Photochemical Reaction System with Temperature Difference Power Generation
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Solution Overview
Problem
Conventional methods for generating hydrogen and oxygen through visible light-induced water decomposition face inefficiencies due to concentration polarization of redox compounds, leading to reverse reactions and potential cessation of hydrogen and oxygen production.
Innovation Solution
A photochemical reaction system employing a hydrogen generating cell and an oxygen generating cell, separated by an ion-permeable membrane, utilizes temperature difference power generation to eliminate concentration polarization by applying heat differentially between the cells, thereby maintaining a favorable redox ratio and preventing reverse reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a redox pair is used in a two-chamber cell for separate hydrogen and oxygen generation, then hydrogen and oxygen can be generated separately, but the redox pair becomes disproportionate and reverse reaction occurs, inhibiting efficient hydrogen generation
Solution Approach 1:
The system is divided into a hydrogen generating cell and an oxygen generating cell separated by an ion-permeable membrane. This segmentation allows independent control of redox compound concentrations in each cell, preventing the disproportionation that occurs in mixed systems while maintaining separate hydrogen and oxygen generation.
Solution Approach 2:
Different local conditions are created in each cell: the hydrogen generating cell maintains high [Red]/[Ox] ratio favorable for hydrogen production, while the oxygen generating cell maintains appropriate redox balance for oxygen production. This local optimization of redox conditions prevents reverse reactions and improves overall efficiency.
2Productivity
If concentration polarization of the redox pair increases in Z-scheme water decomposition, then the initial hydrogen and oxygen generation can proceed, but reverse reaction progresses and the generating reaction may stop
Solution Approach 1:
The system dynamically maintains favorable redox ratios by controlling the distribution of redox compounds between cells and using selective ion transport through the membrane. This parameter control prevents concentration polarization from leading to reverse reactions, enabling continuous operation.
Solution Approach 2:
The ion-permeable membrane acts as an intermediary that selectively transports ions between cells to maintain charge balance and prevent concentration polarization. This mediator enables continuous reaction by preventing the buildup of polarized conditions that would cause reverse reactions.
3Productivity
If additional redox compounds are loaded or electrolytic solutions are replaced to maintain reaction efficiency, then reaction efficiency can be recovered, but device complexity and operation difficulty increase
Solution Approach 1:
The system automatically maintains favorable redox ratios through the ion-permeable membrane's selective ion transport and the natural tendency of the system to equilibrate concentrations. This self-regulating mechanism eliminates the need for manual intervention to replace solutions or add compounds, reducing operational complexity while maintaining efficiency.
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 enhances the efficiency of hydrogen and oxygen production by preventing reverse reactions, allowing for continuous operation without the need for additional redox compounds or electrolyte replacement, thereby increasing the system's operational rate.
Implementation Method 1
concentration polarization of the redox compound generated as a result of generating hydrogen gas from the hydrogen generating cell by irradiating the hydrogen generating cell with light
Implementation Method 2
performing temperature difference power generation between the hydrogen generating cell and the oxygen generating cell
Implementation Method 3
eliminating the concentration polarization of the redox compound by performing temperature difference power generation between the hydrogen generating cell and the oxygen generating cell
Implementation Method 4
hydrogen and oxygen production technology by means of water decomposition reaction using a photocatalyst
Implementation Method 5
utilize visible light to achieve the practical efficiency of energy conversion
Implementation Method 6
an ion-permeable membrane that separates the hydrogen generating cell and the oxygen generating cell
Data Source
Figure 1
Figure 2~3
Figure 4(a)~4(d)
AI summary
To enable the recovery of the efficiency of hydrogen and oxygen generating reaction without loading additional redox compounds and replacing electrolytic solutions, the present invention provides a photochemical reaction system includes a hydrogen generating cell 2, 802 containing a hydrogen generating type photocatalyst, an aqueous medium including a redox compound 5, 805, and an electrolytic solution 4; and an oxygen generating cell 1, 801 containing an oxygen generating type photocatalyst, an aqueous medium including a redox compound 5, 805, and an electrolytic solution 4; and further includes a redox compound concentration polarization elimination part for eliminating the concentration polarization of the redox compound 5, 805 generated as a result of generating a hydrogen gas 115 from the hydrogen generating cell 2, 802 by irradiating the hydrogen generating cell 2, 802 with light and the concentration polarization of the redox compound 5, 805 generated as a result of generating an oxygen gas 114 from the oxygen generating cell 1, 801 by irradiating the oxygen generating cell 1, 801 with light.