First-principles study of two-dimensional material Cr₂B₂ as catalyst for electrochemical nitrogen reduction reaction

Electrochemical nitrogen reduction reaction (NRR) is becoming increasingly promising alternatively to the traditional Haber-Bosch process but developing efficient electrocatalysts is still a challenge. In this job, we searched that the catalytic performance of Cr₂B₂ for NRR by way of density functional theory (DFT) calculations. We mainly screened out four favorable N₂ adsorbed structures, including N₂ adsorption on the B-B bonds, Cr-B bonds, top site of B and Cr atom. It was found that the largest adsorption energy was −1.235 eV when N₂ was adsorbed on the Cr-B bond in a side-on structure, and has a better excellent NRR catalytic activity with the limiting potential is 0.29 V. The catalytic activity of all structures was better in the alternating mechanism of nitrogen reduction reaction. As the antibonding orbitals approach the Fermi level, the number of electrons in the antibonding orbitals increases. The limiting potential of T_Cr_end can also be reduced from 0.88 V to 0.35 V by N–N bond breaking after the second hydrogen, which contribute to the greater NRR performance. We hope that this research will offer a viable strategy for the design of NRR catalysts, and offer a new way of thinking for MBene as a catalyst for NRR.