TiN@TiO2 Core-Shell Nanoparticles as Plasmon-Enhanced Photosensitizers: The Role of Hot Electron Injection

Metal-semiconductor heterostructures have attracted a lot of attention due to their ability to enhance photovoltaic and photocatalytic processes via plasmonic effects. Thus far, most of the proposed heterostructures are designed with noble metals and the potential of alternative plasmonic materials, such as titanium nitride (TiN), is not yet well explored. In this work, TiN@TiO2 core-shell nanoparticles (NPs) are synthesized and proposed as plasmon-enhanced photosensitizers for efficient singlet oxygen generation, with the focus on the role of hot electron injection. Excitation of dilute TiN@TiO2 NP dispersions by a 700 nm femtosecond-pulsed laser effectively converts ground-state oxygen into singlet oxygen (O-1(2)), driven primarily by hot electrons generated during plasmon decay at the TiN-TiO2 interface and injected into the TiO2 layer. Analytical calculations reveal the unique advantages of TiN-TiO2 heterostructures in hot-electron-mediated photocatalysis. Considering the chemical inertness and low cost of TiN, TiN@TiO2 NPs hold great potential as plasmonic photosensitizers for photodynamic therapy and other photocatalytic applications at red-to-near-infrared wavelengths.