Size-dependent AuNPs Plasmonic Activity for the Rational Design of Organic Reactions Catalyst

The rational design of plasmonic catalysts encompasses the manipulation of nanoparticle (NP) size. However, their effects on the overall performance in organic reactions are still poorly understood. Decreasing the metal-catalyst size in nanoclusters is an emerging direction for developing more efficient and cost-effective plasmonic systems. Despite some examples of successful organic reactions driven by plasmons excited on AuNPs of different sizes are reported, consistency in the effect of size on catalytic activity is lacking. Herein, we tested spherical AuNPs of size 3, 13, 22, 32, and 67 nm in common model organic reactions. In this work, we report the discovery of a size effect of commonly used AuNPs. Smaller AuNPs are proven to be multiply more efficient and stable against agglomeration in model reactions compared to larger AuNPs. Turnover frequency (TOF) and quantum yield (QY) were established to describe this phenomenon. Preliminary analysis showed the potential of smaller AuNPs in terms of cost, stability and technological appeal. This was because of a simple preparation procedure and reduced consumption of gold with maximum efficiency. For example, to achieve the same TOF and QY, 22-times more 67 nm AuNPs would be required compared with 3 nm AuNPs. This work suggests a tool for utilization of plasmon catalysis in organic synthesis by minimizing expenses due to energy and catalysts.