Bound States in the Continuum for Hot Electron Generation in Integrated-Resonant Metasurfaces

Hydrogen, as a type of sustainable energy, has the potential to facilitate the achievement of carbon neutrality by replacing fossil fuels. Conventional plasmonic metal nanostructures as efficient photocatalysts have been employed to generate hot electrons, thus further facilitating hydrogen production. However, such structures only contain a single resonance mode, which restricts field enhancement and further limits the hot electron generation rate. In this work, we introduce a novel plasmonic integrated-resonant unit (IRU) that combines local and nonlocal modes and can excite a strong interaction between the modes to generate a quasi-bound state in the continuum (quasi-BIC) regime for enhancing the electric field. As a result, we achieved a maximum field enhancement factor of 168.5 at the excitation wavelength of 734 nm under period P = 750 nm. Correspondingly, the generation rate of hot electrons can exceed 6 × 10¹⁹ s⁻¹, which is 2 orders of magnitude greater than that of the structure without IRU property. This research provides a strategic framework for the development of plasmonic nanostructures to enhance hot electron generation efficiency and photocatalytic activity, which is pivotal for the advancement of clean energy and the realization of a decarbonized future. © 2024 American Chemical Society.