One-Step Synthesis of Copper Single-Atom Nanozymes for Electrochemical Sensing Applications

Single-atom nanozymes (SANs) combine the natural enzymatic properties of nanomaterials with the atomic distribution of metallic sites over a suitable support. Unfortunately, their synthesis is complicated by some key factors, like poor metallic loading, aggregation, time consumption, and low yield. Herein, copper SANs, with a surface metal loading (1.47% ± 0.16%) are synthesized, through a green, facile, minimal solution processing, single-step procedure, using a CO₂ laser to promote the anchoring of the metallic precursor while simultaneously generating the laser-scribed graphene (LSG) support out of a polyimide sheet. The presence of the atomic Cu on the LSG surface is verified using high-angle-annular dark-field-scanning transmission electron microscopy and X-ray photoelectron spectroscopy. To explore the advantages incurred by the incorporation of Cu SANs on LSG, the material is used as a working electrode on an electrochemical sensor for the amperometric detection of H₂O₂, achieving a detection limit of 2.40 μM. The findings suggest that CuSANs can confer enhanced sensitivity to H₂O₂, which is essential for oxidative stress assessment, reaching values up to 130.0 μA mM^-1 cm^-2.