Photocatalytic activity enhancement of PDI supermolecular via π-π action and energy level adjusting with graphene quantum dots

The separation process of photo-generated carriers and photocatalytic process. [Display omitted] •GQDs/PDI has higher photocatalytic performance than PDI under visible light.•GQDs is helpful for the electrons delocalization via π-π action with PDI.•The quantum confinement effect of GQDs helps electron transfer from GQDs to PDI. Herein, perylene bisimide supramolecular (PDI) and graphene quantum dots (GQDs) were successfully layer-by-layer assembled via electrostatic interaction. The apparent rate constant of photocatalytic reaction for phenol degradation of GQDs/PDI-14 % (0.018 min−1) was 4.73 times as high as nano PDI under visible light. Besides, the rate of H2 production of GQDs/PDI-14 % (1.6 mmol g−1· h−1) was 1.88 times over that of pure PDI. GQDs is helpful for the electrons delocalization via π-π action with PDI. Moreover, the quantum confinement effect of GQDs promotes electron transfer from GQDs to PDI, which helps the conduction band of PDI shift to more negative position and further enhance the reduction ability of PDI. The work may afford some interesting ideas for designing efficient quantum dots-modified supramolecular organic photocatalysts.