Nitride Semiconductor Counter Electrode for CO2 Reduction
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Solution Overview
Problem
Existing methods for reducing carbon dioxide require an electric source between the anode and cathode electrodes, which is not necessary in the proposed method.
Innovation Solution
A device comprising a cathode chamber, an anode chamber, and a solid electrolyte membrane with a working electrode and a counter electrode, where the counter electrode includes a nitride semiconductor region irradiated with light of 250-400 nanometers, allowing carbon dioxide reduction without an electric source between the electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If an electric source is used between anode and cathode electrodes, then carbon dioxide reduction can be achieved, but device complexity and energy consumption increase
Solution Approach 1:
The patent replaces the electrical system (electric source, external circuit) with an optical system (light source irradiating the counter electrode). Light irradiation generates electron-hole pairs in the nitride semiconductor counter electrode, driving the electrochemical reaction without external electrical connection between electrodes.
Solution Approach 2:
The counter electrode with nitride semiconductor performs self-activation through light irradiation. The generated electron-hole pairs create internal electric fields that drive the carbon dioxide reduction reaction at the cathode, eliminating the need for external electric sources or complex electrical connection systems.
2Productivity
If an electric source is used between anode and cathode electrodes, then carbon dioxide reduction can be achieved, but energy consumption increases
Solution Approach 1:
The patent changes the energy input parameter from electrical energy (requiring external power sources) to optical energy (light irradiation). By irradiating the nitride semiconductor counter electrode with light, the system generates electron-hole pairs that drive the electrochemical reaction, reducing energy consumption by eliminating the need for continuous external power supply.
3Productivity
If light is irradiated on the working electrode, then carbon dioxide reduction is enhanced, but the working electrode material degrades
Solution Approach 1:
The patent applies local quality by selectively positioning the light-irradiatable nitride semiconductor layer only on the counter electrode, while keeping the working electrode material (such as copper, silver, or gold) free from such coating. This allows the working electrode to maintain its catalytic activity for carbon dioxide reduction without the degradation issues associated with light-exposed semiconductor materials.
Solution Approach 2:
The nitride semiconductor counter electrode acts as an intermediary that absorbs light energy and converts it to electrical energy through photoelectric effect. This intermediary function allows the system to harness optical energy without directly exposing the working electrode to light, thereby protecting the working electrode material from degradation while still enabling the electrochemical reaction.
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
The method effectively reduces carbon dioxide to formic acid and carbon monoxide without the need for an electric source, as demonstrated by increased production of formic acid when the nitride semiconductor region is irradiated with light, indicating a catalytic reaction occurs.
Implementation Method 1
the counter electrode includes a region formed of a nitride semiconductor on the surface thereof. In the device, a first electrolytic solution is held in the cathode chamber, and a second electrolytic solution is held in the anode chamber. The working electrode is in contact with the first electrolytic solution and the counter electrode is in contact with the second electrolytic solution.
Implementation Method 2
irradiating the region with a light having a wavelength of 250 nanometers to 400 nanometers to reduce the carbon dioxide contained in the first electrolyte solution
Data Source
AI summary
The present subject matter provides a method for reducing carbon dioxide with the use of a device for reducing carbon dioxide. The device includes a cathode chamber, an anode chamber and a solid electrolyte membrane. The cathode chamber includes a working electrode which includes a metal or a metal compound. The anode chamber includes a counter electrode which includes a region formed of a nitride semiconductor. First and second electrolytic solutions are held in the cathode and anode chamber, respectively. The working electrode and the counter electrode are in contact with the first and second electrolytic solution, respectively. The solid electrolyte membrane is interposed between the cathode and anode chambers. The first electrolyte solution contains the carbon dioxide. An electric source is not interposed electrically between the working electrode and the counter electrode.