Sulfide pendants in cobalt clathrochelate complexes as a proton pump for the electrochemical H2 generation

• Published in: International journal of hydrogen energy 2016-06, Vol.41 (22), p.9312-9319
• Main Authors: Dolganov, A.V., Tarasova, O.V., Moiseeva, D.N., Muryumin, E.E.
• Format: Article
• Language: English
• Subjects: Aqueous solution; Cage complexes cobalt(II); Electrocatalytic reduction; Hydrogen evolution reaction; Immobilization
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2016.03.131

The cobalt(II) cage complexes with terminal mercapto groups were immobilized on a surface of the working gold electrode. The clathrochelate-modified electrodes demonstrate a high electrocatalytic activity for a long time without loss of catalytic activity in range of pH from 1 to 7 and chemical stability of and an absence of the desorption or decomposition of the immobilized cobalt cage complexes. The controlled-potential electrolysis with gas chromatography analysis confirmed the production of H2 in the high Faraday yields. In aqueous solutions, the sulfide pendants with activated α-hydrogen atoms in the second coordination sphere of this encapsulated metallocenter may undergo a fast deprotonation–reprotonation reaction, which leads to increased rate formation of the H–H bond. The sulfide pendants in the ribbed-functionalized cage cobalt complexes activate and spatially prearrange protons for the faster formation of the HH bond at the encapsulated cobalt ion as a redox-active catalytic metallocentre. As a result, these molecules cause the dramatic increase in the rate of H2 and work as a “proton pump” for H2 generation from water. [Display omitted] •Thiol-terminated cobalt clathrochelates are electrocatalysts for H2 production.•Dependence of potential of electrocatalytic 2H+/H2 process on pH is observed.•General kinetic scheme of 2H+/H2 process is discussed.•Protonation of electrochemically generated cobalt(I) centers is rate-limiting stage.