Femtosecond Laser One‐Step Direct Writing Electrodes with Ag NPs‐Graphite Carbon Composites for Electrochemical Sensing

Abstract The next generation of green electronic products will be flexible, eco‐friendly, have arbitrary patterning, and be produced using simple methods. Here, a silver nanoparticles (Ag NPs)–graphite carbon composite‐based electrochemical sensor is patterned on a flexible substrate by one‐step in situ femtosecond (fs) laser fabrication. Alkali lignin is used as a precursor and nontoxic natural reducing agent to reduce aqueous silver nitrate to produce Ag NPs. The fs laser carbonization process converts lignin into graphite carbon electrodes with diverse three‐dimensional (3D) micro/nano morphologies, causing less thermal damage to the Ag NPs and thin substrate. The 3D micro/nano morphologies combined with Ag NPs effectively increase the active surface area, conductivity, and catalytic activity of the electrode, which is further applied as an electrochemical sensor. This sensor has a wide linear detection range of nitrite from 1–4000 × 10 −6 m , a detection limit of 0.117 × 10 −6 m (S/N = 3), and long lifetime of 30 days. The sensor also has the potential to detect dopamine (DA). A detection limit of 0.098 × 10 −6 m (S/N = 3) is obtained, with a linear detection range of 1–45 × 10 −6 m . The sensor demonstrates a wide range of applications in food safety and human health‐related detection.