Ultrasensitive chemiluminescence detection based on titanium-doped spinel-structured nanoparticles with abundant oxygen vacancies

We successfully synthesized spinel-structured ternary nanocatalyst Ti-Co₃O₄/Fe₃O₄ nanoparticles (NPs) for the first time. Ti-Co₃O₄/Fe₃O₄ NPs exhibited superior catalytic performance compared to the synthesized binary catalysts Co₃O₄/Fe₃O₄. Moreover, Ti-Co₃O₄/Fe₃O₄ NPs can enhance the chemiluminescence (CL) intensity of the luminol/H₂O₂ system by over 3800-fold, attributed to the high density of oxygen vacancies (OVs) within the structure. OVs contribute to electron delocalization, improve conductivity, and are recognized as crucial active sites in the catalytic decomposition of H₂O₂. Based on the inhibitory effect of L-ascorbic acid (AA) on the luminol/H₂O₂ CL system, we developed a sensitive, rapid, effective, and highly selective AA CL assay with a linear range of 0.1 μmol/L to 100 μmol/L and a limit of detection (LOD, S/N = 3) of 0.044 μmol/L. The method was successfully applied to quantify AA in vitamin C tablets with recoveries ranging from 99.7 % to 106.3 %. This research provides a promising prospect for the application of spinel-structured nanoparticles in CL detection platforms and offers valuable insights into nanoparticle size modulation and OV engineering for catalytic optimization.