▎ 摘　　要

In this research, flexible transparent supercapacitor electrode materials were fabricated using cellulose nanofibrils (CNFs) and reduced graphene oxide (RGO) via a layer-by-layer (LbL) self-assembly method. First, a transparent film was obtained by vacuum filtration of a CNF suspension, which was isolated from bamboo materials using a combination of 2,2,6,6-tetramethylpiperidin-1-oxyl radical catalytic oxidation and ultrasonic treatment. Subsequently, graphene oxide (GO) was deposited on the surface of the CNF film using Cu2+ as a cross-linking agent via the LbL self-assembly technique and then was reduced by L-ascorbic acid under mild reaction conditions. The degree of reduction of the GO on the CNF film surface was investigated by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy (Raman), and Fourier transform infrared spectroscopy (FT-IR); concurrently, the effect of the number of self-assembly times on the transparency, mechanical properties, and conductivity was also evaluated. The XPS, Raman, and FT-IR spectral analyses proved that the CNFs/GO composite films were successfully reduced to CNFs/RGO composite films, of which the transparency and mechanical properties decreased with the increase in the number of self-assembly times, while the conductivity remarkably raised. Based on the analysis of the results, the CNFs/RGO composite film obtained after 18 self-assembly cycles exhibited excellent transparency, good tensile strength, and a high conductivity. Therefore, the CNFs/RGO composite film was selected to fabricate a supercapacitor electrode material, and the obtained supercapacitor displayed excellent electrochemical properties, in which the areal specific capacitance was 2.25 mF cm(-2) at a current density of 0.01 mA cm(-2) and the capacitance retention reached 97.3% after 1500 cycles. The presented strategy provides a good reference for the development of transparent and portable energy storage devices.