Polymers for carrying and storing hydrogen

Abstract

Safe and efficient hydrogen-carrying and -storing materials are in high demand for future hydrogen-based energy systems. Series of hydrogen carriers have been studied and examined, such as organic hydrides, metal hydrides and metal-organic frameworks; however, these carriers often suffer from safety issues and usually fix and store hydrogen at energy-consuming high pressures and/or temperatures. Here, we review organic polymers and their molecular design for hydrogen storage. Porous organic polymers, hypercrosslinked polymers and polymers with intrinsic microporosity reversibly stored and released hydrogen through hydrogen physisorption on their highly porous structures. Ketone and N-heterocycle polymers fixed and stored hydrogen at atmospheric pressure through the formation of chemical bonds to form the corresponding alcohol and hydrogenated N-heterocycle polymers, respectively. Electrochemical hydrogenation using water as a hydrogen source was also effective, in which the polymer worked as a scaffold for hydrogenation. The hydrogenated polymers released hydrogen in the presence of catalysts at mild conditions. The potential of using organic polymers in the quest for finding new types of hydrogen-carrying and -storing materials that are very safe and portable is suggested.

Synthesis of Nitrogen-Rich Polymers by Click Polymerization Reaction and Gas Sorption Property

“…During the last few decades, microporous organic polymers (MOPs) have been intensively investigated and applied in various fields such as heterogeneous catalysis [ 1 ], gas adsorption and separation [ 2 , 3 ], the adsorption of radioactive iodine [ 4 ], drug delivery [ 5 , 6 ] and photovoltaics [ 7 , 8 , 9 ] duo to the low density, large surface area, high thermal/chemical stability, functional surface, and diverse building blocks. Until now, numerous MOPs including crystalline covalent organic frameworks (COFs) [ 10 ], covalent triazine frameworks (CTFs) [ 11 ], benzimidazole-linked polymers (BILPs) [ 12 ], porous polymer networks (PPNs) [ 13 ], hyper-crosslinked polymers (HCPs) [ 14 ], conjugated microporous polymers (CMPs) [ 15 ], polymers of intrinsic microporosity (PIMs) [ 16 ], and porous aromatic frameworks (PAFs) [ 17 ] have been synthesized via different polymerization reactions and versatile synthons.…”

Reversible Hydrogen Releasing and Fixing with Poly(Vinylfluorenol) through a Mild Ir‐Catalyzed Dehydrogenation and Electrochemical Hydrogenation

“…Recently, we studied the electrochemical hydrogenation of ketones and N-heterocycle derivatives and applied these results to mild hydrogen fixation reactions with the corresponding polymers using water as the hydrogen source. [19,24] To examine the electrochemical reduction of poly(vinylfluorenone), a poly(vinylfluorenone)/carbon nanofiber composite was prepared as the working cathode, and a tert-butyl alcohol and acetonitrile solution of tetrabutylammonium tetrafluoroborate was used as the electrolyte because in this solvent, the polymer was swollen but insoluble. Poly(vinylfluorenone) exhibited two redox waves at −1.3 and −1.9 V (vs Ag/AgCl) in the cyclic voltammogram (Figure 2, inset), which were ascribed to the two-electron reduction of the fluorenone unit via its anion radical to the dianion (Scheme 2).…”

Preparation and application of sulfonated polysulfone in an electrochemical hydrogen storage system

“…Hydrogen consists of a few electrons with a weak intermolecular force of H‐H molecules; therefore, it can be liquefied at 1 atm pressure. Applying an electric discharge through H 2 gas at low pressure result in molecular dissociation, ionization, recombination, and formation of plasma‐add‐on 3 …”

“…Applying an electric discharge through H 2 gas at low pressure result in molecular dissociation, ionization, recombination, and formation of plasma-add-on. 3 The hydrogen can be stored in the gas form via (a) nondissociative surface physisorption (desorption); (b) surface dissociative chemisorption (recombination); (c) surface absorption (desorption); (d) transferring of hydrogen ad-atoms (H ad. ) from subsurface to bulk via diffusion; and (e) transformation of the phase.…”