Electrochemical CO₂ reduction method

High-efficiency CO₂ electroreduction under hydrothermal conditions

Overview

The electrochemical CO₂ reduction reaction (CO2RR) process, in which CO₂ is electrochemically converted, is attracting attention as a promising CO₂ reduction method. However, the conventional method has a problem of low energy efficiency. The inventor has found that it is possible to improve the efficiency of the CO2RR process by utilizing a high-temperature high-pressure water environment called a hydrothermal conditions. When electrolysis is carried out in high-temperature high-pressure water at 150℃ and 100 atm pressurized with CO₂, the high diffusion coefficient and solubility of CO₂ in the water facilitating efficient CO₂ supply to the electrode, and the energy efficiency is significantly enhanced. Additional assessment has shown that it is possible to synthesize "carbon-negative" basic chemical product (methanol), in which the amount of CO₂ absorbed exceeds the amount of CO₂ emitted, by leveraging low-temperature waste heat from industrial sources and renewable electricity.

Effect of hydrothermal conditions on current density and products ¹

(a) Current density as a function of the applied voltage at various temperatures at 10MPa.
(b)  Faraday efficiency (FE) for each compound produced by the cathodic reduction at ≈100 mA cm−² under hydrothermal conditions (50–150 °C at 10 MPa).
Increasing the temperature enhances current density and enables the reaction to occur at a lower applied voltage, leading to improved energy efficiency.

Product Application

・High‑efficiency CO₂ electroreduction using flue gas and low‑temperature waste heat from factories, power plants, and waste‑to‑energy plants

Related Works

[1] Advanced Sustainable Systems, 2024, 2400489
https://doi.org/10.1002/adsu.202400489

IP Data

IP No.　 ： PCT/JP2025/009449　
Inventor ： TOMAI Takaaki
keyword ： Hydrothermal Reaction, High Temperature, High Pressure, Electrochemical CO₂ Reduction Reaction, CO2RR