‘Under-solvent’ area-selective formation of chemically-functionalized and electrically-connected laser-induced graphene structures

Graphene, a two-dimensional carbon allotrope, exhibits outstanding mechanical, electrical, thermal, and chemical properties enabling widespread applications in flexible electronics, energy storage and harvesting, catalysis, and biosensing. Among the various graphene synthesis strategies, laser-induced graphene (LIG) offers distinct advantages in terms of scalability, simplicity, and direct patternability. However, the functional diversification of LIG remains a significant challenge, primarily due to reliance on multistep post-processing, high-temperature treatments, limited chemical tenability, poor area selectivity, and difficulties in integrating electrical connections and multifunctional graphene architectures within device platforms. Herein, we report, for the first time, an in-situ, under-solvent laser-directed approach that enables the direct, single-step formation and integration of chemically functionalized LIG structures without any post-synthesis. In this strategy, a solid polyimide (PI) film is laser-ablated under a predesigned solvent environment, where the solvent governs the incorporation of specific chemical functionalities into the emerging graphene network, allowing precise control over the chemical composition and morphology of the resulting LIG in a single laser-based step. By systematically tailoring both the solvent chemistry and laser parameters, the structural, physical, electrochemical, and catalytic properties of LIG can be finely engineered. Importantly, this work establishes a universal “toolbox” and efficient blueprint for producing a tunable framework for the area-selective, single-step integration of chemically functionalized LIG into microfluidic and electrochemical platforms. The spatially controlled functionalization enables the direct fabrication of multifunctional electrochemical circuits, in which distinct regions of LIG are selectively modified to perform complementary functions. As proof of concept, we have successfully fabricated a device using region-specific functionalized LIG for an electrochemical sensing platform for hydrogen peroxide (H 2 O 2 ). Cyclic voltammetry was performed at a scan rate of 50 mV/s, with a LOD of 0.2 mM. Furthermore, Platinum (Pt) nanoparticles decorated with LIG electrodes were fabricated through this approach, exhibiting enhanced electrocatalytic activity for water splitting. The electrodes were analyzed for hydrogen evolution (HER) activity in 1 M KOH electrolyte, where the LIG@Pt electrode showed an overpotential of ⁓68 mV at 10 mA cm −2 and a stability overpotential of ⁓68 mV for over 10 h. This solvent-assisted laser strategy provides a scalable and versatile pathway for the direct fabrication of advanced, multifunctional graphene-based devices. • Single-step, under-solvent laser writing enables in-situ chemically-functionalized LIG formation. • Solvent-controlled laser ablation enables direct synthesis of metal nanoparticle-embedded LIG active composites. • Laser-written LIG forms direct, electrically-connected circuits without post-processing steps. • Area-selective functionalization enables integrated multifunctional circuits for next-generation applications. • Pt–LIG composite exhibits low HER overpotential, and stable H₂O₂ sensing with a low LOD of 0.26 mM.