Noble‐Metal‐Free Plasmonic Spectral Filtering of Photonic Reflection in SiO 2 –Transition Metal Nitride Core–Satellite Particles for Programmable Structural Color

ABSTRACT Structural color materials combining photonic and plasmonic effects offer tunable optical functionalities, but most rely on noble metals. Here, a noble‐metal‐free platform based on SiO 2 –metal nitride (TiN and HfN) core–satellite particles is reported, in which photonic reflection is spectrally filtered by the localized surface plasmon resonance (LSPR) of nitride nanoparticles assembled on monodisperse SiO 2 photonic building blocks. The SiO 2 core size governs the photonic response, and the reflection is selectively attenuated in the spectral window set by the satellite LSPR. Contrasting TiN (LSPR at 830 nm) with HfN (LSPR at 630 nm) shows that the position of this attenuation follows the chosen resonance. The ratio of long‐ to short‐wavelength reflection intensity, constant for bare SiO 2 films, decreases systematically in both nitride systems, establishing that the attenuation is wavelength selective rather than uniform. Increasing the core diameter shifts the photonic peak by 287–312 nm, whereas changing the nitride species shifts it by only 7.2 nm. Satellite loading, compared at two levels by X‐ray photoelectron spectroscopy, changes powder color qualitatively; its effect on film attenuation remains to be quantified. Together with the reported ZrN system, the three nitrides enlarge the sampled chromaticity region 5.4‐fold while reducing angular dependence.