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Title: Novel synthesis of nanostructured platinum materials via true liquid crystal templating utilising phytantriol as a structure directing agent
Author: Akbar, Samina
ISNI:       0000 0004 2746 9431
Awarding Body: University of Reading
Current Institution: University of Reading
Date of Award: 2012
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In this investigation, nanostructured platinum materials are fabricated using a type II surfactant phytantriol as a structure directing agent. Nanoscale designing of these materials is achieved on the basis of phytantriol concentration under fixed or excess hydration conditions with or without the presence of additives; Brij-56 and 9-cis-tricosene. Phytantriol is a type II surfactant, when mixed with an aqueous solvent, it forms a diversity of lyotropic liquid crystal phases. Including a lamellar (La), inverse micellar (LII)' and inverse hexagonal (HI/), it also forms two inverse bicontinuous cubic phases (QJ/o and QJ/I) which makes this system ideal for the nanocast synthesis of platinum materials. An addition of Brij-56 induces a swelling of the QIlD phases whereas 9-cis-tricosene makes the HII phases stable at room temperature. Fabrication of nanostructured materials is carried out through the QJ/o, QJ/D , Ql, and HJ/ phases. The later three being stable in excess aqueous conditions allow the successful fabrication using thin coatings of phytantriol on a substrate surface instead of using a traditional bulk liquid crystal templating. A platinum precursor incorporated into the aqueous domains of the liquid crystal phases is deposited electrochemically or chemically (galvanic displacement reactions) utilising a conductive substrate or a less noble metal substrate, respectively. Characterisation of the fabricated materials is carried out using small angle Xray scattering and electron microscopy. Novel 3-D platinum nanowire networks of bicontinuous cubic morphology with the lattice dimensions ranging from 8.9 to 19.9 nm are fabricated using the cubic phases templates. The 3-D networks of nanowires of diameters ranging from 1.9 to 5.4 nm, fabricated through the QIP. QI/o, and Ql phases are shown to exhibit Fd3m, 14/32, and Pm3m symmetry respectively. Structural investigations reveal that the nanostructures are fabricated asymmetrically through one of the aqueous channels of the cubic phases, producing open structures. The addition of Brij-56 to the QJ/D template enables the structural tuning of these materials which is expected to change/enhance their catalytic properties. Fabrication through the HII phases with or without the presence of tricosene produces one dimensional platinum nanowires of diameters ranging from 1.7 to 2.5 nm. The platinum nanowires and nanowire networks are shown to exhibit very high specific surface area ranging from 14-40 m2 g", The nanoscale designing of these materials with excellent transport properties opens up a new general route for the nanowires and nanonetworks which have potential for use in batteries, solar cells, capacitors, and electrocatalysis
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available