Can Plasmonic Effect Cause an Increase in the Catalytic Reduction of p-nitrophenol by Sodium Borohydride over Au Nanorods?

Abstract

The catalytic reduction of p-nitrophenol (4-NP) to 4-aminopyridine (4-AP) over Au nanoparticles can be increased by light illumination. Whether this is caused by the plasmonic effect remains unclear. The present research carried out a careful examination of the effects of light illumination and temperature on the catalytic conversion of 4-NP to 4-AP over Au nanorods. It was seen that light illumination has no effect on the apparent activation energy; this indicates that the catalytic mechanism is unchanged and the activity increase cannot be attributed to the effect of hot electrons. Based on the simulation of finite-difference time domain, the theoretical analysis also showed that plasmonic heating cannot play a major role. Thermographic mapping showed that the temperature of water solutions shows an increase under light illumination. By taking this temperature increase into consideration, the light-induced increase of the 4-NP to 4-AP conversion can agree well with dark catalysis, which cannot be attributed to the plasmonic effects of the Au nanorods.