One melamine molecule per unit cell was also located on each side of the Pt(111) surface in order to represent the melamine-modified surface. As detailed in Section S7 of SI, preliminary calculations using finite-temperature MD simulations with MLFF and conventional FP calculations using harmonic oscillator models indicated that, under the cathode potential of PEMFCs and in water, melamine adsorbs differently compared to the structure found on Pt(111) in a vacuum. As shown in Fig. Further details of the model preparations are provided in Section S8 of SI.