Efficient solar fuel production with a high-pressure CO₂-captured liquid feed

Area of Science:

• Electrochemistry
• Renewable Energy
• Catalysis

Background:

• Solar fuel production from CO2 is crucial for sustainable energy.
• Current methods using gaseous CO2 feeds require energy-intensive regeneration and separation.
• Liquid CO2 feeds face challenges with high over-potential and low solar-to-chemical (STC) efficiency.

Purpose of the Study:

• To develop an efficient solar photovoltaic-powered electrochemical CO2 reduction device with a liquid feed.
• To overcome the limitations of high over-potential and low STC efficiency in liquid CO2-fed systems.
• To introduce a high-pressure operando strategy for enhanced catalyst synthesis and CO2 reduction.

Main Methods:

• Demonstrated a solar photovoltaic-powered electrochemical device utilizing a high-pressure CO2-captured liquid feed.
• Employed a high-pressure operando strategy for catalyst synthesis (50 bar) within a CO2-saturated KHCO3 solution.
• Utilized operando facet engineering and oxide derivation for catalyst development.

Main Results:

• Achieved 95% CO2 reduction reaction (CO2RR) selectivity at a low potential (-0.3 V vs. RHE) with a copper catalyst.
• The device reached a record-high STC efficiency of 21.6% under outdoor illumination.
• The developed system outperformed other liquid-fed CO2-saturated devices and compared favorably to gaseous CO2-fed systems.

Conclusions:

• The high-pressure operando strategy is effective for synthesizing efficient catalysts for CO2 reduction.
• The developed device offers a promising "air-to-barrel" approach for solar fuel production, minimizing energy costs.
• This work advances the field of electrochemical CO2 reduction towards practical solar fuel generation.