Enhancing the performance of electrocatalysts for CO2 reduction towards C1 products

The Industrial Revolution led to significant socio-economic growth and population expansion, yet its environmental consequences have been profound, notably through the increase in anthropogenic greenhouse gases like carbon dioxide (CO2). This imbalance in the carbon cycle contributes to global warming, melting ice caps, biodiversity loss, and extreme weather events. To combat this, international and European authorities aim for carbon neutrality by 2050. Achieving this requires innovative technologies to limit global temperature rise to below 2C above pre-industrial levels. One promising solution is the electrochemical reduction of CO2 (eCO2R), a carbon dioxide utilization technology that reduces atmospheric CO2 and closes the carbon cycle by converting it into valuable chemicals using renewable energy sources such as wind, solar, and geothermal power. Two key products of eCO2R, carbon monoxide and formate, are of particular interest due to their industrial relevance, high market value, and low energy requirements. This dissertation explores the electroreduction of CO2 as a critical solution to mitigate climate change. It delves into the interplay between electrocatalyst performance and interface properties to improve the selectivity, activity, and stability of electrocatalysts used for producing C1 products. The research highlights the challenges faced by current electrocatalysts and suggests ways to enhance their performance. In the context of CO production, the dissertation investigates the limitations of silver (Ag) nanoparticle stability, addressing issues of agglomeration and detachment. The study proposes a nanoparticle confinement strategy to stabilize Ag nanoparticles within nitrogen-doped ordered mesoporous carbon (NOMC). This method significantly reduces instability and improves Faradaic efficiency (FE) towards CO production (>80% at 100 mA cm-2). For formate production, the research focuses on chalcogenide-based electrocatalysts, specifically SnS2 thin films fabricated using atomic layer deposition (ALD) techniques. The study examines the impact of morphology on the electrocatalytic interface and its role in the triple-phase boundary (TPB). Although these SnS2 electrocatalysts exhibit high formate FE (~80%), their long-term stability is limited by the reduction of SnS2 to Sn and morphological degradation. Further investigation into the effect of substrate modifications via ALD reveals that thermal deposition of In2S3 electrocatalysts leads to superior formate selectivity (>90%) and stability compared to plasma-enhanced versions. These findings emphasize the importance of interface properties, such as roughness and wettability, in enhancing electrocatalyst performance. The research provides valuable insights for optimizing electrocatalysts for industrial applications, improving their stability, activity, and selectivity.