Bioinspired Mo tape-porphyrin as an efficient and selective electrocatalyst for ammonia synthesis

Abstract

The efficient N2 fixation to NH3 in the biological system benefits from the electron transfer and catalysis of nitrogenase under ambient conditions, where N2 reduction occurs at Mo and Fe sites. Herein, the electrochemical N2 reduction reaction (NRR) on bioinspired Mo tape-porphyrin (denoted as MoP) has been systematically investigated on the basis of first-principles calculations. The anchoring of Mo atom to the biomolecular porphyrin changes the charge distribution and activates more delocalized π electrons in the fully conjugated π-system. The results reveal that N2 favourably coordinated with Mo atom in end-on configuration and the electronic and magnetic properties of MoP are changed. The most promising reaction pathway for NRR on MoP is via the distal route with overpotential of 0.22 V. The excellent conductivity, highly localized and spin-polarized Mo-4d states of MoP endow it preeminent NRR activity at room temperature. Furthermore, the competitive 2-electron hydrogen evolution reaction (HER) is sufficiently mitigated and circumvented during the NRR progress. The high symmetry of MoP enables a simple synthetic pathway. Our findings provide a ingenious strategy for catalytic N2 reduction and a practical manufacturing method for designing efficient and selective electrocatalyst.