Understanding Electrochemical Growth of Carbon Nanotubes from CO₂

The development of new carbon-negative electrochemical processes are of paramount importance to the future sustainability of human civilization. This presentation will focus on the electrochemical growth of carbon nanostructures from CO₂. Previous works have pioneered the observation of carbon nanotube growth in molten LiCO₃ electrolytes from CO₂. However, in many past works, several CO₂-derived cathodic carbon morphologies were observed, which included carbon particles/spheres, graphite flakes, carbon nanofibers, CNTs, and graphene-like ultrathin carbon sheets. Moreover, these morphologies are often mixed, resulting in a low selectivity and difficult separation towards one single carbon morphology, and the factors leading to various morphologies are not currently well understood. In this talk, we will explore the fundamental growth mechanism to inform the broader long-term goal of improving the selectivity towards carbon nanotubes from CO₂. This present work studied the cathodic growth of carbon nanotubes by utilizing a simple three-electrode configuration consisting of pure Li₂CO₃ electrolyte, pure transition metal foil cathodes, Pt anode, and homemade Ag/Ag₂SO₄ reference electrode to determine the impact of tunable parameters on the resulting electroreduction products. These products are studied via potential-dependent studies as well as via ex-situ techniques such as TEM, XPS, XRD, and Raman spectroscopy to gain insights into the growth of these materials.