Ultrasensitive chemical detection using amorphous MoS ₂ decorated NiS core–shell structures on nickel foam

Abstract Surface‐enhanced Raman spectroscopy (SERS) is a highly sensitive analytical technique extensively employed in bioanalysis, chemical sensing, and environmental monitoring. Transition metal sulfides, such as molybdenum disulfide (MoS 2 ) and nickel sulfide (NiS), exhibit significant potential as SERS substrates, but their performance is often constrained by limited exposure of active sites and inefficient charge transfer, especially in complex sample matrices. In this study, we address these challenges by employing a hydrothermal strategy to synthesize amorphous MoS 2 nanoshells in an urchin‐like MoS 2 ‐NiS core–shell structure grown on nickel foam (A‐MoS 2 /NiS/NF). Further enhancement was realized via neodymium doping, yielding the x Nd‐A‐MoS 2 /NiS/NF. The optimized 0.015Nd‐A‐MoS 2 /NiS/NF substrate demonstrated a high enhancement factor (EF) of 1.56 × 10 9 for methylene blue (MB) and a detection limit as low as 10 –12 M. Density functional theory (DFT) calculations indicate that neodymium doping substantially increases the density of states (DOS) at the Fermi level, thereby enhancing charge transfer and amplifying the Raman signal. The 0.015Nd‐A‐MoS 2 /NiS/NF substrate also exhibited high sensitivity in detecting melamine in real milk samples, confirming its practical applicability. By effectively addressing the challenges of active site exposure and charge transfer in MoS 2 and NiS‐based SERS substrates, this work significantly advances the practical application of transition metal sulfides in SERS. This development paves the way for the broader deployment of these materials in environmental and bioanalytical detection, presenting a promising strategy for improving the sensitivity and versatility of SERS‐based sensors.