Effect of External Electric Field on Nitrogen Activation on a Trimetal Cluster

Abstract

AbstractEfficient nitrogen (N2) fixation and activation under mild conditions are crucial for modern society. External electric fields (Felectric) can significantly affect N2 activation. In this work, the effect of Felectric on N2 activation by Nb3 clusters supported in a sumanene bowl was studied by density functional theory calculations. Four typical systems at different stages of N−N activation were studied, including two intermediates and two transition states. The impact of Felectric on various properties related to N2 activation was investigated, including the N−N bond length, overlap population density of states (OPDOS), total energy of the system, adsorption energy of N2, decomposition of energy changes, and electron transfer. The sumanene not only functions as a support and protective substrate, but also serves as a donor or acceptor under different Felectric conditions. Negative Felectric is beneficial to N−N bond activation because it promotes electron transfer to the N−N region and improves the d–π* orbital hybridization between metals and N2 in the activation process. Positive Felectric improves d–π* orbital hybridization only when the N−N is nearly dissociated. The microscopic mechanism of Felectric′s effects provides insight into N2 activation and theoretical guidance for the design of catalytic reaction conditions for nitrogen reduction reactions (NRR).