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

Abstract

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.