Carbon Nanotubes On The Electrodeposition Of Pd Electro-catalytic Properties Of,

Palladium (Pd) is one of the important materials that show high catalytic activitywith the appropriate structures and morphologies. Extensive studies have beenfocusing on not only the development of different types of Pd nanomaterials but alsotheir applications in the area of gas/chemical sensors, diverse catalysis, automotiveexhaust gas purification , and organic synthesis etc.. Because of its novelty andscarcity, a plenty of efforts have been spent to reduce the loading Pd materials whilekeeping its high catalytic performance. Pd alloy materials have been proved to be agood example with higher activity toward the anodic oxidation of small organcmolecuels than single Pd metal electrode, while at the same time save the use of Pdmaterials. The interest of our study derives from the question if we can obtain a highlyactive Pd-based materials coated onto carbon nanotubes by using a simpleelectrochemical deposition method. The motivation of this study lies in: 1) carbonnanotubes have been proved to be a very good conductive supporting material forcatalyst because of its unique physical, mechanical and electrical properties; 2)electrochemical deposition technique can be an effective technique to form 3-dimension materials that benefit the catalytic reaction and kinetics; 3) in-situ dopingor alloy formation can be expected with the simple electrochemical deposition method.Thus, the research work of this thesis has been focusing on: 1) electrodepositingdispersed Pd nanoparticles onto carbon nanotubes electrodes (Pd/CNTs) and exploringits electrocatalytic activity toward the small organic molecules such as methanol andethanol as well as its application as an enzymeless sensor ; 2) electrodepositingbimetallic Pd-Cu nanoparticles onto carbon nanotubes (Pd-Cu/CNTs) and performingits electrocatalytic analysis toward the oxidation of glucose.The key observations of this study have been summarized as following:1. Fabrication of Pd/CNTs and Pd/GC electrodes and their catalytic oxidationtoward methanol Cyclic voltammetric method has been used to deposit Pd nanoparticles onto bareglassy carbon (GC) electrode and CNTs that immobilized on glassy carbon (GC)electrode, where dispersed Pd nanoparticles were coated onto CNTs surface to form a3-D electrode structure with high permeable surface active area while Pd thin film wasformed on GC electrode surface leading to the lower catalytic performance towardmethanol oxidation. The results indicate that Pd/CNTs can be a good candidate in theapplication of methanol fuel cells.2. Catalytic activity of Pd/CNTs and Pd/GC electrodes toward ethanol oxidationThe study of catalytic activity of two electrodes has been extended to ethanoloxidation because of the limit application of methanol due to its toxicity and safetyconcern as well as the recent active study on the development of ethanol fuel cell. Theresults showed that high catalytic activity was also achieved for Pd/CNTs toward theoxidation of ethanol, demonstrating the flexibility and adaptability of as-fabricatedPd/CNTs substrate.3. Pd/CNTs electrode serving as an enzymeless glucose sensorThe possibility of Pd/CNTs serving as an enzymeless glucose sensor has beenexplored using the as-fabricated electrode. The as-made electrode with essential largesurface area showed the prominent electrocatalytic activity towards the electro-oxidation of glucose in alkaline media , enabling it to detect glucose with theinterference of high concentration of Cl-. The amperometric response was linear toglucose concentration in range of 1-14 mM with a detection limit of 1 M (S/N=3). Theelectrode maintained the same level of its initial catalytic response to glucose after 2months storage in the air at 4°C.4. Construction of Pd-Cu/CNTs electrode and its catalytic activity studyThe bimetallic Pd-Cu nanoparticles have been electrodeposited onto CNTs withcopper serving as the dopant by using a simple potential-step deposition method. ThePd/Cu ratio inside deposition bath was varied in order to obtain the bimetallic Pd-Cu/CNTs electrode with optimal catalytic performance toward the electro-oxidation ofglucose. The experimental results showed that optimal catalytic activity of Pd- Cu/CNTs electrodes was achieved with the bath ratio of Pd:Cu=2:1. The currentresponse toward glucose oxidation is found to be twice of that from Pd/CNTs electrode.And the the detection limit is 0.1 M. These results suggest that bi-metallicnanoparticles modified carbon nanotubes electrode (Pd-Cu/CNTs) may have a betterapplication prospects in glucose sensor or glucose fuel cell.