The photothermal nonlinearity in plasmon-assisted photocatalysis

Abstract

We show that the temperature rise in large ensembles of metal nanoparticles under intense illumination is dominated by the temperature dependence of the thermal conductivity of the host, rather than by the optical properties of the metal or the host. This dependence typically causes the temperature rise to become sublinear, with this photothermal nonlinear effect becoming unusually strong, reaching even several tens of percent. We then show that this can explain experimental observations in several recent plasmon-assisted photocatalysis experiments. This shows that any claim for dominance of non-thermal electrons in plasmon-assisted photocatalysis must account for this photothermal nonlinear mechanism