TiN nanostructures have been shown to exhibit promising plasmonic properties and are potential candidates for various applications, including energy harvesting. However, these properties also show a strong dependence on the processing conditions which have been reported to affect metallicity of TiN. Herein, we report on layered TiN@Au-nanorods (NRs) nanostructures consisting of 20 nm TiN thin layer that is magnetron sputtered on Au-NRs of variable length, yielding different TiN/Au thickness ratios (R). While a 20 nm TiN layer sputtered on the same substrate on which the Au-NRs are grown shows a weak absorption peak in the near IR region, an intense and broad plasmonic peak that lies red from the transverse plasmonic peak of monolithic Au-NRs layer is observed for TiN@Au-NRs. The red-shift is shown to increase with increasing R, attaining 100 nm for R = 1, together with an intense tail in the IR region. These results are interpreted in terms of a strong coupling between TiN and Au that drastically affects the plasmonic behavior of the structure. The results are contrasted with those on Pd@Au-NRs where only a slight blue-shift of few nanometers from the Au peak is observed. Potential applications of the TiN@Au-NRs are mainly in energy harvesting such as water splitting and photocatalysis using electromagnetic radiation in a broad wavelength range, as well as medical applications. Pd@Au-NRs may be used as electrocatalysts with plasmonic enhancement, e.g., for the hydrogen evolution reaction.
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