MIT researchers have created a new electrode that improves electrochemical systems for converting CO2 into essential materials. This innovationdescribed in Nature Communications by MIT PhD student Simon Rufer, Professor Kripa Varanasi and collaborators, aims to make these systems more practical for industrial applications.
Transform CO2 into ethylene and more
The MIT team's work focuses on converting CO2 into ethylene, a versatile chemical typically used to produce plastics and fuels. This process has the potential to generate other high-value chemicals, including methane, methanol and carbon monoxide. Ethylene alone is valued at around 1000 dollars per ton, which makes its production economically attractive.
The team's method involves a water-based electrochemical process using a catalyst on a gas diffusion electrode. These electrodes must strike a balance between two properties: conductivity and hydrophobicity (water resistance).
While conductivity improves electron flow, increasing hydrophobicity reduces interference from the water-based solution. However, balancing these properties is challenging - increasing one often compromises the other.
Innovative design using copper-infused PTFE
MIT's solution incorporates polytetrafluoroethylene (PTFE), also known as Teflon, for its excellent hydrophobic qualities. Because PTFE has no conductivity, the team embedded copper wires in a thin layer of PTFE to create "highways" for electron movement. This addition allows for effective conductivity through the material without sacrificing its hydrophobic nature, allowing for a more efficient conversion process.
To prove scalability, the team created a sheet ten times larger than traditional laboratory samples, carrying out exhaustive tests to assess performance and energy requirements. The results demonstrated that conductivity decreased with increasing electrode size, highlighting the need for embedded conductive materials for industrial-scale applications.
The researchers also developed a model that predicts how voltage and product distribution vary within larger electrodes, allowing them to determine the optimal placement of copper wires to reduce conductivity loss. By incorporating copper into PTFE, they divided the electrode into smaller conductive sections, which maintains efficiency even on larger scales.
To demonstrate durability, the MIT team used a test electrode for 75 hours, observing minimal performance degradation. This design has the potential to make CO2 conversion systems viable for industrial use..
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