Tuning the chemical and electrochemical properties of carbon paper-based electrodes by pyrolysis of polydopamine nanofilms

Tuning the chemical and electrochemical properties of carbon paper-based electrodes by pyrolysis of polydopamine nanofilms

• Autor
• Jaqueline Falchi da Rocha
• Co-autores
• Julia C. de Oliveira , Jefferson Bettini , Mathias Strauss , Guilherme S. Selmi , Anderson K. Okazaki , Rafael F. de Oliveira , Renato S. Lima , Murilo Santhiago
• Resumo

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  Paper-based electrochemical analytical devices hold great promise for high-sensitivity, low-cost, affordable, miniaturized, easy-to-use and decentralized analysis for healthcare applications. In relation to these properties, chemical functionalization plays a key role in tuning the sensitivity, selectivity and surface area of electrodes. However, it is challenging to control different surface properties using a single functionalization route. In this work, we attempt to tune the wettability, chemical composition, and electroactive area of carbon paper-based devices by thermal treatment of polydopamine (PDA) at different temperatures. PDA is a strong candidate for surface functionalization due to its simplicity in introducing O and N-based groups in a thickness-tunable manner. However, it is challenging to tune the surface properties of PDA without adding additional chemical reagents. The PDA nanofilms were first deposited on pyrolyzed paper electrodes and heat treated in the range of 300 – 1000oC in a second step. After PDA deposition, the surface becomes rich in nitrogen and oxygen, hydrophilic and with a large electroactive area. As the temperature increases, the surface becomes hydrophobic and the electroactive area decreases. Furthermore, different chemical compositions of nitrogen species can be tuned on the surface. Surface modifications were followed by Raman, XPS, laser scanning confocal microscopy, contact angle, SEM-EDS, electrochemistry and electrical experiments. Pyrolysis of PDA films up to 1000oC showed surface transitions from superhydrophilic to hydrophobic, reduction in thickness (micrometer to nanometer) and improvement in conductivity. Transmission electron microscopy revealed that as deposited PDA film has globular structures and after pyrolysis a lamellar structure is formed. Pyrolysis also offers a unique way to adjust the R2- NH / =NR ratio on the interface, which is relevant for further applications.  As a proof of concept, we employ PDA-treated surfaces to anchor AuCl4- ions. After electrochemical reduction, we observed that depending on the temperature used, it is possible to control the size, concentration, and position (bulk or external face) of the Au-nanoparticles on the surface. Thus, we conclude that our route opens a new avenue to add versatility to electrochemical interfaces.

   

• Palavras-chave
• Pyrolyzed paper, polydopamine, gold nanoparticles, electrochemical devices
• Modalidade
• Comunicação oral
• Área Temática
• Nanociência e Nanotecnologia