Porous Ni(OH)2 permselective membrane to identify the mechanism of hydrogen evolution reaction in buffered solution

Phosphate buffer solution (PBS) is widely used in hydrogen evolution reaction (HER), however, the HER mechanism in PBS is still unclear whether the phosphate directly react with electrode like H2O. Herein, the porous and defective Ni(OH)(2) permselective membrane covered Pt and Ni electrode was fabricated by the electrodeposition method to identify the reaction mechanism. By obviously rejecting the phosphate and almost unimpededly transferring the OH-, H2O and H-2 , the membrane averts the contact of phosphate with the electrode surface without impeding of the necessary mass transfer of HER. Combining electrochemical analysis and theoretical calculation, the phosphate is found to be the HER reactant of Pt and Ni electrode in PBS. Detailly, the phosphate competes with H2O and accelerates the HER for Pt electrode, while poisons Ni electrode to deteriorate the HER performance. (C) 2021 Elsevier Ltd. All rights reserved.