Concentration ratio of [OH−]/[BH4−]: A controlling factor for the fuel efficiency of borohydride electro-oxidation

The electrooxidation of borohydride: A mechanistic study on palladium (Pd/C) applying RRDE, 11B-NMR and FTIR

“…Based on these electron counts various mechanisms and intermediates were reported. Furthermore, influences on the mechanisms of electrode morphology and concentration ratios are reported [14,18]. The anodic reactions observed during measurements are even more complicated due to electrooxidation of hydrogen that is evolved by parallel hydrolysis.…”

“…(1) the reaction mechanism also strongly depends on the hydroxide concentration or more precisely the concentration ratio [OH − ]/[BH 4 − ] [9,18,22]. Liu et al found a ratio of 5 or higher to be necessary for a complete 8 electron oxidation on gold Au/C and silver Ag/C catalysts and only a 3 electron exchanging mechanism for a ratio of 1 [18]. As can be seen from the short overview above the reaction mechanism is quite complex and still not completely resolved.…”

Pd Modified MmNi50.6Co10.2Mn5.4Al1.2 Alloy as the Catalyst of NaBH4 Electrooxidation

“…So it can be concluded that high currents can be generated by using high concentration NaBH 4 . The flux at the surface is proportional to CD 1/2 (C: concentration, D: diffusion coefficient) [37]. We noticed that when the concentration of NaBH 4 was increased to 0.2 mol dm -3 , gas bubbles were formed on the electrode surface, indicating the occur-rence of hydrogen evolution.…”

Ordered PtSn/C Electrocatalyst: A High Performance Material for the Borohydride Electrooxidation Reaction

“…On the other hand, two main processes took place on Pt: at low potentials, a seven-electron process produced hydride on the Pt surface, and BH 3 OH − adsorption poisoned the electrode; at higher overpotentials, a five-or six-electron process occurred on partially oxidized Pt surface with adsorbed HO − and BH 3 OH − . Liu, Yang, and Li [15] Even though they did not succeed determining i k for the processes occurring at both surfaces due to uncommon Koutecky-Levich relationship, it was proposed a mechanism based on the experimental findings like as number of transferred electrons and dependence on the OH species concentration. Merino-Jimenez et al [19] evaluated the Pd-Ir (1:1) alloy covered by carbon microfibers and supported on a titanium plate as anode for the BOR.…”