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 H2 generation via water splitting. By employing gold superclusters (AuSCs; approximate to 100 nm) instead of ultra-small gold nanoclusters (AuNCs; approximate to 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 (approximate to 18.4 mV) and PDA NPs (approximate to 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.