Photocatalytic Efficiency of g-C3N4/Graphene Nanocomposites in the Photo-Assisted Charging of the Li-Ion Oxygen Battery

In this work, we aimed to synthesize an effective nanocomposite photocatalyst for the photo-assisted charging of the Li-ion oxygen battery. Initially the graphene films were synthesized by chemical vapor deposition, and subsequently, g-C3N4/graphene nanocomposites were synthesized by thermal reduction as photocatalysts. FTIR spectra analysis showed that novel C═C bonds can form between g-C3N4 and graphene films during the synthesis process. The photocurrent measurements indicated that the presence of graphene considerably contributed to the visible light utilization and photocatalytic efficiency of g-C3N4. This contribution was also revealed by the UV–vis diffuse reflectance spectra measurements, which showed that the incremental addition of the graphene reduced the optical band gap of the nanocomposite incrementally. The photocatalyst performance of the g-C3N4/graphene nanocomposite was also observed in the photo-assisted charging tests of the Li-ion oxygen battery, and the presence of 2D graphene in the structure improved the effectiveness of g-C3N4 in the reduction of the charging potential, especially at high current densities.