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The recent development of anion exchange membranes (AEMs) has increased the potential of anion exchange membrane fuel cells (AEMFCs). Although highly active electrocatalysts for specific reactions have been successfully developed by placing the most importance on the fuel species, only a few studies have focused on OH ad (hydroxyl adsorbed species), which is known to be a common reactive species in alkaline environments. In this study, highly oxophilic CeO 2 was selected as a surface modifier for a Pt electrode. We first applied in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy to ionomer-coated Pt and CeO 2 -modified Pt surfaces for clarifying the adsorption behavior of OH ad . As a result, a distinct change in adsorption behavior of OH ad was confirmed in blank KOH solution. These peculiar characteristics were applicable to various electrochemical oxidation reactions. During the ammonia oxidation reaction, the acceleration of the formation of NO ad species was observed in CeO 2 -modified Pt, suggesting the enhancement of OH adsorption. Furthermore, the degree of activity enhancement by CeO 2 addition was investigated for the CO oxidation reaction, methanol oxidation reaction, and ethanol oxidation reaction. Under basic conditions, each of these reactions exhibited distinct activity enhancement. In contrast, under acidic conditions, the promoting effect on these reactions was not observed. These results strongly indicate the potential of our catalyst design strategy and the importance of OH ad species as reactive species in alkaline environments.
Katayama et al. (Thu,) studied this question.