Multifunctional ZnO-Co₃O₄ @ polymer hybrid nanocoatings with controlled adsorption, photocatalytic and anti-microbial...

Triple action pollutant responsive multi-layer hybrid nanocoatings of architecture PEI(PAA/ZnO-Co₃O₄)_n were constructed through ZnO-Co₃O₄ binary oxide co-precipitation followed by its inclusion in multi-layer polymeric thin films using Layer-by-Layer (LbL) deposition. Characterization of the designed architecture was carried out via FTIR, XRD, UV-Vis, and Raman spectroscopic studies to evaluate the chemical nature, bonding, and crystallographic behavior of ZnO-Co₃O₄. Peaks of ZnO-Co₃O₄ were recorded at 586.38, 486.08, and 443.64 cm^-1 while pronounced shifting of ZnO characteristic E₂ (high) peak ~ 450 cm^-1 and appearance of modes around 495, 530, 630, and 719 cm^-1 indexed via Raman studies validated Co₃O₄ impregnation into ZnO structure. XRD patterns of ZnO-Co₃O₄ compared to their previously reported pristine structures also justified the formation of binary oxide as unit composite. SEM micrographs confirmed homogenous multi-layered depositions while EDX analysis confirmed their uniform elemental distribution in the unit structure. Sequential multi-layer buildup up to 48 layer pairs was monitored using ellipsometry with maximum film thickness ~ 89 nm and by UV-Vis at 376 nm. The prepared thin films exhibited significant photodegradation of methylene blue ~ 91% and Cu (II) adsorption capacity ~ 89% within first 90 min of contact, along with prominent bactericidal efficiency against E. coli within 24 h of reaction time. FAAS, ICP-OES, and UV-Vis spectroscopy analyses make these multifunctional hybrid nanocoatings promising for industrial wastewater as well as drinking water purification setups. Furthermore, protuberant recycling and regenerative capacity make these hybrid nanocoatings an eco-friendly system for hydro-remediation.