探討去合金化效應對鉑修飾之鎳錫鈀多尺度觸媒於鹼性環境中氧氣還原反應之影響

由於現今全球能源消耗與日俱增，全球皆致力於尋找新的替代能源，而燃料電池以其低汙染、高效率、便利性等特點成為眾多再生能源中發展的趨勢，但由於陰極氧氣還原觸媒材料的鉑的成本以及反應能障的問題，使得燃料電池依舊無法商業化發展，因此改善觸媒成本並使氧還原活性的提升成為現今研究的主要方向。本研究利用濕式化學法合成多元金屬(鎳、錫、鈀)多尺度結構觸媒，並利用不同當量貴金屬(鉑)的修飾於觸媒表面，再探究其在鹼性環境中氧氣還原催化活性受去合金化製程處理之影響。利用X光繞射光譜(XRD),X光吸收光譜(XAS),高解析電子顯微境(TEM)等儀器分析觸媒結構，並由電化學循環伏安法與一氧化碳剝除法確認合金化處理能改變表面組成，使活性上升。相較商用白金觸媒(J.M.Pt/C)，經過去合金化後含有白金成分(~1.0 wt% Pt)之鎳錫鈀鉑四元觸媒(命名為NiSnPdPt0025)之質量活性(Mass Activity, MA)最高可提升約67倍。顯見該處理對含有氧化物之觸媒在氧氣還原催化效果極佳。改變修飾鉑濃度則可有效抑制表面氧化，且隨著鉑含量的提升，觸媒之奈微結構與表面形貌也會因為賈凡尼置換效應(galvanic replacement)程度增加而改變。本研究所設計之四元奈米觸媒可顯著降低氧還原反應材料之鉑金屬用量，樣品中的氧化問題可藉由些微增加白金或是電化學去合金處理改善，下一步重點在如何有效改善材料之反應耐久性，可能的做法為調整金屬還原程序、成長過程的還原劑用量比、以及表面還原反應改質處理等方法。

關鍵字

去合金化；觸媒；氧氣還原反應；燃料電池；鹼性環境；鉑

並列摘要

Due to the increasing global energy consumption, the world is devoted to finding new alternative energy, and fuel cells with its low pollution, high efficiency, convenience has become a trend in much renewable energy development, but the inherent characteristics of Pt such as its high primitive cost and reaction barrier height make it unfit for commercial application, in this context, searching for highly active and low-cost nanocatalysts (NCs) for the oxygen reduction reaction (ORR) is a crucial endeavor. In this study, quaternary metallic NCs consisting of the Ni, Sn, Pd hierarchical structure are synthesized by the wet chemical reduction method with different Pt contents (0025~03 mole ratio, namely NSPP) , further explore the influence of its oxygen reduction catalytic activity in alkaline environment (0.1M KOH) by dealloying process treatment, the catalyst structure is analyzed by instruments such as X-ray diffraction (XRD), X-ray absorption spectra (XAS), high-resolution electron microscopy (HRTEM). Through analysis of cyclic voltammetry (CV) and carbon monoxide stripping results, we demonstrated that enhanced ORR activities for the dealloying process, resulting in changed surface composition on the NCs. Compared to commercial platinum catalysts (J.M.Pt/C), the mass activity of NiSnPdPt0025 with platinum composition (-1.0 wt% Pt) after dealloying can be increased by up to 67 times. It is shown that the treatment has excellent catalyzing effect on oxygen reduced the catalyst containing oxides. Changing the concentration of modified platinum can effectively inhibit surface from oxidation, and as the platinum content increases, the catalyst's microstructure and surface morphology will also be changed due to the increase in the degree of galvanic replacement effect. The institute designed the four-metal nano-catalyst (NCs) can significantly reduce the amount of platinum metal oxygen reduction reaction material, the oxidation problem in the sample can be optimized by increasing some platinum or through the electrochemical de-alloy treatment, the next topic is focus on how to effectively improve the durability of the material reaction, possibly the practice is to adjust the metal reduction procedure, loading of reducing agent during growth, as well as surface reduction reaction modification treatment methods.