Constructing a coplanar heterojunction through enhanced π-π conjugation in g-C3N4 for efficient solar-driven water splitting

Adjusting the electronic structure of graphitic carbon nitride (g-C3N4) photocatalyst through pi-pi conjugation is an effective method to achieve efficient photogenerated carrier separation. One key challenge of pi-pi conjugation control is to tune the degree of such conjugation without destroying the g-C3N4 structure. Herein we report a conceptual design that achieves a coplanar heterojunction by enhancing the pi-pi conjugation via the doping of crystalline g-C3N4 using a conjugated double bond ring molecule, 1,3,5-benzenetriol, during calcination process. The selection of the dopant enables the facile creation of a unique coplanar heterojunction which not only retains the pristine network structure of g-C3N4, but remarkably promotes separation and transfer of photogenerated carriers through the enhanced pi-conjugated endogenous electric field. As a result, the new g-C3N4 photocatalyst efficiently photocatalytically produces hydrogen from water under visible light irradiation with a high H-2 production rate up to 94.94 mu mol/h, and a notable external quantum efficiency of 16.4% at 420 nm. (C) 2021 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

Automated summary

This study achieves efficient photogenerated carrier separation by adjusting the electronic structure of graphitic carbon nitride (g-C3N4) photocatalyst through pi-pi conjugation. A coplanar heterojunction is created by doping crystalline g-C3N4 with a conjugated double bond ring molecule, resulting in the retention of the g-C3N4 network structure and enhanced separation and transfer of photogenerated carriers. The new g-C3N4 photocatalyst demonstrates high hydrogen production efficiency under visible light irradiation.