Efficient Photocatalytic Hydrogen Production Using In‐Situ Polymerized Gold Nanocluster Assemblies

Abstract Gold nanoparticles (NPs) are widely recognized as co‐catalysts in semiconductor photocatalysis for enhancing hydrogen production efficiency, but they are often overlooked as primary catalysts due to the rapid recombination of excited‐state electrons. This study presents an innovative gold‐based photocatalyst design utilizing an in situ dopamine polymerization‐guided assembly approach for efficient H 2 generation via water splitting. By employing gold superclusters (AuSCs; ≈100 nm) instead of ultra‐small gold nanoclusters (AuNCs; ≈2 nm) before polymerization, unique nanodisk‐like 3D superstructures consisting of agglomerated 2D polydopamine (PDA) nanosheets with a high percentage of uniformly embedded AuNCs are created that exhibit enhanced metallic character post‐polymerization. The thin PDA layer between adjacent AuNCs functions as an efficient electron transport medium, directing excited‐state electrons toward the surface and minimizing recombination. Notably, the AuSCs@PDA structure shows the largest potential difference (26.0 mV) compared to AuSCs (≈18.4 mV) and PDA NPs (≈14.6 mV), indicating a higher population of accumulated photo‐generated carriers. As a result, AuSCs@PDA achieves a higher photocurrent density, improved photostability, and lower charge transfer resistance than PDA NPs, AuSCs, or AuNCs@PDA, with the highest hydrogen evolution rate of 3.20 mmol g −1 h −1 . This work highlights a promising in situ polymerization strategy for enhancing photocatalytic hydrogen generation with metal nanoclusters.