Building Oxime-Ni²⁺ Complex on Polymeric Carbon Nitride: Molecular-Level Design of Highly Efficient Hydrogen Generation Photocatalysts

We report an effective strategy to in situ construct the oxime-Ni²⁺ complex unit on polymeric carbon nitride (PCN) as a molecular catalyst for the highly efficient hydrogen evolution reaction (HER). The PCN was functionalized with oxime groups that allowed for immobilizing Ni²⁺ to form oxime-Ni²⁺ complex units on the PCN surface with uniform distribution. The electrochemical characterizations reveal that these oxime-Ni²⁺ units can effectively capture photogenerated electrons from PCN and serve as active catalytic sites for proton reduction. Notably, the oxime-Ni²⁺ enriched PCN showed even higher activities for photocatalytic hydrogen evolution than the Pt-loaded PCN. This work provides a new way to synthesize low-cost photocatalysts with surface grafting of noble-metal-free molecular HER catalysts for efficient light-driven hydrogen generation.