Electrochemical Reduction of Carbon Dioxide with Functionalized Catalyst for Industrial Application

This PhD project was designed to advance sustainable development by exploring innovative large-scale solutions to reduce atmospheric carbon dioxide emissions. The research focuses on the identification of catalytic systems capable of converting CO₂ into valuable products through electrochemical reduction. The long term idea is to develop a technology suitable for industrial implementation, facilitating a circular economy where carbon dioxide emissions are minimized and, ideally, the reliance on fossil fuels is eliminated; this work is a small but significative step towards the industrial application. The PhD research has focused on the study of catalysts for electrochemical reduction of carbon dioxide, in order to identify the most suitable candidates for industrial applications. The work begins with an overview of the global carbon dioxide situation, highlighting the main challenges and discussing the most common research approaches used to address this issue. A significant part of the study explores bipyridine complexes based on four different metals, manganese, rhenium, tungsten and molybdenum. Their electrochemical behavior is analyzed, and spectroelectrochemical analyses are described for selected complexes. In particular, for the molybdenum complex, the catalytic cycle is elucidated for the first time. Another aspect of the research is focused on porphyrins catalysts based on three different metals: Co, Fe and Cu. These compounds were synthesized by Professor Emma Gallo’s research group at the University of Milan. On these complexes an electrochemical study is conducted, with particular attention to the liquid products from the carbon dioxide reduction. In addition to molecular catalysts, an heterogeneous catalyst composed of copper and selenium is presented. This copper selenide is obtained via electrodeposition. This synthetic approach significantly reduces the costs of the material production in terms of time, energy and solvents consumption. The chapter details the optimization of the deposition procedure, in order to reach the most efficient catalyst for carbon dioxide reduction. On the basis of the investigations presented in the first four chapters, two catalysts were selected for subsequent industrial application. The fifth and final chapter of this thesis describes the results that emerged from the collaboration with the company Hysytech S.r.l. The industrial partner provided a small-scale pilot setup equipped with an electrochemical cell to test the scale-up of catalysts. Despite some initial challenges and difficulties, promising results demonstrate the potential of the project. Though continuous confrontation with the industrial partner, technical issues were identified and addressed; some solutions have already been implemented while others remain pending due to time constrain. The results of the electrochemical reduction of carbon dioxide with this system are presented in detail, along with the description of the encountered challenges and the modifications applied. The thesis concludes with a summary of the key findings from this three-year research project, highlighting the most relevant contributions to the field and the potential impact of the proposed catalytic systems.