Electrogenerated hydrophilic carbon nanomaterials with tailored electrocatalytic activity. (10th April 2019)

• Record Type: Journal Article
• Authors: Meirinho, S.G.; Ferraria, A.M.; Botelho do Rego, A.M.; Fernandes, A.J.S.; Viana, A.S.; Oliveira, M.C.
• Is Part Of: Electrochimica acta. Volume 302(2019)
• Page Start: 402
• Page End: 413
• Publication Date: 2019-04-10
• Subjects: Electrocatalysis -- Oxygen reduction -- Peroxide reduction -- Hydrophilic carbon -- Autocatalysis; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2019.02.025
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: This work investigates the influence of the type of buffer electrolyte used in the generation of Electrochemical Hydrophilic Carbon (EHC) on their physical-chemical properties and electrocatalytic activity. The EHC nanomaterials were prepared in three different biological buffers, phosphate, glycine and citrate buffers (EHC@phosphate, EHC@glycine, EHC@citrate) and their surface properties were fully characterized by AFM, XPS and Raman. The EHC nanomaterials drop cast onto a glassy carbon electrode were electrochemically characterized in [Fe(CN)6 ] 3-/4- and [Ru(NH3 )6 ] 3+/2+ redox probes solutions, and their electrocatalytic activity was investigated towards hydrogen peroxide and oxygen reduction reactions (ORR) in a phosphate buffer solution. It was found that the nature of buffer electrolyte strongly influences the surface chemical state of the EHC materials, disorder degree in the hexagonal sp 2 carbon network and oxygen functional groups, affecting both the EHC electrocatalytic activity towards the ORR and H2 O2 reduction reaction. The most catalytic material for the ORR was EHC@citrate, whereas EHC@glycine showed the highest oxygen conversion (n ≅ 2.7 to 3). Moreover, it was shown that the content of oxygen singly bonded to carbon correlates strongly with the number of electrons transferred. A very singular behaviour in the electrochemical reduction of hydrogen peroxide was observed on EHC@glycine, qualitatively interpreted as an autocatalytic reaction. In contrast, a blocking-like effect was depicted on EHC@phosphate. These results must have an important impact in the development of materials with peroxidase-like activity and in the design of O2 sensors with non-sensitivity to H2 O2 .