Stacked Dual Cathode Device for CO2 Reduction Selectivity
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Solution Overview
Problem
Current electrochemical systems face challenges in achieving high selectivity and single-pass conversion ratios for reducing CO2 into molecules containing more than one carbon atom using a single cathodic electrode.
Innovation Solution
A stacked dual cathode device is integrated into an electrochemical system, where a first cathode layer converts CO2 to carbon monoxide, and a second cathode layer further converts carbon monoxide to ethylene, using a conductive membrane that prevents gas crossover between the layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single cathodic electrode is used for CO2 reduction, then the device structure is simple, but the selectivity for multi-carbon molecules is low
Solution Approach 1:
The cathode is divided into multiple stacked layers (first cathode layer, second cathode layer, etc.), each performing a specific reaction step. The first cathode layer converts CO2 to CO, while the second cathode layer converts CO to multi-carbon molecules like ethylene. This segmentation allows each layer to be optimized for its specific function, achieving high selectivity for multi-carbon products while maintaining a relatively simple overall device structure.
Solution Approach 2:
The patent transitions from a traditional single-plane cathode configuration to a stacked three-dimensional architecture. Multiple cathode layers are arranged vertically with conductive membranes separating them, creating a multi-layered structure that enables sequential reactions. This dimensional change allows reactants to flow through multiple reaction zones, improving selectivity without significantly increasing device footprint.
2Adaptability or versatility
If multiple catalytically-active surfaces are placed next to each other, then dual cathode functionality is achieved, but control over tandem reactions is limited
Solution Approach 1:
The cathode is divided into multiple stacked layers (first cathode layer, second cathode layer, etc.), each performing a specific reaction step. The first cathode layer converts CO2 to CO, while the second cathode layer converts CO to multi-carbon molecules like ethylene. This segmentation allows each layer to be optimized for its specific function, achieving high selectivity for multi-carbon products while maintaining a relatively simple overall device structure.
Solution Approach 2:
Conductive membranes are introduced as intermediaries between the cathode layers. These membranes serve multiple functions: they separate the reaction zones to prevent gas crossover, allow ionic conduction for electrochemical reactions, and permit electronic conduction to maintain electrical connectivity. This intermediary structure enables precise control over the tandem reactions by regulating what passes between layers while maintaining electrical continuity.
3Reliability
If a conductive membrane is used to separate cathode layers, then gas crossover is prevented, but device complexity increases
Solution Approach 1:
The conductive membrane performs multiple functions simultaneously: it acts as a physical separator to prevent gas crossover between layers, serves as an ionic conductor to enable electrochemical reactions, and functions as an electronic conductor to maintain electrical connectivity between cathode layers. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving reliable gas separation.
Solution Approach 2:
The conductive membrane is constructed as a composite material combining ion-exchange materials (for ionic conductivity) with conductive polymers like PEDOT:PSS (for electronic conductivity). This composite structure enables the membrane to simultaneously achieve gas separation, ionic conduction, and electronic conduction in a single component, rather than requiring multiple separate layers or materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables controlled reactant flow and complete reaction in the first cathode layer before initiating the second reaction, improving product conversion efficiencies and achieving high selectivities for multi-carbon molecule production.
Implementation Method 1
a first cathode layer which is in contact with an ion exchange membrane that separates the cathode from the anode
Implementation Method 2
a conductive membrane that is both electronically and ionically conductive, but impedes or prevents undesired gas crossover between the first cathode layer and the second cathode layer
Implementation Method 3
The electrochemical device can be used to reduce CO2. The first cathode layer achieves the conversion of carbon dioxide (CO2) (or some other compound) to carbon monoxide (CO) (or another intermediate product). The carbon monoxide is then converted, for example, to ethylene, on a second cathode layer.
Data Source
AI summary
This disclosure provides systems, methods, and apparatus related to a stacked dual cathode device. In one aspect, a device includes an anode chamber and a cathode chamber. The anode chamber includes an anode layer. The cathode chamber includes a first cathode layer and a second cathode layer. The device further includes an ion exchange membrane. The anode layer is in contact with a first side of the ion exchange membrane. A first side of the first cathode layer is in contact with a second side of the ion exchange membrane. The cathode chamber further includes a conductive membrane. A first side of the conductive membrane is in contact with a second side of the first cathode layer and a second side of the conductive membrane is in contact with a first side of the second cathode layer.