Synergistic photocatalytic mitigation of imidacloprid pesticide and antibacterial activity using carbon nanotube decorated phosphorus doped graphitic carbon nitride photocatalyst

In the current work, we have doped g-C3N4 (GCN), a conjugated polymer based on heptazine-group with phosphorous and synthesized phosphorous doped g-C3N4 (PCN) has been coupled with CNT to enhance its photodegradation activity. Herein, CNT/PCN nanocomposites (having different CNT wt% i.e. 0.01, 0.02 and 0.03) were successfully fabricated via straight forward sonochemical method while GCN and PCN were prepared through direct thermal polycondensation method for Imidacloprid (IMI) pesticide degradation. Photodegradation activity of nanocomposite was enormously affected by doping but more significantly by nature of CNT content and addition of H2O2. EIS and PL analysis confirmed enhanced photogenerated charge carriers separation in CNT/PCN nanocomposite than GCN and PCN. Through BET analysis increase in surface area (SBET) of CNT/PCN nanocomposite was observed than PCN (2.8401 m2 g − 1 to 14.0294 m2 g − 1). Photodegradation processes follow pseudo-first order kinetics as R2 values were attained between 0.95–0.98. Synthesized 0.02 wt% CNT/PCN and 0.02 wt% CNT/PCN/H2O2 nanocomposite (without H2O2 and with H2O2) exhibited superior IMI photodegradation efficiency i.e. 93% and 97% respectively, than other photocatalysts (GCN, PCN, 0.01 wt% CNT/PCN, 0.03 wt% CNT/PCN, GCN/H2O2, PCN/H2O2, 0.01 wt% CNT/PCN/H2O2, 0.03 wt% CNT/PCN/H2O2) after visible light illumination. The most Plausible photocatalytic mechanism was also illustrated stipulating significance of h+, •O2−reactive species for CNT/PCN nanocomposite and •OH radicals for CNT/PCN/H2O2 nanocomposite in photodegradation process. Furthermore, antimicrobial and cytotoxic studies revealed that CNT/PCN confers antibacterial activity but do not cause harm to normal human cells.