Functionalization And Electrochemical Investigations Of Layered Transitional Metal Oxides

The layered transitional metal oxides (LTMO) have attracted extensive research interests during the past decades due to their availability, interesting ion exchange/intercalation properties and environmental benign property. Three main routes are normally used to functionalize these layered materials for potential application in photocatalysis, photoluminescence, and battery electrode materials: (1) ion exchange/intercalation; (2) electrostatic self-assembley (SAM); (3) electrophoresis. Little work emerged recently on the utilization of functionalized LTMO in electroccatalysis.Transitional metal-based materials (TMM) are well known good candidates in electrocatalysis for small organic molecules. Various TMM-based composite electrode materials that might be applied in electrocatalysis and electroanalysis could be prepared by intercalation of the functional components into LTMO layers. In this thesis, attention is paid on the preparation of a series of functionalized TMM-based LTMO composite electrode materials by the modified ion exchange and electrostatic self-assembley methods. The electrochemical and electrocatalytic properties of these electrode materials were investigated in detail. This work was mainly consisted of following three parts:In the first part, the feasibility of electrochemical preparation of the copper-based/titanate intercalation electrode material was demonstrated for the first time. Cupric ion was first intercalated into one of the typical layered titanates by ion exchange and subsequent electrochemical reduction resulted in the copper/titanate intercalation electrode materials. The resulting materials were characterized by SEM, XRD, XPS and ICP-AES. The copper/titanate intercalation electrode materials showed high sensitivity, good stability, and wide linear range in glucose determination, suggesting promising candidates for amperometric enzymeless glucose sensor.In the second part, the layered titanate was firstly exfoliated with n-propylamine, and the electrostatic self-assembled titanate films were fabricated and used as substrate to co-electrodeposite copper and nickel. The charge transfer processes, the morphology and structures of the self-assembled titanate films were characterized by EIS, SEM and XRD respectively. The electrooxidation of glucose and other carbohydrates at the Cu-Ni co-electrodeposits on the self-assembled titanate films were also investigated. The glucose electrooxidation activities on the films were largely dependent on the Cu∶Ni ratio in the composites which can be controlled by the potential for electrodeposition. The glucose electrooxidation activities on the Cu-Ni/titanate films were much improved comparing with the bulk copper electrode. These results suggested that a novel Cu-Ni/titanate electrode material prepared by co-electrodeposition of copper and nickel on electrostatic self-assembled titanate films for glucose sensing.In the third part, the layered nickel manganese oxide (NMO) was synthesized by the combined ion exchange and hydrothermal processes. Immobilization of NMO onto the electrode surface resulted in a stable film electrode with high electrocatalytic activities to ethanol, glucose and methanol.In summary, the LTMOs can be functionalized by either electrochemical reduction following ion exchange or the SAM technique. The functionalized LTMOs act as promising electrodes materials in electrocatalysis towards small organic molecules that may also pave ways to the potential sensor applications.