To Molecularly Block Hydrogen Evolution Sites of Molybdenum Disulfide toward Improved Catalytic Performance for Electrochemical Nitrogen Reduction.

2H-molybdenum disulfide (2H-MoS 2 ) represents a classical catalyst for the electrochemical N 2 reduction reaction (NRR) in water that offers a promising technology toward sustainable production of NH 3 driven by renewable energy. While the catalytic efficiency is severely limited by a simultaneous and competing H 2 evolution reaction (HER). Herein, it is proposed that the S edge of 2H-MoS 2 , which is known as main sites to afford HER, is intentionally covered by cobalt phthalocyanine (CoPc) molecules through axial coordination. While the Mo sites with S vacancies at 2H-MoS 2 edge is recognized as highly NRR active, and can keep structurally intact in the CoPc based modification. The resultant composite thus exhibits high NRR performance with Faradic efficiency and NH 3 yields increase by fourfold and twofold, respectively, comparing to pristine 2H-MoS 2 . These findings provide a deep insight into the mechanism of 2H-MoS 2 based NRR catalysis and suggest an efficient molecular modification strategy to promote NRR in water.