Enhancing CO₂ Capture and Conversion to Formic Acid via a Membrane-Photocatalytic Hybrid System with ZnO-ZnS...

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Exhaust emissions pose environmental challenges, necessitating innovative CO2 capture and conversion strategies.
• Hybrid systems combining membrane contactors and photocatalysis offer a promising route for CO2 utilization.

Purpose of the Study:

• To develop and optimize a hybrid membrane-photocatalytic system for CO2 conversion to formic acid.
• To investigate the synthesis of ZnO-ZnS heterojunction photocatalysts with controlled precursor concentrations and calcination temperatures.

Main Methods:

• Synthesis of ZnO-ZnS heterojunction photocatalysts with varying ratios and calcination temperatures.
• Characterization of catalysts using XRD, SEM, HRTEM, and optical methods.
• Photocatalytic evaluation of CO2 conversion to formic acid under UV and visible light irradiation.

Main Results:

• Optimized ZnO-ZnS catalysts (Z1, Z2, Z4) showed significant formic acid yields, with Z1 achieving 0.643 mmol/(L gcat) h.
• The highest yield of 0.936 mmol/(L gcat) was observed at low CO2 concentration (15 vol%).
• Z1 catalyst demonstrated high selectivity and stability, with enhanced charge transfer efficiency indicated by EIS analysis.

Conclusions:

• Optimized ZnO-ZnS heterojunction catalysts are effective for selective CO2 conversion to formic acid under visible light.
• The hybrid membrane-photocatalytic technology presents a viable approach for reducing emissions from power plants.
• Further research into catalyst optimization and system integration can enhance CO2 utilization efficiency.