Rotating ring-disc electrode (RRDE) investigation of borohydride electro-oxidation

Electrochemical impedance spectroscopy study of borohydride oxidation reaction on gold—Towards a mechanism with two electrochemical steps

“…Some authors claim it would include several EC steps [22,34,37,38], the chemical ones being fast [39], overall yielding to near-complete faradaic efficiency. On the contrary, recent studies [19,20,40] point towards an overall CE pathway at low reaction overpotential, overall yielding to lower-than-expected faradaic efficiency, because gold cannot electrooxidize all the H 2 formed, as recently demonstrated using on-line electrochemical mass spectrometry (OLEMS) [20]. One may admit that improving the engineering of the BOR electrocatalysts and the design of the future electrode materials is not an easy task when the pathway of the reaction of interest is not known with more precision.…”

“…Even gold, albeit often erroneously considered as a material not promoting the heterogeneous hydrolysis of BH 4 − (up to now, there was almost unanimity on that point), yields BH 3 OH − [40] and H 2 [20], both molecules translating the gold catalytic activity regarding the heterogeneous chemical decomposition of sodium borohydride. The instability generated by such phenomena (e.g.…”

First principles mechanistic study of borohydride oxidation over the Pt(111) surface

“…Postulated mechanisms are mainly based on cyclic voltammetry studies, a method severely limited in its ability to discern elementary reactions for an eight electron reaction based on one to three oxidation features. Chronoamperometric experiments [22] and rotating ring disk electrode studies [23] have also failed to provide definitive results to identify elementary reaction steps. Definitive experimental determination of the reaction mechanism is difficult, motivating our use of DFT methods to study borohydride oxidation and hydrogen evolution over the Pt surface.…”

Nanoporous gold anode catalyst for direct borohydride fuel cell

“…The room temperature deactivation originated from an increase in ligament size which resulted in pore clogging and a decrease in active surface area. Secondly, NPG exhibits good thermal stability and resistance to oxidation [19] and thus can overcome the aggregation or sintering limitations which Au nanoparticles encounter at elevated temperatures or in an oxidative environment [20]. NPG in a foam type structure has been shown to exhibit high CO oxidation activity, however, the catalytic reactions only occur at the foam surface [22].…”