Rational Design of Stable Electrocatalysts on Corrosion Free Carbon Supports: Improving Fuel Cell Performance

Two of the main global challenges that humanity faces, climate change and the depletion of traditional fossil fuel energy resources, are intrinsically connected. Both can be addressed through the development of new catalyst-based technologies that move society away from a reliance on the burning of fossil fuels with the ability to operate net-carbon neutral. Using catalyst based systems to help achieve this goal is incredibly important. Catalysts help speed up reactions without being chemically consumed themselves.

Electrocatalysis, catalysis driven by an electrochemical potential (voltage), is at the heart of many clean energy generation systems, for example, the conversion of carbon dioxide from the atmosphere to useful products, the electrocatalytic splitting of water to create the clean burning fuel hydrogen and the generation of electricity via electrocatalytic conversion of hydrogen and oxygen to water. In these systems the electrocatalyst typically takes the form of a metal (or alloy) in nanoparticle (NP) form, which sits on a support surface which itself is electrically conducting. The NP morphology is much more efficient at converting reactant to product than if the whole surface was metal, and is also a means to reduce the amount of catalyst needed, especially important when precious metals are employed. Importantly, NP shape (morphology) also controls the effectiveness of the catalyst. To be considered as viable candidates for clean energy production, electrocatalysts and their support materials must be long-term stable to be efficient and cost-effective.

Unfortunately, during operation, performance decrease with time. A major factor is that the NP electrocatalyst changes shape due to many factors e.g. dissolution, agglomeration with neighbouring NPs, loss of atoms etc. These processes are very much influenced by NP size and spacing from other NPs, chemical state and corrosion of the support. This complicated array of processes makes understanding of how operating conditions affect these processes extremely difficult. We address this challenge, by introducing a new corrosion free catalyst support, boron doped diamond (BDD), developed jointly with industry. With a combination of new experimental approaches, we study the atomic-scale degradation mechanisms of electrocatalysts on BDD. This enables us to establish a rational design strategy for the optimal configuration of NP catalysts on this corrosion-free catalyst-support, for long-term stable, more efficient industrially-viable electrocatalysis.

We combine high-resolution electrochemical meniscus cells and atomic-resolution scanning transmission electron microscopy for the controlled electrochemical deposition of NPs and the study of the atomic-level structural changes over time during electrocatalysis. This will enable us to reveal the 3D atomic structure of NPs and the individual reaction mechanisms that define NP degradation during electrocatalytic operation.

In collaboration with industry, the work will be brought full circle by applying this understanding to optimise electrocatalyst loading on BDD, prepared in a high surface area (particulate) form, for proof-of-concept tested in hydrogen/oxygen electrocatalytic energy conversion systems.

This project is suited to chemists, physicists or engineers(you should have obtained, or be about to obtain a First or Upper Second Class UK Honours degree) and involves collaboration with major international industrial partners.