Electrochemistry of Al3+- Catechol System: Kinetics Vs. Thermodynamics (A1-Triple I)

Abstract

Carbonyls, and quinones among them in particular, occupy a place of choice among organic reversible redox systems for electrocatalysis [1] and energy storage [2]. Their electrochemical behavior is marked by coupled proton and electron transfer (CPET) [3-5]. We have studied this subject in the context of flow batteries [6] and hydrogen carriers [7]. On the other hand, metal ion – catecholate (o-dioxolene) binding [8] attracts attention in different and rather independent domains, including active materials for metal-ion and redox flow batteries [2]. Redox transformations of o-dioxolene-metal complexes are therefore coupled to competitive binding with metal ion and proton at the electrochemical timescale, raising the complexity in the system above that of CPET. These effects have not received proper attention e.g. in aqueous metal-ion battery research.The subject of this communication is the electrochemistry of Al3+ - catechol system in aqueous solution. We discuss the conditions and measurable electrochemical signatures of complex formation, as well as the role of buffer. We explain why our observations are contrasting those on catechol containing polymers proposed for universal metal-ion batteries [9, 10] by considering which reactions attain equilibrium and which are obeying kinetics only.[1] K. Tammeveski et al. J. Electroanal. Chem. 2001, 515 , 101; DOI: 10.1016/S0022-0728(01)00633-7[2] B. Häupler et al. Adv. Energy Mater. 2015, 5 , 1402034; DOI: 10.1002/aenm.201402034[3] M. Quan et al. J. Am. Chem. Soc. 2007, 129 , 12847; DOI: 10.1021/ja0743083[4] J. Wang et al. J. Electroanal. Chem. 2007, 601 , 107; DOI: 10.1016/j.jelechem.2006.10.036[5] Q. Lin et al. J. Phys. Chem. C 2015, 119 , 1489; DOI: 10.1021/jp511414b[6] H. Ghorbani Shiraz et al. J. Energy Chem. 2022, 73 , 292; DOI: 10.1016/j.jechem.2022.06.015[7] M. Vagin et al. Adv. Funct. Mat. 2020, 30 , 2007009; DOI: 10.1002/adfm.202007009[8] R. Maskey et al. Encycl. Inorg. Bioinorg. Chem.; DOI: 10.1002/9781119951438.eibc2810[9] N. Patil et al. ACS Appl. Energy Mater. 2019, 2, 3035; DOI: 10.1021/acsaem.9b00443[10] K. Pirnat et al. Macromolecules 2019, 52, 8155; DOI: 10.1021/acs.macromol.9b01405