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

The combination of two-dimensional materials and metal nanoparticles (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 μM) 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.R.A.-D. acknowledges funding from the European Union Horizon 2020 Programme under grant no. 881603 (Graphene Flagship Core 3). ICN2 is funded by CERCA Programme, Generalitat de Catalunya. Grant SEV-2017-0706 is funded by MCIN/AEI/10.13039/501100011033. The authors also acknowledge the project PID2021-124795NB-I00 funded by MCIN/AEI/10.13039/501100011033/and FEDER Una manera de hacer Europa. F.D.P. and D.C. acknowledge the Ministry of Education, University and Research (MIUR) and European Social Fund (ESF) for the PON R&I 2014e2020 program, action 1.2 0AIM: Attraction and International Mobility’ (AIM1894039-3). C.C.C.S. acknowledges funding through CAPES─PRINT (Programa Institucional de Internacionalização; grant #88887.310281/2018-00 and 88887.467442/2019-00) and Mackpesquisa-UPM.Peer reviewe