# From Formation to Failure: The Role of Hydrogen Peroxide in Proton Exchange Membrane Technologies

## TL;DR

This paper reviews how hydrogen peroxide harms proton exchange membrane technologies and explores ways to detect and mitigate its effects.

## Contribution

The paper provides a systematic review of hydrogen peroxide's formation, detection, and mitigation in PEMFCs and PEMWEs.

## Key findings

- Hydrogen peroxide degrades PEM components through reactive radicals, reducing device efficiency and lifespan.
- Current detection methods for hydrogen peroxide are inadequate under real operating conditions.
- Emerging catalytic strategies aim to suppress hydrogen peroxide-induced damage in PEM technologies.

## Abstract

Hydrogen peroxide
is a catalytic byproduct in proton
exchange membrane
fuel cells (PEMFCs) and proton exchange membrane water electrolyzers
(PEMWEs). It may be produced as a side product of the electrochemical
processes occurring at the cathode in PEMFCs, or at the anode in PEMWEs,
or it may be produced due to gas crossover through either catalytic
chemical or electrocatalytic processes. The challenge posed by H2O2 is its catalytic decomposition into highly reactive
hydroxyl and peroxyl radicals, which trigger cascading degradation
of critical components. This degradation directly compromises device
efficiency and shortens the lifespan, representing a limiting factor
in the durability of PEMFCs and PEMWEs. However, existing methods
for detecting and quantifying in situ H2O2 generation
are limited in their ability to accurately reflect real operating
conditions (e.g., high current densities, mixed reactant environments),
hindering a complete understanding of its dynamic (electro)­catalytic
formation and impact. To address these gaps and advance the performance
of hydrogen-based energy technologies, a comprehensive analysis of
H2O2 (electro)­catalytic generation mechanisms,
detrimental effects, and catalytic mitigation strategies is essential.
In this work, we systematically review recent progress in H2O2 research for PEMFCs and PEMWEs, focusing on (1) underlying
H2O2 (electro)­catalytic formation mechanisms,
(2) the role of gas crossover in (electro)­catalytic H2O2 formation, (3) current detection techniques (and their limitations),
and (4) emerging catalytic strategies for suppressing damage due to
H2O2. This review highlights the need for improved
in situ detection tools and targeted suppression approaches to enhance
the reliability and longevity of PEMFCs and PEMWEsimportant
technologies for hydrogen-based energy systems.