# Fluorine-Free Ion Exchange Membranes for (Photo)electrochemical Applications

## TL;DR

This paper reviews fluorine-free ion exchange membranes as sustainable alternatives to traditional fluorinated ones for photoelectrochemical energy systems.

## Contribution

The paper provides a comprehensive review of fluorine-free ion exchange membranes for (photo)electrochemical applications.

## Key findings

- Fluorine-free membranes can match fluorinated ones in ionic conductivity and durability.
- Emerging materials address environmental and economic concerns of traditional membranes.
- Characterization methods and performance metrics are crucial for evaluating fluorine-free alternatives.

## Abstract

The increasing global demand for sustainable energy solutions
has
driven significant advancements in photoelectrochemical (PEC) technologies,
particularly for hydrogen production and biomass valorization. A key
challenge for PEC cells is the selection of ion exchange membranes
(IEMs) that ensure efficient product separation between anode and
cathode half-cells while enabling efficient ion transport. Moreover,
these membranes also need to show long-term stability. Traditionally,
perfluorinated membranes such as Nafion have been widely used due
to their high proton conductivity and chemical resilience. However,
their high cost, environmental concerns, and the impending regulatory
restrictions on per- and polyfluoroalkyl substances necessitate the
development of fluorine-free alternatives. This review explores the
latest advancements in fluorine-free IEMs for (photo)­electrochemical
applications, highlighting their synthesis, physicochemical properties,
appropriate characterization methods, and performance metrics. We
discuss emerging materials that offer comparable ionic conductivity,
durability, and operational efficiency while addressing recyclability
and environmental impact. By assessing the potential of these next-generation
membranes, we aim to provide insights into their role in advancing
photo- and electrochemical systems toward a more sustainable and economically
viable future.