Amorphization activated FeB2 porous nanosheets enable efficient electrocatalytic N2 fixation

Designing active, robust and cost-effective catalysts for the nitrogen reduction reaction (NRR) is of paramount significance for sustainable electrochemical NH3 synthesis. Transition-metal diborides (TMB2) have been recently theoretically predicted to be a new class of potential NRR catalysts, but direct experimental evidence is still lacking. Herein, we present the first experimental demonstration that amorphous FeB2 porous nanosheets (a-FeB2 PNSs) could be a highly efficient NRR catalyst, which exhibited an NH3 yield of 39.8 mu g h(-1) mg(-1) (-0.3 V) and a Faradaic efficiency of 16.7% (-0.2 V), significantly outperforming their crystalline counterpart and most of existing NRR catalysts. First-principle calculations unveiled that the amorphization could induce the upraised d-band center of a-FeB2 to boost d-2 pi* coupling between the active Fe site and *N2H intermediate, resulting in enhanced *N2H stabilization and reduced reaction barrier. Out study may facilitate the development and understanding of earth-abundant TMB2-based catalysts for electrocatalytic N-2 fixation. (C) 2020 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.

Automated summary

This study demonstrates experimentally that amorphous FeB2 porous nanosheets can serve as a highly efficient catalyst for the nitrogen reduction reaction, outperforming crystalline counterparts and existing catalysts. Amorphization of FeB2 enhances *N2H stabilization and reduces reaction barrier, showing promise for the development of earth-abundant TMB2-based catalysts for electrocatalytic N-2 fixation.