Reducing the photocatalysis induced by hot electrons of plasmonic nanoparticles due to tradeoff of photothermal heating.

Silver nanotetrahedron (AgNT) two-dimensional arrays on a glass substrate generate nonthermal hot electrons, which induced photocatalytic oxidation of 4,4-dimercaptoazobenzene (DMAB) adsorbed onto its surface. The rate of the photocatalytic oxidation of DMAB is found to decrease upon increasing the intensity of the excitation light, unlike traditional photocatalysis reactions. The amount of 4-nitrothiophenol (4-NTP) resulting from the photocatalytic oxidation of DMAB is lower than expected, suggesting the partial desorption of DMAB or 4-NTP molecules from the surface of the AgNTs. However, the hot electrons remaining from the photocatalysis reaction thermalize and transfer their energy to the nanoparticle lattices, generating heat. The photothermal heat is sufficient to dissociate the Ag-S bond causing desorption of both DMAB and 4-NTP.