Investigations of a platinum–ruthenium/carbon nanotube catalyst formed by a two-step spontaneous deposition method

Platinum (Pt) is a popular catalyst for hydrogen oxidation on the anode side of solid polymer fuel cells (SPFC). It increases the electrode activity, which catalyzes the reaction of the fuel cell. There are two methods commonly used to produce hydrogen for SPFC: fuel reforming and methanol decomposition. Both of these methods produce carbon monoxide, which is considered to be a poison for SPFC because it deactivates Pt easily. Adding ruthenium (Ru) to a Pt catalyst is an efficient way to improve the inhibition of carbon monoxide (CO) formation and reduce the Pt loading requirement.This study introduces a method to synthesize a bimetal catalyst that is suitable for SPFC. To improve the electrocatalyst activity, a new process with two spontaneous deposition steps is adopted. In the first step, Ru is deposited on the wall of carbon nanotubes (CNTs) to obtain Ru/CNTs. Pt is then added in the second deposition step to form Pt–Ru/CNTs. The morphology and microstructure of catalysts are characterized with microscopes, and the performance of membrane electrode assembly is evaluated by cyclic voltammetry method. Experimental results have proved that even with a lower Pt loading, this home-brewed bimetal catalyst performs a compatible electrocatalytic activity, and is capable of resisting attack from CO when a syngas (H2 + 20 ppm CO) is provided.

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► A two-step spontaneous deposition method for preparing a bimetal catalyst with platinum and ruthenium on carbon nanotubes is proposted.
► It is possible to obtain higher Ru and Pt loadings by repeating the spontaneous deposition procedure consecutively.
► When Pt–Ru/CNTs are used as catalysts on the anode side of a PEM fuel cell, even with lower Pt loading (25% decrease) and 20 ppm, CO existed in the H2 fuel, and the oxidization function of the catalyst was still maintained consistently.
► This type of electrocatalyst is suitable for fuel cells running on reformat, and is able to reduce the cost and improve the efficiency for SPFC.