Nanocomposite interface coupled with thickness optimization promoting water dissociation in heterogeneous bipolar membrane

Abstract

AbstractBipolar membranes (BPMs) are multilayered composite film containing an interface layer sandwiched between cation exchange layer (CEL) and anion exchange layer (AEL), and are capable of dissociating water molecules under reverse bias potential. Woven fabric supported heterogeneous bipolar membranes (HBMs) were synthesized adopting layer‐by‐layer solvent casting technique. Nanocomposite layer based on sulfonated polyether ether ketone (SPEEK) and GO (graphene oxide) were applied at the interface of CEL/AEL made of cation/anion exchange resins and poly (vinyl chloride) as binder to advance water dissociation in HBMs. Thickness of monopolar layers were initially optimized without any interfacial layer. Introduction of SPEEK interface substantially lowered onset water dissociation potential, Udiss (~1.87 V) relative to the HBM without interface (~3.27 V), which got further reduced (~1.80 V) by nanocomposite (GO + SPEEK) interface. Udiss recorded with SPEEK + GO as interface was much lower than some of the recently reported homogeneous BPM. The NaOH production from NaCl (1.0 mol⋅L−1) solution in a bipolar membrane electrodialysis set up containing synthesized HBM with nanocomposite interface (SPEEK + GO) was double than that of NaOH concentration obtained with HBM having no interface, where the current density was fixed at 50.0 mA·cm−2. Careful optimization of monopolar/interface layer thickness and composition of nanocomposite interface results in developing cost effective HBMs facilitating water dissociation at lower potential.