What are the Tower's method products: Metal-hydroxides or metal-glycerolates?

Author(s)

Goncalves, Josue M. ; Lima, Irlan S. ; Phakatkar, Abhijit H. ; Pereira, Rafael S. ; Martins, Paulo R. ; Araki, Koiti ; Angnes, Lucio ; Shahbazian-Yassar, Reza

• Document type: Journal article
• Source: MATERIALS CHARACTERIZATION; v. 196, p. 9-pg., 2023-01-03.

Abstract

It has been long believed that colloidal nickel hydroxide nanoparticles are produced by the reaction of nickel salts, glycerol and potassium hydroxide known as the Tower method. In the present work, we challenge this belief and reveal the reasons for error in identification of nickel products produced by the Tower method. We propose that Ni-based precursor complexes are the primary products of the Tower method reaction, and these precursors undergo transition to layered Ni-glycerolate derivatives upon thermal treatment. We demonstrated the presence of Ni2+ coordinated to different types of O-donor ligands (glycerol, glycerolate ion, acetate ion and/or OH-) forming Ni-complex precursors. Using in-situ transmission electron microscopy, we showed that Ni-based precursor complexes can be converted to nickel nanoparticles upon exposure to electron beam, but no evidence of nickel hydroxide nanoparticle formation was found. The nickel hydroxide nanoparticles are only formed upon further reaction of Ni-glycerolate precursors with an aqueous alkaline solution. Those new findings shed light on the nature of the metal derivatives obtained by the reaction of Ni2+ and glycerol in the Tower method and provide more solid foundation to design electrode materials for batteries, supercapacitors, electrocatalysts and electrochemical sensors. (AU)

• FAPESP's process: 18/21489-1 - Supramolecular nanotechnology: design, materials and devices
• Grantee: Henrique Eisi Toma
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 14/50867-3 - INCT 2014: National Institute of Science and Technology in Bioanalysis
• Grantee: Marco Aurelio Zezzi Arruda
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/16896-7 - Development of amperometric and impedimetric sensors based on double hydroxides of nickel and vanadium (alpha-NixV1-x(OH)2) and their nanocomposites with expandable graphite/graphene
• Grantee: Josué Martins Gonçalves
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 20/06176-7 - Studying the layered hydroxide electrode materials with in situ transmission electron microscopy
• Grantee: Josué Martins Gonçalves
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor