Enhanced Peroxidase-like Activity of Graphdiyne-Based Nanozymes by Fe and N Codoping for Colorimetric Determination of H2O2 and Ascorbic Acid

As a typical carbon nanomaterial, graphdiyne (GDY) is expected to contribute to the field of nanozymes due to its unique structure and properties. However, the limited intrinsic enzyme-like activity of the pristine GDY nanomaterial suppressed its further development and application. In this paper, a heteroatom (Fe and N)-doping strategy was adopted to prepare GDY-based nanozymes. It has been found that heteroatom doping can improve the peroxidase-like activity of GDY nanomaterials, especially when Fe and N are codoped. The codoping of Fe and N not only increased the number of active sites, which could be uniformly distributed on the carbon substrate because of the coordination of N and Fe, but also changed the reactivity of substrates with nanozymes. As a result, the peroxidase-like activity of the Fe1.5-N-GDY nanozyme after the codoping of Fe and N into GDY was 18 times that of the N-GDY nanozyme and 14 times that of the Fe1.5-GDY nanozyme. Moreover, the sensing application of the Fe1.5-N-GDY nanozyme was explored in the determination of H2O2 and ascorbic acid (AA) through colorimetric assays, while the linear relationship was 100–800 and 800–2000 μM with a detection limit of 52.96 μM for H2O2 and was 5–100 μM with a detection limit of 5.95 μM for AA. This work provides not only an excellent peroxidase-like nanozyme for sensing but also a valuable reference for the design and synthesis of GDY-based nanozymes.