I have read a couple of research articles regarding Triboelectric Nanogenerators. Almost all of the papers mentioned about different selection of materials including pristine material, modified material-surface modification using nanoparticles, nanostructures and internal matrix modification etc. I have gone through the triboelectric series too. However, I have a few questions that need to be answered and am presenting them as follows:

1. How should I choose a suitable material (as I noticed in some works that they worked on materials which are not in triboelectric series) and how will I understand that whether the surface or inner matrix requires any modification or not?

2. How will I understand that what kind of modification technique should be used, if it requires modification?

If anyone can help me by giving your valuable comments or any links, It'll be very helpful.

Thanks.