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1.
Artigo em Inglês | MEDLINE | ID: mdl-31922711

RESUMO

In this work, a new type of hybrid energy storage device is constructed by combining the zinc-ion supercapacitor and zinc-air battery in mild electrolyte. Reduced graphene oxide with rich defects, large surface area, and abundant oxygen-containing functional groups is used as active material, which exhibits two kinds of charge storage mechanisms of capacitor and battery simultaneously. Apart from the physical adsorption/desorption of anions on the surface of graphene, the zinc ions in electrolyte will be electrochemically adsorbed/desorbed onto the oxygen-containing groups of graphene during the charge/discharge process, contributing extra capacitance to the device. Moreover, the defects in graphene will further improve the electrochemical performance of the energy storage device via catalyzing the oxygen reduction reaction with exposure to air. Consequently, the synergistic effect leads to a record high capacitance of 370.8 F g-1 at a current density of 0.1 A g-1, which is higher than that of zinc-ion supercapacitors reported previously. Furthermore, the hybrid device exhibits a superior cycling stability with 94.5% capacitance retention even after 10000 charge/discharge cycles at a high current density of 5 A g-1. Interestingly, the developed hybrid device can be self-charging automatically after the power is exhausted in the ambient atmosphere. Other electrode materials, such as carbon nanotube paper, are also used to build a hybrid device to verify the feasibility of this strategy. This facile, green, and convenient strategy provides new insight for developing a high performance storage device, showing great application prospect in other hybrid energy storage devices in mild electrolyte.

2.
Adv Mater ; 32(6): e1907005, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31850657

RESUMO

Microsized supercapacitors (mSCs) with small volume, rapid charge-discharge rate, and ultralong cyclic lifetime are urgently needed to meet the demand of miniaturized portable electronic devices. A versatile self-shrinkage assembling (SSA) strategy to directly construct the compact mSCs (CmSCs) from hydrogels of reduced graphene oxide is reported. A single CmSC is only 0.0023 cm3 in volume, which is significantly smaller than most reported mSCs in fiber/yarn and planar interdigital forms. It exhibits a high capacitance of up to 68.3 F cm-3 and a superior cycling stability with 98% capacitance retention after 25 000 cycles. Most importantly, the SSA technique enables the CmSC as the building block to realize arbitrary, programmable, and multi-dimensional integration for adaptable and complicated power systems. By design on mortise and tenon joint connection, autologous integrated 3D interdigital CmSCs are fabricated in a self-holding-on manner, which thus dramatically reduces the whole device volume to achieve the high-performance capacitive behavior. Consequently, the SSA technique offers a universal and versatile approach for large-scale on-demand integration of mSCs as flexible and transformable power sources.

3.
Front Chem ; 7: 725, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31781535

RESUMO

Benefiting from unique planar structure, high flexibility, splendid thermal, and electric properties; graphene as a crucial component has been widely applied into smart materials and multi-stimulus responsive actuators. Moreover, graphene with easy processing and modification features can be decorated with various functional groups through covalent or non-covalent bonds, which is promising in the conversion of environmental energy from single and/or multi-stimuli, to mechanical energy. In this review, we present the actuating behaviors of graphene, regulated by chemical bonds or intermolecular forces under multi-stimuli and summarize the recent advances on account of the unique nanostructures in various actuation circumstances such as thermal, humidity, electrochemical, electro-/photo-thermal, and other stimuli.

4.
ACS Appl Mater Interfaces ; 11(34): 30927-30935, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31379149

RESUMO

Spontaneous electricity generation through water evaporation is becoming a hot research area. However, low power output, limited material availability, and unscalable fabrication largely hinder its wide applications. Here, we report scalable painting and blade coating approaches for the mass production of flexible hydroelectric films (HEFs) based on solid oxides (e.g., Al2O3), which are of tolerance to mechanical deformation and are compatible with three-dimensional diverse configuration. The electricity power is generated continuously and can last for more than 10 days in ambient conditions. A single HEF unit is capable of supplying an output voltage of more than 2.5 V and even up to 4.5 V at specific conditions. The accumulative energy output can be tuned conveniently by means of series/parallel connections or size control to meet the practical needs of commercial electronics. A family of solid oxides has been verified to have the ability for water evaporation-induced electricity generation, which offers considerable room for the development of high-performance energy-supplying devices.

5.
Nanoscale ; 10(33): 15706-15713, 2018 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-30091774

RESUMO

The rational design of an efficient and robust oxygen reduction reaction (ORR) electrocatalyst is vital for energy conversion and storage systems, especially for metal-air batteries. Herein, we report a highly nanocrumpled and nitrogen, phosphorus-codoped nanocarbon (NC-NPC) synthesized by direct pyrolysis of melamine and triphenylphosphine. With the rich nano-crumpled structure and codoping of heteroatoms, this low-cost catalyst exhibits an excellent ORR performance, and possesses a half-wave potential of 0.84 V vs. RHE, a small Tafel slope of 70.2 mV dec-1, and good electrocatalytic stability. More importantly, it can also be applied in zinc-air batteries as an efficient electrode which delivers an open-circle voltage of 1.38 V, a specific capacity of 782 mA h gZn-1, and a long cycling life of 210 h, superior to the commercial Pt/C catalyst.

6.
Small ; 14(38): e1801916, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30141574

RESUMO

High-pressure resistant and multidirectional compressible materials enable various applications but are often hindered by structure-derived collapse and weak elasticity. Here, a super-robust graphene foam with ladder shape microstructure capable of withstanding high pressure is presented. The multioriented ladder arrays architecture of the foam, consisting of thousands of identically sized square spaces, endow it with a great deal of elastic units. It can easily bear an iterative and multidirectional pressure of 44.5 MPa produced by a sharp blade, and may completely recover to its initial state by a load of 180 000 times their own weight even under 95% strain. More importantly, the foam can also maintain structural integrity after experiencing a pressure of 2.8 GPa through siphoning. Computational modeling of the "buckling of shells" mechanism reveals the unique ladder-shaped graphene foam contributes to the superior cut resistance and good resilience. Based on this finding, it can be widely used in cutting resistance sensors, monitoring of sea level, and the detection of oily contaminants in water delivery pipelines.

7.
Adv Mater ; 30(22): e1706805, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29682818

RESUMO

The use of abundant solar energy for regeneration and desalination of water is a promising strategy to address the challenge of a global shortage of clean water. Progress has been made to develop photothermal materials to improve the solar steam generation performance. However, the mass production rate of water is still low. Herein, by a rational combination of photo-electro-thermal effect on an all-graphene hybrid architecture, solar energy can not only be absorbed fully and transferred into heat, but also converted into electric power to further heat up the graphene skeleton frame for a much enhanced generation of water vapor. As a result, the unique graphene evaporator reaches a record high water production rate of 2.01-2.61 kg m-2 h-1 under solar illumination of 1 kW m-2 even without system optimization. Several square meters of the graphene evaporators will provide a daily water supply that is enough for tens of people. The combination of photo-electro-thermal effect on graphene materials offers a new strategy to build a fast and scalable solar steam generation system, which makes an important step towards a solution for the scarcity of clean water.

8.
ACS Appl Mater Interfaces ; 9(29): 24608-24615, 2017 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-28616958

RESUMO

Electrocatalytic hydrogen evolution reaction (HER) is of great significance to produce clean, sustainable, and cost-effective hydrogen. However, the development of low-cost and high-efficiency non-noble-metal catalysts with a combination of superior catalytic activity and long-time stability still remains a challenge. Herein, we demonstrate a rationally designed three-dimensional architecture assembled from one-dimensional molybdenum carbide (MoC)-based nanoribbons where the MoC nanoparticles are embedded within the nitrogen-doped crystallized carbon nanolayers (MoC@NC nanoribbon). Such unique architecture of the MoC@NC nanoribbon not only provides abundant edge active sites and multielectron pathways for efficient mass/charge transportation but also greatly accelerates the hydrogen release from the reaction surface, thus boosting its electrocatalytic performances for HER either in an acid or in an alkaline aqueous solution. This advance provides a promising candidate toward the replacement of the noble-metal-based catalysts for a highly stable and efficient HER electrocatalysis.

9.
ACS Appl Mater Interfaces ; 5(8): 3071-4, 2013 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-23544791

RESUMO

Through zone melting method, a certain amount of Te nano precipitations were in situ generated in the p-type BiSbTe matrix because of the addition of graphene. Both the microstructure and thermoelectric performance were investigated. Increased carrier concentration was obtained to improve the electrical performance, and the lattice thermal conductivity was simultaneously lowered about 25% by Te nano precipitations as phonon scattering centers. Consequently, an optimization of the thermoelectric figure-of-merit ZT between 375 and 550 K was achieved.

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