Research Projects

CO₂ conversion to useful chemicals such as hydrocarbon is an alternate to carbon capture and sequestration that could provide new economic prospects on top of reduced CO₂ emission. CO₂ can be converted to a series of products including CO, HCOOH, C₂H₅OH, CH₄, C₂H₄ etc. depending on the number of electrons involved in the reduction process. CO is considered to be toxic. Alternatively, CH₄, CH₃OH, C₂H₅OH and low-carbon olefin would be the most desired products as they will have very high energetic value due to their high energy density, ease of compressibility and ease of storage & transportation. The most commonly used CO₂ reduction technique is the energy-intensive thermo-catalytic process due to the requirement of high temperature and high pressure. However, since the last decade photochemical CO₂ reduction is being explored widely because of its multiple advantages including i) mild conditions, ii) sustainable process, iii) less chances of carbon deposition. For this, abundant and cost-effective catalysts are needed to ensure sustainable scaleup of the process. Metal nanoparticles, metal oxides, metal sulphides, N-doped graphene materials has been explored as photocatalysts for CO₂ reduction. One of the major challenges of these materials is the poor efficiency because of their low tunability of the materials. Metal Organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs), two different porous solids involving different chemistries but having a lot of similarities in terms of ordered porosity, tuneable pore size, thermal & chemical stability are currently being explored for the development of potential photocatalysts. In most cases, the photochemical CO₂ reduction processes suffer from low quantum efficiency limiting the scaleup of the technology. This project targets to convert CO₂ to some useful C1 and C2 products such as HCOOH, CH₃OH, C₂H₅OH, CH₄ and C₂H₄ in a photochemical approach using robust and durable MOF and COF-based photocatalyst. Similarly, solar energy-driven nitrogen reduction to ammonia could provide an environment-friendly and sustainable NH₃ production process. Subsequently, conversion of NH₃ to urea in the same pot will be another added advantage. However, activating this inert nitrogen molecule is challenging because of its high bond energy. Different metal oxides (TiO₂ and Ni-doped TiO₂, Fe-oxides), bismuth oxyhalides (BiOCl, BiOBr, BiOI) etc have been employed for this purpose. Usually, Fe-based catalysts lower the stability of the nitrogen molecule thereby increasing the chances of nitrogen reduction. Hence, Fe-based catalysts including Fe-oxides and single-atom catalysts are the most active nitrogen fixation catalysts. However, the major challenge is the activity of the catalyst due to the lower surface area and the recombination of photogenerated carriers. In this regard, MOFs and COFs containing Fe-species would be the most desired catalysts that could solve the issues related to nitrogen fixation.