Graphene and g-C₃N₄Nanosheets Cowrapped Elemental α-Sulfur As a Novel Metal-Free Heterojunction Photocatalyst for Bacterial Inactivation under Visible-Light

Abstract

A new class of metal-free heterojunction photocatalysts was prepared by wrapping reduced graphene oxide (RGO) and g-C3N4 (CN) sheets on crystals of cyclooctasulfur (α-S8). Two distinctive structures were fabricated by wrapping RGO and CN sheets in different orders. The first was RGO sheets sandwiched in heterojunction of CN sheets and α-S8 (i.e., CNRGOS8), while the second structure was the other way around (i.e., RGOCNS8). Both structures exhibited antibacterial activity under visible-light irradiation. CNRGOS8 showed stronger bacterial inactivation than RGOCNS8 in aerobic conditions. However, RGOCNS8 was more active than CNRGOS8 under anaerobic condition. A possible mechanism was proposed to explain the differences between photocatalytic oxidative inactivation and reductive inactivation. As a proof-of-concept, this work could offer new inroads into exploration and utilization of graphene sheets and g-C3N4 sheets cowrapped nanocomposites for environmental applications.

Visible-light-driven inactivation of Escherichia coli K-12 over thermal treated natural pyrrhotite

“…Mechanisms of bactericidal function from various ROSs has been well-documented: • OH and • O 2 − with powerful oxidative ability were suggested to attack cell directly; and H 2 O 2 can diffuse into inner part of the bacterial cell to produce a long-range inactivation effects, and then followed by the increase in the cell envelope permeability and ROSs penetration into cytoplasm, and ultimately caused the cell death [4,24,34]. Therefore, scavenger experiments [4,34] were conducted to identify the differences of primary bactericidal agents between pristine NP and the most effective NP600. Before the experiments, the concentration of each scavenger reagent was optimized to avoid the possible toxicity to cells.…”

CTAB-assisted synthesis of S@rGO composite with enhanced photocatalytic activity and photostability

“…S@rGO composites were synthesized by electrostatic attraction with the assistance of CTAB, using Na 2 S 2 O 3 ·5H 2 O, HCl and GO aqueous suspension as the starting materials, according to reference with some modifications [22][23][24]. In a typical experiment, 5 g Na 2 S 2 O 3 ·5H 2 O and 0.05 g CTAB were dissolved into 500 mL DIwater and then dispersed by ultrasonic for 10 min.…”

Graphene‐Based Photocatalysts for Energy Applications: Progress and Future Prospects

“…The photochemical reduction is also applicable to construct graphene-wrapped core-shell structures. Our group has prepared RGO and g-C 3 N 4 (CN) nanosheets co-wrapped α-S 8 as a new family of metal-free photocatalysts [89]. Two distinctive structures were fabricated by wrapping RGO and CN sheets in different orders.…”