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Study of field emission properties of pure graphene-CNT heterostructures connected via seamless interface

2019-07-05T11:08:54+00:00July 5th, 2019|Categories: Uncategorized|Tags: , |

Vertically aligned carbon nanotubes (CNTs) have proven to be one of the best materials for use as an efficient field emitter. To further improve their efficiency as well as long-term use in practical devices, it is necessary to reduce the quantum resistance originating from the interface between electrode and emitters and the entanglement of the CNTs in a bundle texture. Thus, the incorporation of graphene at the bottom of CNT bundles via a seamless carbonaceous interface can easily solve this bottleneck. In this work we have demonstrated for the first time, growth and field emission properties of pure seamless graphene-CNT heterostructures and pure seamless graphene-vertically patterned oriented CNTs heterostructures (SGVCNTs) on Si/SiO 2 substrates in contrast to the bare CNT mats and few-layer graphene structures without using any tedious post transfer processes. It was observed that seamless SGVCNTs show better field emission performance in terms of higher current …

Janus Graphene Liquid Crystalline Fiber with Tunable Properties Enabled by Ultrafast Flash Reduction

2019-07-02T00:18:57+00:00July 2nd, 2019|Categories: Uncategorized|Tags: , |

Ultrafast photothermal treatment by flash light can effectively reduce graphene oxide liquid crystalline fibers. Resultant flash induced graphene fibers with different reduction conditions enable delicate controllability of the mechanical properties and electrical conductivity along with spatial control of reduction level. Humidity sensors are fabricated from flash reduced graphene fibers and reveal superior sensing performance over conventional thermally reduced counterparts. Abstract Flash photothermal treatment via Xenon lamp with a broad wavelength spectrum can effectively remove oxygen functionalities and restore sp2 domains at graphitic carbon materials. The chemical composition and relevant structure formation of flash reduced graphene oxide liquid crystal (GOLC) fibers are investigated in accordance with flash irradiation conditions. Owing to the spatial controllability of reduction level via anisotropic flash irradiation, the mechanical properties and electrical conductivity of graphene fibers can be delicately counterbalanced to attain desired properties. High sensitivity humidity sensors can be fabricated from the flash reduced fibers demonstrating notably higher sensitivity over the thermally reduced counterparts. This ultrafast flash reduction holds great promise for multidimensional macroscopic GO based structures, enabling a wide range of potential applications, including textile electronics and wearable sensors.

Graphene bridge rectifier based on self-switching diode arrays

2019-06-21T13:53:15+00:00June 21st, 2019|Categories: Uncategorized|Tags: |

Here, we present theory and measurements for a bridge rectifier formed from arrays of graphene self-switching diodes (GSSDs). Despite graphene’s lack of a bandgap and high carrier concentration causing a reduced rectification ratio, the extremely high carrier mobility will allow GSSDs to work at frequencies well into the THz region. Compared with a single SSD array, the bridge rectifier structure allows for full-wave rectification of an AC signal. Here we derive an equation for the voltage output of a bridge rectifier formed from GSSDs, which predicts a quadratic relationship between output voltage and input current. This relationship is confirmed using AC and DC measurements. The fabricated rectifier is found to have a high room temperature intrinsic responsivity of ##IMG## [http://ej.iop.org/images/0957-4484/30/36/364004/nanoab25fdieqn1.gif] {$4395,{rm{V}},{{rm{W}}}^{-{rm{1}}}$} at low frequency and a low noise equivalent power of ##IMG##

Solution‐Phase Epitaxial Growth of Perovskite Films on 2D Material Flakes for High‐Performance Solar Cells

2019-06-20T17:25:12+00:00June 20th, 2019|Categories: Uncategorized|Tags: |

Solution‐phase van der Waals epitaxy growth of MAPbI3 perovskite films on MoS2 flakes is observed. The in‐plane coupling between the perovskite and the MoS2 crystal lattices leads to perovskite films with larger grain size, lower trap density, and preferential growth orientation. Consequently, the efficiency of fabricated perovskite solar cells is substantially improved by the MoS2 flakes as interfacial layers. Abstract The quality of perovskite films is critical to the performance of perovskite solar cells. However, it is challenging to control the crystallinity and orientation of solution‐processed perovskite films. Here, solution‐phase van der Waals epitaxy growth of MAPbI3 perovskite films on MoS2 flakes is reported. Under transmission electron microscopy, in‐plane coupling between the perovskite and the MoS2 crystal lattices is observed, leading to perovskite films with larger grain size, lower trap density, and preferential growth orientation along (110) normal to the MoS2 surface. In perovskite solar cells, when perovskite active layers are grown on MoS2 flakes coated on hole‐transport layers, the power conversion efficiency is substantially enhanced for 15%, relatively, due to the increased crystallinity of the perovskite layer and the improved hole extraction and transfer rate at the interface. This work paves a way for preparing high‐performance perovskite solar cells and other optoelectronic devices by introducing 2D materials as interfacial layers.

Ionic Glass–Gated 2D Material–Based Phototransistor: MoSe2 over LaF3 as Case Study

2019-06-17T16:36:40+00:00June 17th, 2019|Categories: Uncategorized|Tags: |

For the first time, a 2D material–based photodetector is reported using ionic glass as the electrostatic gating method, choosing MoSe2 over LaF3 ionic glass as an archetypal system. The wider possibilities offered by this architecture are unveiled, and a careful analysis of its unique optoelectronic properties is provided. Abstract Modulating the carrier density of 2D materials is pivotal to tailor their electrical properties, with novel physical phenomena expected to occur at a higher doping level. Here, the use of ionic glass as a high capacitance gate is explored to develop a 2D material–based phototransistor operated with a higher carrier concentration up to 5 × 1013 cm−2, using MoSe2 over LaF3 as an archetypal system. Ion glass gating reveals to be a powerful technique combining the high carrier density of electrolyte gating methods while enabling direct optical addressability impeded with usual electrolyte technology. The phototransistor demonstrates I ON/I OFF ratio exceeding five decades and photoresponse times down to 200 µs, up to two decades faster than MoSe2 phototransistors reported so far. Careful phototransport analysis reveals that ionic glass gating of 2D materials allows tuning the nature of the carrier recombination processes, while annihilating the traps’ contribution in the electron injection regime. This remarkable property results in a photoresponse that can be modulated electrostatically by more than two orders of magnitude, while at the same time increasing the gain bandwidth product. This study demonstrates the potential of ionic glass gating to explore novel photoconduction processes and alternative architectures of devices.

An Ultrastable Presodiated Titanium Disulfide Anode for Aqueous “Rocking‐Chair” Zinc Ion Battery

2019-06-15T22:59:59+00:00June 15th, 2019|Categories: Uncategorized|Tags: , |

The chemically presodiated TiS2 (Na0.14TiS2) is demonstrated to be a high performance intercalated anode material for aqueous Zn‐ion batteries. Experimental and theoretical studies reveal that the presodiation process can improve the physical and chemical performance of TiS2. On this basis, a rechargeable aqueous “rocking‐chair” Zn‐ion full battery is realized with Na0.14TiS2 anode, ZnMn2O4 cathode, and 2 m Zn(CF3SO3)2. Abstract Rechargeable aqueous Zn‐based batteries are attractive candidates as energy storage technology, but the uncontrollable Zn dendrites, low stripping/plating coulombic efficiency, and inefficient utilization of Zn metal limit the battery reliability and energy density. Herein, for the first time, a novel presodiated TiS2 (Na0.14TiS2) is proposed and investigated as an intercalated anode for aqueous Zn‐ion batteries, showing a capacity of 140 mAh g−1 with a suitable potential of 0.3 V (vs Zn2+/Zn) at 0.05 A g−1 and superior cyclability of 77% retention over 5000 cycles at 0.5 A g−1. The remarkable performance originates from the buffer phase formation of Na0.14TiS2 after chemically presodiating TiS2, which not only improves the structural reversibility and stability but also enhances the diffusion coefficient and electronic conductivity, and lowers cation migration barrier, as evidenced by a series of experimental and theoretical studies. Moreover, an aqueous “rocking‐chair” Zn‐ion full battery is successfully demonstrated by this Na0.14TiS2 anode and ZnMn2O4 cathode, which delivers a capacity of 105 mAh g−1 (for anode) with an average voltage of 0.95 V at 0.05 A g−1 and preserves 74% retention after 100 cycles at 0.2 A g−1, demonstrating the feasibility of Zn‐ion full

Dual Cocatalysts in TiO2 Photocatalysis

2019-06-15T14:52:25+00:00June 15th, 2019|Categories: Uncategorized|Tags: , , |

Dual cocatalysts with different functions have attracted much attention for TiO2 photocatalysis due to their extended light absorption, enhanced reactant adsorption, and promoted charge‐carrier‐separation efficiency. Categories based on the components and integrated architectures of dual cocatalysts are summarized and discussed in detail, followed by the conceivable challenges and future directions of binary cocatalysts. Abstract Semiconductor photocatalysis is recognized as a promising strategy to simultaneously address energy needs and environmental pollution. Titanium dioxide (TiO2) has been investigated for such applications due to its low cost, nontoxicity, and high chemical stability. However, pristine TiO2 still suffers from low utilization of visible light and high photogenerated‐charge‐carrier recombination rate. Recently, TiO2 photocatalysts modified by dual cocatalysts with different functions have attracted much attention due to the extended light absorption, enhanced reactant adsorption, and promoted charge‐carrier‐separation efficiency granted by various cocatalysts. Recent progress on the component and structural design of dual cocatalysts in TiO2 photocatalysts is summarized. Depending on their components, dual cocatalysts decorated on TiO2 photocatalysts can be divided into the following categories: bimetallic cocatalysts, metal–metal oxide/sulfide cocatalysts, metal–graphene cocatalysts, and metal oxide/sulfide–graphene cocatalysts. Depending on their architecture, they can be categorized into randomly deposited binary cocatalysts, facet‐dependent selective‐deposition binary cocatalysts, and core–shell structural binary cocatalysts. Concluding perspectives on the challenges and opportunities for the further exploration of dual cocatalyst–modified TiO2 photocatalysts are presented.

Published in: "Advanced Materials".

Light-assisted recovery of reacted MoS 2 for reversible NO 2 sensing at room temperature

2019-06-12T13:50:10+00:00June 12th, 2019|Categories: Uncategorized|Tags: |

Two-dimensional (2D) nanomaterials have been extensively explored as promising candidates for gas sensing due to their high surface-to-volume ratio. Among many 2D nanomaterials, molybdenum disulfide (MoS 2 ) is known to be functional in detecting harmful gases at room temperature; therefore, it has been actively studied as a gas sensing material. However, there has been a limitation in recovering the original signal from reacted MoS 2 after exposure to the target gas. This work demonstrates the recovery of the initial resistance of reacted chemical vapor deposition-grown MoS 2 by illuminating it with a UV light-emitting diode (LED). A novel mechanism involving photo-generated electron–hole pairs in MoS 2 is proposed and experimentally verified. The fabricated sensor detects nitrogen dioxide (NO 2 ) and distinguishes between concentrations from 1 to 10 ppm with the proposed recovery process. Reversible detection after repeated expos…

Ultralong cycle life and outstanding capacitive performance of 10.8 V metal-free micro-supercapacitor with highly conducting and robust laser-irradiated graphene for integrated storage device

2019-06-07T14:33:38+00:00June 7th, 2019|Categories: Uncategorized|Tags: , |

Energy Environ. Sci., 2019, Accepted ManuscriptDOI: 10.1039/C9EE01458F, PaperNavpreet Kamboj, Taniya Purkait, Manisha Das, Subhajit Sarkar, Kiran Shankar Hazra, Ramendra Sundar DeyInterconnected porous graphene plays a crucial role as supercapacitive material as well as a current collector in developing metal-free microsupercapacitor (MSC) due to its unique structure and superior conductivity. Electrochemical…The content of this RSS Feed (c) The Royal Society of Chemistry

Published in: "Energy & Environmental Science".

All-region-applicable, continuous power supply of graphene oxide composite

2019-05-08T16:31:54+00:00May 8th, 2019|Categories: Uncategorized|Tags: , , |

Energy Environ. Sci., 2019, Accepted ManuscriptDOI: 10.1039/C9EE00838A, CommunicationYaxin Huang, Huhu Cheng, Ce Yang, Houze Yao, Chun Li, Liangti QuGreen energy has aroused huge interest in face with increasingly serious environmental pollution and energy crisis. Herein, we develop an all-region-applicable moist-electric generator (MEG) based on graphene oxide composite to…The content of this RSS Feed (c) The Royal Society of Chemistry

Published in: "Energy & Environmental Science".

A flexible back-contact perovskite solar micro-module

2019-05-03T10:31:50+00:00May 3rd, 2019|Categories: Uncategorized|Tags: |

Energy Environ. Sci., 2019, Advance ArticleDOI: 10.1039/C8EE03517B, Paper Open Access &nbsp This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.Michael Wong-Stringer, Thomas J. Routledge, Trevor McArdle, Christopher J. Wood, Onkar S. Game, Joel A. Smith, James E. Bishop, Naoum Vaenas, David M. Coles, Alastair R. Buckley, David G. LidzeyBack-contact PSCs are fabricated by depositing charge-selective electrodes and MAPbI3 into micron-sized polymeric grooves, micro-modules are formed by serially-connecting grooves.To cite this article before page numbers are assigned, use the DOI form of citation above.The content of this RSS Feed (c) The Royal Society of Chemistry

Published in: "Energy & Environmental Science".

Regulating the allocation of N and P in codoped graphene via supramolecular control to remarkably boost hydrogen evolution

2019-04-27T00:32:01+00:00April 27th, 2019|Categories: Uncategorized|Tags: , |

Energy Environ. Sci., 2019, Accepted ManuscriptDOI: 10.1039/C9EE00555B, PaperHao Wu, Zhimin Chen, Ying Wang, Erping Cao, Fei Xiao, Shuo Chen, Shichao Du, Yiqun Wu, Zhiyu RenAlthough, as early as 2014, theoretical investigations have illuminated that the nonmetallic heteroatom doped graphene (NHDG) is anticipated to achieve excellent catalytic activity approaching that of platinum for the hydrogen…The content of this RSS Feed (c) The Royal Society of Chemistry

Published in: "Energy & Environmental Science".

Unique Interfacial Thermodynamics of Few-Layer 2D MoS2 for (Photo)electrochemical Catalysis

2019-04-12T20:31:57+00:00April 12th, 2019|Categories: Uncategorized|Tags: , |

Energy Environ. Sci., 2019, Accepted ManuscriptDOI: 10.1039/C9EE00513G, PaperGerard Michael Carroll, Hanyu Zhang, Jeremy R. Dunklin, elisa m miller, Nathan R. Neale, Jao van de LagemaatThe electronic structure of few-layer MoS2 is studied by in-situ and operando spectroelectrochemistry in conditions relevant to its use as an electrocatalyst. We show that electron injection into the conduction…The content of this RSS Feed (c) The Royal Society of Chemistry

Published in: "Energy & Environmental Science".

Triperyleno[3,3,3]propellane triimides: Achieving a New Generation of Quasi-D3h Symmetric Nanostructures in Organic Electronics

2019-04-12T08:44:39+00:00April 12th, 2019|Categories: Uncategorized|

Chem. Sci., 2019, Accepted ManuscriptDOI: 10.1039/C9SC00849G, Edge Article Open Access &nbsp This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Lingling Lv, Josiah Roberts, Chengyi Xiao, Zhenmei Jia, Wei Jiang, Guowei Zhang , Chad Risko, Lei ZhangRigid three-dimensional (3D) polycylic aromatic hydrocarbons (PAH), and in particular 3D nanographenes, have garnered interest due to their potential use in semiconductor applications, and as models to study through-bond and…The content of this RSS Feed (c) The Royal Society of Chemistry

Triperyleno[3,3,3]propellane triimides: Achieving a New Generation of Quasi-D3h Symmetric Nanostructures in Organic Electronics

2019-04-12T08:44:33+00:00April 12th, 2019|Categories: Uncategorized|

Chem. Sci., 2019, Accepted ManuscriptDOI: 10.1039/C9SC00849G, Edge Article Open Access &nbsp This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.Lingling Lv, Josiah Roberts, Chengyi Xiao, Zhenmei Jia, Wei Jiang, Guowei Zhang , Chad Risko, Lei ZhangRigid three-dimensional (3D) polycylic aromatic hydrocarbons (PAH), and in particular 3D nanographenes, have garnered interest due to their potential use in semiconductor applications, and as models to study through-bond and…The content of this RSS Feed (c) The Royal Society of Chemistry

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