Computational material discovery on TMCs for electrochemical CO2RR reduction reaction

• Main Author: Diego Bitzenhofer Betolaza 1998-
• Other Authors: Háskóli Íslands
• Format: Master Thesis
• Language: English
• Published: 2024
• Subjects: Umhverfis- og auðlindafræði; Endurnýjanleg orka; Kolefnisbinding; Reykjavík
• Online Access: https://hdl.handle.net/1946/48616

Capturing the emitted CO2 from the atmosphere and converting it electrochemically, through renewable energy, into usable products, i.e. synthetic fuels, is a promising tool for removing the industries´ unsustainable fossil-fuel dependency. Optimizing the electrochemical process for an efficient electrochemical conversion of CO2, i.e. by using suitable catalysts, is key to the technology’s scalability and function to replace fossil fuels and promote the use of renewable energy. Novel transition metal-based materials were investigated for the possibility of CO2 reduction reaction (CO2RR). The assessment parameters were based on energy efficiency, selectivity, activity and stability. Thermodynamically favorable reaction paths achievable under ambient conditions were explored for seven metal- and carbon-terminated materials, which were found stable, out of eleven surfaces. Considered CO2RR products were carbon monoxide, formic acid, methane, methanol and methanediol. The study found that metal-terminated surfaces were more suitable for CO2RR via the surface mechanism than the carbon-terminated surfaces. The reason being that such surface type was more active for CO2RR due to different adsorption sites between CO2 and hydrogen. Most materials showed sufficient stability, which was measured by analysis of the kinetic barrier for carbon migration from the sublayer to the surface. Vanadium-, Tantalum-, Niobium- and Wolfram-based materials were found to reduce CO2 to methane selectively as onset potentials needed to release the other considered products were comparatively high. Tantalum-based material was the most energy-efficient due to the lowest potential needed, which was -0.67 V vs. RHE. The study concludes that metal-terminated surfaces of Ta, V and Nb are suitable for CO2RR and recommends further experimental investigation. Partially funded by Reykjavík Energy (grant no. VOR23-85)