High Mass Transfer Rate in Electrocatalytic Hydrogen Evolution Achieved with Efficient Quasi-Gas Phase System

The adhesion of H₂ bubbles on the electrode surface is one of the main factors limiting the performance of H₂ evolution of electrolytic water, especially at high current density. To overcome this problem, here a "quasi-gas phase" electrolytic water reaction system based on capillary effect is proposed for the first time to improve the mass transfer efficiency of H₂. The typical feature of this reaction system is that the main site of H₂ evolution reaction is transferred from the bulk aqueous solution to the gas phase environment above the bulk aqueous solution, thus effectively inhibiting the aggregation of H₂ bubbles and reducing the resistance of their diffusion away. Electrochemical test results show that the proposed quasi-gas phase system can significantly reduce the potential required in H₂ evolution reaction process at high current density compared with the conventional electrolytic reaction system. Specifically, the overpotential potential is reduced by 0.31 V when the H₂ evolution current density of 250 mA cm^-2 is achieved.