High selective photocatalytic CO2 conversion into liquid solar fuel over a cobalt porphyrin-based metal-organic framework.

In the present study, porphyrin-based metal-organic framework (Co/PMOF) was synthesized and characterized by different spectra analyses. The photoluminescence properties of porphyrin and Co/PMOF revealed that the photoluminescence of Co/PMOF was quenched compared to the porphyrin, indicating that the lifetime of photo-generated charge carriers in Co/PMOF is longer than porphyrin. The prepared Co/PMOF was applied as an efficient photocatalyst for CO2 photoconversion to formate in the presence of triethanolamine (TEOA) as a sacrificial agent under visible-light irradiation. The photoreaction results showed that 23.21 µmol HCOO- was produced over Co/PMOF during the 6 h photocatalytic reaction under visible illumination, showing much better activity than the porphyrin, 4.56 µmol HCOO-. No other products were detected, suggesting that this reaction over Co/PMOF has high selectivity. Co/PMOF reusability and stability were examined through recycling tests and there were no remarkable losses of photoactivity even after three cycles of photoreaction. Moreover, FTIR measurement and UV-Vis spectra demonstrated no notable changes in Co/PMOF structure. As a result, superior photocatalytic behavior of Co/PMOF was implied for CO2 photoreduction which highlights the great potential of assembly porphyrin and cobalt into MOFs for CO2 photoreduction.