Delamination treatment is crucial in promoting the activity of bulk graphitic carbon nitride (g-C3N4). However, most of the currently used methods of exfoliating bulk g-C3N4 to achieve g-C3N4 thin layers suffer from low yield and environmental pollution. Herein, we developed a facile bacterial etching approach for the preparation of high-quality g-C3N4 nanosheets by exfoliating bulk g-C3N4 under room temperature. Morphology and physicochemical characterizations show that the bacteria-treated g-C3N4 (BT-CN) samples, especially BT-CN-2d, have a lamina-like two-dimensional (2D) in-plane porous structure, a significantly enlarged specific surface area (82.61 m2 g-1), and a remarkable narrow band gap (2.11 eV). X-ray photoelectron spectroscopy and electron paramagnetic resonance spectra confirm the dramatic enrichment of unpaired electron in the BT-CN-2d g-C3N4 nanosheets. EIS spectra and photocurrent tests indicate the fast electron transportation. As a result, the representative BT-CN-2d g-C3N4 photocatalyst shows an optimal visible light-driven photocatalytic performance in water disinfection (fourfold higher than bulk g-C3N4), as well as good cycle stability. This moderate and clean bacterial etching process can be realized in tens of gram scale in the laboratory and should be readily extended to kilogram scale. The present work provides fundamental knowledge about the scalable production of high-quality g-C3N4 by bioengineering method, offering extendable availability for designing and fabricating other functional 2D materials.
Keywords: bacterial etching; graphitic carbon nitride (g-C3N4); unpaired electrons; visible-light-driven photocatalyst; water disinfection.