ELECTRODEPOSITION OF CATALYTIC METALS USING PULSED ELECTRIC FIELDS

摘要

A gas diffusion electrode (200) for a proton exchange membrane fuel cell isprepared by electrodeposition of a catalytic metal innanocrystalline form on a substrate (202) by contacting an electricallyconductive substrate (202) and a counterelectrode (216) with a platingbath (214) containing ions of a metal to be deposited on the substrate (202)and passing a pulsed electric current between the substrate andthe counterelectrode (216) having pulses that are cathodic with respect to thesubstrate (202) and have a short on-time and/or a short dutycycle with a frequency from about 10 hertz to about 5000 hertz. In a preferredembodiment the electric current is a modulated reversingelectric current having pulses that are cathodic with respect to the substrate(202) and pulses that are anodic with respect to the substrate(202), the cathodic pulses having a short on-time and/or short duty cycle, thecharge transfer ratio of the cathodic pulses to the anodicpulses being greater than one, and the frequency of the pulses ranging fromabout 0.5 hertz to about 5 kilohertz.