本研究旨在探討實驗室自製的鉑奈米溶膠觸媒中的殘餘成份(氯、鈉與檸檬酸根離子)對電催化活性的影響。而針對安定劑含量的影響,吾人比較以不同檸檬酸鈉用量製備Pt奈米溶膠。實驗中以UV-vis觀察不同條件下Pt前驅物還原情形並以TEM分析所得Pt溶膠顆粒大小,再比較Pt奈米溶膠製成薄膜電極的電催化活性,以驗證Pt奈米顆粒觸媒中殘氯量、殘鈉量與安定劑用量對活性的影響。 溶膠製備針對溶膠中所含的殘氯量影響的探討,吾人以三種不同氯含量的Pt前驅物製備Pt奈米溶膠,在相同配方與製程條件下製得大小相近的Pt溶膠,並比較電催化氧氣還原反應(ORR)活性。針對殘鈉量影響的探討,吾人比較以檸檬酸與檸檬酸鈉製備Pt之奈米溶膠,Pt顆粒大小與穩定性也很相近,氧氣還原反應中的副產物H2O2生成選擇率皆小於5%,實驗結果發現殘氯與殘鈉對鉑奈米溶膠觸媒電催化活性的影響皆不明顯,而檸檬酸鈉的用量影響也不明顯,但Citrate/Pt比例為1.5所得奈米溶膠活性面積最大,比例超過1.5時,其活性面積降低,氧氣還原反應中的副產物H2O2生成選擇率中除了Citrate/Pt=2.5在0.85V的選擇率高達41%以外其餘選擇率皆小於15% 。
This research studies the effect of residues in Pt sols on the catalytic activity of Pt sols for half-cell reactions in PEFCs. The residues in the Pt sols prepared from MeOH-citrate include Cl, citrate and Na. Pt sols are prepared from different precursors with similar procedure, e.g. from PtCl4 , H2PtCl6 and Pt(NH3)4Cl2 to obtain Pt sols with different amount of residual chlorine. The sodium residue was examined by comparing Pt sols prepared from citric acid and from sodium citrate. Regarding the Pt sols with different amount of residual citrate, we apply different citrate/Pt ratio during Pt sols. Results indicate that the specific activity (per cm2Pt) of ORR and HOR are not influenced by residual chlorine and sodium. However, citrate at a ratio of citrate/Pt>2 will decrease the specific catalytic activity of Pt sols.