Global warming has occurred due to the usage of fossil fuels and greenhouse gas emissions. Therefore, a change in the energy paradigm can overcome the problems of global warming and air pollution and provide new energy to humanity continuously. Fuel cells are an eco-friendly system that utilizes the electricity generated during the process of producing water from hydrogen fuel. In general, 20 wt% Pt/C is used as the commercial catalyst for polymer electrolyte fuel cells (PEFCs), but challenges remain to solve such as cost and durability. In PEFCs, oxygen reduction reaction (ORR) is an important key as a rate-determining step (RDS) to react the overall reaction. Therefore, it is necessary to develop efficient materials (electrode, membrane, cell, etc.) for improving RDS. Recently, transition metal oxide (TMO) composite electrodes have gained interest in the electrochemical fields. Especially, nickel, cobalt, iron-based oxides are promising materials as non-noble metal electrocatalysts due to their high electric conductivity and various oxidation state.The purpose in this research is to improve ORR performance by controlling active sites and electric conductivity using low amount of noble metals on transition metal doped oxides for the use at the electrode. We have developed composite oxide electrodes with noble-transition metal alloy using solid-state methods. Small amount of noble metal can be alloyed with transition metal to form appropriate oxygen binding energy for oxygen adsorption and desorption, which can improve ORR activity. To check the catalytic activity, cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were analyzed using a rotating disk electrode, and it was found that the noble metal-transition metal alloy oxide composite electrode was effective in enhancing the ORR kinetics. Additionally, the strong interaction between the alloy nanoparticles and oxide support surface enhances chemical stability when used in harsh environments such as acidic media. Furthermore, based on the previous ORR data, we fabricated membrane electrode assembly (MEA) using developed catalysts and confirmed their potential for PEFCs applications.
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