Insights into morphology-dependent MIL-100(Fe) catalyst towards high efficiency photothermal reduction of CO2 by H2O

Abstract

The photothermal catalytic CO₂ reduction has emerged as a promising technology for the effective use of solar energy and the reduction of greenhouse gas emissions. MIL-100(Fe), as a MOF material, is always considered an excellent catalyst due to its excellent porous structure, low toxicity, extraordinarily high chemical stability and abundant active sites. However, the relationship between morphology and photothermal catalytic CO₂ reduction is still being explored and studied. Here, we prepared the MIL-100(Fe) catalysts with different morphologies of nanospheres, nanoparticles and bulk to investigate their photothermal catalytic CO₂ reduction performance. The results showed that the nanospherical sample exhibited the highest activity for photothermal CO₂ reduction by H₂O with CO productivity of 124.04 μmol·g^-1·h^-1 higher than the other two samples. The characterization results and mechanism analysis indicated that the nanospherical sample had a lower band gap energy value, lower luminescence intensity and stronger transient photocurrent response, which effectively promoted the separation of photo generated electron-hole pairs. More importantly, the AQE calculation results indicated that the nanospherical sample exhibited more lower activation energy in the presence of both light and heat, which is beneficial for photothermal CO₂ catalytic to CO. This interesting find will provide experimental evidence for studying the morphology effect on photothermal catalytic CO₂ reduction process.