Controlling the Dynamic Conversion Process of the Water Molecules on the Electrolyte Interface for Producing Free Water

Abstract

ABSTRACT Proton exchange membrane water electrolysis (PEMWE) is a highly promising green hydrogen production method and technology, and it is also one of the important means for scientists and engineers to achieve carbon reduction, carbon emission, and carbon neutrality. Years of research have shown that the oxygen evolution reaction (OER) has slow kinetics and expensive catalysts. We have successfully established a new method for regulating the microstructure and distribution of water at the catalyst–electrolyte interface, activating inert non‐noble transition metal atoms toward acidic OER. Successfully regulating this process is attributed to the new two‐dimensional carbon material of graphdiyne (GDY), a new type of two‐dimensional all‐carbon material. In situ characterization and theoretical calculations demonstrate that GDY drags H 2 O molecules to the catalyst–electrolyte interface and accelerates the dynamic transformation of the rigid hydrogen‐bond network to free water. The free water‐enriched interface is in favor of the activation of water and the replenishment of oxygen vacancies, thereby significantly lifting activity and stability. Consequently, when the active‐insufficient MnO x is coupled with GDY (MnO x /GDY), OER performance is remarkably improved as evidenced by a reduced overpotential from 427 to 339 mV at 10 mA cm −2 in acidic media. More importantly, the PEMWE device using MnO x /GDY as the anode catalyst exhibits a cell voltage of only 1.91 V at 1.0 A cm −2 and maintains robust activity for 500 h at 0.25 A cm −2 .