On the current-potential curve of a very fast hydrogen evolution process up to high current densities

Qualitative and quantitative identification of copper oxides

“…Electrolyte at 0.1 M concentration was found to have a maximum current density. [54,55] This study was confirmed by the current EIS measurement of different concentrations. Electrolyte concentration at 0.1 N (or 0.1 M) had the lowest value of time constant.…”

Maximizing Hydrogen Evolution Performance on Pt in Buffered Solutions: Mass Transfer Constrains of H2 and Buffer Ions

“…For a more rigorous treatment, the Stefan–Maxwell equation must be solved for the concentrated multicomponent electrolyte, , which requires cross-diffusion coefficients between interacting ions and the solvent. Moreover, bubble-induced stirring effect might have promoted mass transport . Such optimizations of the model may achieve complete reproduction of the rotation-dependent voltammograms, but these details lie outside the scope of this paper.…”

“…In this study, buffer species were assumed to be electroinactive, as shown in eq , and H 3 O + is the sole reactant although direct buffer ion reduction to achieve HER may be possible. Although the H 2 bubble starts to appear and the bubble-induced stirring effect is reported on a Pt RDE below −5 mA cm –2 in 5 mol L –1 H 2 SO 4 , they are not considered in the present model for simplification. The current density is determined by the pure HER reaction rate ( r HER ) and pure HOR reaction rate ( r HOR ), which are defined by Zheng et al where F is Faraday constant.…”

“…In an acidic solution, HER/HOR current on a Pt rotating disk electrode (RDE) is purely determined by the diffusion of H 2 even in the presence of vigorous rotation (3600 rpm). 4,6,7 Because of facile kinetics in an acid solution and sufficient mass transport of protons, the local activity of H 2 at the electrode surface is equilibrated with the electrode potential of the Nernst equation; it determines the flux of H 2 between the electrode and bulk electrolyte solution and the resultant HER current density, which Zheng et al and Durst et al defined as (Nernstian) diffusion current of H 2 product. 4,8 In this case, it is difficult to obtain kinetic current using RDE configuration.…”

“…Classically measured data for HER exchange current density were recently questioned by several authors. − It has been well described that an accurate measurement of the exchange current density cannot be achieved in a conventional electrochemical setup for the extremely active Pt, as diffusion contribution cannot be excluded for such cases. In an acidic solution, HER/HOR current on a Pt rotating disk electrode (RDE) is purely determined by the diffusion of H 2 even in the presence of vigorous rotation (3600 rpm). ,, Because of facile kinetics in an acid solution and sufficient mass transport of protons, the local activity of H 2 at the electrode surface is equilibrated with the electrode potential of the Nernst equation; it determines the flux of H 2 between the electrode and bulk electrolyte solution and the resultant HER current density, which Zheng et al and Durst et al defined as (Nernstian) diffusion current of H 2 product. , In this case, it is difficult to obtain kinetic current using RDE configuration. Instead, measurement techniques are necessary that can provide sufficient mass transport of H 2 , such as H 2 pump method with membrane electrode assembly, ,, ultramicroelectrode, , and scanning electrochemical microscopy. , Durst et al reported the exchange current density for Pt to be as high as 70 mA cm –2 , which is 70 times higher than Trasatti’s data (1 mA cm –2 ). ,− …”