Electrocatalytic N 2 O Reduction Catalyzed by Carbon-Supported Metal–Bis(diaryldithiolene) Complexes in Water

We report the electrocatalytic nitrous oxide reduction reaction (N 2 ORR) activity of iron, cobalt, and nickel complexes with a noninnocent ligand of diaryldithiolene in alkaline media. At −0.3 V vs RHE, the cobalt complex on a carbon black of Ketjenblack (CoL 2 /KB) showed the highest N 2 ORR activity with a turnover frequency (TOF) of (3.6 ± 0.5) × 10 2 h –1, 98% Faradaic efficiency to N 2 and almost no degradation over 24 h. At −0.6 V vs RHE, CoL 2 /KB exhibited a TOF of (8.6 ± 1.1) × 10 2 h –1, surpassing those of previously reported molecular-based electrocatalysts for the N 2 ORR. X-ray absorption spectroscopy and density functional theory calculations revealed that the square-planar Co I –S 4 coordination environment with high Co–S covalency serves as the active site with high N 2 ORR activity. This work will guide us in designing and developing precious metal-free electrocatalysts with high N 2 ORR activity.