Electronic modulation of single and dual-atom Ru catalysts for N2 activation by nanosheet supports

Abstract

Supported metal catalysts exhibit excellent catalytic activity in N₂ activation and serve as crucial materials for NN triple bond cleavage. However, the mechanism of supports in facilitating this bond cleavage and its relationship with the N₂ activation energy barrier (E_a) at the atomic and electronic level remain unclear. In this study, we employed density functional theory (DFT) calculations to investigate the structures, energetics, orbital interactions, and electron transfer during N₂ activation on Ru single-atom catalysts (Ru-SACs) with and without supports. From the perspective of catalysts, we demonstrate that catalysts with electron-withdrawing supports are more conducive to N₂ activation. From the perspective of mechanism, the electronic metal–support interaction (EMSI) modulates the E_a of the N₂ activation on supported Ru-SACs by regulating the electron transfer (ET) between the Ru atom and supports. Furthermore, the synergistic effect of EMSI and N₂ adsorption controls the energy separation (E_d) between the d-band center (ε_d) and the Fermi level (E_f) of the Ru 4d orbits, thereby modulating the E_a of N₂ activation. The ET and E_d are two potentially important catalyst descriptors affecting the E_a value. Some key findings about the effect of the support in the Ru-SAC systems are rather consistent with those in the case of dual Ru and Os atom catalysts, which have much lower E_a. As a whole, this report provides deeper insights into the effect of the support on single and dual atom metal catalysts for N₂ activation, and can help design better ammonia-synthesis catalysts in the future.