Corrosion and Transformation of Solution Combustion Synthesized Co, Ni and CoNi Nanoparticles in Synthetic Freshwater with and without Natural Organic Matter

Abstract

Pure metallic Co, Ni, and their bimetallic compositions of Co3Ni, CoNi, and CoNi3 nanomaterials were prepared by solution combustion synthesis. Microstructure, phase composition, and crystalline structure of these nanoparticles (NPs) were characterized along with studies of their corrosion and dissolution properties in synthetic freshwater with and without natural organic matter (NOM). The nanomaterials consisted of aggregates of fine NPs (3–30 nm) of almost pure metallic and bimetallic crystal phases with thin surface oxide covered by a thin carbon shell. The nanomaterials were characterized by BET surface areas ranging from ~ 1 to 8 m2/g for the Ni and Co NPs, to 22.93 m2/g, 14.86 m2/g, and 10.53 m2/g for the Co3Ni, CoNi, CoNi3 NPs, respectively. More Co and Ni were released from the bimetallic NPs compared with the pure metals although their corrosion current densities were lower. In contrast to findings for the pure metal NPs, the presence of NOM increased the release of Co and Ni from the bimetallic NPs in freshwater compared to freshwater only even though its presence reduced the corrosion rate (current density). It was shown that the properties of the bimetallic nanomaterials were influenced by multiple factors such as their composition, including carbon shell, type of surface oxides, and the entropy of mixing.

Cu/CuO-Doped ZnO Nanocomposites via Solution Combustion Synthesis for Catalytic 4-Nitrophenol Reduction

“…The porous morphology of NPs and NCs was confirmed from the SEM and TEM images. HRTEM images confirmed the slight d-spacing value differences between the single ZnO crystal and the Cu-doped 19,20,43 with further improvement using the solution combustion synthesis method. The PVA-polymerstabilized ZnO NPs were synthesized by dissolving the zinc nitrate (Zn(NO 3 ) 2 •6H 2 O) precursor in the previously dissolved and cooled PVA suspension.…”

Comparison of different methods for Li2MTi3O8 (M – Co, Cu, Zn) synthesis

“…This work aims at obtaining powders of Li 2 M Ti 3 O 8 titanates (where M – Co, Cu, Zn) by the use of three different methods: sol–gel; self‐propagating high‐temperature synthesis (SHS method) from glycine‐citrate nitrates mixtures without preliminary dissolution of the starting components; and the SHS method from aqueous solutions. In addition, a study of their phase composition, thermal stability, dispersion, microstructure and electrochemical characteristics was made 26‐28 …”