Breaking linear scaling relationships in NRR with hydrogen bonding in confined space: A case study of g-C3N4 covered Ru(001) system

The electrochemical nitrogen reduction reaction (NRR) is a very efficient method for sustainable NH3 production under mild conditions, but it requires effective catalysts to expedite the NRR kinetics. However, the linear scaling relationships between the energies of elementary steps in NRR severely limit the rates of thermally catalysis reactions. Using density functional theory calculations, we demonstrate that these scaling relations can be circumvented by introducing hydrogen bonding and confinement field in g-C3N4/Ru(Rh) catalysis. Specially, the adsorption strength of key intermediate *N2H can be enhanced on the g-C3N4/Ru(Rh) own to the formation of H···N hydrogen bonding, while the adsorption of N2 is weakened due to the steric confinement field of the covered g-C3N4, resulting a significantly decrease of the energy barrier for the potential-limiting step in g-C3N4/Ru(Rh) system compared that in pure Ru(Rh) surface. Moreover, the hydrogen bonding strength between g-C3N4 and *NxHy increases with increasing of H atoms, which lower the energy barrier for the following protonation steps. Our results provide guidance for optimizing catalysts for application with hydrogen bonding and steric confinement.