Electrochemical conversion system for carbon dioxide

Abstract

We provide an electrochemical conversion system for carbon dioxide. [Solution] This invention relates to an electrochemical conversion system (100) for carbon dioxide designed to efficiently electrochemically convert carbon dioxide into high value-added chemical products. The system (100) comprises a reactor housing (102) defining an electrochemical chamber, a counter electrode assembly (106), an ion-conducting separator (108), a controlled electrolyte environment, a carbon dioxide gas supply device, and a power control unit (116) configured to adjust electrochemical operating conditions. During operation, carbon dioxide is selectively adsorbed within a porous metal-organic structure and electrochemically reduced at the catalytically active metal center, while the graphene component promotes efficient electron transport and mechanical reinforcement.

Description

Technical Field

[0001] This invention generally relates to the fields of electrochemical energy conversion and carbon recovery and utilization technologies. More specifically, it relates to an electrocatalytic system employing a metal-organic framework-graphene hybrid electrode for electrochemically converting carbon dioxide into value-added chemical products.

Background Art

[0002] The continuous increase in the atmospheric carbon dioxide concentration due to industrial activities, fossil fuel combustion, and chemical manufacturing processes has become a major environmental problem because it directly contributes to climate change and global warming. While conventional carbon dioxide capture and storage strategies are effective in emissions reduction, they are accompanied by high operating costs, energy penalties, and long-term storage risks. Therefore, research on carbon dioxide capture and utilization technologies that convert carbon dioxide into fuels, chemicals, and industrial raw materials is being vigorously pursued.

[0003] Electrochemical carbon dioxide conversion has attracted attention as a promising route because it can directly utilize electrical energy including renewable power and promote the reduction of carbon dioxide under normal temperature or near-normal temperature conditions. However, existing electrochemical systems have problems such as low catalyst selectivity, high overvoltage, insufficient current density, and limitations in electrode stability. Conventional metal electrodes such as copper, silver, and tin have limited effective surface areas and surface deterioration occurs during long-term operation. Furthermore, mass transfer limitations and inefficient electron transfer pathways further reduce the efficiency of the system.

[0004] At the system level, conventional electrochemical reactors for carbon dioxide reduction often rely on simple planar electrode configurations immersed in liquid electrolytes. Such structures suffer from severe limitations in mass transfer, particularly with gaseous carbon dioxide, which has low solubility in aqueous electrolytes. As a result, the rate of carbon dioxide supply to the catalyst surface becomes a limiting factor, leading to increased competition between low current density and hydrogen evolution. To address this problem, gas diffusion electrodes have been introduced, enabling direct contact between gaseous carbon dioxide and the catalyst layer. However, integrating advanced catalyst materials into stable gas diffusion electrode structures remains a challenge.

[0005] Another significant drawback of current solutions is the limited durability of electrodes under continuous operation. Repeated redox cycles, localized pH fluctuations, and the accumulation of reaction intermediates can lead to structural collapse of porous materials, metal dissolution, and surface poisoning. These effects are particularly pronounced in hybrid systems where the mechanical and thermal properties of the components are mismatched, resulting in delamination and cracking over time. The lack of robust electrode structures capable of maintaining the adhesion between conductive and catalytic components even under operating stress is a major barrier to commercialization.

[0006] Given these challenges, the need for an electrocatalytic system that combines high catalyst site density, efficient electron transport, controlled mass transfer, and structural stability within an integrated system structure is clear. While existing solutions have addressed individual aspects of the problem, they have not provided a comprehensive system that enables sustainable, efficient, and selective carbon dioxide conversion. The development of an electrocatalytic system utilizing hybrid electrodes of metal-organic structures and graphene within a specially designed electrochemical device structure represents a significant advance in overcoming the limitations of conventional technologies and enabling practical carbon dioxide utilization technologies. [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] This disclosure provides an electrocatalytic system utilizing a metal-organic structure-graphene hybrid electrode configured for the electrochemical conversion of carbon dioxide to reduced carbon products such as carbon monoxide, formate, hydrocarbons, or alcohols. The system integrates a structurally designed hybrid electrode with controlled gas supply, electrolyte management, and electrical control to achieve high conversion efficiency, enhanced selectivity, and long-term operational stability. Furthermore, the invention provides a device structure including an electrochemical reactor housing, electrode assembly, current collection architecture, and fluid management components designed to optimize electron transfer, ion transport, and reactant access.

[0008] The objective of this invention is to provide an electrocatalytic system capable of efficiently converting carbon dioxide into high-value-added chemical products by employing a hybrid electrode that integrates a metal-organic structure and a graphene-based conductive material. This achieves improved catalytic activity and electron transfer characteristics compared to conventional electrode systems. This invention aims to overcome the inherent conductivity limitations of the metal-organic structure while maintaining its high catalytic activity site density and adjustable coordination environment. Another objective of this invention is to provide an electrochemical system structure that enables high current density operation with reduced overvoltage by forming a continuous, low-resistance electrical path between the external power source and the catalytically active metal center within the hybrid electrode structure. By ensuring efficient charge transport and minimizing interfacial resistance, this invention aims to improve the overall energy efficiency of the carbon dioxide electrolysis process.

[0009] A further objective of this invention is to enhance selectivity for the target carbon dioxide reduction product while simultaneously suppressing competing side reactions such as hydrogen evolution by stabilizing specific reaction intermediates within the porous structure of the metal-organic structural component. This invention aims to provide a controlled catalytic microenvironment that enables a predictable and tunable product distribution. A further objective of this invention is to provide a mechanically robust and chemically stable electrode structure that can maintain catalytic performance even under long-term electrochemical operation. This invention aims to prevent degradation phenomena such as catalyst delamination, pore collapse, and structural delamination by ensuring strong interfacial integration between the metal-organic structure and the graphene component.

[0010] A further objective of this invention is to enable the integration of electrocatalytic systems with renewable energy sources by allowing operation under dynamically changing electrical inputs without compromising catalyst stability or selectivity. This invention is intended to promote sustainable carbon utilization by aligning electrochemical conversion processes with intermittent renewable power generation.

[0011] Another objective of this invention is to provide an electrocatalytic system with improved operational monitoring and control capabilities, thereby enabling adjustment of electrochemical parameters such as potential, current density, temperature, and reactant flow rate to maintain optimal conversion efficiency and system lifespan. [Means for solving the problem]

[0012] To solve the above problems, the present invention provides a carbon dioxide electrochemical conversion system, comprising a reactor housing comprising a sealed electrochemical chamber; a working electrode assembly disposed within the electrochemical chamber, the working electrode assembly comprising a conductive support and an electrocatalyst layer formed as a hybrid structure including a metal-organic structural material integrated with a graphene-based conductive material, the metal centers of the metal-organic structural material configured as catalytically active sites for carbon dioxide reduction; a counter electrode assembly disposed opposite the working electrode assembly at a distance within the electrochemical chamber; and a device disposed between the working electrode assembly and the counter electrode assembly to prevent direct electrical contact between these electrode assemblies. The reactor comprises: an ion-conducting separator configured to enable ion transport while stopping; an electrolyte encapsulation unit configured to hold an electrolyte connected in an ion-conducting state to the working electrode assembly and the counter electrode assembly; a gas supply unit fluidly connected to the reactor housing and configured to introduce carbon dioxide into the working electrode assembly under controlled flow conditions; a current collection unit electrically connected to the working electrode assembly and the counter electrode assembly; and a power control unit electrically connected to the current collection unit and configured to drive the electrochemical reduction of carbon dioxide by applying a controlled potential or current between the working electrode assembly and the counter electrode assembly. [Effects of the Invention]

[0013] The electrochemical conversion system for carbon dioxide according to this invention employs a working electrode having a hybrid electrocatalytic structure formed by integrating a metal-organic structure and a graphene-based conductive material, thereby achieving a high density of catalytic active sites, enhanced electrical conductivity, and structural stability. [Brief explanation of the drawing]

[0014] These features, aspects, and advantages of the present invention, as well as other features, aspects, and advantages, will be better understood by reading the following detailed description in conjunction with the accompanying drawings. In the drawings, the same symbol indicates the same part throughout all drawings.

[0015] Figure 1 is a block diagram showing the electrochemical conversion system of carbon dioxide.

[0016] Furthermore, those skilled in the art will understand that elements in the drawings are shown for simplification and are not necessarily drawn to actual size. For example, flowcharts illustrate the method with respect to the most prominent steps involved to aid in understanding aspects of the disclosure. Also, with respect to the configuration of the apparatus, one or more components of the apparatus may be represented in the drawings by conventional symbols, and the drawings may show only certain details relevant to understanding embodiments of the disclosure so as not to obscure the drawings with details that are easily understood by those skilled in the art who enjoy the description herein. [Modes for carrying out the invention]

[0017] For the purpose of facilitating the understanding of the principles of the invention, the embodiments shown in the drawings will be referenced and specific terminology will be used in describing them. However, this is not intended to limit the scope of the invention, and it should be understood that any modifications or further improvements to the illustrated system, and further applications of the principles of the invention shown therein, are within the realm of what a person skilled in the art would ordinarily conceive.

[0018] Those skilled in the art will understand that the above-mentioned general description and the following detailed description are for illustrative purposes only and not intended to limit the present invention.

[0019] Throughout this specification, the phrases “one aspect,” “another aspect,” or similar expressions mean that a particular function, structure, or feature described in relation to an example is included in at least one example. Therefore, the occurrence of phrases “in one example,” “in another example,” and similar expressions throughout this specification does not necessarily refer to the same example.

[0020] The expressions “includes,” “is included,” or other similar expressions are intended to be non-exclusive, and a process or method containing a list of steps does not include only those steps, but may include other steps not expressly stated or inherent in the process or method. Similarly, one or more devices, subsystems, elements, structures, or components preceding “includes…” does not, unless further restricted, exclude the existence of other devices, other subsystems, other elements, other structures, other components, additional devices, additional subsystems, additional elements, additional structures, or additional components.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which this invention pertains. The systems, methods, and embodiments described herein are illustrative and not intended to be limiting.

[0022] Examples of the embodiments described herein will be described in detail below with reference to the attached drawings. Referring to FIG. 1, a block diagram showing an electrochemical conversion system for carbon dioxide is shown. System 100 includes the following: a reactor housing (102) that defines a sealed electrochemical chamber; a working electrode assembly (104) disposed within the electrochemical chamber. The working electrode assembly is formed as a hybrid structure including a conductive support and an electrocatalytic layer including a metal-organic framework material (104a) integrated with a graphene-based conductive material (104b). Here, the metal center of the metal-organic framework is configured as a catalytic active site for carbon dioxide reduction; a counter electrode assembly (106) disposed within the electrochemical chamber and spaced apart from the working electrode assembly; an ion conductive separator (108) disposed between the working electrode assembly and the counter electrode assembly and configured to allow ion transport while preventing direct electrical contact between the electrode assemblies; an electrolyte holding unit (110) configured to hold an electrolyte connected in an ion conductive state to the working electrode assembly and the counter electrode assembly; a gas supply unit (112) fluidly connected to the reactor housing and configured to introduce carbon dioxide to the working electrode assembly under controlled flow conditions; a current collection unit (114) electrically connected to the working electrode assembly and the counter electrode assembly; and a power control unit (116) electrically connected to the current collection unit and configured to apply a controlled potential or current between the working electrode assembly and the counter electrode assembly to drive the electrochemical reduction of carbon dioxide.

[0023] In one embodiment, the metal-organic framework material includes a crystalline coordination network formed from metal ions or metal clusters coordinated with organic linker molecules, where the metal ions or metal clusters are selected to provide a specific binding affinity for carbon dioxide molecules within the pores of the metal-organic framework.

[0024] In one embodiment, the graphene-based conductive material (104b) includes graphene sheets, reduced graphene oxide sheets, or doped graphene sheets arranged to form a continuous conductive network penetrating the electrocatalytic layer.

[0025] In one embodiment, the electrocatalyst layer is formed by in-situ growing a metal-organic framework material on the surface of a graphene-based conductive material, thereby establishing a direct interfacial contact between the catalyst sites and the conductive pathways.

[0026] In one embodiment, the conductive support of the working electrode assembly (104) includes a porous conductive substrate configured to mechanically support the electrocatalyst layer while allowing the transport of electrolyte ions and gaseous carbon dioxide.

[0027] In one embodiment, the gas supply unit (112) includes a gas diffusion structure disposed adjacent to the working electrode assembly and configured to uniformly distribute carbon dioxide over the entire active surface of the electrocatalyst layer.

[0028] In one embodiment, the working electrode assembly (104) is configured as a gas diffusion electrode such that the first side of the electrocatalyst layer is exposed to gaseous carbon dioxide and the opposite side of the electrocatalyst layer is in contact with the electrolyte.

[0029] In one embodiment, the ion conductive separator (108) includes a polymer membrane configured to selectively conduct cations or anions generated during the electrochemical operation while restricting the crossover of reaction products between the electrode compartments.

[0030] In one embodiment, the electrolyte encapsulation unit (110) is configured to hold an aqueous electrolyte having a controlled ionic strength and pH to stabilize the electrochemical reduction reaction occurring at the metal centers of the metal-organic framework (MOF).

[0031] In one embodiment, the electrolyte encapsulation unit (110) is configured to hold a non-aqueous or mixed solvent electrolyte selected to suppress hydrogen generation and enhance the selectivity for carbon dioxide reduction products.

[0032] During initialization, the reactor housing is prepared by introducing a selected electrolyte into the electrochemical chamber via an electrolyte encapsulation unit. This process ensures that the working electrode assembly and the counter electrode assembly are completely wetted at their respective electrolyte contact surfaces. An ion-conducting separator establishes ionic continuity between the electrode assemblies while simultaneously insulating them electrically. At the same time, a gas supply unit initiates a controlled inflow of carbon dioxide into the electrochemical chamber, guiding the gas towards the working electrode assembly through a gas diffusion structure. This system technology ensures that the partial pressure and flow rate of carbon dioxide are maintained within predefined thresholds to avoid gas deficiencies or excessive pressure increases in the electrocatalytic layer.

[0033] After the electrochemical environment has stabilized, the power control unit applies an initial potential between the working electrode assembly and the counter electrode assembly via a current collection unit. The magnitude of the applied potential is selected based on saved operating parameters corresponding to the metal-organic structure composition and graphene network configuration of the electrocatalyst layer. This initial bias is applied in stages to prevent abrupt current surges that could induce localized heat generation or structural stress within the hybrid electrode. The technology monitors the current response in real time and compares the measured current density with a predicted value derived from calibration data.

[0034] When an electrical bias is applied, electrons are transported from the power control unit through the current collection unit to the conductive support of the working electrode assembly. The graphene-based conductive material within the electrocatalytic layer forms a continuous electron transport network, enabling rapid distribution of electrons to the metal core of the metal-organic structure. Carbon dioxide molecules introduced from the gas supply unit diffuse through the pores of the gas diffusion structure and enter the porous network of the metal-organic structure. There, the molecules are adsorbed onto the catalytically active metal sites. This technique implicitly controls this step by maintaining stable electrical and mass transport conditions that promote adsorption rather than desorption.

[0035] Adsorbed carbon dioxide molecules undergo stepwise electrochemical reduction at the metal center of the metal-organic structure. This technique maintains an applied potential within a controlled operating range, suppressing competing hydrogen evolution reactions while promoting the formation of the desired reaction intermediate. Stabilization of the intermediate occurs through coordination interactions within the pore environment of the metal-organic structure, which is maintained by avoiding excessive overpotential. The graphene network ensures that electron supply to each catalyst site is not the rate-limiting step, thereby supporting uniform reaction kinetics across the electrode surface.

[0036] Throughout the reduction process, the sensing unit continuously acquires operational data such as electrode potential, current density, temperature in the electrochemical reaction chamber, and carbon dioxide flow rate. These measurements are transmitted to the power control unit, which dynamically adjusts the applied potential or current using feedback technology. If the current density deviates from a predefined target range, the power control unit gradually changes the electrical input to restore steady-state operation. Similarly, if temperature fluctuations are detected, the thermal control unit activates to dissipate excess heat or provide auxiliary heating to maintain reaction stability.

[0037] This technology further considers the balance of mass transfer by correlating the measured current density with the carbon dioxide flow rate. If an increase in current demand indicates an increase in reactant consumption, the gas supply unit is controlled to proportionally increase the carbon dioxide supply. Conversely, if the current density decreases due to temporary saturation or product accumulation, the gas flow rate is reduced to maintain efficient utilization of the supplied carbon dioxide. The reaction products generated in the working electrode assembly are carried out from the electrocatalyst layer through a controlled electrolyte circulation and a product discharge path formed within the reactor housing.

[0038] On the counter electrode side, complementary electrochemical reactions occur to equilibrate charge transfer across the ion-conducting separator. The separator allows ions generated at the working electrode to move to the counter electrode side, maintaining electrical neutrality within the electrochemical cell. This technique ensures sufficient ion conductivity is maintained by monitoring the electrolyte state and adjusting the electrolyte replenishment amount when fluctuations in conductivity or pH are detected.

[0039] During continuous operation, this technology implements periodic stabilization cycles. These cycles briefly adjust the applied potential within a narrow range to reduce surface fouling and prevent the accumulation of firmly bound intermediates on the metal-organic structure sites. These stabilization cycles are designed to maintain catalytic activity without inducing structural degradation of the hybrid electrode. The graphene component provides mechanical reinforcement during these cycles, preventing delamination and pore collapse under repeated electrochemical stress.

[0040] During continuous or long-term operation, the system implements maintenance techniques that evaluate the long-term trend of current efficiency, selectivity indicators derived from product detection, and the overall electrical resistance of the working electrode assembly. When progressive degradation of performance is detected, the power control unit modifies operating parameters to compensate while maintaining the target conversion output. If a predefined degradation threshold is exceeded, the system initiates a controlled shutdown sequence. During this process, the electrical bias is gradually reduced, the gas flow rate is decreased, and the electrolyte circulation is stabilized to prevent damage to the electrocatalyst layer.

[0041] The described technical control and operating logic enable the efficient, selective, and sustained electrochemical conversion of carbon dioxide. By coordinating electrical input, mass transport, thermal management, and real-time feedback, the system maintains optimal reaction conditions in the metal-organic structure-graphene hybrid electrode, achieving the functional objectives defined in the system claims.

[0042] In accordance with this disclosure, an electrocatalytic system is provided in which at least one working electrode comprises a hybrid electrocatalytic layer formed by integrating a metal-organic structural material and a graphene-based conductive matrix. The metal-organic structural comprises a crystalline coordination network consisting of metal ions or metal clusters linked by organic ligands, where the metal centers are catalytically active for carbon dioxide reduction reactions. The graphene component comprises a graphene sheet, graphene oxide, reduced graphene oxide, or doped graphene, and is configured to provide continuous electron conduction pathways throughout the hybrid structure.

[0043] Hybrid electrodes of metal-organic structures and graphene are fabricated by growing the metal-organic structure in situ on the graphene surface or by depositing it as a conformal porous layer fixed to a graphene sheet. This configuration enables close interfacial contact between catalytically active metal-organic structure sites and the conductive graphene network, minimizing charge transfer resistance and promoting electron injection into the catalyst center during electrochemical operations. The porous structure of the metal-organic structure provides a high surface area and diffusion pathways for carbon dioxide molecules, while the graphene matrix ensures mechanical strength and electrical connectivity.

[0044] The electrocatalytic system further includes an electrochemical cell configured to house a metal-organic structure-graphene hybrid working electrode, a counter electrode, and an ion-conducting separator or membrane placed between the electrodes. The separator allows ion transport while preventing short circuits through electrical insulation between the electrodes. An electrolyte is introduced into the cell. This electrolyte is aqueous, non-aqueous, or in a solid state and is selected to support efficient ion conductivity and stability under the applied electrochemical potential.

[0045] Carbon dioxide is supplied to the working electrode via a controlled gas supply interface. This interface may include a gas diffusion layer positioned adjacent to the metal-organic structure (MOF)-graphene hybrid electrode. The gas diffusion layer promotes uniform distribution of carbon dioxide across the electrode surface and enhances gas-liquid-solid interface contact. In certain embodiments, the metal-organic structure-graphene hybrid electrode itself is configured as a gas diffusion electrode, and the porous hybrid layer reduces limitations on mass transfer by directly bonding gaseous carbon dioxide on one side and the electrolyte on the opposite side.

[0046] An external power supply is electrically connected to the working electrode and counter electrode via a current collector, allowing for the application of a controlled potential or current between the electrodes. Upon application of an electrical bias, electrons move from the external circuit through the graphene network to the metal center of the metal-organic structure, where carbon dioxide molecules adsorbed within the pores of the metal-organic structure undergo electrochemical reduction. The reaction intermediates are stabilized by the coordination environment of the metal-organic structure, improving selectivity for the desired reduction product. The reduced carbon product is then desorbed and recovered, removed from the electrode surface.

[0047] Furthermore, this system features a temperature control component integrated within the electrochemical cell housing, stabilizing the reaction rate by maintaining the operating temperature within a predetermined range and preventing degradation of the metal-organic structure-graphene hybrid structure. In addition, the incorporation of sensors to monitor parameters such as electrode potential, current density, gas flow rate, electrolyte composition, and product concentration enables closed-loop control of the electrocatalytic process.

[0048] The drawings and the preceding description illustrate examples of embodiments. Those skilled in the art will understand that one or more of the described elements may be integrated into a single functional element. Alternatively, certain elements may be divided into multiple functional elements. It is also possible to add elements of one embodiment to another. For example, the order of processes described herein is modifiable and is not limited to the methods described herein. Furthermore, the operations in the flowchart do not necessarily have to be implemented in the order shown, nor do all operations necessarily have to be performed. Operations that do not depend on other operations may be performed in parallel with other operations. The scope of embodiments is by no means limited by these specific examples. Numerous variations are possible, including differences in structure, dimensions, and use of materials, whether or not they are expressly described in the specification. The scope of embodiments is at least as broad as or broader than the scope given by the following claims.

[0049] The advantages, other benefits, and solutions to problems have been described above with respect to specific embodiments. However, these advantages, benefits, solutions to problems, and any components that may result in the occurrence or enhancement of any advantages, benefits, or solutions should not be construed as essential, necessary, or intrinsic features or components in any or all of the claims.

Claims

1. A carbon dioxide electrochemical conversion system, A reactor housing that defines a sealed electrochemical chamber; A working electrode assembly located in an electrochemical chamber, the working electrode assembly comprising a conductive support and an electrocatalyst layer formed as a hybrid structure including a metal-organic structural material integrated with a graphene-based conductive material, wherein the metal centers of the metal-organic structural material are configured as catalytically active sites for carbon dioxide reduction; A working electrode assembly and a counter electrode assembly positioned opposite each other at a distance within the electrochemical chamber; An ion-conducting separator positioned between the working electrode assembly and the counter electrode assembly, configured to allow ion transport while preventing direct electrical contact between these electrode assemblies; An electrolyte encapsulation unit configured to hold an electrolyte connected in an ion conduction state to the working electrode assembly and the counter electrode assembly; A gas supply unit, which is fluidly connected to the reactor housing and configured to introduce carbon dioxide into the working electrode assembly under controlled flow conditions; A current collection unit electrically connected to the working electrode assembly and the counter electrode assembly; and An electrochemical conversion system for carbon dioxide, characterized by comprising: a power control unit electrically connected to the current collection unit and configured to drive the electrochemical reduction of carbon dioxide by applying a controlled potential or current between the working electrode assembly and the counter electrode assembly.

2. The electrochemical conversion system for carbon dioxide according to claim 1, characterized in that the conductive support of the working electrode assembly includes a porous conductive substrate configured to mechanically support an electrocatalyst layer while enabling the transport of electrolyte ions and gaseous carbon dioxide, and the gas supply unit is disposed adjacent to the working electrode assembly and includes a gas diffusion structure configured to uniformly distribute carbon dioxide across the entire active surface of the electrocatalyst layer.

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