Kinetics of Hydrogen Evolution Reactions in Acidic Media on Pt, Pd, and MoS2

Hydrogen evolution reaction (HER) are investigated on Pt, Pd, and MoS2 in a 0.5 M H2SO4 electrolyte in a rotating disk electrode (RDE) configuration in the temperature range of 285-335 K. The reaction is temperature-sensitive on all of the three catalyst surfaces at their respective overpotential ranges. The kinetic parameters (activation enthalpy (Delta H-#), free energy of activation (Delta G(#)), and preexponential factor (A(f))) toward HER are obtained from the Arrhenius and Eyring relations, and the overall kinetics on the catalyst surfaces is analyzed. Delta H-# for HER is a strong function of the overpotential in the case of both Pt and Pd. On the other hand, the trend in A(f) suggests that the electrocatalysis of HER on MoS2 originates from an increase in entropy factor, perhaps due to the solvent-dipole interaction at the interface. Such analysis is pivotal to the investigation of electrocatalysis of HER, especially on surfaces for which determination of active-site density is not established.

Automated summary

The hydrogen evolution reaction (HER) on Pt, Pd, and MoS2 in a 0.5 M H2SO4 electrolyte was studied in a rotating disk electrode (RDE) configuration. The kinetic parameters and overall kinetics were analyzed. The results showed that the activation enthalpy for HER on Pt and Pd is strongly dependent on the overpotential, while the electrocatalysis of HER on MoS2 may originate from an increase in entropy factor.