Gas-Phase Fluorination of g-C(3)N(4) for Enhanced Photocatalytic Hydrogen Evolution

Graphitic carbon nitride (g-C(3)N(4)) has attracted much attention because of its potential for application in solar energy conservation. However, the photocatalytic activity of g-C(3)N(4) is limited by the rapidly photogenerated carrier recombination and insufficient solar adsorption. Herein, fluorinated g-C(3)N(4) (F-g-CN) nanosheets are synthesized through the reaction with F(2)/N(2) mixed gas directly. The structural characterizations and theoretical calculations reveal that fluorination introduces N vacancy defects, structural distortion and covalent C-F bonds in the interstitial space simultaneously, which lead to mesopore formation, vacancy generation and electronic structure modification. Therefore, the photocatalytic activity of F-g-CN for H(2) evolution under visible irradiation is 11.6 times higher than that of pristine g-C(3)N(4) because of the enlarged specific area, enhanced light harvesting and accelerated photogenerated charge separation after fluorination. These results show that direct treatment with F(2) gas is a feasible and promising strategy for modulating the texture and configuration of g-C(3)N(4)-based semiconductors to drastically enhance the photocatalytic H(2) evolution process.