Unraveling the Path to Efficient Plasmon Catalysts: Investigating Size Effects of Gold Nanoparticles in Organic Reactions

Recently, light-to-chemical energy conversion achieved by excitation of plasmon resonance on noble metal nanoparticles (NPs) has become a useful tool in organic synthesis to substitute harsh reaction conditions and complex catalytic systems. The rational design of plasmonic catalysts encompasses the manipulation of NP size to regulate both surface characteristics and optical properties. Here, we tested 3, 13, 22, 32, and 67 nm spherical gold nanoparticles (AuNPs) in the common model organic reactions, namely, 4-nitrophenol reduction, dye degradation and alkoxyamine homolysis. Plasmon activity of AuNPs as a function of their size is evaluated by calculating turnover frequency and quantum yield. The smallest 3 nm AuNPs were the most efficient in all model reactions in 2-17 times compared to 67 nm AuNPs. These results suggest advances in the design of plasmonic catalytic systems that maximize the efficiency of organic reactions via minimizing expenses to energy and catalysts.