(149e) Photocatalytic Conversion of Carbon Dioxide to Methanol Using Visible Light Responsive MOF Nanocomposites

Due to global warming and shortage of energy, the demand for sustainable energy sources has been increasing. Carbon emissions are significant contributors to the problem of global warming. This opportunity can be targeted incorporating unique compounds like photo catalysts or membranes of metal-organic frameworks (MOFs). MOFs application in fields like energy storage, heterogeneous catalysis, sensing and gas storage is found to be very promising. The objective of this project is to successfully synthesize and characterize the bismuth , graphene and copper based MOF nanocomposites for utilization of visible light for photocatalytic reduction of carbon dioxide to renewable fuels like methanol and to compare their efficiency in terms of methanol production as it will help us to determine the better conditions for the conversion of CO₂.The MOF nano-composites synthesised and characterized were used for the conversion of carbon dioxide to methanol are Cu₃BTC_2, rGO-CuO nanocomposites and ZIF-8/BiVO₄. In this work, three different nanocomposites were synthesized successfully using three different approaches. Cu₃BTC₂ metal organic framework was synthesized using a microwave method whereas rGO-CuO nanocomposite was prepared by combining rGO and CuO under a nitrogen atmosphere with the help of APTMS. The ZIF-8/BiVO₄ nanocomposite was synthesized via in-situ growth method where ZIF-8 nanoparticles were made to grow on BiVO₄ sheets, BiVO₄ for this nanocomposite was synthesized via a hydrothermal method. Synthesis of Cu₃BTC₂ is carried out by dissolving aqueous Copper (II) nitrate trihydrate solution in a solution of 1,3,5-benzene tricarboxylic acid (H₃BTC) in 1:1:1 mixture of ethanol, N,N-dimethylformamide (DMF) and DI water. rGO-CuO nanocomposites are synthesized using in-situ growth method of implanting CuO nanorods into the rGO framework. ZIF-8/BiVO₄ framework is obtained by in-situ growth of ZIF-8 on BiVO₄ nanosheets. The MOFs are then dissolved into a solution and CO₂ is passed through them under a visible light irradiation for conversion to methanol. The corresponding yields obtained through each MOF are compared and analysed for maximum output. Characterization was done using XRD analysis, the surface area of the sample was determined by BET and the morphology was determined by STEM-EDS analysis and Raman spectroscopy and the data obtained indicates successful synthesis of the sample and also sheds light on some of the internal structure properties of the sample. The crystallinity and the morphology of rGO-CuO nanocomposites were determined by XRD and STEM analysis respectively and the same holds true for ZIF-8/BiVO₄ nanocomposites. Thus this newly designed photoreactor can yield competitive amounts of fuels from CO₂ photoreduction via visible light/solar light irradiation using synthesized MOF nanocomposites.