Research project: Russell: Non-platinum electrocatalysts for oxygen reduction and oxygen evolution

The electrochemistry of oxygen is also important in sensors (oxygen reduction), water electrolysers (oxygen evolution), and metal-air batteries (both oxygen reduction and oxygen evolution). Whilst platinum-based catalysts remain the most widely used in acidic media, especially for oxygen reduction owing to their superior activity and stability in the harsh conditions found in the electrochemical environment, non-platinum catalysts offer less expensive alternatives, especially in alkaline media where Ni, Fe, and Co based catalysts are stable.

A number of projects are currently active under this broad heading, as briefly described below. In each case we are employing a combination of electrochemical and structural (XRD and TEM) or spectroscopic (XAS) techniques to characterise the activity of new catalysts formulations and to provide fundamental information regarding how the structure and/or composition of the catalyst determines activity and/or durability.

• Sensors: with City Technology we are exploring new catalysts and electrode structures to improve the design of electrochemical gas sensors.
• Water Electrolysers: with ITM Power we have recently completed a study exploring the effects of composition and particle size on the activity and durability of RuO2 and IrO2 mixed oxide catalysts. In this project in situ XANES was used to determine the effects of composition and applied potential on the oxidation states of the components. An electrochemical cell was designed for the in situ XANES studies to allow data acquisition under conditions of gas evolution.
• Metal-air batteries: as part of the EU FP7 project POWAIR, coordinated by C-Tech Innovation, and continuing further we are developing more active and durable air electrodes for use in redox flow metal-air batteries. The challenges are in achieving a catalyst that is active for both oxygen reduction and oxygen evolution and durable, particularly under oxygen evolution conditions. The catalysts are based on either compositional or structural modifications to NiCoO spinels, which are characterised by ex situ and in situ XRD and XAS.