Pt 含量对Co@Pt/C核壳结构催化剂性能的影响

采用两步还原法制得Co@Pt/C核壳结构催化剂, 其中Co与Pt 的总质量分数为20%. 通过改变金属前驱体的用量, 制备了不同Co:Pt 原子比的Co@Pt/C 催化剂, 以20% (w) Co@Pt(1:1)/C 与20% (w) Co@Pt(1:3)/C 表示. 采用透射电镜(TEM)、光电子射线能谱分析(XPS)、循环伏安(CV)、线性扫描伏安(LSV)等方法考察了其结构与性能, 并与实验室早先制备的40% (w) Co@Pt/C 催化剂进行了比较. 自制20% Co@Pt(1:1)/C 与20% Co@Pt(1:3)/C 催化剂的金属颗粒直径约为2.2-2.3 nm, 在碳载体上分散均匀, 粒径分布范围较窄, 电化学活性比表面积(ECSA)分别为56 和60 m²·g^-1, 均超过商用催化剂20% Pt/C(E-tek) (ECSA=54 m²·g^-1). 20%Co@Pt(1:1)/C 与20% Co@Pt(1:3)/C 的半波电位相较于40% Co@Pt(1:1)/C 和40% Co@Pt(1:3)/C 均向正向移动, 表现出更好的氧还原(ORR)催化活性, 并有望降低催化剂的成本, 在质子交换膜燃料电池领域表现出良好的应用前景.

Effects of Pt Content on the Catalytic Performance of Co@Pt/C Core-Shell Structured Electrocatalysts

Core-shell structured Co@Pt/C electrocatalysts containing different mass fractions of Co to Pt, which are represented as 20% (w) Co@Pt(1:1)/C and 20% (w) Co@Pt(1:3)/C, were prepared by changing the ratio of metallic precursors using a successive reduction method. The structure and electrochemical performance of the as-prepared catalysts were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV). The performance of the as-prepared catalysts was compared with that of 40% (w) Co@Pt/C catalyst we synthesized previously. The sizes of Co@Pt(1:1) and Co@Pt(1:3) particles ranged from 2.2 to 2.3 nm, and the metal particles were well dispersed on the carbon support. The electrochemical specific area (ECSA) of 20% Co@Pt(1:1)/C (56 m²·g^-1) and 20% Co@Pt(1:3)/C (60 m²·g^-1) were higher than that of commercial 20% Pt/C (E-tek) (54 m²·g^-1). Compared with those of 40% Co@Pt(1:1)/C and 40% Co@Pt(1:3)/C, the half-wave potentials of 20% Co@Pt(1:1)/C and 20% Co@Pt(1:3)/C shifted to the positive direction, and they correspondingly showed improved catalytic performance. The low cost and high performance of the 20% Co@Pt/C catalyst make it a promising low-Pt catalyst for proton exchange membrane fuel cells.