Pyridine Homopolymers Axial Ligation on Cobaloxime for Efficient Hydrogen Production

Abstract Photocatalytic hydrogen (H ₂ ) production by mimicking natural light‐harvesting complexes offers a sustainable route to solar fuel generation. Here, a pyridine‐based homopolymer‐chelated cobalt complex is reported as an efficient and stable catalyst for H ₂ production via water splitting. This study introduces a series of reversible addition‐fragmentation chain transfer (RAFT)synthesized homopolymers with pyridine moieties that axially coordinate to a cobaloxime core. This study investigates the effect of linker position (meta vs para) on proton reduction affinity in cobaloxime catalysts. The catalysts demonstrate potential for H ₂ generation under visible light, with repetitive runs and maintain morphological integrity. Both photochemical and electrochemical H ₂ production results align with and reinforce the catalytic efficacy of the system, achieving an H ₂ generation rate of up to 42.99 mmol h ⁻¹ g ⁻¹ for P4VP‐Co and 29.58 mmol h ⁻¹ g ⁻¹ for P3MP‐Co in a neutral aqueous solution with a sacrificial electron donor. The superior electrochemical activity of P4VP‐Co over P3MP‐Co is due to the higher electroactive surface area in P4VP‐Co. The density functional thoery (DFT) studies reveal the active site for the reaction and examine the role of homopolymers in enhancing H ₂ evolution reaction. This study presents a unique example of a cobaloxime core chelated with electron‐donating polymers for renewable energy conversion applications.