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| Author(s): |
Rafael Luiz Romano
Total Authors: 1
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| Document type: | Master's Dissertation |
| Press: | São Carlos. |
| Institution: | Universidade de São Paulo (USP). Instituto de Química de São Carlos (IQSC/BT) |
| Defense date: | 2020-11-24 |
| Examining board members: |
Hamilton Brandão Varela de Albuquerque;
André Henrique Baraldi Dourado;
Raphael Nagao de Sousa
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| Advisor: | Hamilton Brandão Varela de Albuquerque |
| Abstract | |
Dynamic instabilities can occur in electrochemical systems that are far from the state of thermodynamic equilibrium. Depending on the experimental conditions, current and potential oscillations can be observed during the catalytic electro-oxidation of small organic molecules, such as methanol, formic acid and glucose, on platinum. When two or more systems are coupled, it is possible to modify the individual oscillatory dynamics of each system, so that the resultant will depend on the nature and the intensity of the coupling. Additionally, the coupling allows studying a phenomenon of great importance for many physical and chemical processes: the synchronization. In this work, the unidirectional coupling of electrocatalytic oscillators was studied. Particularly, we investigated how the identity of the Master oscillator affects the oscillatory dynamics of the Slave in terms of frequency, amplitude and waveform of the oscillations. Two sets of oscillators were considered: Master(methanol)-Slave(methanol) and Master(formic acid)-Slave(methanol). We observed that both the identity of the Master oscillator and the magnitude and sign of the coupling constant have a direct impact on the potential applied to the Slave and, consequently, affect the temporal evolution of this oscillator. For the Master(methanol)-Slave(methanol) coupling, different synchronization states could be identified by varying the constant k: the oscillators shown lag and complete synchronization when using k equal to -150 and -850 V/A, respectively. For the Master(formic acid)-Slave(methanol) coupling, phase synchronization was identified when k = 150 V/A: the oscillators shown a phase-locking with 2:3 ratio (Slave:Master). The same type of synchronization was identified when k = 300 V/A, but in this case, Master and Slave shown phase-locking with 1:2 ratio. Additionally, the lag and complete synchronization were observed by using k equal to -500 and -850 V/A, respectively. In general, the waveform and values of frequency, amplitude and mean potential of the Slave oscillations could be modified by means of unidirectional coupling. Even by coupling chemically distinct Master and Slave oscillators, different behaviors could be induced on the Slave, with conditions in which its dynamics were similar to that of the Master. (AU) | |
| FAPESP's process: | 18/23942-5 - Electrical coupling of individual electrocatalytic oscillators |
| Grantee: | Rafael Luiz Romano |
| Support Opportunities: | Scholarships in Brazil - Master |