Delamination treatment is crucial in promoting the activity of bulk graphitic carbon nitride (g-CN). However, most of the currently used methods of exfoliating bulk g-CN to achieve g-CN thin layers suffer from low yield and environmental pollution. Herein, we developed a facile bacterial etching approach for the preparation of high-quality g-CN nanosheets by exfoliating bulk g-CN under room temperature. Morphology and physicochemical characterizations show that the bacteria-treated g-CN (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 m g), 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-CN nanosheets. EIS spectra and photocurrent tests indicate the fast electron transportation. As a result, the representative BT-CN-2d g-CN photocatalyst shows an optimal visible light-driven photocatalytic performance in water disinfection (fourfold higher than bulk g-CN), 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-CN by bioengineering method, offering extendable availability for designing and fabricating other functional 2D materials.

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Surface amino group regulation and structural engineering of graphitic carbon nitride (g-CN) for better catalytic activity have increasingly become a focus of academia and industry. In this work, the ammonia plasma produced by a microwave surface wave plasma generator was developed as a facile source to achieve fast, controllable surface modification, and structural engineering of g-CN by ultrafast plasma treatment in minutes, thus enhancing photocatalytic performance of g-CN. The morphology, surface hydrophilicity, optical absorption properties, and states of C–N bonds were investigated to determine the effect of plasma immersion modification on the g-CN catalyst. The structure and photoelectric features of the plasma-modified samples were characterized by X-ray diffractometry, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. The results indicate that the ammonia plasma-treated g-CN–NH3 exhibits an ultrathin nanosheet structure, enriched amino groups, and an ideal molecular structure, a narrower band gap (2.35 eV), extended light-harvesting edges (560 nm), and enhanced electron transport ability. The remarkably enhanced photocatalytic activity demonstrated in the photoreduction and detoxification of hexavalent chromium (Cr­(VI)) can be ascribed to the optimization of the structural and photoelectric properties induced by the unique ammonia plasma treatment. The effective and ultrafast approach developed in this work is promising in the surface amino group regulation and structural engineering of various functional materials.

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Highly-dispersed FeNi nano-catalysts embedded in bacterial derived graphitic carbon were successfully synthesized as sustainable and efficient tar cracking catalysts.