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Ainoa Paradelo Rodriguez
Ainoa Paradelo Rodriguez

Analysis of Transient Electrochemical Processes by Mass Spectrometry

Announcement: Friday November 3, 2023 Ainoa Paradelo Rodriguez will defend her thesis titled:


Ainoa is a PhD student in the Photocatalytic Synthesis Group. Supervisors are prof.dr. Guido Mul and dr. Bastian Mei, from the Faculty of Science & Technology. 



This PhD thesis goes from the fundamentals of electrochemical reactions to the

application. First, we evaluate the Electrochemistry - Mass Spectrometry (EC-MS) setup

for the fundamental mechanistic study of electrochemical reactions over metal surfaces.

Among others, the electro-oxidation mechanism of ethanol over a platinum surface and

the electrochemical reduction of nitrate to ammonia over Ti, Ag and bimetallic TiAg

electrodes have been investigated. Furthermore, there have been collaborations using

the EC-MS for other reactions that confirmed the sensitivity and versatility of this

instrument in several applications. In the last chapter, we focus on the application of the

acquired mechanistic knowledge in the nitrate electrochemical reduction over TiAg for

more practical purposes using Ti hollow fiber electrodes.

The ethanol electrochemical oxidation reaction on Pt in acidic media has been

investigated in Chapter 2. Here, with the help of the EC-MS, ethylene was revealed as an

intermediate product. Moreover, the hydrogenation of ethylic fragments was proven by

performing experiments with H2 pulses.

Chapter 3 presents a summary of the different studies in which the use of EC-MS

facilitated the investigation of electrochemical reaction mechanisms, demonstrating its

versatility. Some of the reactions investigated are the (non)-Kolbe reaction and nitrate

reduction on Ti. Moreover, the high sensitivity of the setup allowed us to detect small

amounts of NO produced by a chemical donor. Finally, the possibility of using a gaseous

reactant as a gas carrier allowed the detection of intermedia products in NO reduction

and CO2 reduction with nitrate in the electrolyte on Cu.

The nitrate reduction mechanism of bimetallic TiAg electrodes was investigated in

Chapter 4. First, chronoamperometry measurements showed a lower overpotential at

enhancement in Faradaic efficiency of the TiAg electrodes in comparison to the pure

metals (Ti, Ag). Later, the synergy between the metals was revealed by the pronounced

enhancement of NO evolution detected by the EC-MS.

After proving TiAg synergy, Ti tubular porous electrodes were modified with Ag

particles to evaluate the catalytic performance of the bimetallic material and to

understand the influence of mass transport in Chapter 5. A significant dependence of

the performance of the electrode on mass transport was discovered.