沈積在不同的碳載體之奈米Pt觸媒的電化學活性

Electrochemical Activity of Platinum Nanocatalysts Deposited on Carbon Supports

江右君(Yu-Chun Chiang) ； 吳帛軒(Pai-Hsuan Wu) ； 岳恆屹(Heng-I Yueh) ； 梁家鈞(Chia-Chun Liang) ； 鍾均炳(Chun-Ping Chung)

《燃燒季刊》 90期 (2015/08) Pp. 5-14

https://doi.org/10.30041/CQ.201508_(90).0001

摘要

電化學觸媒的活性和穩定性為質子交換膜燃料電池商品化之主要關鍵技術需求之一。可利用減小Pt粒徑、改善Pt粒子披覆在基材上之分散性等，以提升Pt在基材上之活性面積。本研究利用反微胞法合成奈米Pt觸媒，選用經氧化的多壁奈米碳管（cCNT）和石墨烯（cG）作為Pt粒子的載體。研究發現，Pt/cCNT、Pt/cG和Pt/C之Pt平均粒徑分別為1.90 ± 0.99、2.08 ± 0.52和1.96 ± 0.50 nm。Pt的結晶化程度和抗氧化能力均呈現下列趨勢：Pt/cG~Pt/cCNT ＞ Pt/C；但Pt表面之化態分佈並未受到基材不同而有顯著差異，均以金屬Pt（零價）最多，分別占52 (Pt/cCNT)、60 (Pt/cG)、和53 (Pt/C) at. %。由循環伏安法分析結果發現，Pt/cCNT、Pt/cG 和Pt/C之電化學活性面積（ECSA）分別約為55、88和46 m2/g，在循環操作600圈後，ECSA的衰減率分別約為8 % (Pt/cCNT)、7 % (Pt/cG)和33 % (Pt/C)。

關鍵字

奈米碳管 ； 石墨烯 ； 觸媒 ； 電化學活性 ； 材料特性分析

並列摘要

Electrochemical activity and stability of the catalysts applied on proton exchange membrane fuel cells (PEMFCs) are one of the most important know-how for PEMFCs towards commercialization. In general, the enhancement of the activity can be achieved by reducing the particle sizes of the catalysts or improving the dispersion of the particles on the supports. In this study, the platinum (Pt) nanoparticles were deposited on oxidized carbon nanotubes (cCNT) or graphene sheets (cG) using the reverse micelle process. Results showed that the Pt nanoparticles on Pt/cCNT and sizes of Pt nanoparticles were 1.90 ± 0.99 and 2.08 ± 0.52 nm, respectively, where the mean size of Pt particles on Pt/C (J particles and the oxygen resistance of the samples followed the order of Pt/cG ~ Pt/cCNT ＞ Pt/C. The metal Pt was the predominant Pt chemical state on all samples, where 52 at. % on Pt/cCNT、60 at. % on Pt/cG and 53 at. % on Pt/C (JM) were observed. The results from the cyclic voltammetry analysis showed that the values of electrochemical surface area (ECSA) were 88 m2/g (Pt/cG) and 55 m2/g (Pt/cCNT), much higher than that of Pt/C (JM, 46 m2/g). The long-term test illustrated the degradation in ECSA exhibited the order of Pt/C (33 %) ＞ Pt/cCNT (8 %) ＞ Pt/cG (7 %).

並列關鍵字

Carbon nanotubes ； Graphene ； Catalyst ； Electrochemical activity ； Characterization