Background
Knowledge of molecular mechanisms of electrocatalytic reactions is crucial to improve performance and lower costs of CO2 electrolysis. The integration of the components of CO2 electrolysis is incredibly complex, hence characterising operation at scales from single atoms to a full electrolyser system is a grand challenge in electrocatalysis. This challenge requires a new toolbox of experimental and computational techniques spanning extreme spatiotemporal resolution, and with higher sensitivity and accuracy than currently possible.
Aims
To develop a toolbox of advanced characterisation and computational modelling methods to advance fundamental knowledge of CO2 electrolyser and components from atom to system levels.
Outcomes
Understanding the chemical nature and behaviour of catalysts and membranes at the atomic level will underpin models for electrolyser scale-up and optimisation. New operando reaction cells and computational models for studying dynamic transport and reaction processes will significantly benefit catalysis, materials and corrosion science, and chemical engineering communities.
RT4A: Cell designs for operando spectroscopy and microscopy
Project Lead – Professor Karen Wilson
Cell designs for operando spectroscopy and microscopy: This project will establish capability for operando characterisation of working electrocatalysts by developing multiplexed reaction cells to enable synchronous analysis of electrocatalysts by e.g., electron microscopy, X-ray absorption spectroscopy (XAS) and other spectroscopies during applied external stimuli with real-time gas/liquid product analysis. Operando cells should permit dynamic measurements free from gas and electrolyte diffusion limitations, beam-induced damage, and window deformation. Multiplexed operando electrocatalytic cells that overcome these issues will be modelled by CFD to assess mass transport characteristics and optimal design constructed. Online analytical capability will also be established for operando electrochemical measurements. Cells will comprise a common comprise a detachable microfluidic microelectromechanical system base chip with SiN windows coupled to gas/liquid flow control and heating compatible with complementary spectroscopies. A suite of such cells will be developed to: (i) improve imaging resolution; (ii) permit microfluidic microelectromechanical system imaging with flow, heating and bias; and (iii) enable a standard microfluidic microelectromechanical system with online mass spectrometry or chromatography product analysis that replicates the electrochemical behaviour and kinetics of CO2 conversion for the standardised, high-throughput testing protocols from RT2. Projects for HDR students will be based around operando studies of model catalysts in support of T2 and FP1-3.
RT4B: Advanced imaging
Project Lead – Associate Professor Ruth Knibbe
Advanced imaging characterisation provides understanding of morphological and phase changes in materials. New techniques (hardware and software) are being continuously developed for advanced imaging, but are typically developed using model, simple materials. As such, when using these new techniques for investigating more complex real material systems researchers still encounter many experimental challenges. This project focuses on the application of established and emerging imaging tools to understand material synthesis, performance and degradation. These tools include operando liquid electrochemical TEM; in-situ heating TEM; cryo-TEM; 4D-STEM and HR-STEM. These tools will have application across the three themes – electrodes, membranes and catalysts.
RT4C: Kinetics and mechanism across length scales
Project Lead – Professor Debra Bernhardt
This project will develop the key electrode level model necessary for analysis, design and scale-up of the electrolyser. The main resistance to transport lies in the carbon and catalyst layers that comprise packings of nanoparticles, with the carbon layer being infiltrated by gas, and the catalyst layer having both gas and liquid electrolyte. Molecular dynamics simulations will be used to understand the transport in each of these layers and determine multicomponent transport coefficients, and the results will be interpreted using suitable models that are tractable and can be used in electrode-level modelling. For the multiphase transport in the catalyst layer, we aim to develop a model capturing the interplay between energy, gas and electrolyte transport and their phase equilibrium in the electrode. As another component of electrode level modelling, a microkinetic model of the electrocatalytic reaction will be developed, that can be combined with the transport models for analysis at the electrode level. The various energy, transport and reaction models will be combined to develop a working model of the electrode, considering the reaction-diffusion process in the catalytic layer facilitated by the charge transport in the electrode. Joule heating of the electrode will also be considered. The outcome will be a comprehensive model of reaction and transport in the electrode that can be used in process design and scale-up of the electrochemical cell for electrocatalytic carbon dioxide reduction.