Determining Plasmonic Hot Electrons and Photothermal Effects during H2 Evolution with TiN-Pt Nanohybrids

Hydrogen storage in chemical compounds is a promising strategy to enable lightweight, high-density, and safe hydrogen technologies. However, the hydrogen release rate from these chemicals is limited by the intrinsic catalytic activity of metal catalysts, which can be enhanced by light irradiation. Here, nanohybrids including a core of plasmonic TiN and multiple Pt nanocrystal catalytic centers are assembled and show, under resonant conditions at 700 nm, hot electron-driven hydrogen evolution from ammonia borane at an apparent quantum yield of 120%. It is also demonstrated that solar irradiation enhances the activity of TiN-Pt nanohybrids by one order of magnitude through two synergistic mechanisms: hot electrons and collective-heating contributions. Using the microscopic calculation of the photo-induced temperature around a single nanocrystal, it is revealed that the collective plasmonic heating regime dominates the macroscopic temperature distribution in the system. The presented data show that plasmonic hot electrons and photothermal heating can be used in synergy to trigger hydrogen release from ammonia borane on demand, providing a general strategy for greatly enhancing the activity of metal catalysts in the dark.