Unraveling the dependency on multiple passes in laser-induced graphene electrodes for supercapacitor and H2O2 sensing

Laser-induced graphene (LIG) has emerged as an exciting material, which can be patterned on flexible substrates in an ambient condition using a fast and facile laser irradiation process and has been used for several applications. Popular low-power infrared laser cutter systems are facilitating the widespread use of LIG materials. Typically, a single laser pass on the substrate is used to achieve the LIG material. In this work, the effect of multiple laser passes is explored on the fabrication of LIG electrodes. The multiple-lased LIG electrodes are used for supercapacitor and H2O2 sensing applications to unravel the dependency on multiple passes in their performances. The properties of the LIG materials exhibit a significant dependence on the number of laser passes. The thickness of the LIG film increases with the number of laser passes, with a maximum thickness of 94.2 ± 14.9 µm after laser pass 3. Further laser passes result even in a decrease in the thickness. The electrical conductivity shows a minimal change with the number of laser passes. As inferred from Raman spectra, the degree of graphitization shows a similar trend as the film thickness, with the highest degree of graphitization again for three laser passes. Multiple laser passes yield a more porous morphology with a finer fibril microstructure compared to the single-pass LIG material. The LIG electrode from a three-pass laser process also shows the best performance as supercapacitors and in H2O2 sensing applications, which can be attributed to a combination of effects deriving from the layer thickness, degree of graphitization, and microstructure. © 2021