Abstract
A highly efficient, yet cost effective electrocatalysts for oxygen reduction reaction (ORR) is among the major bottlenecks for large scale development of fuel cells. Electrocatalysts support materials are also of great concern due to lack of stability and durability of most support materials. It is significant to design highly efficient and cost-effective electrocatalysts for the electroreduction of oxygen to enable large scale commercialization of fuel cell devices. Palladium-based metallophthalocyanines electrocatalysts could be a great solution to this problematic reaction. Carbon also possesses unique physical and structural properties, which makes carbon-based materials interesting for application as electrocatalysts support in electro-catalysis. Carbon nanodots (CNDs) was synthesized using simple and cheap method by pyrolysis of oats. The Pd/CNDs electrocatalyst was synthesized by the in-situ reduction method. The calculated particle sizes were found to be 6.0, 0.974 and 3.0 nm for CNDs, Pd and Pd-RuPc nanoparticles respectively. CNDs supported metallophthalocyanine electrocatalysts were also synthesized in this work. Oxygen reduction reaction was investigated in an alkaline medium at the surface of the electrocatalysts deposited on a glassy carbon electrode. FTIR revealed the functional groups present in both CNDs and RuPc molecule, which confirmed the structure of RuPc in all the electrocatalysts. SEM-EDX showed uniform distribution of Ru and Pd in Pd-RuPc/CNDs. XPS revealed the elemental composition of the synthesized electrocatalysts and the different oxidation states of Pd and Ru in the electrocatalysts. The reaction kinetics of the Pd/CNDs was found to have an onset potential of -0.111 V, which is 0.052 V lower than that of Pd/C. The CNDs is a good electrocatalysts support, as supported by the durability and stability studies which showed improved durability and stability when CNDs is used as the support material for the Pd nanoparticles compared to Pd/C. The Pd-RuPc/CNDs was found to have high current densities, stability and durability for oxygen reduction in alkaline media.
M.Sc. (NanoScience)