Harnessing Photocatalytic and Photothermal Effects of C-Doped Graphitic Carbon Nitride for Efficient Bacterial Disinfection

Abstract

In this work, the photocatalytic and photothermal effects of carbon-ring-doped graphitic carbon nitride materials against bacteria were systematically studied in a dispersed solution and on a membrane. C-doped graphitic carbon nitride materials C-CN 0.15, 1.5, and 7.5 were synthesized by mixing urea precursor with 0.15, 1.5, and 7.5 wt % glucose. With the increase in the doping level, the photothermal effect was clearly enhanced while the generation of reactive oxygen species (ROS) was slightly inhibited. With exposure to irradiation under a 100 mW cm −2 Xeon lamp with a cutoff filter (λ ≥ 420 nm), the ROS concentration of C-CN 1.5 increased 30% in the dispersed solution and its temperature increased about 10 °C in the dispersed solution and on the membrane compared to that of pristine carbon nitride. As a result, the bactericidal activity of C-CN 1.5 was improved by an order of magnitude in the dispersed solution and more than 2 orders of magnitude on the membrane immersed in a solution at 40 °C. To investigate the fundamental light absorption process on the membrane, an optical model using the finite-difference time-domain method was developed based on the topography of the membrane. The simulation results may explain that although C-CN produces more ROS in a solution; however, with a larger extinction coefficient, the power absorption is lower near the surface of the membrane. The ROS production is therefore inhibited and the bactericidal activity is dominated by the photothermal effect. Our experimental and simulation results provide a basis for designing high-performance photoactive disinfection materials and surfaces.

Photocatalytic degradation of ciprofloxacin in freshwater aquaculture wastewater by a CNBN membrane: mechanism, antibacterial activity, and cyclability

“…2(d), the E g of the CN, BN, CNBN and CNBN membrane 42 Meanwhile, a weak diffraction peak at 27.4°can be observed from the high-resolution XRD spectra of CNBN, which may be attributed to the (002) crystal surface characteristic peak of trace CN. 43 This result was similar to the previous study. 22 In addition, the wide peak at 19.7°was from the cellulose acetate membrane, and no other characteristic peaks were observed, indicating that the CNBN loaded on the cellulose Environmental Science: Nano Paper acetate membrane maintained a high purity crystalline phase.…”

3D macroporous CUPC/g-C3N4 heterostructured composites for highly efficient multifunctional solar evaporation

“…S3† that the major ROS component generated by CN is ˙O 2 − , followed by H 2 O 2 , and the amount of ˙OH is negligible. 28 We thus took the rate of decrease of the fluorescence intensity of ROS dye by adding the ˙O 2 − scavenger to indicate the concentration of ˙O 2 − . As shown in Fig.…”

“…We have used various scavengers to identify the major ROS generated by photocatalysis in our previous work. 28 It can be seen from Fig. S3 † that the major ROS component generated by CN is…”

“…The bacteria E. coli were cultivated as described previously. [27][28][29] Briefly, the bacterial suspension was diluted to approximately 10 7 colony-forming units (CFUs) per mL in 0.9% NaCl solution, to which CN and CUPC-CN materials were added at a concentration of 5 mg mL −1 . After irradiation for 30 min under the xenon lamp at 600 W m −2 , the number of viable cells was evaluated by subsequent dilution and the CFU counting method.…”

“…and the amount of • OH is negligible. 28 We thus took the rate of decrease of the fluorescence intensity of ROS dye by adding the decreased with the loading ratio of CUPC, which is consist-ent with the results of dye degradation. The results suggest that the photo-degradation property is counterbalanced by the photothermal conversion.…”