Proceedings of Catalyst Design Strategies for Photo- and Electrochemical Fuel Synthesis (ECAT25)
Publication date: 19th December 2024
The electrocatalytic reduction reaction of CO2 (eCO2RR) represents one of the most interesting ways to convert H2O and CO2 into high-value products [1]. This process can be powered by exploiting sunlight as a clean and renewable energy source in artificial leaf-type systems, which can produce simultaneously green hydrogen and liquid carbon products [2]. However, improvements are needed in electrocatalyst and cell development to enhance the selectivity of eCO2RR towards carbonaceous products of industrial interest.
This study focuses on achieving selective production of a single carbon product, i.e. formate/formic acid, while minimizing the formation of carbon monoxide (CO). Formate is a promising liquid energy carrier working under ambient conditions, showing potential as a hydrogen carrier in the emerging hydrogen economy.
For preparing the electrodes, copper sulphides (Cu-S) in different crystalline forms were synthesized via solvothermal and reactive thermal annealing methods, and subsequently doped with non-critical raw materials (no CRMs), such as aluminium (Al). Then, copper sulphides were deposited on porous nanocarbon substrates to fabricate gas-diffusion-electrodes (GDEs). These electrodes were fully characterized using XRD, SEM, BET analysis, as well as characterized by advanced electrochemical techniques, like Electrochemical Impedance Spectroscopy (EIS), and finally tested in a custom-designed flow-type electrochemical device for eCO2RR.
The results demonstrated a maximum of Faradaic Efficiency (FE) of over 80% to formate, with CO formation below 0.5%. Further work is now addressed to optimize cell and electrode design, using zero-gap technology. This configuration minimizes the distance between electrodes, thereby reducing cell overpotential and enabling operation at higher currents.
This work was funded by the European Union through the H2020 Project “SUPERVAL” (ID: 101115456), which is gratefully acknowledged.