DES-guided engineering of N-doped carbon for mussel-inspired, oxygen-vacancy-rich CeO2 nanozymes toward H2O2 sensing

Rational design of highly dispersed CeO 2 nanozymes with abundant oxygen vacancies is critical for achieving efficient and sensitive H 2 O 2 detection. Herein, we report a deep eutectic solvent (DES)-guided engineering strategy to construct an N-doped carbon (NC) framework integrated with mussel-inspired, uniformly dispersed CeO 2 nanoparticles. The DES acts both as a green C/N source and a self-templating medium, regulating heteroatom distribution and graphitization degree to yield a conductive carbon scaffold. Dopamine undergoes oxidative self-polymerization under mild alkaline conditions, and its catechol–amine functionalities strongly chelate Ce 3+ ions, directing homogeneous nucleation and suppressing nanoparticle aggregation. This molecularly engineered architecture produces an oxygen-vacancy-rich interface enriched with redox-active Ce 3+ /Ce 4+ sites, enabling rapid electron transfer and accelerated H 2 O 2 redox kinetics. The optimized CeO 2 /NC electrode delivers a diffusion-controlled amperometric response with dual linear ranges (0.05–60 and 60–300 μM), a low detection limit of 0.036 μM, and sensitivities of 94.8 and 49.3 mA M -1 cm -2 , respectively, surpassing most reported CeO 2 -based sensors. Furthermore, the sensor exhibits excellent selectivity and retains 89 % of its initial response after prolonged operation. This work provides a scalable, eco-friendly pathway for constructing bioinspired, oxygen-vacancy-rich nanozymes, offering broad applicability in advanced electrocatalytic sensing platforms.