One-Step Laser Nanostructuration of Reduced Graphene Oxide Films Embedding Metal Nanoparticles for Sensing Applications

The combination of two-dimensional materials and metal nano-particles (MNPs) allows the fabrication of novel nanocomposites with unique physical/chemical properties exploitable in high-performance smart devices and biosensing strategies. Current methods to obtain graphene-based films decorated with noble MNPs are cumbersome, poorly reproducible, and difficult to scale up. Herein, we propose a straightforward, versatile, surfactant-free, and single-step technique to produce reduced graphene oxide (rGO) conductive films integrating "naked" noble MNPs. This method relies on the instantaneous laser-induced co-reduction of graphene oxide and metal cations, resulting in highly exfoliated rGO nanosheets embedding gold, silver, and platinum NPs. The production procedure has been optimized, and the obtained nanomaterials are fully characterized; the hybrid nanosheets have been easily transferred onto lab-made screen-printed electrodes preserving their nanoarchitecture. The Au@rGO-, Ag@rGO-, and Pt@ rGO-based electrodes have been challenged to detect caffeic acid, nitrite, and hydrogen peroxide in model solutions and real samples. The sensors yielded quantitative responses (R2 >= 0.997) with sub-micromolar limits of detections (LODs <= 0.6 mu M) for all the analytes, allowing accurate quantification in samples (recoveries >= 90%; RSD <= 14.8%, n = 3). This single-step protocol which requires low cost and minimal equipment will allow the fabrication of free-standing, MNP-embedded rGO films integrable into a variety of scalable smart devices and biosensors.