Triboelectric (nano-) generators basically involves electrostatic charging between two surfaces, and as these charged surfaces move they induce a potential on the electrode, that causes current to flow. Here is one article describing the process: https://la.disneyresearch.com/wp-content/uploads/Project_PaperGenerators_uist2013_paper1.pdf.
Can I use FreeFEM to simulate electrostatic field? If yes, can you please guide and help me, so that I can start. I am completely new to this platform, and any help is much appreciated.
You need to model your problem by partial differential equations with boundary conditions. FreeFEM cannot do this for you. If you have such equations FreeFEM is able to provide accurate approximations of the solutions to these equations.
I am looking of a tool available for Linux using which I could model Triboelectric Nanogenerators. Something like what is done in this video with Comsol, https://youtu.be/jt6RTQN9pKg .
This has come up before you can search forum for related terms like tribo or piezo maybe.
Open literature may be indexed on google scholar and appear on arxiv although
other sources like IEEE may be useful. Probably college lecture notes com up too.
Once you have an equation in mind, you can find related FF examples.