Synergistic phase and defect engineering in nitrogen-doped MoS2/Co9S8/CdS nanozyme for sensitive hydroquinone monitoring

Hydroquinone (HQ), a toxic and persistent pollutant, requires sensitive and reliable detection strategies beyond conventional chromatographic or electrochemical methods. Here, we report a nitrogen-doped 1T/2H-MoS 2 /Co 9 S 8 /CdS ternary nanozyme synthesized via a urea-mediated hydrothermal route. Urea acts as a bifunctional agent, simultaneously stabilizing the metastable 1T-MoS 2 phase and introducing sulfur vacancies through nitrogen substitution. This defect-phase engineering optimizes the electronic structure, as evidenced by a 0.2 eV positive shift in Mo 3d binding energy, and exposes coordinatively unsaturated Mo sites that accelerate hydroxyl radical (•OH) generation. Coupled with the redox activity of Co 9 S 8 and the adsorption capability of CdS, the composite exhibits markedly enhanced peroxidase-like activity, characterized by higher catalytic turnover and stronger H 2 O 2 affinity compared to undoped systems. A colorimetric sensor constructed from this platform enabled ultrasensitive HQ detection with a detection limit of 0.29 μM and excellent recoveries (100.18% to 101.64%) in spiked real water samples, while maintaining strong selectivity and operational stability. This work establishes a nitrogen-doping-driven paradigm for phase stabilization and defect regulation, offering a generalizable strategy for designing high-performance nanozymes for environmental monitoring.