Improvement of fuel cell catalyst performance through zirconia protective layer coating by atomic layer deposition

Abstract In this study, the performance of the cathode catalyst of polymer electrolyte membrane fuel cells is improved by the atomic layer deposition (ALD) of a protective layer. An atomic layer-scale zirconia protective layer is coated on the platinum catalyst for surface treatment. The results indicate that a very thin layer deposition with two ALD cycles or less is required to minimize the deterioration of the activity of the catalyst. Further, it is also confirmed that the catalyst aggregation can be effectively suppressed by its encapsulation with the protective layer through several ALD cycles from the analysis of the electrochemical surface area by cyclic voltammetry and the change in the catalyst particle size. According to the results, even two ALD cycles, which provide less than one atom layer, has decreased the deterioration rate to one-fourth of that of the untreated catalyst, with a minor decrease in the fuel cell power. In addition, the I–V data and impedance spectroscopy confirms that the overall stability of the membrane electrode assembly is improved by the ALD treatment. Thus, the ALD of a protective layer is considered to be a very promising strategy to improve the stability and performance of fuel cell catalysts.