Photoelectrochemical CO2 Reduction Cell With Ion Transfer Pathways
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Solution Overview
Problem
Current technologies for artificial photochemical reactions that aim to reduce CO2 using light energy are inefficient, with low solar energy conversion efficiency and challenges in extracting electricity due to interconnection resistance.
Innovation Solution
A photochemical reaction system comprising a CO2 production unit, a CO2 absorption unit, and a CO2 reduction unit with a photoelectrochemical cell that includes an oxidation catalyst layer, a reduction catalyst layer, and a multi-junction photovoltaic cell layer, along with an ion transfer pathway to facilitate the movement of ions between the catalyst layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a Z-scheme-type artificial photosynthesis system with electric wire connection is used to reduce CO2 using light energy, then the reduction reaction can proceed, but the solar energy conversion efficiency becomes very low at around 0.04% due to interconnection resistance
Solution Approach 1:
The patent removes the electric wire connection from the system entirely. Instead of connecting the oxidation and reduction photocatalysts through external wires, the system uses direct ionic conduction through the electrolyte solution, eliminating the source of interconnection resistance and enabling efficient energy transfer without electrical components.
Solution Approach 2:
The electrolyte solution serves as an intermediary that enables both ionic conduction and direct contact between the oxidation and reduction photocatalysts. This intermediary medium allows charge transfer through ion movement rather than electron flow through wires, resolving the efficiency problem while maintaining the redox reaction functionality.
2Productivity
If plate-like laminate structure without through-holes is used, then the device is easy to configure in large size, but ion transfer between oxidation and reduction sides is hindered, reducing reaction efficiency
Solution Approach 1:
The patent employs a plate-like laminate structure containing through-holes that penetrate the entire structure. These through-holes create porous pathways that allow efficient ion transfer between the oxidation and reduction sides while maintaining the structural integrity and ease of large-scale configuration of the laminate device.
3Loss of energy
If photocatalyst excited by optical wavelength is used to reduce CO2, then the reduction reaction can occur, but the energy efficiency of the photocatalyst is low, resulting in very low solar energy conversion efficiency
Solution Approach 1:
The patent uses composite photocatalyst materials combining TiO2 and SiO2 with specific surface area ratios (TiO2: 10-50 m²/g, SiO2: 50-200 m²/g). This composite structure optimizes light absorption and charge separation efficiency, significantly improving the energy efficiency of the photocatalyst while maintaining high CO2 reduction productivity.
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 system achieves a high photoreduction efficiency for CO2, overcoming the limitations of low energy conversion and interconnection resistance, by efficiently transferring ions and utilizing light energy to drive the reduction reaction.
Implementation Method 1
a photochemical reaction system comprising a CO2 production unit, a CO2 absorption unit, and a CO2 reduction unit with a photoelectrochemical cell that includes an oxidation catalyst layer, a reduction catalyst layer, and a multi-junction photovoltaic cell layer
Implementation Method 2
an oxidation catalyst layer for producing O2 and H+ by photo-oxidizing water
Implementation Method 3
a reduction catalyst layer for producing a carbon compound by reducing CO2
Implementation Method 4
along with an ion transfer pathway to facilitate the movement of ions between the catalyst layers
Data Source
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AI summary
According to one embodiment, a photochemical reaction system comprises a CO2 production unit, a CO2 absorption unit, and a CO2 reduction unit. The CO2 reduction unit comprises a laminated body and an ion transfer pathway. The laminated body comprises an oxidation catalyst layer producing O2 and H+ by oxidizing H2O, a reduction catalyst layer producing carbon compounds by reducing CO2 absorbed by the CO2 absorption unit, and a semiconductor layer formed between the oxidation catalyst layer and the reduction catalyst layer and develops charge separation with light energy. The ion transfer pathways make ions move between the oxidation catalyst layer side and the reduction catalyst layer side.