Kinetics of light assisted catalytic reduction of 4-NP over Ag/PDA

Abstract

In this work, Ag nanoparticles as surface plasmon catalysts were prepared on polydopamine microspheres via in-situ reduction for catalytic 4-nitrophenol to 4-aminophenol in the presence of sodium borohydride. The kinetics of catalytic reaction under light and dark conditions was compared. It was found that the reaction rate constant under light condition was increased by 53.6% due to the surface plasmon resonance effect. The transition state theory was used to reveal the enhanced mechanism of catalytic conversion of 4-nitrophenol under light condition. It is demonstrated that the light-excited high-energy electrons are responsible for the shift of the adsorbed reactants to the excited state with higher potential energy, lowering the apparent activation energy from 47.2 kJ/mol to 32.6 kJ/mol and thereby enhancing the conversion of 4-nitrophenol to 4-aminophenol. This study offers a deep insight into the contribution of surface plasmon resonance to catalytic conversion of 4-nitrophenol by surface plasmon catalysts.