利用脈衝式電鍍法製備鉑鎳合金觸媒應用於提升質子交換膜燃料電池陰極端之氧氣還原效能

PtNi Alloy Catalyst for Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cell by a Pulse Electrodeposition Technique

本研究利用脈衝式電鍍法製備鉑鎳二元觸媒於成長奈米碳管之碳布上，應用於質子交換膜燃料電池之陰極端以提升氧氣還原反應效能。奈米碳管藉由化學氣相沉積法成長於碳布上以增加電極表面積，試片經親水處理後，先後以脈衝式電鍍法於奈米碳管上沉積金屬鎳與白金顆粒；純鉑之單元觸媒（Pt/CNTs）亦以脈衝式電鍍法製備做為對照組。
在測試方面透過在0.1M過氯酸溶液中進行循環伏安法（CV）及旋轉電極的線性掃描伏安法（LSV）做為電化學特性分析，結構與組成透過SEM、XPS及ICP-MS觀測；根據旋轉電極測試結果，PtNi/CNTs之極限電流密度可到達24 mA/cm2；同時，PtNi/CNTs之起始電位（onset potential）比起商用Pt/C更早發生，顯示PtNi二元觸媒的表現優於商用觸媒，其可能原因為藉由Ni的添加造成Pt對於含氧物質吸脫附行為的改變，進而提升氧氣還原之效率。

In this study, Pt-Ni binary alloy catalysts supported on carbon nanotubes (PtNi/CNTs) were developed for enhancing the oxygen reduction reaction (ORR) efficiency for proton exchange membrane fuel cell (PEMFC) application by electrodeposition procedure. The CNTs were directly grown on carbon cloths by chemical vapor deposition method and the specimen were treated with hydrophilic process. The nickel nanoparticles were deposited on CNTs by pulse electro-planting in acid solution, and then the platinum particles were reduced on them by pulse electro-planting in base solution to form binary alloy catalysts. Electrochemical characteristics of the PtNi/CNTs catalyst were investigated via cyclic voltammetry analysis and rotating disk electrode test in 0.1 M perchloric acid. Structure and elementary composition were measured by SEM, XPS and ICP-MS. In ORR test, the limiting current density of PtNi/CNTs could reach to 24 mA/cm2, while that of commercial Pt/C was 10 mA/cm2. It was found that the limiting current density and onset potential of PtNi/CNTs specimen were better than those of commercial Pt/C specimen. The outcome signified better PtNi alloy catalyst in adsorption and desorption behavior of oxygen to increase the ORR rate.