Amphoteric Membrane Loaded with a Noble Metal-Free Hollow Spherical NiCoP@rGO Bifunctional Electrocatalyst for Alkaline Water Electrolyzers

For overall water splitting and simultaneous hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) processes in alkaline media, a bifunctional electrocatalyst loaded on both surfaces of an amphoteric ion exchange membrane (AIEM) was conceptualized to improve the efficiency. Herein, we report a partially fluorinated polymer (poly(vinylidene fluoride-co-hexafluoropropylene))-based AIEM grafted with sulfonic acid and quaternary amine functional groups. The prepared AIEM was utilized as a substrate for the loading of the electrocatalyst (hollow spherical NiCoP@rGO) to prepare a membrane electrode assembly. The morphology-dependent bifunctional performance of the NiCoP@rGO electrocatalyst was assessed for overall water splitting (HER and OER). The prepared electrocatalyst exhibited a low potential (0.297 V for the HER and 1.57 V for the OER) at 10.00 mA/cm2 current density, corresponding to 129 and 110 mV/dec Tafel slopes, respectively. Thus, the prepared MEA exhibited better overall water splitting performance in comparison to other commercialized membrane substrates and reported electrocatalysts in the literature, at 30 °C under 400 mA/cm2 in alkaline medium (1.0 M KOH). A stable fluorinated polymer-based AIEM and hollow spherical NiCoP@rGO electrocatalyst provide a significant improvement in water electrolysis and simultaneous H2 and O2 production via HER and OER processes.