The Electronic Origin of the Zeta Potential is Supported by the Redox Mechanism on an Aqueous Dispersion of Exfoliated Graphite

Autor(es)

Damasceno, Joao Paulo Vita ; Kubota, Lauro Tatsuo

• Tipo de documento: Artigo Científico
• Fonte: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION; v. 61, n. 12, p. 6-pg., 2022-11-23.

Resumo

Herein we have proposed that a redox mechanism can produce surface charges and negative zeta potential on an aqueous graphite dispersion. Graphite was kept in contact with a concentrated ammonia aqueous solution, washed, and exfoliated in water, resulting in a dispersion with lyophobic nature. Ammonia treatment did not provide functional groups or nitrogen doping to graphite. Moreover, this material was washed twice before sonication to remove most hydroxide. Therefore, neither functional groups, nitrogen atoms, nor hydroxide excess is responsible for the zeta potential. Kelvin probe force microscopy has shown that the ammonia-treated and exfoliated graphite has higher Fermi level than the water-treated material, indicating that the contact between ammonia and graphite promotes redox reactions that provide electrons to graphite. These electrons raise the Fermi level of graphite and generate the negative zeta potential, consequently, they account for the colloidal stability. (AU)

• Processo FAPESP: 13/22127-2 - Desenvolvimento de novos materiais estratégicos para dispositivos analíticos integrados
• Beneficiário: Lauro Tatsuo Kubota
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 20/06604-9 - Tintas condutoras à base de nanomateriais carbonáceos para preparação de eletrodos aplicados em dispositivos eletroquímicos
• Beneficiário: João Paulo Vita Damasceno
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 14/50867-3 - INCT 2014: Instituto Nacional de Ciência e Tecnologia de Bioanalítica
• Beneficiário: Marco Aurelio Zezzi Arruda
• Modalidade de apoio: Auxílio à Pesquisa - Temático