fig2

Figure 2. Structural formula of some environment-friendly organic electrode materials. (A) Pyrene-4, 5, 9, 10-tetraone^[26]. (B) Polypeptide anode and cathode polypeptide materials^[27]. (C) [2.2.2.2]paracyclophane-1, 9, 17, 25-tetraene^[28].