Search

Molecule aggregation in solution is acknowledged to be universal and can regulate the molecule's physiochemical properties, which however has been rarely investigated in electrochemistry. Herein, an electrochemical method is developed to quantitatively study the aggregation behavior of the target molecule methyl viologen dichloride. It is found that the oxidation state dicationic ions stay discrete, while the singly‐reduced state monoradicals yield a concentration‐dependent aggregation behavior. As a result, the molecule's energy level and its redox potential can be effectively regulated. This work does not only provide a method to investigate the molecular aggregation, but also demonstrates the feasibility to tune redox flow battery's performance by regulating the aggregation behavior. [ABSTRACT FROM AUTHOR]

Metal–organic framework (MOF) films can be made by cathodic electrodeposition, where a Brønsted base is formed electrochemically which deprotonates the MOF linkers that are present in solution as undissociated/partially dissociated weak acids. However, the co‐deposition of metal and the narrow range of possible metal nodes limit the scope of this method. In this work, we propose the use of hydrogen peroxide (hydrogen peroxide assisted cathodic deposition or HPACD), to overcome these limitations. Electrochemical measurements indicate that in DMF, hydrogen peroxide is reduced to superoxide anions that deprotonate the carboxylic ligands. This single‐electron reduction happens at much higher potentials than all previous reported methods. This prevents the co‐deposition of metal and extends the range of possible metal nodes. Various pure MOF films (HKUST‐1, MIL‐53(Fe) and MOF‐5) were prepared via this approach. HPACD was also used for the preparation of patterned MOF films and of flexible Cu‐BTC coated paper membranes which reject 99.1 % of Rose Bengal from water with a permeance of 8.4 L m−2 h−1 bar−1. [ABSTRACT FROM AUTHOR]

A novel organic molecule, 2,4,6‐tris[1‐(trimethylamonium)propyl‐4‐pyridiniumyl]‐1,3,5‐triazine hexachloride, was developed as a reversible six‐electron storage electrolyte for use in an aqueous redox flow battery (ARFB). Physicochemical characterization reveals that the molecule evolves from a radical to a biradical and finally to a quinoid structure upon accepting four electrons. Both the diffusion coefficient and the rate constant were sufficiently high to run a flow battery with low concentration and kinetics polarization losses. In a demonstration unit, the assembled flow battery affords a high specific capacity of 33.0 Ah L−1 and a peak power density of 273 mW cm−2. This work highlights the rational design of electroactive organics that can manipulate multi‐electron transfer in a reversible way, which will pave the way to development of energy‐dense, manageable and low‐cost ARFBs. [ABSTRACT FROM AUTHOR]