Roles of alcohol group in functionalized carbon nitride for photocatalytic oxidation

Rational design of new active sites for g-C3N4-based photocatalysts to accelerate its charge transfer represents an advanced direction for pollutant photodegradation. Herein, alcohol group-modified g-C3N4 via integrated C-N site and -OH site using in situ C-N coupling is developed. The alcohol-modified g-C3N4 exhibits elevated phenol removal efficiency than g-C3N4. Experimental results and theoretic calculations disclosed that the C-N site adjacent to the introduced alcohol group not only constructs a built-in electric field for driving charge transfer but also acts as a new site for the activation of O2 molecules; the -OH site of alcohol group works as the adsorption site of phenol. Additionally, the discrepancy in activity between ethyl alcohol and methyl alcohol modification is due to the different oxidation ability, which is triggered by transfer rate of separated electrons. Importantly, this work achieved unique role of each active sites, providing a theoretical basis to the design of super-active photocatalysts, and reveals a clear pathway for evolution of ROS and phenol mineralization.