添加Al对燃料电池阴极催化剂(Pt-Fe)/Pt合金微观组织及氧还原催化性能的影响

Impact of Al Addition on Microstructure and Oxygen Reduction Catalytic Performance of(Pt-Fe)/Pt Alloy Used as Fuel Cell Cathode Catalyst

为提高燃料电池阴极催化剂(Pt-Fe)/Pt合金的氧还原催化活性和稳定性,在Pt-Fe合金体系中引入元素Al,熔炼得到中间合金(Pt-Fe)Al,再经过NaOH溶液定向腐蚀得到(Pt_(1-x)Fe_x)_3Al/Pt合金,用其作为燃料电池氧还原反应的催化剂,并对其结构、催化活性和稳定性进行了研究。结果表明,所制备的催化剂材料(Pt_(1-x)Fe_x)_3Al/Pt合金具有由几个原子层厚的纯Pt外壳和成分为(Pt_(1-x)Fe_x)_3Al的内核构成的双模孔隙且内部互通的包覆式结构。相比于传统燃料电池的氧还原反应催化剂Pt/C材料以及由Pt-Fe体系制备的Pt_(46)Fe_(54)/Pt合金,(Pt_(1-x)Fe_x)_3Al/Pt合金的比活性分别是Pt_(46)Fe_(54)/Pt合金、Pt/C比活性的1.21倍和2.69倍,其质量活性分别是Pt_(46)Fe_(54)/Pt和Pt/C的1.17倍和5.3倍。在催化稳定性方面,(Pt_(1-x)Fe_x)_3Al/Pt的电化学活性面积在10 000圈伏安循环后衰减到89%,然后趋于稳定,且循环40 000圈后其仍保留80%的电化学活性面积。由此可见,所制备的催化剂材料(Pt_(1-x)Fe_x)_3Al/Pt合金具有较高的催化活性及催化稳定性。

Aiming at improving the oxygen reduction catalytic activity and stability of the fuel cell cathode catalyst(Pt-Fe)/Pt alloy,Al element was introduced in the Pt-Fe alloy system,and the master alloy(Pt-Fe)Al was first obtained by smelting,then(Pt1-x Fe x)3Al/Pt alloy,the catalyst for oxygen reduction reaction of the fuel cell,was obtained by directional corrosion of NaOH solution.The structure,catalytic activity and stability of the prepared catalyst were studied in depth.The results indicated that the prepared(Pt1-x Fe x)3Al/Pt alloy bear an internally interconnected dual-mode pore structure composed of pure Pt shells with thickness of several atomic layers and a core of(Pt1-x Fe x)3Al.Compared with the traditional oxygen reduction catalysts Pt/C materials and the Pt46Fe54/Pt alloys,the prepared(Pt1-x Fe x)3Al/Pt alloy presented higher specific activity,which was1.21and2.69times of that of Pt46Fe54/Pt and Pt/C,and it also showed higher mass activity,which was1.17and5.3times of that of Pt46Fe54/Pt and Pt/C,respectively.In terms of catalytic stability,the electrochemical active area of(Pt1-x Fe x)3Al/Pt tended to be stabilized after decaying to89%at10000cycles of volt-amperes,and remained at80%after40000cycles.It can be concluded that the(Pt1-x Fe x)3Al/Pt alloy is endowed with favorable catalytic activity as well as satisfactory stability.