Low curvature combined with high amorphization improves SERS sensitivity of semiconducting Rh-Se mesoporous nanospheres toward non-adsorbing resistant pollutants.

Amorphous metal-selenium (M-Se) alloys hold promise for applications such as catalysis, electronics, and surface-enhanced Raman spectroscopy (SERS) sensing due to their surface reactivity, isotropic properties, and tunable bandgap. However, controlling the synthesis of nanostructured noble-metal-based M-Se materials is difficult, as the strong metallic bonding and low chemical reactivity of noble metals hinder homogeneous selenization. Here we show a one-step micellar self-assembly reduction method to produce amorphous semiconducting Rh-Se mesoporous nanospheres (a-Rh-Se MNs). We systematically investigate how composition, surface curvature, and crystallinity affect SERS performance. a-Rh-Se MNs with low curvature and high amorphization achieve enhanced sensitivity toward typically non-adsorbing, low-polarizability analytes, including hexachlorobenzene, anthracene, and polytetrafluoroethylene microplastics (even in wastewater). Combined experimental and theoretical analyses reveal that co-modulating curvature and amorphization tunes key electronic descriptors (e.g., d-band center and work function), thereby promoting resonant charge transfer. This finding overturns the conventional paradigm that prioritizes high-surface-area substrates. Our work establishes mesostructured a-Rh-Se for SERS applications and provides insights into M-Se surface chemistry for designing advanced SERS materials.