New insights into electrocatalysis based on plasmon resonance for the real-time monitoring of catalytic events on single gold nanorods.

Gold nanoparticles (GNPs) have been widely applied in industrial catalysis and electrocatalysis. Owing to their wide variety of shapes, sizes, and compositions, a range of different catalytic properties is possible. Thus, it is important to monitor catalytic processes and their mechanisms on single GNP surfaces to avoid averaging effects in bulk systems. Therefore, a novel method based on dark-field scattering spectroscopy was developed to monitor, in real-time, the electrocatalytic oxidation of hydrogen peroxide on a single gold nanoparticle surface. The catalytic mechanism was revealed via the plasmon resonance scattering spectral shift of single gold nanorod with the elimination of bulk effect. Moreover, we found that the presence of chloride ions could block the catalytic activity of nanorods for the oxidation of H2O2. Most importantly, it was discovered that individual nanoparticles have variable properties with different spectra shifts during the catalytic process. The obtained optical signals from individual nanorods not only offer versatile information regarding the reaction but also improve the understanding of electrochemistry and the catalysis mechanism of single nanoparticles.