Research Projects

Electrochemical CO₂ conversion to fuels/chemicals using cheap renewable electricity is one of the most attractive options to achieve the net-zero emissions target by 2070, as committed by India at COP26. However, industrial flue gas streams consist of CO₂ with low partial pressures, and reactive gases such as O₂ and O₂ concentration in the flue gas stream is as high as 4%. Lower CO₂ concentrations lead to parasitic hydrogen evolution reaction (HER). Our preliminary experiments also demonstrated that the presence of O₂, even 1%, in the inlet stream competes with the CO₂ reduction reaction (CO₂R), and 90% of the applied current is wasted towards ORR. Separation of O₂ from the industrial flue gas streams is an energy-intensive process and limits the commercialization of CO₂R. The researchers have limitedly explored the fabrication of oxygen-tolerant electrodes, coating layers that block the O₂ transport onto the electrode, and the development of oxygen-tolerant CO₂R processes. Researchers demonstrated that hydrophilic ionomers (anion exchange ionomers) as a coating onto Cu catalysts show significant improvement on CO₂R activity compared to when they are coated with hydrophobic ionomers (cation exchange ionomers). As differences in the volatility of CO₂ and O₂ in the water are the key parameter in determining the CO₂R over ORR, high water uptake of the ionomer will be considered as one of the design parameters. In addition, since cations play an essential role in stabilizing the CO₂R intermediates and determining the CO₂R selectivity, organic cations will be considered as another design parameter. Since different properties of anion exchange ionomers (AEIs) envisage that all the AEIs are potentially suitable for use as a permeable layer, it is necessary to experimentally screen the best AEIs for this application and understand the reason behind their best performance. In this proposal, we would like to screen the best AEI for CO₂R when flue gas is used as CO₂ feedstock and understand the underlying factors determining its selectivity and activity. The novelty lies in circumventing the energy-intensive CO₂ separation from the flue gas step and instead utilizing a selective CO₂ permeable layer on the cathode. This strategy represents a significant advancement in energy efficiency, and process intensification. The objectives of the project include. 1. Experimentally screen the commercially available anion exchange ionomers for a permeable layer onto the cathode for the direct utilization of industrial flue gas. 2. Tune the best performing ionomers to realize the current densities in the range of 300 mA/cm², stability to 100 h, enhance the CO₂R selectivity from 10% to 80%. 3. Develop a lab-scale system with an electrode area of 25 cm², testing in the MEA setup with simulated flue gas. The cathode (1 cm²) will be fabricated by airbrushing/spray coating the copper catalyst/ionomer ink onto the gas diffusion electrode (GDE). Airbrush inks will be prepared with 20 mg of carbon black, 10 mg of copper nanoparticles, 2 mg of AE ionomer, and 0.6 mL of methanol. The cathode will be examined with scanning electron microscopy (SEM) to check if any cracks have formed. Simulated flue gas (15% CO₂, 4% O₂, balance N₂) will be fed to the cathodic chamber of the MEA cell at a 20 SCCM flow rate, and 1 M KOH will be used as an anolyte. The performance of the electrocatalysts is evaluated at different potentials, liquid products are quantified by 1H NMR, and gaseous products are quantified by gas chromatography. This proposal, by integrating CO₂ separation from flue gas and electrochemical conversion into a single-step, scalable system, addresses both technological and operational gaps. By advancing the current state of the art in carbon capture and utilization technologies, the project is anticipated to have far-reaching impacts on carbon-neutral fuel production, reduced energy consumption, and accelerate the commercialization of the CO₂R process.