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. Surface-enhanced Raman spectroscopy can be used to detect hard-to-measure pollutants, but amorphous nanomaterials pose challenges in terms of morphology and composition control. Here, the authors illustrate the interplay of curvature and amorphization in semiconducting mesoporous Rh–Se nanospheres for maximizing SERS activity.