Enhancement in carrier separation of ZnO-Ho2O3-Sm2O3 hetrostuctured nanocomposite with rGO and PANI supported direct dual Z-scheme for antimicrobial inactivation and sunlight driven photocatalysis

In this work, a direct dual Z-scheme ZnO-Ho2O3-Sm2O3 (NC), polyaniline PANI-ZnO-Ho2O3-Sm2O3 (NCP), and reduced graphene oxide rGO-ZnO-Ho2O3-Sm2O3 (NCR) heterostructure nanocomposites were fabricated successfully. The XRD diffractograms confirmed that ZnO has hexagonal, while Ho2O3, and Sm2O3 have cubic phases in all grown composites. FTIR data exhibited the existence of the PANI, rGO, and metal–oxygen vibration. Raman spectra revealed the presence of optical phonon modes of individual oxides in nanocomposites. PL results disclose the lower charge carrier recombination rate in NCR. SEM images confirmed the anchoring of roughly spherical nanoparticles of NC with PANI and rGO. The UV–Vis analysis showed that the optical energy bandgap was 2.95 eV, 2.88 eV, and 2.81 eV for NC, NCP, and NCR, respectively. The EIS results exhibited a lower charge transfer resistance of NCR than others. The photocatalytic performance against MB, MR, and P-Nitro dyes under sunlight exhibited NCR > NCP > NC efficiency for all dyes in 60 min. The recyclability tests have confirmed the reusability upto six cycles. The antibacterial activity against E. coli, S. aureus, and P. Vulgaris bacteria displayed a higher activity for NCR. The boosted photocatalytic and antibacterial performance of NCR have ascribed the existence of Z-scheme supported with rGO, promote electron/hole separation and hinder the charge carrier’s recombination. The results clearly demonstrate that the as-grown nanocomposites can be used as an effective material for bacterial disinfection and wastewater treatment.