Hi Axil, If I'm right i don't think this experiment is meant to be a strict Lugano test replication but rather a Lugano/Celani Hybrid based on the use of a wire. It's an interesting idea to check out I think.
Regarding the use of carbon, I'm wondering if Boron Carbide might be interesting as an alternative. In-particular Li dispersed Boron Carbide Nanotubes.
We need to educate ourselves on the proper method to build fuel. There are chemical rules to be discovered. One rule from Holmlid in how to form hydrogen Rydberg matter is to keep hydrogen from combining with another element to avoid the formation of covalent bonds, when hydrogen is absorbed and desorbed. It might be best to kept the elements in the neighborhood of the hydrogen as limited as possible. Specifically this means nickel, carbon that does not bond with hydrogen at high temperatures, an alkali like lithium and or potassium and hydrogen. Carbon desorbes hydrogen because carbon holds on to hydrogen at low temperatures by releases it at higher temperatures as the temperature rises. Boron might be disruptive of the chemical bonding formation process.
What carbon does chemically is based on how its atoms are bonded. Carbon comes in many forms based on its bonding. Graphite is the optimal form of carbon for hydrogen absorption and desorption. I don't know is carbon nanotubes are considered graphite. Diamond is chemically inert because all its atoms are bonded to each other in a lattice. Diamond might be a preferred coating to prevent lithium corrosion.
For example, I would coat tungsten with diamond in a long lived reactor shell to protect that metal from corrosion.