Proposition of a New Power Dissipation Model and Its Analytic Formulation for Electric-Field-Driven Water Dissociation in the Cationic/ Anionic Bipolar Polymer Membranes Junctions

Bipolar Polymer Membranes (BPMs) enable the creation of large, stable pH gradients by drivingwater dissociation (WD) at the cation/anion junction under reverse bias, a process central to electrodialysis, CO₂ capture, and emerging acid–alkaline water electrolysis. Yet, despite decades of study, the mechanism by which intense interfacial electric fields accelerate WD remains debated and is often modeled with ad hoc assumptions. Here, we outline key limitations of existing models of field-enhanced WD in BPMs and we present a power-dissipation model and its formalism that address them. In this new framework, we emphasize that minority ions from water autoprotolysis act as carriers that continuously dissipate field-supplied power in the hydrated nanometric junction. This dissipative input raises the local probability of heterolytic O–H bond cleavage and leads analytically to the dissociation rate’s quadratic dependence on the field. Without adjustable parameters, the model reproduces the required orders of magnitude for the enhancement ratio kd(E)/kd(0), where kd(E) is the field-enhanced water-dissociation rate constant and kd(0) its zero-field value, across typical BPM fields and yields a quadratic current–voltage junction law. A proof-of-principle measurement on a commercial Fumasep® FBM confirms the quadratic current–voltage​ trend, supporting a power dissipation field-driven WD and providing a concise, falsifiable baseline for future studies.