Periodic nanopatterning and reduction of graphene oxide by femtosecond laser to construct high-performance micro-supercapacitors

Reduction and patterning of graphene oxide (GO) have been extensively applied in the field of electronic devices such as sensor, transistors and power source. Surface morphology and reduction level of reduced graphene oxide (rGO) directly influence the performance of devices. Herein, we put forward a new method of one-step periodic nanopatterning and reduction of GO using femtosecond laser pulses in air environment. Three-dimensional (3D) laser induced periodic surface structures (LIPSSs) with subwavelength ripples and flakes were obtained at the irradiation of laser fluences higher than the threshold of GO reduction (∼9 mJ/cm²). Meanwhile, the change in chemical compositions and phase structure transformation of femtosecond laser reduced GO (Fs-LRGO) was identified through X-ray photoelectron spectroscopy, Raman spectroscopy and X-ray diffraction. The excited surface plasma polaritons (SPPs) and photochemical effect were put forward to reveal the mechanism in the formation and reduction of Fs-LRGO with nanopatterns. By virtue of the periodic nanopatterns of Fs-LRGO, we also constructed the all-solid-state interdigital rGO micro-supercapacitors (MSCs) with ultralow electrode interspace of ∼10 μm and different connection ways, indicative of superior flexibility and cycle stability. This work provides new insights into the fundamental mechanism and utility of ultrafast periodic nanopatterning and reduction of GO for the application of multifunctional electronic device engineering.