Design of organic materials for nature-inspired photochemical and electrical energy storage

Abstract

Energy storage technologies have attracted great attention as global demand for energy is increasing rapidly. This thesis describes the design strategies of organic materials using bio-inspired peptides and single organic molecules for photochemical and electrical energy storage. Chapter 1 report the synthesis of self-assembled, insulin-based amyloid nanofibrils that are hybridized with light-responsive dyes (i.e., thioflavin-T, ThT) to mimic natural photosystems. The work presents the potential of self-assembled amyloid nanofibrils as a light-harvesting scaffold for visible light driven NADH regeneration with a biocatalytic module for enzymatic reduction reaction in colloidal system. Chapter 2 demonstrates visible-light driven regeneration of nicotinamide adenine dinucleotide (NAD+) using solvatochromic Congo red (CR) hybridized with an amyloid-derived peptide (Fmoc-FF) hydrogel system. This study adds a new dimension to the research on self-assembled amyloid materials for biocatalytic oxidized photochemical storage. Chapter 3 unveils that the proton-coupled redox reaction of a single organic molecule in an aqueous solution can be translated to the lithium-coupled redox reaction of a single organic molecule in a lithium-based organic electrolyte by using phenoxazin-3-one (i.e., resorufin) as a new bio-inspired redox active molecule. The phenoxazin-3-one cathode delivered a high discharge capacity (298 mAh g-1) and fast rate capability (65% capacity retention at 10 C). The result provides insight into the design of a new class of bio-inspired organic electrode materials. Chapter 4 presents the self-reinforced inductive effect in the symmetric bipolar QA derivative, N,N'-dimethylquinacridone (DMQA), which enables outstanding battery performance in the lithium-ion rechargeable battery system. DMQA, the symmetric bipolar organic molecule, exhibited the excellent battery performance. Excellent capacity retention is achieved at the average voltage of 3.85 V (vs. Li+/Li) and 1.68 V (vs. Li+/Li) during both p- and n-type reaction, which are suitable to work as the cathode and anode of the batteries, respectively. This chapter provides a new insight about energy storage capability of symmetric bipolar organic molecule and its self-reinforced inductive effect.