Tailoring the Electronic Properties of Graphene Quantum Dots by P Doping and Their Enhanced Performance in Metal-Free Composite Photocatalyst

Graphene quantum dots (GQDs) as new 0-dimensional (OD) materials have exhibited promising applications in numerous fields, and these enormous potentials are largely dependent on their electronic properties. Herein we tailored the semiconductive behavior of GQDs and transformed the n-type hydrothermally synthesized GQDs to p-type via the modification of P=O groups With an electron-withdrawing ability. The obtained highly dispersed and stable P-doped GQDs (P-GQDs) had uniform size and thickness, high crystallinity, and wide visible, light absorption region. The Subsequent assembly with the n-type graphitic carbon nitride (CN) formed a stable metal-free photocatalyst because of the pi-pi interaction between conjugated GQDs sheets and CN layers and the possible hydrogen, bonds as well. Due to the formation of p-n junction on the P-GQDs/CN interface, the photogenerated charges were efficiently separated which resulted in an enhanced photocatalytic performance. This strategy illuminates the GQDs applications by controlling the electronic structure of GQDs based on the detailed application, not only for photocatalysis but also for many other fields such as solar cells, catalysis, electrocatalysis, and so on.