Ball milling synthesis of porous g-C3N4 ultrathin nanosheets functionalized with alkynyl groups for strengthened photocatalytic activity

Herein, the alkynyl groups are grafted on g-C3N4 via ball milling of g-C3N4 and CaC2. The successful functionalization of g-C3N4 by alkynyl is demonstrated by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Ultrathin wrinkle-like structure with abundant pores is observed for the resulted alkynyl functionalized g-C3N4 nanosheets, which can furnish abundant photocatalytic active sites. The photocatalytic NH3 production rate of 0.12 mmol.gcat(-1).h(-1) is gained for alkynyl functionalized g-C3N4 under UV-visible irradiation, which is 2.0-folds higher than pristine g-C3N4 (0.058 mmol.gcat(-1).h(-1)). A maximum of 1.9 and 1.5 folds enhancements are achieved for the photodegradation of rhodamine B and levofloxacin over functionalized g-C3N4 compared to pristine g-C3N4. The improved mechanism is investigated by linear sweep voltammetry, transient photo-current, Tafel plots, electrochemical impedance spectroscopy, Mott-Schottky curves, turnover frequency, transient decay time, photoluminescence spectra, etc. The modification technique proposed in this paper can also be adopted to prepare other alkynyl functionalized semiconductors for photocatalytic application.

Automated summary

The study demonstrated successful functionalization of g-C3N4 with alkynyl groups via ball milling, resulting in ultrathin wrinkle-like structures with abundant pores. The alkynyl functionalized g-C3N4 showed higher photocatalytic activity for NH3 production and significant enhancements in photodegradation compared to pristine g-C3N4. Various characterization techniques were used to investigate the improved mechanism, and the modification technique has potential for preparing other alkynyl functionalized semiconductors for photocatalytic applications.