Laser-induced graphene on axially oriented alginate–tannic acid–clay aerogel for energy harvesting and storage applications

In this work, a bio-based aerogel with axially oriented morphology was used as a substrate for laser induced graphene (LIG) conversion to fabricate carbon-based electrodes for energy harvesting and storage devices. The substrate materials provide intrinsic flame-retardancy and, together with the anisotropic structure, enable facile and controlled laser writing. The resulting LIG preserves the directional anisotropy of the aerogel, guiding heat propagation. Dye-Sensitized Solar Cells (DSSCs) including the developed material, achieved a fill factor of 0.72 and photoconversion efficiency of 2.2 % under indoor conditions (1000 lux) using γ-valerolactone (GVL) as the electrolyte solvent. Supercapacitors (SCs) were also developed employing LIG electrodes, exhibiting typical electrical double layer capacitor (EDLC) behaviour and remarkable rate capabilities under both cyclic voltammetry and galvanostatic cycling tests, with negligible resistive losses. The areal capacitance reached 1.49 mF/cm2, and the Ragone plot showed areal energy and power densities comparable to other sustainable LIG-based SCs. Overall, the aerogel has proven to be a sustainable alternative compatible with laser conversion processes. Remarkably, the aerogel's initial structure is preserved after the laser conversion process, allowing for substrate morphology pre-design to control the final LIG structure. These aerogels' features allow for tailoring carbon-based electrode morphologies toward optimized energy harvesting and storage.