Photocatalytic Efficiency of g-C 3 N 4 /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-C 3 N 4 /graphene nanocomposites were synthesized by thermal reduction as photocatalysts. FTIR spectra analysis showed that novel C=C bonds can form between g-C 3 N 4 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-C 3 N 4 . 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-C 3 N 4 /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-C 3 N 4 in the reduction of the charging potential, especially at high current densities.