Synthesis and Characterization of a tri- metal catalyst used for the water electrolyzer and fuel cell NFL Lab.1 STUT, Mechanical Engineering SPEACH : En-Xian Lin Student ID: M991A203

Outline NFL Lab.2  Introduction  Expermental  Catalysts fabrication  Membrane electrode assembly (MEA) prepartoin & Single Cell Device  Result and discussion  Conclusion

 Fuel cell applications is very wide, power generation can be divided into three categories according to:  Portable electronic products, all kinds of transport, set-type generator 年 元智大學燃料電池國際研討會漢 氫科技 ( 股 ) 公司 展示一個筆記型電 腦燃料電池內鍵卡匣式儲氫器 圖片來源：台灣經濟研究院 ZESIV.5 圖片來源：亞太燃料電池 ( 股 ) 公司 1kW 可攜式燃料電池緊急發電機 圖片來源： 工業技術研究院 能源與 環境研究所 Introduction

 The mid-1980s, the development of Solid Polymer Electrolyte (SPE), up to 70 ~ 80% efficiency, output high-purity hydrogen and oxygen. This system can match with the Proton exchange membrane fuel cell ( PEMFC) system, due to the use of components does not differ greatly between the two, each chemical reaction is the reverse reaction, combined this two device can be achieved simply by changing the mode of operation of power generation and hydrogen production capabilities, is the single Unitized Regenerative Fuel Cell (URFC). NFL Lab.4 PEMFCSPE + URFC What is the URFC?

Anode electrocatalystsCathode electrocatalysts Pt–IrPt/C Pt–Ru–IrPt-Ru/C Pt–IrO 2 Pt-Ru-HxWO3/C Pt–IrO 2 –RuO 2  Platinum (Pt) is often used in various types of fuel cells, such as AFC, PAFC, PEMFC, etc...., because there is good for hydrogen adsorption capacity, it was one of fuel cell catalysts options..  However, the effect of carbon with water molecules in the water electrolysis, when the supply voltage increase than 0.118V it will be generates CO 2 to Corrosion the plate. NFL Lab.5 Table 2. Common and applicable to URFC catalyst.

URFC (Unitized Regenerative Fuel Cell) NFL Lab.6  URFC (Unitized Regenerative Fuel Cell)  Water electrolyzer Mode  Fuel Cell Mode

Single Cell Assembly NFL Lab.7  As shown, a single cell from the inside out in order of MEA, the diffusion layer, sealing gasket, flow field plates, electrodes, plate combination.  Most of the diffusion layer with low porosity and drainage of carbon cloth (paper).  Flow field plates are generally used carbon plate, metal plate or composite graphite fibers.  As URFC functions must perform water electrolysis, so the experimental use of titanium metal plate as a flow field plate. Expermental

Preparation of reversible membrane electrode assemblies  Typical metal loadings of 0.7 and 2.4 mg/cm −2 were obtained for cathodes and anodes, respectively. Finally, membrane-electrode assemblies (MEAs) were prepared by hot pressing the Ti-supported electrocatalytic layers against each side of the Nafion ® membrane NFL Lab.8 1. Resistance to chemical corrosion. 2. Operating temperature up to 190 ℃. 3. High ionic conductivity. 4. Sulfonic acid has a strong function of proton exchange. 5. Nafion has very selective and high permeability of water. Schematic diagram of MEA Process

Tri-catalysts processes  We have two sample of catalysts.  Sample A: Without IPA  Sample B: With IPA NFL Lab.9 Chloroplatinic acid

NFL Lab.10  Black titanium can be used as catalyst carrier, if the beginning of serious agglomeration area will result in reduction of its activity.  Sample A was serious accumulative, cause specific surface area decreased.  Sample B after adding IPA slow aggl- omeration. Fig. 1 The TEM image of Sample A (a)di-metal Pt-IrO 2 (b)tri-metal Pt- Sample B (c) di-metal(d) tri-metal Result and discussion IrO 2 /Ti

Electrochemical analysis Fig. 2 Cyclic voltammetry at room temperature and at a sweep rate of 20 mV -1 for the electrolyzer equipped with Pt-IrO2 and Pt- IrO2/Ti. NFL Lab.11  For the particles described in Fig. 1 are shown in Fig. 2  The hydrogen desorption and adsorption reaction of the Pt- IrO 2 sample occurred on potential between 0.2V-0.8V.  The characteristic potential of the Pt-IrO 2 /Ti is better than Pt- IrO2 which implies that the activity Pt-IrO 2 /Ti is better than Pt-IrO2.

 Fig 3. Shown in AC impendence of Pt-IrO 2 and Pt-IrO 2 /Ti catalysts with or without the addition of IPA. The resistance of the tri-metal catalyst is lower than that of di-metal catalyst, the Rct value of tri-metal and di-metal catalysts is 1.4 and 0.8 respectively. NFL Lab.12 Fig. 3.AC impendence of catalysts (a) without IPA and (b) with IPA addition. 。 a

Single Cell Test NFL Lab.13  Performance indicators:  Voltage Efficiency:

Water Electrolysis Test NFL Lab.14  The operation voltage of water electrolysis was about 1.5V~1.6V  Fig.4 shows the water electrolysis performance of Pt-IrO 2 /Ti in different IPA concentration in the current density of 100mA/cm 2. The voltage efficiency of ratio IPA:DI water=1:1,2:1 was 32.8% and 42.2%, respectively.

Conclusions  In this study, di-metals Pt-IrO2 and tri-metals Pt-IrO2/Ti catalysts were prepared by spontaneous deposition.  The Pt coated on the IrO 2 particle tightly and Ti-black supported Pt- IrO 2 catalyst has larger active area and better water electrolysis efficiency.  Higher IPA concentration can dispersed the composite particle well.  From water electrolysis performance tests obtained with the addition of IPA to reduce the catalyst agglomeration, significantly improved catalyst utilization, so the efficiency of water electrolysis voltage difference between two samples of about 10%. NFL Lab.15

NFL Lab.16 謝謝聆聽 Thank you for your attention !