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

Abstract

Abstract Copper vanadate quantum dots (Cu 3 V 2 O 8 QDs) based graphitic carbon nitride (g-C 3 N 4 ) was fabricated to investigate its photocatalytic disinfection towards Escherichia coli ( E. coli ) bacteria. The g-C 3 N 4 was successfully synthesized by pyrolysis of urea, whereas different weightage of Cu 3 V 2 O 8 QDs, (10 wt.%, 15 wt.% and 20 wt.%) was incorporated into g-C 3 N 4 by using ultrasonic process to produce 10 wt.% Cu 3 V 2 O 8 /g-C 3 N 4 , 15 wt.% Cu 3 V 2 O 8 /g-C 3 N 4 and 20 wt.% Cu 3 V 2 O 8 /g-C 3 N 4 . Pure g-C 3 N 4 showed agglomerated and wrinkled surface while 20 wt.% Cu 3 V 2 O 8 /g-C 3 N 4 became looser and had a flower-like structure with high specific surface area. All composites consist of the elements which present in both g-C 3 N 4 and Cu 3 V 2 O 8 QDs. Fourier transform infrared (FTIR) spectra of Cu 3 V 2 O 8 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-C 3 N 4 and all the composites. X-ray diffraction (XRD) peaks appeared in pure g-C 3 N 4 and Cu 3 V 2 O 8 QDs were detected in the composites. Based on the results obtained from antibacterial growth of E. coli , 20 wt.% Cu 3 V 2 O 8 /g-C 3 N 4 with higher specific surface area among the composites demonstrated an excellent antibacterial efficacy of 97%. This proved that Cu 3 V 2 O 8 QDs successfully narrowed the energy band gap of the composite to increase the antibacterial efficacy of E. coli . The scavenger tests revealed that the ·O 2 - and h + were the most reactive radical species in the photocatalytic disinfection of E. coli .