Graduate Student Zahed Ghelichkhah

"Development of Gas-Diffusion Electrodes for Iron oxide Nanoparticles Synthesis"

Gas-diffusion electrocrystallization (GDEx)1 provides a new green route for metal recovery to synthesize commercial nanoparticles. This new technology electrochemically removes metal and metalloid ions from aqueous solutions and transforms them into important amorphous or crystalline solids2. A gas-diffusion cathode reduces oxygen, producing hydroxyl ions (OH−) and oxidants (H2O2 and HO2−), which act as reactive intermediates for the formation of stable iron oxide nanoparticles (IONPs)3. The compositional selectivity, morphology, stoichiometry, redox state, particle size, crystallite size, and lattice parameter of the solid iron oxide nanoparticles (IONPs) products can be controlled by varying operational parameters such as pH, ionic strength, metal/metalloid ion concentration, gas composition, and electrochemical potential. Addition of weak acid like NH4Cl enhances the production of H2O2 and hence iron oxide nanoparticles (IONPs)4. Cathodic deprotonation of NH4+ by OH- is the main reason for enhancement of H2O2 production that encourages the reaction proceeds in the forward direction to produce more H2O2.

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[2]. X. D. Benetton , Y. A. Gallego, C. P. Carrero , K, Gijbels, S. Rajamani , an electrochemical process for preparing a compound comprising a metal or metalloid and a peroxide , ionic or radical species, (2018), Pub . No.: US 2018 / 0023201 A1.
[3]. Prato, R.A., Van Vught, V., Eggermont, S. et al. Gas Diffusion Electrodes on the Electrosynthesis of Controllable Iron Oxide Nanoparticles. Sci Rep, 9 (2019) 15370 https://doi.org/10.1038/s41598-019-51185-x.
[4]. R. C. Burgos-Castillo, A.Garcia-Mendoza, Y. Alvarez-Gallego, J. Fransare, M. Sillanpää, X. Dominguez-Benetton, pH Transitions and electrochemical behavior during the synthesis of iron oxide nanoparticles with gas-diffusion electrodes, J. Anal. At. Spectrom, 35 (2020) 2023-2032.