Potassium‐Ion‐Assisted Regeneration of Active Cyano Groups in Carbon Nitride Nanoribbons: Visible‐Light‐Driven Photocatalytic Nitrogen Reduction

Abstract As a metal‐free nitrogen reduction reaction (NRR) photocatalyst, g‐C 3 N 4 is available from a scalable synthesis at low cost. Importantly, it can be readily functionalized to enhance photocatalytic activities. However, the use of g‐C 3 N 4 ‐based photocatalysts for the NRR has been questioned because of the elusive mechanism and the involvement of N defects. This work reports the synthesis of a g‐C 3 N 4 photocatalyst modified with cyano groups and intercalated K + ( m CNN), possessing extended visible‐light harvesting capacity and superior photocatalytic NRR activity (NH 3 yield: 3.42 mmol g −1 h −1 ). Experimental and theoretical studies suggest that the ‐C≡N in m CNN can be regenerated through a pathway analogous to Mars van Krevelen process with the aid of the intercalated K + . The results confirm that the regeneration of the cyano group not only enhances photocatalytic activity and sustains the catalytic cycle, but also stabilizes the photocatalyst.