Photochemical CO₂ Reduction Using a Lead-Free Cs₂AgMCl₆ (M= Bi, In, and Sb) Double Perovskite toward Selective Formic...

Area of Science:

• Materials Science
• Catalysis
• Photochemistry

Background:

• Perovskite materials are recognized for their potential in photocatalysis, particularly for carbon dioxide (CO2) reduction.
• Their unique optical and physicochemical properties make them attractive for energy conversion applications.

Purpose of the Study:

• To investigate lead-free halide double perovskites, specifically Cs2AgMCl6 (M-Bi, In, Sb), as photocatalysts for CO2 reduction.
• To evaluate the selectivity and efficiency of these materials in producing valuable chemicals from CO2.

Main Methods:

• Synthesis and characterization of lead-free halide double perovskites (Cs2AgMCl6).
• Photocatalytic reduction of CO2 using the synthesized perovskites under specific conditions.
• Product selectivity analysis and conversion rate determination.
• Density functional theory (DFT) calculations to elucidate reaction mechanisms and selectivity.

Main Results:

• Double perovskite photocatalysts exhibited high selectivity (>80%) for formic acid production.
• Cs2AgInCl6 demonstrated the highest performance with a formic acid conversion rate of 85.5 μmol g-1 h-1.
• The materials displayed excellent structural stability over 24 hours of photocatalytic operation.
• DFT calculations confirmed a low free-energy barrier for formic acid formation, favoring it over CO and methane.

Conclusions:

• Lead-free halide double perovskites are effective and selective photocatalysts for CO2 reduction to formic acid.
• Cs2AgInCl6 is a promising material for efficient CO2 conversion.
• The Ag site on the [110] terminated surface is identified as a key active site for the catalytic reduction process.