Fabrication of Pt-Co Alloy for Polymer Electrolyte Membrane Fuel Cell Cathode by Sequential Pulse Electrodeposition Method

초록

Polymer electrolyte membrane fuel cell(PEMFC) is considered to be a reliable power source for transportation vehicles, stationary and potable applications because it is eco-friendly and has low driving temperature and high energy efficiency. Conventional electrodes have been made by spraying Pt/C powder catalyst on carbon sheet. The cathode prepared by conventional method has relatively large inactive electrocatalytic surface area and high reactant gas transfer resistance because of its thick catalyst layer. Recently, studies on fabrication method of thin film cathode in variety of ways are in progress. A cathode prepared by pulse electrodeposition method can solve conventional problems because it has thin catalyst layer and its nanosized Pt particles are concentrated nearby electrode-electrolyte membrane interface. Meanwhile, several Pt-based alloy catalysts with various transition metals have been suggested to enhance the catalytic activity and to reduce the Pt loading amount. Among them, Pt-Co alloy catalyst is known as favorable catalyst because of its high durability and efficiency. In this study, Pt-Co alloy catalyst for PEMFC cathode is fabricated by sequential pulse electrodeposition method. At first, Pt seeds were predeposited with additive, Polyvinylpyrrolidone, followed by pulse electrodeposition of Pt-Co catalyst layer. Co content was controlled by NaCl concentration in plating bath. Electrochemical characteristics of alloy cathode were analyzed with Cyclic Voltammetry(CV) and surface morphology was observed with scanning electron microscopy(SEM) and Energy-dispersive X-ray spectroscopy(EDX). Cell performances of fabricated membrane electrode assemblies(MEAs) were measured. Electrode prepared by this novel method showed improved electrochemical surface area(ECSA) and cell performance with controlled Pt-Co particle size than former pulse electrodeposition method.