Pt modified Ni-PES membrane for simultaneous hydrogen production and separation via alkaline water electrolysis

Alkaline water electrolysis (ALK) faces technological challenges including low electrolysis efficiency, high energy consumption, and limitation of membrane technology. Herein, we report a nickel-polyethersulfone (Ni-PES) composite membrane modified by platinum (Pt) to function simultaneously as a highly active hydrogen evolution reaction (HER) electrode and a hydrogen-selective membrane. The Ni-PES membrane was prepared by phase inversion tape casting and atmospheric sintering, in which PES polymer provides the structural skeleton and metallic nickel serves as the electronic conductor and HER catalyst. Moreover, proper heat-treatment changes the microstructure and hydrophobicity of Ni-PES membrane, and Pt electrodeposition significantly boosts HER activity. The optimized Pt@Ni-PES-400 membrane electrode achieves a low overpotential of 104.9 mV@100 mA cm −2 and a Tafel slope of 125.8 mV dec −1 in concentrated alkaline electrolyte (30 wt% KOH). Furthermore, we design and fabricate a H-type, diaphragm-free, and two-chamber electrolytic cell, which is separated by Ni-PES-based membrane. Such membrane-based H cell realizes the combination of hydrogen production and separation processes: the in-situ generated hydrogen via water electrolysis is transported through the Pt@Ni-PES-400 membrane to the gas collection chamber, with a hydrogen purity of up to 99.95 % and a hydrogen permeation rate of 0.18 mL min −1 cm −2 at an overpotential of −500 mV, and the cell performance remains stable during 100 h of operation.