Adsorption Structure of Protonated Melamine on Single Crystal Pt Surfaces

Pt electrodes modified with melamine significantly activates the oxygen reduction reaction (ORR). A comprehensive understanding of the activation mechanism by melamine is essential for the identification of organic additives that can further activate the ORR. Herein, we investigated the coadsorption structure of water with melamine on single-crystal Pt surfaces using Infrared spectroscopy under ultrahigh vacuum conditions. Protonated melamine was dosed on the Pt surfaces using the electrospray method to model the adsorption structure under acidic conditions. The orientation of the adsorbed melamine depends on the atomic arrangement of the Pt substrate as well as the coexistence of water. The melamine-modified Pt electrode obtained by the electrospray method was transferred to an electrochemical cell, and its ORR activity was evaluated. The kinetic current density of the ORR on the transferred Pt was comparable to that obtained by the conventional wetting modification method. This result indicates that the adsorption structure of melamine prepared by the electrospray method is similar to that obtained by the wetting modification.