13 research outputs found
Making 2âD Materials Mechanochemically by TwinâScrew Extrusion:Continuous Exfoliation of Graphite to MultiâLayered Graphene
Mechanochemistry has developed rapidly in recent years for efficient chemicals and materials synthesis. Twin screw extrusion (TSE) is a particularly promising technique in this regard because of its continuous and scalable nature. A key aspect of TSE is that it provides high shear and mixing. Because of the high shear, it potentially also offers a way to delaminate 2âD materials. Indeed, the synthesis of 2âD materials in a scalable and continuous manor remains a challenge in their industrialization. Here, as a proofâofâprinciple, the automated, continuous mechanochemical exfoliation of graphite to give multiâlayer graphene (MLG, â6 layers) by TSE is demonstrated. To achieve this, a solidâandâliquidâassisted extrusion (SLAE) process is developed in which organic additives such as pyrene are rendered liquid due to the high temperatures used, to assist with the exfoliation, and simultaneously solid sodium chloride is used as a grinding aid. This gave MLG in high yield (25 wt%) with a short residence time (8 min) and notably with negligible evidence for structural deterioration (defects or oxidation)
Scalable production of large quantities of defect-free few-layer graphene by shear exfoliation in liquids
To progress from the laboratory to commercial applications, it will be necessary to develop industrially scalable methods to produce large quantities of defect-free graphene. Here we show that high-shear mixing of graphite in suitable stabilizing liquids results in large-scale exfoliation to give dispersions of graphene nanosheets. X-ray photoelectron spectroscopy and Raman spectroscopy show the exfoliated flakes to be unoxidized and free of basal-plane defects. We have developed a simple model that shows exfoliation to occur once the local shear rate exceeds 10(4) s(-1). By fully characterizing the scaling behaviour of the graphene production rate, we show that exfoliation can be achieved in liquid volumes from hundreds of millilitres up to hundreds of litres and beyond. The graphene produced by this method performs well in applications from composites to conductive coatings. This method can be applied to exfoliate BN, MoS2 and a range of other layered crystals
Porous exfoliated poly(Δ-caprolactone)/clay nanocomposites:Preparation, structure, and properties
Relative modulus-relative density relationships in low density polymer-clay nanocomposite foams
Structure-property relationships of polymer blend/clay nanocomposites:Compatibilized and noncompatibilized polystyrene/propylene/clay
Making 2âD materials mechanochemically by twinâscrew extrusion: continuous exfoliation of graphite to multiâlayered graphene
Mechanochemistry has developed rapidly in recent years for efficient chemicals and materials synthesis. Twin screw extrusion (TSE) is a particularly promising technique in this regard because of its continuous and scalable nature. A key aspect of TSE is that it provides high shear and mixing. Because of the high shear, it potentially also offers a way to delaminate 2-D materials. Indeed, the synthesis of 2-D materials in a scalable and continuous manor remains a challenge in their industrialization. Here, as a proof-of-principle, the automated, continuous mechanochemical exfoliation of graphite to give multi-layer graphene (MLG, â6 layers) by TSE is demonstrated. To achieve this, a solid-and-liquid-assisted extrusion (SLAE) process is developed in which organic additives such as pyrene are rendered liquid due to the high temperatures used, to assist with the exfoliation, and simultaneously solid sodium chloride is used as a grinding aid. This gave MLG in high yield (25 wt%) with a short residence time (8 min) and notably with negligible evidence for structural deterioration (defects or oxidation)
Making 2âD Materials Mechanochemically by TwinâScrew Extrusion:Continuous Exfoliation of Graphite to MultiâLayered Graphene
Mechanochemistry has developed rapidly in recent years for efficient chemicals and materials synthesis. Twin screw extrusion (TSE) is a particularly promising technique in this regard because of its continuous and scalable nature. A key aspect of TSE is that it provides high shear and mixing. Because of the high shear, it potentially also offers a way to delaminate 2âD materials. Indeed, the synthesis of 2âD materials in a scalable and continuous manor remains a challenge in their industrialization. Here, as a proofâofâprinciple, the automated, continuous mechanochemical exfoliation of graphite to give multiâlayer graphene (MLG, â6 layers) by TSE is demonstrated. To achieve this, a solidâandâliquidâassisted extrusion (SLAE) process is developed in which organic additives such as pyrene are rendered liquid due to the high temperatures used, to assist with the exfoliation, and simultaneously solid sodium chloride is used as a grinding aid. This gave MLG in high yield (25 wt%) with a short residence time (8 min) and notably with negligible evidence for structural deterioration (defects or oxidation)
All-iron redox flow battery in flow-through and flow-over set-ups: the critical role of cell configuration
Significant differences in performance between the two prevalent cell configurations in all-soluble, all-iron redox flow batteries are presented, demonstrating the critical role of cell architecture in the pursuit of novel chemistries in non-vanadium systems. Using a ferrocyanide-based posolyte, and a negolyte containing a hydroxylamine-based iron complex, higher maximum power density, energy efficiency, and electrolyte utilisation were observed with a flow-over cell that incorporated a carbon paper, compared with a flow-through configuration that used a graphite felt. Capacity fade was lower in the flow-over case, likely the result of a set-up with lower overpotentials, as indicated by polarisation curve analysis. Capacity fade in the flow-through case increased upon lowering current density, suggesting a different degradation pathway, dominated instead by electrolyte cross-over. These findings highlight the potential of novel non-vanadium chemistries in both flow-through and flow-over cells, prompting further research exploration of cell architectures.</p
Making 2âD Materials Mechanochemically by TwinâScrew Extrusion: Continuous Exfoliation of Graphite to MultiâLayered Graphene
Mechanochemistry has developed rapidly in recent years for efficient chemicals and materials synthesis. Twin screw extrusion (TSE) is a particularly promising technique in this regard because of its continuous and scalable nature. A key aspect of TSE is that it provides high shear and mixing. Because of the high shear, it potentially also offers a way to delaminate 2âD materials. Indeed, the synthesis of 2âD materials in a scalable and continuous manor remains a challenge in their industrialization. Here, as a proofâofâprinciple, the automated, continuous mechanochemical exfoliation of graphite to give multiâlayer graphene (MLG, â6 layers) by TSE is demonstrated. To achieve this, a solidâandâliquidâassisted extrusion (SLAE) process is developed in which organic additives such as pyrene are rendered liquid due to the high temperatures used, to assist with the exfoliation, and simultaneously solid sodium chloride is used as a grinding aid. This gave MLG in high yield (25Â wt%) with a short residence time (8Â min) and notably with negligible evidence for structural deterioration (defects or oxidation).</p