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班 級 : 碩研能源一甲. 學 生 : 林恩賢. Outline. Introduction Experimental Deposition synthesis and characterization of RuO2–IrO2/Pt electrocatalyst Electrochemical studies Preparation of membrane and electrode assembly (MEA)and evaluation of URFC Results and discussion Conclusions Future work.
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班 級:碩研能源一甲 學 生:林恩賢
Outline • Introduction • Experimental • Deposition synthesis and characterization of RuO2–IrO2/Pt electrocatalyst Electrochemical studies • Preparation of membrane and electrode assembly (MEA)and evaluation of URFC • Results and discussion • Conclusions • Future work
Introduction(I) • One of the main technical challenges of URFC is the development of efficient bifunctional electrocatalysts for oxygen redox reaction.
Introduction(II) • Colloid deposition of RuO2-IrO2/Pt provides advantages as followings. • The deposition method with iso-propanol as a dispersing agent . • 1.Good combined with Pt black . • 2.Betterelectron conductivity . • 3.Better bifunctional performance . • Compare with RuO2 and IrO2:
ExperimentalDeposition synthesis and characterization of RuO2–IrO2/Pt electrocatalyst Electrochemical studies • Pt black was blended with RuO2-IrO2 solid solution obtained byAdams method to prepare mixed RuO2-IrO2/Pt electro catalyst.
Experimental Preparation of membrane and electrode assembly (MEA)and evaluation of URFC • Oxygen electrode • 2 mg cm−2 =RuO2-IrO2/Pt • 0.6 mg cm−2=Nafion. • Hydrogen electrode • 0.4 mg cm−2 =Pt/C • 0.4 mg cm−2 =Nafion.
Results and discussion • XRD patterns samples obtained by deposition method. • RuO2 and IrO2 were easy to form solid solution . • The XRD peaks of IrO2 disappear and the XRD peaks of IrO2 shift to those of RuO2,which indicates the formation of RuO2-IrO2 solid solution.
TEM images • The mixed and deposited RuO2-IrO2/Pt electrocatalyst of particles size Pt-black (3-8 nm), with RuO2-IrO2(2-3nm). • Prove the dispersing agent (i.e. iso-propanol) is useful. Fig. 2. TEM images of deposited RuO2–IrO2/Pt (a), mixed RuO2–IrO2/Pt (b), Pt black (c) and RuO2–IrO2 (d) obtained by Adams method.
The evaluation of URFC in fuel cell mode and water electrolysis mode • Operated and tested • Fuel cell mode for 2 h • Electrolysis mode for 1 h. • Compare with this two method • The electron conduction path tends to be hindered by RuO2-IrO2 solid solution in the mixed RuO2-IrO2/Pt electrocatalyst.
Effect of cell temperatures on the performance • The influence of cell temperatures on performance of URFC with deposited RuO2–IrO2/Pt electrocatalyst . • Increasing temperature can enhance : • 1.Reaction activity of electrocatalyst . • 2.Lower the over-potential of electrodes
Cyclic performance of URFC • The average terminal voltages of fuel cell/electrolysis of URFC are : • 0.73/1.53V at 0.4A cm−2 • 0.67/1.56V at 0.5A cm−2 • Promising for practical application.
Conclusions • A RuO2-IrO2/Pt electrocatalyst for URFC was prepared by even deposition of iridium hydroxide hydrate and ruthenium hydroxide hydrate on Pt black and calcination in air. • There are differences in morphology and structure between deposited RuO2-IrO2/Pt and mixed RuO2-IrO2/Pt. • The experiments reveal that the performance of URFC using deposited RuO2-IrO2/Pt electrocatalyst with high dispersion is better than that of URFC using mixed RuO2-IrO2/Pt electrocatalyst.
Future work • 以原製程為基礎並在溶劑中添加分散劑iso-propanol，期望能增加觸媒的分散性以減少團聚現象。
