Tailoring the d-Band Center of Double-Perovskite LaCo x Ni 1- x O 3 Nanorods for High Activity in Artificial N 2 Fixation.

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 LaCo _x Ni _{1- x} O ₃ (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 NH ₃ 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 (ε _d = -0.96 eV vs Fermi level), thus confirming that LCNO-III shows the strongest adsorption ability for N ₂ molecules (adsorption energy value of -2.01 eV) for the subsequent N ₂ 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.