In situ electrochemical recomposition of decomposed redox-active species in aqueous organic flow batteries

Nature Chemistry · 2022 · 144 citations

• Chemistry
• Combinatorial chemistry
• Inorganic chemistry

Extremely Stable Anthraquinone Negolytes Synthesized from Common Precursors

Chem · 2020 · 174 citations

• Chemistry
• Chemical engineering
• Inorganic chemistry

Near Neutral pH Redox Flow Battery with Low Permeability and Long‐Lifetime Phosphonated Viologen Active Species

Advanced Energy Materials · 2020 · 190 citations

• Inorganic chemistry
• Chemistry
• Photochemistry

Abstract A highly stable phosphonate‐functionalized viologen is introduced as the redox‐active material in a negative potential electrolyte for aqueous redox flow batteries (ARFBs) operating at nearly neutral pH. The solubility is 1.23 m and the reduction potential is the lowest of any substituted viologen utilized in a flow battery, reaching −0.462 V versus SHE at pH = 9. The negative charges in both the oxidized and the reduced states of 1,1′‐bis(3‐phosphonopropyl)‐[4,4′‐bipyridine]‐1,1′‐diium dibromide ( BPP−Vi ) effect low permeability in cation exchange membranes and suppress a bimolecular mechanism of viologen decomposition. A flow battery pairing BPP−Vi with a ferrocyanide‐based positive potential electrolyte across an inexpensive, non‐fluorinated cation exchange membrane at pH = 9 exhibits an open‐circuit voltage of 0.9 V and a capacity fade rate of 0.016% per day or 0.00069% per cycle. Overcharging leads to viologen decomposition, causing irreversible capacity fade. This work introduces extremely stable, extremely low‐permeating and low reduction potential redox active materials into near neutral ARFBs.

pH swing cycle for CO₂capture electrochemically driven through proton-coupled electron transfer

Energy & Environmental Science · 2020 · 195 citations

• Chemistry
• Inorganic chemistry
• Photochemistry

This study analyzes the energetic cost of CO₂ separation using a pH swing created by electrochemical redox reactions of organic molecules involving PCET in aqueous electrolyte, and compares the experimental energetic cost to other methods.