CO2 photo-reduction with polyoxometalates-porphyrin based COF: A deep dive into spectroscopy and thermal behavior

Abstract

The reduction of carbon dioxide (CO₂) to valuable fuels is crucial for mitigating the climate change and developing the sustainable energy sources. This study explored the use of photo catalyst namely ZnADCOF@MnTP containing metalloporphyrin and χ-Anderson polyoxometalates (POMs) for CO₂ reduction. This is clearly demonstrated that ZnADCOF@MnTP exhibited significant changes in its environment after interaction with CO₂, as evidenced by shift in spectra of FT-IR (Fourier Transform infrared spectroscopy), UV–visible (Ultra-violet visible spectroscopy), and Raman spectra, along with TGA (Thermogravimetric analysis), and DSC (Differential scanning calorimetric) analysis. These changes indicate the formation of new carbon containing species, and modifications in its oxidation state. ZnADCOF@MnTP showed a remarkable reduction in thermal stability upon interaction with CO₂, which is due to its enhanced photocatalytic activity, and also indicated that adsorption, has been occurred. CO₂ adsorption and desorption capacities for ZnADCOF@MnTP has also been studied to analyze the adsorption and desorption capacities of the ZnADCOF@MnTP for fresh and regenerated catalyst. The maximum amount of CO₂ that has been adsorbed, by ZnADCOF@MnTP is found to be 2.045 (mmol/g) and desorbed capacity is found to be 30 %. GC–MS spectra showed the reduction of CO₂ to methanol and formic acid with 0.16 %, and 0.09 % relative concentration which inferred that the ZnADCOF@MnTP is more selective for photoreduction of CO₂ to methanol as compared to formic acid.