Plasmonic heating has been utilized in many applications, including photocatalysis, photothermal therapy, and photocuring. However, the heat dissipation process of plasmonic nanoparticles (NPs) and the surrounding matrix is complex. How high the temperature of the matrix that surrounds the plasmonic NPs, such as the catalyst and substrate, can reach is unclear. Herein, we study the dissipation of plasmonic heat generated by resonantly excited gold (Au) NPs dispersed on a P25 TiO