Fabrication of Cobalt-Based Nano-Composite Film for Corrosion Mitigation of Copper in Flow Chloride Medium

Corrosion of metals leads to high maintenance costs, as well as potential threats to structural health and safety. Here, we demonstrate the coating of cobalt tungstate (CoWO4) nanoparticles (NPS)/5-mercapto-1-phenyl-1 H-tetrazole derivative (MPT) used as a nano-composite film on Cu surface for the blocking of micropores to hinder the propagation of metastable pits in an aggressive NaCl medium. The mechanism of interaction between the nanoparticles and tetrazole derivative, in addition to the mode of anchoring to the metal surface and blocking the penetration of chloride ions (Cl−), are all investigated. In this investigation, CoWO4 is synthesized via a wet chemical route and thereafter, is combined with MPT at an optimized ratio thus formulating a nano-composite corrosion inhibitor which in solution gets coated on Cu surface. Atomic force and scanning electron microscopic images of the bare Cu reveal dip pits, which by the coating of the nano-composite are suppressed at the nucleation stage during exposure to the aggressive 3.5% NaCl electrolyte under flow conditions. Electrochemical analysis shows high protection of Cu up to 97% efficiency in the presence of the newly formulated nano-composite inhibitor film.

Hydrothermal Synthesis, Characterization and Exploration of Photocatalytic Activities of Polyoxometalate: Ni-CoWO4 Nanoparticles

This study demonstrated the hydrothermal synthesis of bimetallic nickel-cobalt tungstate nanostructures, Ni-CoWO4 (NCW-NPs), and their phase structure, morphology, porosity, and optical properties were examined using X-ray Diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Scanning electron microscopy- energy dispersive X-ray spectroscopy (SEM-EDS), high resolution Transmission electron microscopy (HR-TEM), Brunauer-Emmett-Teller (BET) and Raman instruments. It was found that as-calcined NCW-NPs have a monoclinic phase with crystal size ~50–60 nm and is mesoporous. It possessed smooth, spherical, and cubic shape microstructures with defined fringe distance (~0.342 nm). The photocatalytic degradation of methylene blue (MB) and rose bengal (RB) dye in the presence of NCW-NPs was evaluated, and about 49.85% of MB in 150 min and 92.28% of RB in 90 min degraded under visible light. In addition, based on the scavenger’s study, the mechanism for photocatalytic reactions is proposed.