Copper vanadate quantum dots and graphitic carbon nitride composite for water disinfection

Copper vanadate quantum dots (Cu3V2O8 QDs) based graphitic carbon nitride (g-C3N4) was fabricated to investigate its photocatalytic disinfection towards Escherichia coli (E. coli) bacteria. The g-C3N4 was successfully synthesized by pyrolysis of urea, whereas different weightage of Cu3V2O8 QDs, (10 wt.%, 15 wt.% and 20 wt.%) was incorporated into g-C3N4 by using ultrasonic process to produce 10 wt.% Cu3V2O8/g-C3N4, 15 wt.% Cu3V2O8/g-C3N4 and 20 wt.% Cu3V2O8/g-C3N4. Pure g-C3N4 showed agglomerated and wrinkled surface while 20 wt.% Cu3V2O8/g-C3N4 became looser and had a flower-like structure with high specific surface area. All composites consist of the elements which present in both g-C3N4 and Cu3V2O8 QDs. Fourier transform infrared (FTIR) spectra of Cu3V2O8 QDs and all composites had the stretching vibration of both Cu-O and V-O. C-N, C=N and C-H stretching vibrations were found in FTIR spectra of pure g-C3N4 and all the composites. X-ray diffraction (XRD) peaks appeared in pure g-C3N4 and Cu3V2O8 QDs were detected in the composites. Based on the results obtained from antibacterial growth of E. coli, 20 wt.% Cu3V2O8/g-C3N4 with higher specific surface area among the composites demonstrated an excellent antibacterial efficacy of 97%. This proved that Cu3V2O8 QDs successfully narrowed the energy band gap of the composite to increase the antibacterial efficacy of E. coli. The scavenger tests revealed that the ·O2- and h+ were the most reactive radical species in the photocatalytic disinfection of E. coli. © Published under licence by IOP Publishing Ltd.