以置換反應製備PtRu核殼奈米顆粒應用於電化學催化反應

Abstract

循環伏安法(CV)電化學裂解Nafion Ionomers，產生大量含氧官能基吸附Pt金屬離子製作甲醇氧化陽極電極材料。透過XPS C1s分析的結果顯示C=O，C-COOH的含量有明顯的增加，證明碳材上的含氧官能基可有效地快速產生。再離子色譜法證明經由CV掃描後硫酸根離子的殘留含量，直接證明了Nafion Ionomers 裂解產生小分子在水溶液中。ICP-MASS的結果也顯示出CV掃描處理樣品擁有較多金屬含量，相對於未破壞樣品金屬離子增加170%。X-ray吸收光譜技術分析吸附Pt4+的Nafion Ionomer 含氧官能基樣品為物理吸附現象，相對於Pt4+的碳材表面為化學吸附現象。電化學甲醇氧化行為分析結果得知，在Nafion Ionomer 含氧官能基樣品有較高的活性，並且在CV500 圈中有相當高的穩定性。TEM 結果也顯示出甲醇氧化CV500 圈測試中，Nafion Ionomer 含氧官能基樣品的顆粒大小維持不變在2~4nm。商用觸媒E-TEK Pt/C 在甲醇氧化CV500 圈測試後，其Pt顆粒嚴重聚集大小約7~15 nm。這證明了Nafion Ionomer含氧官能基也可以有效低協助Pt氧化甲醇的能力，可有效增加其電化學穩定性。

The massive oxygenated functional groups, which increase absorbed Pt metallic ion, are produced by CV –degraded Nafion ionomers to fabricate anode material for methanol oxidation reaction. The result of XPS C1s analysis suggests the noticeable increment of C=O and C-COOH in content, proving that oxygenated functional groups can be produce effectively and quickly. The residual content of Sulfate ion after CV scanning is attained by ion chromatography, showing that Nafion ionomers degradation generating smaller molecules in the aqueous solution. Through ICP-MS, the much more metal content (170%) is observed in the sample after CV-Scan treatment. XAS analysis indicates that the Pt4+ is physically absorbed on oxygenated functional groups of Nafion ionomers, related to the chemical absorption of Pt4+ on surface of carbonaceous material. Electrochemical analysis for methanol oxidation determined the higher activity and stability for Nafion ionomers with oxygenated functional groups. In the CV500 test for methanol oxidation, TEM results shows that the particle size of Nafion ionomers with oxygenated functional groups is maintained in the range of 2~4 nm； while in the case of commercial E-tek Pt/C electrocatalyst, the particles aggregate seriously, which making the size reach to 7~15nm. The above results provide clear evidence that Nafion ionomers with oxygenated functional groups are able to enhance the Pt catalytic activity of methanol oxidation reaction, and improve the electrochemical stability effectively as well.