Block Copolymer Lyotropic Liquid Crystal Template Electrochemical Deposition Of Noble Metal Nanomaterials

Nano-structured materials have been one of the most important aspects of material science for their unique physical and chemical properties. Combining the lyotropic liquid crystals with rich phases and electrochemical deposition technology to produce nanomaterials has also attracted much attention. The main work of this paper is about how to obtain nanomaterials by electrochemical deposition from lyotropic liquid crystals templates. The research work can be divided into two main parts in the paper.In the first part, nanostructured platinum has been successfully prepared by electrochemical deposition from the lamellar and hexagonal liquid crystals phases, which are composed of 0.02 mol/L H₂PtCl₆ aqueous solution and amphiphilic block copolymers, EO₂₀PO₇₀EO₂₀ (Pluronic P123) or EO₁₀₆PO₇₀EO₁₀₆ (F127). The experiments have been done using a three-electrode configuration and a saturated calomel electrode (SCE) is used as a reference. Small angle X-ray scattering (SAXS) results show that steady phases have also been gained after H₂PtCl₆ aqueous solution is used to substitute for water. The structures of templates, deposition potential and deposition time have great effects on the products structure. At the higher potential or shorter time, little amount of product will be produced and its structure is defective and irregular. When the potential becomes too low or the time is too long, the faster growing rates, the more side reactions, and the stack of the deposits will destroy the ordered deposit structure. At the condition of-0.1 V and 600 s, bunchy nanomaterials have been produced. The observation of the morphology and the surface is done by the transmission electron microscope (TEM) and scanning electron microscope (SEM). Energy disperse X-ray (EDX) results suggest the platinum metal nature of the deposit. Cyclic voltammetry is a method to characterize the surface speciality. The results show that the specific surface area increases with more ordered nanostructure being produced, and the value for typical bunchy nanostructure is calculated as high as about 55 m²/g. For the lyotropic liquid crystals composed of P123, hollow box or cage structures are obtained in the same condition, too. This may relate to the distortion of the liquid crystals phases or forming the mix phases. Though the product dose not duplicated the...