Electrochemistry in Confined Nanoscale Geometries

Supervisor
Professor Mary Ryan
University
Imperial College London
Industry Co-Sponsor
BASF
Project Description
Coating systems are complex multi-component and dynamic, and critical to operational lifetime and safety of engineering materials. They typically fail due to delamination caused by electrochemical reactions at alloy-coating interfaces. Some of the inter-related parameters are shown schematically below. In this project we will improve mechanistic understanding of undercoating degradation processes with particular focus on surface dissolution, oxygen reduction and polymer degradation processes (in particular in response to by-products of oxygen reduction). We aim to deconvolute how the nature and concentrations of reactive species in the confined space between metal and coating play a role in polymer degradation.

This process is an example of reactions that occur in constrained geometries – where mass transport dominates the system – and the approaches developed will be applicable across many areas of electrochemical materials science (including catalysis, batteries etc).

Stage one of this project involves the design and creation artificial systems using 3D printing and nanolithography that mimic confined geometries and defects of under-coating corrosion – and establishing protocols to link these model systems to industrial systems. Ultrasensitive on chip electrochemical mass spectrometry be developed to study products of cathodic reactions, enabling elucidation of the and the role of substrate chemistry and local defect structures in driving these reactions. A key outstanding question is how these electrochemical reactions lead to polymer-coating degradation, these related processed will be studied via in situ Raman/IR methods.

This approach will allow us to elucidate coupling between electrochemical reactions on metal surfaces to polymer degradation, leading to new insights for coating development.

Key Techniques
We will develop on-chip electrochemical mass spectrometry to study the formation of side reactions during oxygen reduction in electrochemical systems. This approach is enabled by new equipment being set up in IS’ lab (part of the Henry Royce Institute at Imperial). This novel approach has not been applied to this system and development for cells and sample geometry is required. Electrochemical EPR will be used to identify damaging radicals generated during ORR.

The correlated polymer degradation will be studied using operando vibrational techniques (Raman/IR) as well as ex situ SIMS and XPS.

A key aspect will be characterisation (environmental-SEM) of model nano-architectured defects.

For information on how to apply for this project please visit cdt-acm.org/phd-opportunities

Joshua Bailey

Being part of the CDT-ACM was an all-round fantastic experience; I not only received great training in a range of advanced characterisation techniques, but I also made strong links with industry and strong bonds with my cohort which have both led to fruitful collaborations.