Gas diffusion electrode for CO2 electrolysis
The electrochemical conversion of CO2 to valuable molecules or fuels, such as methanol, using green electricity is crucial for restoring the carbon cycle in industry and transportation. While water electrolysis for green hydrogen production is a proven technology, the electrolysis of CO2 faces challenges in throughput and catalyst stability. The Gas-Diffusion-Electrode (GDE) concept, which compensates for low CO2 solubility, has limitations, including stability issues, limited current density, and difficulty in upscaling due to pressure balance issues. Overcoming these challenges is essential for advancing the technology from green hydrogen to green carbon-base molecule production (e.g., methanol) by electrolysis.
A groundbreaking innovation in the electrochemical conversion of CO2 involves redesigning the Gas-Diffusion-Electrode (GDE) nano-architecture into a Gas-Diffusion Membrane-Electrode-Assembly (GD-MEA). The core objectives are achieving high throughput (>1A/cm2) for both dilute and concentrated CO2 sources, ensuring stable long-term operation, and creating a scalable and cost-effective technology. Initially, the focus is on demonstrating these breakthroughs in electroreduction of CO2 to syngas, serving as a precursor for methanol, e-fuels, and steel. Subsequent steps will extend the technology to direct conversion to methanol or ethylene.
The innovative approach involves a deterministically designed nano-electrode architecture where each catalytic site has direct gas phase access through a thin liquid sorption layer. This design allows current scaling directly with effective surface area, enabling compatibility with dilute CO2 sources. imec, a research center, plays a crucial role in developing the nanotechnology blocks for engineering and fabricating the device. The metal nanomesh, such as silver or copper, with exceptional properties, including high surface area (approximately 100x enhancement) and high porosity (about 75%), is at the core of this technology.
The nanomesh, only a few micrometers thick, rivals the thickness of a typical catalyst layer on carbon support but boasts greater conductivity and openness with regular spacing for efficient catalyst access and mass transport. The performance benefits and upscalability were demonstrated with a nickel catalytic nanomesh for green hydrogen by the startup company Hyve. A second key component involves functionalizing individual nanowires for direct gas-phase contact during electrochemical reactions. This functional coating not only facilitates gas-liquid diffusion to each nanowire but also ensures ionic coupling with the membrane. The project’s main technological focus includes developing this coating and assembling the catalytic nanomesh with a membrane into a gas-diffusion MEA, and through collaboration with VITO, a demo is projected to be delivered by 2025.
Partners
