Chen Yizhe, Zhao Xiao, Yan Huangli, Sun Liangyu, Chen Shengli, Zhang Shiming, Zhang Jiujun
Institute for Sustainable Energy/College of Sciences, Shanghai University, Shanghai 200444, China.
College of Chemistry and Molecular Sciences, Wuhan University, Hubei Key Laboratory of Electrochemical Power Sources, Wuhan 430072, Hubei, China.
J Colloid Interface Sci. 2023 Dec 15;652(Pt A):1006-1015. doi: 10.1016/j.jcis.2023.08.134. Epub 2023 Aug 22.
Designing Pt-skin on the catalyst surface is critical to developing efficient and stable electrocatalysts toward oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. In this paper, an acidic reductant is proposed to synchronously manipulate in-situ growth of Pt-skin on the surface of alloyed Pt-Cu nanospheres (PtCu) by a facile one-pot synthesis in an aqueous solution. Ascorbic acid can create a Pt-skin of three atomic layers to make the typical PtCu-alloy@Pt-skin core/shell nanostructure rather than the uniform alloys generated by using alkaline reductants. Surfactant as soft-template can make the alloyed PtCu with a three-dimensional porous network structure. Multiple characterizations of XRD, XPS and XAFS are used to confirm Pt-alloying with Cu and formation of core/shell structure of such a catalyst. This PtCu/C exhibits a half-wave potential of 0.913 V (vs. RHE), with mass activity and specific activity about 3.5 and 6.4 times higher than those of Pt/C, respectively. Fuel cell tests verify the excellent activity of PtCu/C catalyst with a maximum power density of about 1.2 W cm. Moreover, this catalyst shows excellent stability, achieving a long-term operation of 40,000 cycles. Furthermore, theoretical calculations reveal the enhancement effect of characteristic PtCu-alloy@Pt-skin nanostructure on both catalytic ORR activity and stability.
在质子交换膜燃料电池中，设计催化剂表面的铂皮对于开发高效稳定的氧还原反应（ORR）电催化剂至关重要。本文提出一种酸性还原剂，通过在水溶液中简便的一锅法合成，同步控制合金化铂铜纳米球（PtCu）表面铂皮的原位生长。抗坏血酸可形成三层原子的铂皮，从而得到典型的PtCu合金@铂皮核壳纳米结构，而非使用碱性还原剂生成的均匀合金。表面活性剂作为软模板可使合金化的PtCu具有三维多孔网络结构。利用XRD、XPS和XAFS等多种表征手段来证实铂与铜的合金化以及这种催化剂核壳结构的形成。这种PtCu/C的半波电位为0.913 V（相对于可逆氢电极），质量活性和比活性分别比Pt/C高约3.5倍和6.4倍。燃料电池测试验证了PtCu/C催化剂的优异活性，最大功率密度约为1.2 W/cm。此外，这种催化剂表现出优异的稳定性，可实现40000次循环的长期运行。此外，理论计算揭示了特征性PtCu合金@铂皮纳米结构对催化ORR活性和稳定性的增强作用。
