Ag Nanoparticles for Plasmon-Driven Conversion of pATP to DMAB under LED Excitation

The photocatalytic conversion of para-aminothiophenol (pATP) in 4,4'-dimercaptoazobenzene (DMAB) on the surface of noble metal nanoparticles has played a fundamental role in understanding plasmon-driven catalytic reactions. The conversion of pATP into DMAB depends on factors like plasmonic material, pATP concentration, irradiation conditions, temperature, and environment. However, the effects of surface coverage, irradiation wavelength, and temperature remain largely unexplored. Therefore, in this study, we aim to systematically investigate the plasmon-driven photocatalytic conversion of pATP into DMAB on the surface of spherical silver nanoparticles (Ag NPs) under LED irradiation. Surface functionalization with pATP at concentrations between 4 and 12 μM revealed that optimal photocatalytic efficiency occurs at 9 μM for the proposed catalytic system. The successful formation of DMAB was also confirmed by density functional theory (DFT) simulations. Next, we proved that the incubation temperature of pATP with the NPs plays a significant role in the conversion efficiency; thus, controlled incubation is required for reproducibility. Furthermore, by exploring the influence of the irradiation wavelength and the thermoplasmonic effect, a three-phase mechanism for the plasmon-driven catalysis of pATP into DMAB under continuous LED irradiation at the LSPR-resonant wavelength was identified. This mechanism highlights the roles of molecular reorientation, hot charge carrier generation, localized heating, and reaction saturation, providing valuable insights into the dynamics of the photocatalytic process. Our study seeks to advance the understanding of plasmon-driven catalysis and provide insights into optimizing nanoparticle-based catalytic systems.