Development of Innovative Components for Integrated Electrochemical Carbon Capture and Utilization

In response to the global climate emergency caused by increasing atmospheric carbon dioxide (CO₂) concentrations, one of the most promising strategies is the capture and conversion of CO₂ (CCU) into value-added products. Among the various approaches, the Electrochemical CO₂ Reduction Reaction (eCO₂RR) enables the transformation of CO₂ into useful compounds through the use of electrolysers and specific electrocatalysts. In this context, bicarbonate electrolysers represent an innovative solution, capable of combining carbon capture and utilization in a single system, removing energy demanding process. However, these devices still present significant challenges for future scale-up and industrial implementation. This thesis focuses on the development of advanced materials and components to optimize integrated CO₂ capture and utilization in bicarbonate electrolysers, with the specific objective of designing a low-energy consumption, efficient electrolyser for the selective conversion of CO₂ into carbon monoxide (CO). Experimental activities were carried out on a MEA (Membrane Electrode Assembly) electrolyser equipped with different catalytic systems. As a benchmark, silver nanoparticles-based gas diffusion electrodes (GDEs) were tested using 3 M KHCO₃ as catholyte and 0.05 M H₂SO₄ as anolyte. The electrochemical performance was monitored while optimizing silver-based catalysts. Improved activity was observed when silver nanoparticles were combined with sputtered silver layers on porous carbon substrates, enhancing both catalytic behavior and Faradaic efficiency. Additional tests in temperature and pressure conditions provided further information for the potential scalability of the system for industrial applications. In parallel, alternative low-cost catalysts were investigated to address the economic limitations associated with noble metals. In particular, cobalt phthalocyanine (CoPc), an organometallic single-atom catalyst, was investigated combined with carbon supports. Hybrid materials obtained by coupling CoPc with carbon nanotubes (CNTs) and carbon black (CB) were produced and characterized. The hybrid electrocatalysts were characterised using XPS, XRD and FESEM techniques in addition to electrochemical characterizations. Among these, the CoPc-CB hybrid, with ratio 1:3, exhibited the best catalytic performance, achieving a Faradaic efficiency for CO of up to 56% under current densities of 200 mA cm⁻². Overall, the results highlight the potential of integrating innovative catalyst design with advanced electrolyser architectures to overcome the limitations of conventional CCU systems. The optimized materials developed in this work demonstrate significant progress toward scalable, energy-efficient electrochemical processes, contributing to the vision of a circular carbon economy and sustainable industrial technologies.