Recent progress on exploring exceptionally high and anisotropic H<sup>+</sup>/OH<sup>−</sup> ion conduction in two-dimensional materials

Sun, Pengzhan; Ma, Renzhi; Sasaki, Takayoshi

doi:10.1039/c7sc04019a

Cited by 55 publications

(53 citation statements)

References 69 publications

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“…In their work, Sun et al have studied the in‐plane and cross‐plane hydroxyl ion conductivities for different single‐layer and multilayers LDHs, lamellar membranes composed of overlapped and stacked LDH nanosheets and for pelletized samples containing randomly orientated lamellar LDHs platelets. Micrometer‐sized hexagon‐shaped lamellar LDH platelets were also assembled onto comb electrodes similar to the single‐layer nanosheets . Results reported show in‐plane conductivities of nearly 10 −1 S cm −1 at a relative humidity (RH) of 80% and 60 °C for the single layer, and values of 10 −2 S cm −1 for multilayer LDHs nanosheets at same condition.…”

Section: D Materials For Ion Exchange Membranesmentioning

confidence: 88%

“…In addition, AEMs are based on polymeric quaternary ammonium groups which usually have highly toxic preparation techniques . In addition, problems like poor thermal and mechanical stability of these membranes have led researchers to search for other AEMs with good ion conductivity …”

Section: D Materials For Ion Exchange Membranesmentioning

confidence: 99%

“…The host layer is made of divalent/trivalent heterogeneous metal cations placed between two hydroxyl blocks. To balance the positive host charge, the interlayer hydrated anions are situated above/below the trivalent cationic centers, creating a hydrogen bond network among hydroxyl groups, interlayer anions, and water molecules in the gallery …”

Section: D Materials For Ion Exchange Membranesmentioning

confidence: 99%

“…By contrast, the bulk and average conductivities values obtained from pellet samples containing randomly orientated LDH platelets are in the same order of magnitude as the platelets measured along the plate plane direction on comb electrodes. In summary, in‐plane conductivity values of LDH nanosheets are comparable to the proton conductivities of Nafion, showing promise for applications of single‐layer LDHs nanosheets as AEMs membranes …”

Section: D Materials For Ion Exchange Membranesmentioning

confidence: 99%

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Single Layer 2D Crystals for Electrochemical Applications of Ion Exchange Membranes and Hydrogen Evolution Catalysts

Pérez-Page

Sahoo

Holmes

2019

Adv Materials Inter

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to be generated in an environmentally benign manner.Fuel cells are electrochemical devices which convert the chemical energy produced by an electrochemical reaction into electricity. Polymer electrolyte membrane fuel cells (PEMFCs) are one of the most promising systems, and they have been used for stationary and automobile applications as well as for small scale portable devices. Hydrogen as a fuel and oxygen as an oxidant are the most common reactants used for these fuel cells. Other fuels such as methanol and formic acid are also used in PEMFC. The heart of fuel cells is the membrane electrode assembly (MEA) which is composed of two electrodes, the anode and the cathode, and the electrolyte. The electrolyte is a proton exchange membrane (PEM) which allows protons to pass through from anode to cathode side. The membrane needs to have high proton conductivity, electrical insulation, thermal and mechanical strength; it needs to be light weight, flexible, have low permeability to reactant species, resistance to fuel transport, highly durable and facilitate quick electrode kinetics, suitable for use with different fuels, and low in cost. The electrolyte in a fuel cell has three main functions, to act as ion conductor, electronic insulator, and a separator for the reactant gases. [4] Nafion is the most widely used polymeric membrane in PEMFC. It has a particular structure which requires hydration leading to high proton conductivity. It cannot be used at temperatures beyond 100 °C since the proton conductivity decrease when Nafion is not perfectly hydrated. Another drawback of Nafion is fuel crossover, which is the permeability of the fuel from the anode side to the cathode side leading to a decrease in the efficiency of the fuel cell. This particular problem is more significant in direct methanol fuel cells (DMFC) which use methanol as a fuel which can easily permeate through Nafion. In all fuels contexts, great efforts have been made to find a new electrolyte membrane which can replace Nafion, and 2D materials can play an important role in this.Graphene is the name given to a flat monolayer of carbon with a 2D honeycomb lattice and is the basic building block for graphitic materials of all other dimensionalities. [5] It has particular properties such as notably high surface area around 2630 m 2 g −1 , [1,6] exceptionally high electrical conductivity, 104.36 S cm −1 , [1,7] high flexural strength, 44.28 MPa, [1,8] and good chemical and thermal stability, [1,9] which make it a potential material for a large number of applications.The isolation of graphene is considered as the beginning of a new generation of 2D materials and 2D crystals. Because of their particular layered structure, with planar topology and a thickness from single to few atomic layers, which provide them with unique properties, 2D material are expected to have important applications in the next generation of energy systems. Electrochemical energy storage devices such as batteries or supercapacitors have already incorporated these materials as electro...

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Section: D Materials For Ion Exchange Membranesmentioning

confidence: 88%

Section: D Materials For Ion Exchange Membranesmentioning

confidence: 99%

Section: D Materials For Ion Exchange Membranesmentioning

confidence: 99%

Section: D Materials For Ion Exchange Membranesmentioning

confidence: 99%

See 2 more Smart Citations

Single Layer 2D Crystals for Electrochemical Applications of Ion Exchange Membranes and Hydrogen Evolution Catalysts

Pérez-Page

Sahoo

Holmes

2019

Adv Materials Inter

View full text Add to dashboard Cite

show abstract

“…Ion binding and transport through microporous and mesoporous materials is of considerable importance in water purification and in membrane science [1,2]. Recent interest has arisen in particular in the porosity of new types of lamellar nanostructures (in particular graphene oxide [3,4]), which are linked to ion transport [5] and water transport [6] phenomena, and the desire to exploit new types of lamellar 2D-materials more widely [7]. There are now ranges of novel materials available based, for example on 2D-nanosheets of modified carbons [8], phosphorous [9], oxides [10], chalcogenides [11] and mixed oxides such as BiVO 4 [12] and MXenes [13].…”

Section: Introductionmentioning

confidence: 99%

Processes associated with ionic current rectification at a 2D-titanate nanosheet deposit on a microhole poly(ethylene terephthalate) substrate

Putra

Harito

Bavykin

et al. 2019

J Solid State Electrochem

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Films of titanate nanosheets (approx. 1.8-nm layer thickness and 200-nm size) having a lamellar structure can form electrolytefilled semi-permeable channels containing tetrabutylammonium cations. By evaporation of a colloidal solution, persistent deposits are readily formed with approx. 10-μm thickness on a 6-μm-thick poly(ethylene-terephthalate) (PET) substrate with a 20-μm diameter microhole. When immersed in aqueous solution, the titanate nanosheets exhibit a p.z.c. of − 37 mV, consistent with the formation of a cation conducting (semi-permeable) deposit. With a sufficiently low ionic strength in the aqueous electrolyte, ionic current rectification is observed (cationic diode behaviour). Currents can be dissected into (i) electrolyte cation transport, (ii) electrolyte anion transport and (iii) water heterolysis causing additional proton transport. For all types of electrolyte cations, a water heterolysis mechanism is observed. For Ca 2+ and Mg 2+ ions, water heterolysis causes ion current blocking, presumably due to localised hydroxide-induced precipitation processes. Aqueous NBu 4 + is shown to 'invert' the diode effect (from cationic to anionic diode). Potential for applications in desalination and/or ion sensing are discussed.

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Graphene Oxide‐Based Solid Electrolytes with 3D Prepercolating Pathways for Efficient Proton Transport

Cao

Yang

et al. 2018

Adv Funct Materials

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Graphene oxide (GO) with unprecedentedly fast ion transport ability has become emerging building blocks for solid electrolytes. However, the inferior through‐plane transport properties, along with the agglomeration and discontinuity of GO nanosheets in composite electrolytes represent a major obstacle for efficient proton conduction. Herein, a 3D prepercolating sulfonated GO (3D sGO) network is designed by a freeze‐casting method, and further fabricated composite electrolytes by infusing polymer electrolytes into the 3D sGO networks. The sGO laminates are well integrated into percolative nanoarchitectures, which enables the 3D sGO networks a high proton conduction capability (five times higher than Nafion membrane, a state‐of‐art solid electrolyte) and isotropic transport feature. The prepercolating strategy avoids sGO nanosheets agglomeration and provides continuously proton‐conductive pathways that percolate throughout the whole electrolytes. Consequently, the composite electrolytes exhibit a remarkable and simultaneous improvement in both in‐plane and through‐plane proton conductivity, which is unattainable for the existing 2D nanofiller–polymer electrolytes. Particularly, the highest through‐plane proton conductivity reaches 0.29 S cm−1, outperforming the current 2D nanofiller‐based composite electrolytes. This prepercolating strategy may open a new avenue to fully utilizing the inherently rapid conduction of 2D materials for efficient transport of diverse ions/molecules.

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Recent progress on exploring exceptionally high and anisotropic H⁺/OH⁻ ion conduction in two-dimensional materials

Abstract: An overview of recent advances in measuring and understanding the exceptionally high and anisotropic H+/OH– ion conductivities of representative 2D materials.

Cited by 55 publications

References 69 publications

Single Layer 2D Crystals for Electrochemical Applications of Ion Exchange Membranes and Hydrogen Evolution Catalysts

Single Layer 2D Crystals for Electrochemical Applications of Ion Exchange Membranes and Hydrogen Evolution Catalysts

Processes associated with ionic current rectification at a 2D-titanate nanosheet deposit on a microhole poly(ethylene terephthalate) substrate

Graphene Oxide‐Based Solid Electrolytes with 3D Prepercolating Pathways for Efficient Proton Transport

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Recent progress on exploring exceptionally high and anisotropic H+/OH− ion conduction in two-dimensional materials

Abstract: An overview of recent advances in measuring and understanding the exceptionally high and anisotropic H+/OH– ion conductivities of representative 2D materials.

Cited by 55 publications

References 69 publications

Single Layer 2D Crystals for Electrochemical Applications of Ion Exchange Membranes and Hydrogen Evolution Catalysts

Single Layer 2D Crystals for Electrochemical Applications of Ion Exchange Membranes and Hydrogen Evolution Catalysts

Processes associated with ionic current rectification at a 2D-titanate nanosheet deposit on a microhole poly(ethylene terephthalate) substrate

Graphene Oxide‐Based Solid Electrolytes with 3D Prepercolating Pathways for Efficient Proton Transport

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Recent progress on exploring exceptionally high and anisotropic H⁺/OH⁻ ion conduction in two-dimensional materials