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目的：通过对电沉积过程中基体亲水性及电解液温度参数的控制,实现对Pt-Ni催化剂的形貌及催化性能的控制。方法采用恒电压沉积技术制备Pt-Ni合金催化剂。利用5%(质量分数) Nafion对多孔碳布基体表面进行亲水修饰,并控制电解液温度,合成具有不同形貌的Pt-Ni合金催化剂。利用X射线衍射( XRD)、扫描电子显微镜( SEM)、能量色散谱( EDS)、循环伏安( CV)、单电池极化性能等测试技术对制备的催化剂进行物理及电化学表征。结果碳布基体表面经适量的Nafion修饰后,电沉积制备的合金催化剂颗粒细小,分布均匀。当碳布基体表面修饰的Nafion含量达到0.8 mg/cm2时,催化剂单电池极化性能最佳。另外,较高电解液温度下制备得到的球状形貌具有更大的电化学活性表面积( ECSA),更高的催化活性,优于较低温下制备的“雪花”状催化剂的性能。其中,50℃下电沉积制备的Pt-Ni合金催化剂ECSA达到47.6 m2/(g Pt),单电池运行过程中最大功率密度达到77.8 mW/cm2,具有最高的催化活性。结论适量Nafion修饰后的亲水多孔碳布基体上电沉积Pt-Ni合金催化剂性能更加优越。电解液温度的控制对恒电压沉积的Pt-Ni合金表面形貌控制有重要意义。

ABSTRACT:Objective To artificially control the morphology and electro-catalytic performance of Pt-Ni alloy catalysts in the process of electrodeposition by controlling the parameters of carbon cloth hydrophilicity and electrolyte temperature. Methods Po-tentiostatic electrodeposition was employed to prepare Pt-Ni alloy catalysts with different morphologies. 5 wt% Nafion was used to modify the surface hydrophilicity of the carbon cloth substrates. The electrolyte temperature was subsequently controlled. The phy-sical and electrochemical performances of the electrodeposited catalysts were characterized by X-ray diffraction ( XRD) , scanning electron microscope (SEM), energy dispersive spectrograph (EDS), cyclic voltammetry (CV), and single cell polarization test technique. Results The Pt-Ni alloy particles electrodeposited on the Nafion-modified carbon cloth were fine and homogeneous. Sin-gle cell performance of the electrode with moderate Nafion loading of 0. 8 mg/cm2 was the best. Compared with Pt-Ni alloy with snowflake-like particles fabricated at lower temperature, the Pt-Ni alloy with spherical particles fabricated at higher electrolyte tem-perature had higher electrochemical active surface area ( ECSA) and better electrocatalytic performance. Among them, the Pt-Ni prepared at 50 ℃ had the highest ECSA of 47. 6 m2/(g Pt) and the highest power density of 77. 8 mW/cm2 in single cell. Con-clusion The electrocatalytic performance of Pt-Ni electrodeposited on the Nafion-modified carbon cloth is more superior to that of unmodified samples. Electrolyte temperature has significant impact on the morphology of electrodeposited Pt-Ni alloy catalysts.