct synthesis of graphene with well‐defined nanoscale pores over large areas can transform the fabrication of nanoporous atomically thin membranes (NATMs) and greatly enhance their potential for practical applications. However, scalable bottom‐up synthesis of continuous sheets of nanoporous graphene that maintain integrity over large areas has not been demonstrated. Here, it is shown that a simple reduction in temperature during chemical vapor deposition (CVD) on Cu induces in‐situ formation of nanoscale defects (≤2–3 nm) in the graphene lattice, enabling direct and scalable synthesis of nanoporous monolayer graphene. By solution‐casting of hierarchically porous polyether sulfone supports on the as‐grown nanoporous CVD graphene, large‐area (>5 cm2) NATMs for dialysis applications are demonstrated. The synthesized NATMs show size‐selective diffusive transport and effective separation of small molecules and salts from a model protein, with ≈2–100× increase in permeance along with selectivity better than or comparable to state‐of‐the‐art commercially available polymeric dialysis membranes. The membranes constitute the largest fully functional NATMs fabricated via bottom‐up nanopore formation, and can be easily scaled up to larger sizes permitted by CVD synthesis. The results highlight synergistic benefits in blending traditional membrane casting with bottom‐up pore creation during graphene CVD for advancing NATMs toward practical applications.

Published in: "Advanced Materials".

Gas‐Permeable, Multifunctional On‐Skin Electronics Based on Laser‐Induced Porous Graphene and Sugar‐Templated Elastomer Sponges

2018-12-15T22:34:12+00:00December 15th, 2018|Categories: Publications|Tags: |

A simple, versatile, and effective approach for making multifunctional, on‐skin bioelectronic sensing systems using laser‐induced porous graphene as the sensing components and sugar‐templated elastomer sponges as the substrates is reported. The porous structures of the devices can facilitate perspiration transport and evaporation, and minimize discomfort and inflammation risks, thereby improving their long‐term feasibility. Abstract Soft on‐skin electronics have broad applications in human healthcare, human–machine interface, robotics, and others. However, most current on‐skin electronic devices are made of materials with limited gas permeability, which constrain perspiration evaporation, resulting in adverse physiological and psychological effects, limiting their long‐term feasibility. In addition, the device fabrication process usually involves e‐beam or photolithography, thin‐film deposition, etching, and/or other complicated procedures, which are costly and time‐consuming, constraining their practical applications. Here, a simple, general, and effective approach for making multifunctional on‐skin electronics using porous materials with high‐gas permeability, consisting of laser‐patterned porous graphene as the sensing components and sugar‐templated silicone elastomer sponges as the substrates, is reported. The prototype device examples include electrophysiological sensors, hydration sensors, temperature sensors, and joule‐heating elements, showing signal qualities comparable to conventional, rigid, gas‐impermeable devices. Moreover, the devices exhibit high water‐vapor permeability (≈18 mg cm−2 h−1), ≈18 times higher than that of the silicone elastomers without pores, and also show high water‐wicking rates after polydopamine treatment, up to 1 cm per 30 s, which is comparable to that of cotton. The on‐skin devices with such attributes could facilitate perspiration transport and evaporation, and minimize discomfort and inflammation risks, thereby improving their long‐term

Published in: "Advanced Materials".

Edge‐Functionalized Graphene Nanoplatelets as Metal‐Free Electrocatalysts for Dye‐Sensitized Solar Cells

2018-12-15T22:34:07+00:00December 15th, 2018|Categories: Publications|Tags: , , |

Edge‐functionalized graphene nanoplatelets (EFGnPs), as counter electrode (CE) materials, have demonstrated an excellent performance for dye‐sensitized solar cells (DSSCs). Specific edge groups can provide electrocatalytic active sites for iodine and cobalt reduction reactions. Given the promising potential in metal‐free CEs, research directions are suggested to discover more efficient functional groups and to realize metal‐free‐carbon‐based DSSCs. Abstract A scalable and low‐cost production of graphene nanoplatelets (GnPs) is one of the most important challenges for their commercialization. A simple mechanochemical reaction has been developed and applied to prepare various edge‐functionalized GnPs (EFGnPs). EFGnPs can be produced in a simple and ecofriendly manner by ball milling of graphite with target substances (X = nonmetals, halogens, semimetals, or metalloids). The unique feature of this method is its use of kinetic energy, which can generate active carbon species by unzipping of graphitic CC bonds in dry conditions (no solvent). The active carbon species efficiently pick up X substance(s), leading to the formation of graphitic CX bonds along the broken edges and the delamination of graphitic layers into EFGnPs. Unlike graphene oxide (GO) and reduced GO (rGO), the preparation of EFGnPs does not involve toxic chemicals, such as corrosive acids and toxic reducing agents. Furthermore, the prepared EFGnPs preserve high crystallinity in the basal area due to their edge‐selective functionalization. Considering the available edge X groups that can be selectively employed, the potential applications of EFGnPs are unlimited. In this context, the synthesis, characterizations, and applications of EFGnPs, specifically, as metal‐free carbon‐based electrocatalysts for dye‐sensitized solar

Published in: "Advanced Materials".

Controllable Growth of Graphene on Liquid Surfaces

2018-12-15T22:34:04+00:00December 15th, 2018|Categories: Publications|Tags: |

Recent advancement in the controllable growth of graphene on liquid surfaces is comprehensively reviewed. Melted liquids offer a smooth surface, which enables uniformly tailoring the morphologies of graphene, and a rheological surface, which allows for self‐adjusted movement of graphene grains. The exciting progress in controlled growth behaviors of graphene on the liquid surface is presented and discussed in depth. Abstract Controllable fabrication of graphene is necessary for its practical application. Chemical vapor deposition (CVD) approaches based on solid metal substrates with morphology‐rich surfaces, such as copper (Cu) and nickel (Ni), suffer from the drawbacks of inhomogeneous nucleation and uncontrollable carbon precipitation. Liquid substrates offer a quasiatomically smooth surface, which enables the growth of uniform graphene layers. The fast surface diffusion rates also lead to unique growth and etching kinetics for achieving graphene grains with novel morphologies. The rheological surface endows the graphene grains with self‐adjusted rotation, alignment, and movement that are driven by specific interactions. The intermediary‐free transfer or the direct growth of graphene on insulated substrates is demonstrated using liquid metals. Here, the controllable growth process of graphene on a liquid surface to promote the development of attractive liquid CVD strategies is in focus. The exciting progress in controlled growth, etching, self‐assembly, and delivery of graphene on a liquid surface is presented and discussed in depth. In addition, prospects and further developments in these exciting fields of graphene growth on a liquid surface are discussed.

Published in: "Advanced Materials".

Graphene Oxide as an Optical Biosensing Platform: A Progress Report

2018-12-15T22:33:58+00:00December 15th, 2018|Categories: Publications|Tags: , |

Graphene oxide (GO) is studied as an advantageous platform for optical biosensing. The progressively discovered GO properties that influence the overall optical biosensing performance are highlighted. From a critical point of view, new trends in GO‐based optical biosensing are also discussed, along with research challenges, opportunities, and future perspectives in this topic. Abstract A few years ago, crucial graphene oxide (GO) features such as the carbon/oxygen ratio, number of layers, and lateral size were scarcely investigated and, thus, their impact on the overall optical biosensing performance was almost unknown. Nowadays valuable insights about these features are well documented in the literature, whereas others remain controversial. Moreover, most of the biosensing systems based on GO were amenable to operating as colloidal suspensions. Currently, the literature reports conceptually new approaches obviating the need of GO colloidal suspensions, enabling the integration of GO onto a solid phase and leading to their application in new biosensing devices. Furthermore, most GO‐based biosensing devices exploit photoluminescent signals. However, further progress is also achieved in powerful label‐free optical techniques exploiting GO in biosensing, particularly using optical fibers, surface plasmon resonance, and surface enhanced Raman scattering. Herein, a critical overview on these topics is offered, highlighting the key role of the physicochemical properties of GO. New challenges and opportunities in this exciting field are also highlighted.

Published in: "Advanced Materials".

Ultrahigh‐Sensitive Broadband Photodetectors Based on Dielectric Shielded MoTe2/Graphene/SnS2 p–g–n Junctions

2018-12-15T22:33:56+00:00December 15th, 2018|Categories: Publications|Tags: , , , |

h‐BN/MoTe2/graphene/SnS2/h‐BN van der Waals heterostructure photodetectors present an extraordinary broadband responsivity exceeding 2.6 × 103 A W−1 and detectivity up to ≈1013 Jones in a wide spectrum, which is attributed to the enhanced light absorption and high‐effective exciton dissociation originated from the vertical built‐in electric field and multiple photoactive layers in the unique heterostructures. Abstract 2D atomic sheets of transition metal dichalcogenides (TMDs) have a tremendous potential for next‐generation optoelectronics since they can be stacked layer‐by‐layer to form van der Waals (vdW) heterostructures. This allows not only bypassing difficulties in heteroepitaxy of lattice‐mismatched semiconductors of desired functionalities but also providing a scheme to design new optoelectronics that can surpass the fundamental limitations on their conventional semiconductor counterparts. Herein, a novel 2D h‐BN/p‐MoTe2/graphene/n‐SnS2/h‐BN p–g–n junction, fabricated by a layer‐by‐layer dry transfer, demonstrates high‐sensitivity, broadband photodetection at room temperature. The combination of the MoTe2 and SnS2 of complementary bandgaps, and the graphene interlayer provides a unique vdW heterostructure with a vertical built‐in electric field for high‐efficiency broadband light absorption, exciton dissociation, and carrier transfer. The graphene interlayer plays a critical role in enhancing sensitivity and broadening the spectral range. An optimized device containing 5−7‐layer graphene has been achieved and shows an extraordinary responsivity exceeding 2600 A W−1 with fast photoresponse and specific detectivity up to ≈1013 Jones in the ultraviolet–visible–near‐infrared spectrum. This result suggests that the vdW p–g–n junctions containing multiple photoactive TMDs can provide a viable approach toward future ultrahigh‐sensitivity and broadband photonic detectors.

Published in: "Advanced Materials".

Quantitative Principles for Precise Engineering of Sensitivity in Graphene Electrochemical Sensors

2018-12-15T22:33:49+00:00December 15th, 2018|Categories: Publications|Tags: |

Fast‐scan cyclic voltammetry of dopamine reveals that the sensitivity of multilayer graphene electrodes is linearly proportional to the average density of point defects. This observation is used for precise engineering and prediction of sensitivity in graphene electrodes. A microscopic model based on the physics of point defects in graphene is presented, providing a quantitative framework for explaining this phenomenon. Abstract A major difficulty in implementing carbon‐based electrode arrays with high device‐packing density is to ensure homogeneous and high sensitivities across the array. Overcoming this obstacle requires quantitative microscopic models that can accurately predict electrode sensitivity from its material structure. Such models are currently lacking. Here, it is shown that the sensitivity of graphene electrodes to dopamine and serotonin neurochemicals in fast‐scan cyclic voltammetry measurements is strongly linked to point defects, whereas it is unaffected by line defects. Using the physics of point defects in graphene, a microscopic model is introduced that explains how point defects determine sensitivity. The predictions of this model match the empirical observation that sensitivity linearly increases with the density of point defects. This model is used to guide the nanoengineering of graphene structures for optimum sensitivity. This approach achieves reproducible fabrication of miniaturized sensors with extraordinarily higher sensitivity than conventional materials. These results lay the foundation for new integrated electrochemical sensor arrays based on nanoengineered graphene.

Published in: "Advanced Materials".

Phototransistors: Graphene/Organic Semiconductor Heterojunction Phototransistors with Broadband and Bi‐directional Photoresponse (Adv. Mater. 49/2018)

2018-12-15T22:33:47+00:00December 15th, 2018|Categories: Publications|Tags: |

In article number 1804020, Jun Wang, Xinran Wang, and co‐workers incorporate an organic heterojunction (C60/pentacene) on graphene to realize a broadband (405–1550 nm) phototransistor with high gain and fast response speed. A bidirectional photoresponse (positive and negative photocurrent) is demonstrated at different wavelengths, due to the opposite charge‐transfer direction of the photoexcited carriers, which provides an efficient way to enhance the spectral responsivity and range for graphene detectors.

Published in: "Advanced Materials".

Nanoporous Graphene: Facile Fabrication of Large‐Area Atomically Thin Membranes by Direct Synthesis of Graphene with Nanoscale Porosity (Adv. Mater. 49/2018)

2018-12-15T22:33:39+00:00December 15th, 2018|Categories: Publications|Tags: |

Facile fabrication of large‐area atomically thin membranes is reported by Piran R. Kidambi, Rohit Karnik, and co‐workers in article number 1804977. A simple reduction in temperature during the synthesis allows direct formation of nanopores in graphene. By solution‐casting a hierarchically porous support on nanoporous graphene, large‐area atomically thin membranes for dialysis applications are demonstrated. The image shows nanoporous graphene transferred on to porous polycarbonate supports (photograph by Felice Frankel).

Published in: "Advanced Materials".

Sodium‐Ion Batteries: C‐Plasma of Hierarchical Graphene Survives SnS Bundles for Ultrastable and High Volumetric Na‐Ion Storage (Adv. Mater. 49/2018)

2018-12-15T22:33:37+00:00December 15th, 2018|Categories: Publications|Tags: |

Hierarchical graphene‐bundled tin sulfide is derived by an ingenious in situ C‐plasma route, as described by Rajdeep Singh Rawat, Hong Jin Fan, and co‐workers in article number 1804833, and tested as a flexible anode for sodium‐ion batteries. This flexible anode shows unprecedented cycling lifespan and retention of volumetric capacities. Density functional theory calculation verifies the formation mechanism of graphene by catalysis of metallic Sn.

Published in: "Advanced Materials".

Gas‐Generating Nanoplatforms: Material Chemistry, Multifunctionality, and Gas Therapy

2018-12-15T22:33:35+00:00December 15th, 2018|Categories: Publications|Tags: , |

The construction of gas‐generating nanoplatforms (GGNs) plays the determining role for precise gas therapy. The recent developments of the rational design and chemical construction of versatile GGNs for efficient gas therapies are summarized. The biosafety issue, challenges faced, and future developments on the rational construction of GGNs are also discussed for further promotion of their clinical translation. Abstract The fast advances of theranostic nanomedicine enable the rational design and construction of diverse functional nanoplatforms for versatile biomedical applications, among which gas‐generating nanoplatforms (GGNs) have emerged very recently as unique theranostic nanoplatforms for broad gas therapies. Here, the recent developments of the rational design and chemical construction of versatile GGNs for efficient gas therapies by either exogenous physical triggers or endogenous disease‐environment responsiveness are reviewed. These gases involve some therapeutic gases that can directly change disease status, such as oxygen (O2), nitric oxide (NO), carbon monoxide (CO), hydrogen (H2), hydrogen sulfide (H2S) and sulfur dioxide (SO2), and other gases such as carbon dioxide (CO2), dl‐menthol (DLM), and gaseous perfluorocarbon (PFC) for supplementary assistance of the theranostic process. Abundant nanocarriers have been adopted for gas delivery into lesions, including poly(d,l‐lactic‐co‐glycolic acid), micelles, silica/mesoporous silica, organosilica, MnO2, graphene, Bi2Se3, upconversion nanoparticles, CaCO3, etc. Especially, these GGNs have been successfully developed for versatile biomedical applications, including diagnostic imaging and therapeutic use. The biosafety issue, challenges faced, and future developments on the rational construction of GGNs are also discussed for further promotion of their clinical translation to benefit patients.

Published in: "Advanced Materials".

C‐Plasma of Hierarchical Graphene Survives SnS Bundles for Ultrastable and High Volumetric Na‐Ion Storage

2018-12-15T22:33:33+00:00December 15th, 2018|Categories: Publications|Tags: |

Hierarchical graphene bundled tin sulfide (SnS) is fabricated by an ingenious in situ C‐plasma route and tested as a flexible anode for sodium‐ion batteries with unprecedented cycling lifespan, maintaining ultrahigh areal and volumetric capacities. Density functional theory calculation verifies the formation mechanism of graphene by catalysis of Sn. Abstract Tin and its derivatives have provoked tremendous progress of high‐capacity sodium‐ion anode materials. However, achieving high areal and volumetric capability with maintained long‐term stability in a single electrode remains challenging. Here, an elegant and versatile strategy is developed to significantly extend the lifespan and rate capability of tin sulfide nanobelt electrodes while maintaining high areal and volumetric capacities. In this strategy, in situ bundles of robust hierarchical graphene (hG) are grown uniformly on tin sulfide nanobelt networks through a rapid (5 min) carbon‐plasma method with sustainable oil as the carbon source and the partially reduced Sn as the catalyst. The nucleation of graphene, CN (with size N ranging from 1 to 24), on the Sn(111) surface is systematically explored using density functional theory calculations. It is demonstrated that this chemical‐bonded hG strategy is powerful in enhancing overall electrochemical performance.

Published in: "Advanced Materials".

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