ELECTRODE DEVELOPMENT FOR THE REDUCTION OF CARBON DIOXIDE INTO FORMIC ACID THROUGH ELECTROCHEMICAL METHODS

• Main Author: Nurul Aulia Irawan, Silmia
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/87016
• Institution: Institut Teknologi Bandung

Most of the increasing concentration of carbon dioxide in the atmosphere is caused by human activities that produce energy from fossil fuels. This increase in the amount of carbon dioxide in the atmosphere can have negative impacts on the environment such as increasing global temperatures and climate change. With the negative impacts of carbon dioxide emissions, it is necessary to treat carbon dioxide emissions so that it does not have a worse impact on the environment. A relatively new approach that has received a lot of attention in processing CO2 gas by producing other value-added compounds from CO2 gas. One technology that can be applied is CO2 electrochemical reduction technology, which can convert carbon dioxide into other compounds such as formic acid. Formic acid is used in various applications in industry. In addition, formic acid is an attractive option as a hydrogen carrier in liquid form. It has proven to be a readily available material for implementing hydrogen storage technologies, thus avoiding the installation of expensive new infrastructure. Electrode modification was carried out by electrodeposition process using Lead(II) nitrate (Pb(NO3)2) electrolyte solution with a concentration of 0.01 M, nitric acid (HNO3) with a concentration of 0.1 M, and sodium fluoride (NaF) with a concentration of 0.01 M mixed with a ratio of 1:1:1. The electrodeposition process was carried out without stirring. Electrodeposition was carried out at current density variations of 0.5, 1, 2, and 3 A/cm2. In addition, the deposition time variation was also set for 5, 20, 60 seconds. The deposition electrodes were cleaned using aqua DM and dried using nitrogen gas at room temperature. The electrodeposition time and current density in cathode fabrication will be further investigated regarding their effect on cathode morphology. This electrochemical reduction of CO2 to formic acid research uses a sparger to produce CO2 bubbles in 0.5 M KHCO3 electrolyte solution. The anolyte solution used was 0.1 M H2SO4. The catholyte solution was bubbled with CO2 gas for approximately 1 hour at a CO2 bubbling rate of 50 mL/minute. The electrolyte was circulated using a pump into a Proton Exchage Membrane (PEM) type reactor in which the cathode and anode chambers were separated by a Nafion 212 Membrane. The electrodes used, the cathode made of Cu metal with modification using Pb through electrodeposition process and the anode made of Pt-Ir alloy metal. With the modification of the electrodes, it will be further investigated on the effect on Faraday Efficiency and percentage yield of formic acid produced from CO2 electrochemistry. To determine the effect of electrode modification on Faraday Efficiency and percentage yield of formic acid produced by electrolysis, a comparative study was conducted on the results of electrolysis of Pb-Sn electrodes. With the increase in electrodeposition time, the addition of Pb deposit mass on the Pb/Cu 2 A/cm2;5s electrode was 0.00065 ± 0.00007 grams, the Pb/Cu 2 A/cm2;20s electrode was 0.0029 ± 0.0003 grams, and the Pb/Cu 2 A/cm2;60s electrode was 0.009 ± 0.007 grams. In addition, the increase in current density caused an increase in the mass percentage of Pb with the Pb/Cu 3 A/cm2;5s electrode by 10.02%, this value is higher than the Pb/Cu 0.5 A/cm2;20s electrode by 0.47%. Modifying the Pb/Cu electrode affects the current efficiency and the percentage yield of formic acid produced from CO2 electrolysis. The Pb/Cu 2 A/cm2;20s electrode became the best electrode with the largest current efficiency and formic acid yield percentage compared to other electrodes. The current efficiency was 8.73%, while the formic acid yield percentage was 5.16%. However, the Pb/Cu 0.5 A/cm2;20s electrode became the electrode with the smallest current efficiency and formic acid yield percentage compared to other electrodes. The current efficiency was 2.35%, while the formic acid yield percentage was 1.64%.