炭黑负载Pt-Sn双金属催化剂对乙醇的电催化氧化性能

采用一步还原法(乙二醇为还原剂)与两步还原法(在聚乙烯吡咯烷酮PVP保护下,先用硼氢化钠还原制备Sn溶胶,沉积Pt后用乙二醇还原)制备了炭黑负载Pt-Sn双金属催化剂,利用循环伏安法和计时电流法考察了催化剂制备方法、Pt/Sn原子比、溶液p H值、PVP/Sn质量比、反应介质等对乙醇室温电催化氧化活性和稳定性的影响.以X光衍射、透射电镜及电化学活性面积测定对所得催化剂进行了表征.发现引入Sn明显提高了Pt催化剂对乙醇的电催化活性与稳定性,两步还原法得到的Pt3Sn/C催化剂具有更小的颗粒尺寸,更大的电化学活性面积及更高的乙醇氧化活性与稳定性.与酸性介质相比,该催化剂在碱性介质中的电化学活性更好.

Ethanol Electrocatalytic Oxidation Performance of Carbon Black-supported Pt-Sn Bimetallic Catalysts

The Pt-Sn bimetallic catalysts supported on Vulcan XC-72 with various Pt/Sn ratios were prepared by one-step reduction process using ethylene glycol as reduction agent and by two-step reduction process using sodium borohydride reduction and PVP as stabilizer to tin colloid and sequential deposition of Pt reduced by ethylene glycol reduction. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electrochemical surface area (ECSA). The activities and stabilities for electrocatalytic oxidation of ethanol on the catalysts were evaluated by cyclic voltammetry measurements and chronoamperometry at room temperature in 0.5mol/L H2SO4 solution and in 1.0 mol/L KOH solution. The influences of preparation parameters such as Pt/Sn ratios, pH values, reduction temperature, PVP content, and reaction medium were studied. The results demonstrated that the addition of Sn into the Pt catalyst promotes the electrochemical activity and stability of ethanol oxidation. The Pt3Sn/C catalyst prepared by two-step method showed the superior performance in comparing with the Pt/C and Pt3Sn/C catalysts obtained by one-step method, attributing to its smaller particles, larger electrochemical surface area and therefore higher activity and stability. The activity in acidic solution is higher than in alkaline solution.