Visiable-Light-Driven F/C Co-Doping G-C3n4  Nanosheets for Efficient Hydrogen Evolution: Charge Redistribution on C4 Delocalized Large Π Bond

Abstract

Developing photocatalytic hydrogen evolution technology based on graphitic carbon nitride (g-C3N4, CN) has emerged as a potential solution for the future energy shortage in recent years. Herein, carbon (C) and fluorine (F) co-doping graphitic carbon nitride nanosheets (CFCN) were synthesized via a one-pot co-thermal method without introducing any metal element. Exceptional hydrogen production activity (3.87 mmol/h/g) was achieved by CFCN under visible light irradiation, which was 4.2-fold increase compared to the pristine CN. It could be attributed to the large specific surface area (51.59 m2/g) and efficient mass transfer facilitated by the porous sheet-like morphology of CFCN. Additionally, the modification of the band structure and internal charge redistribution were investigated via density functional theory (DFT) calculations, which confirmed there was a unidirectional and fast electron transfer channel from N through the C4 delocalized large π bond to F. This creative research uncovered the pivotal role of F/C co-doping in enhancing photocatalytic hydrogen evolution efficacy, offering cutting-edge insights into the design of sustainable and eco-friendly photocatalysts based on metal-free CN.

Keywords: photocatalytic hydrogen evolution, Graphitic carbon nitride, F/C co-doping, charge redistribution, delocalized large π bond