Masaru Kato, Naoto Kuwamura, Zhengwei Ma, Haruto Tsukamoto, Ken Tokunaga, Taichi Kobayashi, Takeshi Watanabe, Hiroyuki Setoyama, Hiroyuki Asakura, Kenji Ishii, Ichizo Yagi
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.