Hydrogen is an attractive future energy source. Developing a hydrogen carrier, without any safety risk, i.e., high pressure and toxicity, is an urgent issue. Herein we present a fluorenone/fluorenol polymer sheet as a hydrogen carrier featuring high safety, moldability, and ease of handling. An iridium catalyst allows the polymer sheet to fix and release hydrogen gas under milder conditions (< 100°C and ambient pressure), [a

No abstract

Organic redox-active materials have been extensively studied as electrode-active materials to enable innovative battery designs with low environmental burdens. Facile condensation of 4,5-dihydroxyanthraquinone-2-carboxylic acid and poly­(allylamine) in water produces hydrophilic 1,8-dihydroxyanthraquinone (DHA)-substituted poly­(allylamine) (PDHA). Its high hydrophilicity originates from the poly­(allylamine) main chain, and the distorted structure of the DHA inhibits intermolecular stacking of the polymer side chain. This made it possible to achieve a high electron and proton diffusion coefficient of 10–11 cm2/s, which is an order of magnitude higher than that of conventional redox polymers that have one-step, two-electron redox capability. The electrode, composed of appropriately synthesized PDHA, showed a full capacity of 140 mAh g–1 with excellent cyclability (>97% capacity maintenance after 500 cycles) and high rate capabilities (e.g., 120 C) in an acidic aqueous electrolyte under inert gas. These electrochemical properties were maintained even in air, making PDHA a promising candidate for a robust, electrode-active material. A polymer–air secondary battery was fabricated with PDHA, Pt/C, and a 0.5 M H2SO4 aqueous solution as the anode material, cathode material, and electrolyte, respectively, without any separator, inert gas, or strict sealing. This open-air battery displayed a discharge voltage of 1.05 V, with high cyclability greater than 500 cycles and high rate capabilities (e.g., 60 C), demonstrating a new battery concept and potential for large-scale applications.

No abstract

The development of hydrogen carriers that are free from safety risks such as explosivity, volatility and toxicity is essential for safe hydrogen storage. In this study, we synthesize a safe and hydrophilic isopropanol/acetone‐substituted polymeric hydrogen carrier by a facile synthetic procedure that is conducted in water and only requires dialysis with water for purification. A simple nucleophilic substitution of poly(allylamine) and 2‐bromoacetone produces a hydrophilic acetone‐substituted poly(allylamine) derivative, facilitating control over the hydrophilicity of the polymer according to the degree of substitution. The polymer is readily hydrogenated using NaBH4 to obtain a hydrophilic isopropanol‐substituted poly(allylamine). The high density of the repeating units and high hydrophilicity of the amine groups enable the maximization of the mass hydrogen storage density of the redox polymer to ca 1.5 wt%. Reversible hydrogen gas fixation/release from the polymeric hydrogels via chemical bond formation/disconnection is realized with complete conversion, with dehydrogenation occurring at 65–95 °C in the presence of an iridium complex catalyst. © 2021 Society of Industrial Chemistry.