Tailoring the d-Band Center of Double-Perovskite LaCo<i>_x</i>Ni_1–<i>x</i>O₃ Nanorods for High Activity in Artificial N₂ Fixation

Abstract

The d-band center of a catalyst can be applied for the prediction of its catalytic activity, but the application of d-band theory for the electrocatalytic nitrogen reduction reaction (eNRR) has rarely been studied in perovskite materials. In this work, a series of double-perovskite LaCoxNi1–xO3 (LCNO) nanorods (NRs) were synthesized as models, where the d-band centers can be modulated by changing the stoichiometric ratios between Co and Ni elements. Experimentally, the LCNO-III NRs (x = 0.5) attained the highest faradic efficiency and NH3 yield rate among various LCNO NRs. This result matches well with the finding from theoretical calculations that LCNO-III has the most positive d-band center (εd = −0.96 eV vs Fermi level), thus confirming that LCNO-III shows the strongest adsorption ability for N2 molecules (adsorption energy value of −2.01 eV) for the subsequent N2 activation and reduction reactions. Therefore, this work proposes a general rule to adopt for developing novel catalysts (especially perovskite-based catalysts) for substantially increasing the eNRR activity by modulating the corresponding d-band centers.