Integration of High-Entropy Oxide with Nitrogen-Doped Graphene for the Ultrasensitive Electrochemiluminescence Detection of Trolox and Dopamine

Developing luminol-dissolved O2 (luminol-DO) electrochemiluminescence (ECL) systems with high performance as well as excellent stability to enhance the low ECL efficiency of DO is highly desired for real applications. Here, we prepared a composite of high-entropy oxide (HEO) and nitrogen-doped graphene (HEO/N-G), with well-defined abundant oxygen vacancies, and used it for performance-enhanced luminol-DO ECL sensing applications. Benefiting from its unique electronic structure, reactive oxygen species could be efficiently produced, followed by reaction with electrochemically generated luminol anion radicals to generate a much-enhanced signal of the resulting ECL system. The developed HEO/N-G-based luminol-DO ECL system was further successfully exploited for the ultrasensitive detection of Trolox and dopamine in the linear ranges of 1 nM to 25 μM and 100 pM to 10 nM, with detection limits of 1.0 and 0.00093 nM, respectively. The underlying ECL mechanism of the HEO/N-G luminol-DO ECL system was also discussed.