Mineral Hydrogel from Inorganic Salts: Biocompatible Synthesis, All‐in‐One Charge Storage, and Possible Implications in the Origin of Life

Abstract

This study reports a novel hydrogel synthesized using only water and the inorganic salts of FeCl 3 .6H 2 O and (NH 4 ) 6 Mo 7 O 24 .4H 2 O, which offers a stable host for various ions (including Li + , Na + , Mg 2+ , Zn 2+ , Mn 2+ , or Ca 2+ ), affording high ionic conductivity. More interestingly, the redox pair Fe 2+ / Fe 3+ of the gel renders considerable pseudo-capacitance, delivering a high volumetric energy density (4.8 mWh cm −3 , based on the one-piece half-cell) and cycling stability. This simple one-piece approach is convenient and effective-by pairing the mineral gel-based half-cell with another matching electrode, a novel type of charge storage device is formed, with the gel serving as one electroactive material, the electrolyte, and the membrane separator. Furthermore, the mineral hydrogel reported here is of low cytotoxicity, self-bondable and healable, and highly resistant against swelling and disintegrating, with no collapse or volume expansion observed even after being soaked in water for 60 days. To our knowledge, this is the first time that mineral hydrogels have been synthesized from all-inorganic agents in a fully biocompatible setting, which also sheds light on the myth-ridden topic of pre-cell evolution in the prebiotic age.

Strong and Tough Physical Eutectogels Regulated by the Spatiotemporal Expression of Non‐Covalent Interactions

“…[ 1–7 ] At present, traditional gels using water, organic solvents, or ionic liquids as continuous phases are facing the problems of poor temperature‐resistance, low conductivity, bio‐incompatibility, and high cost, realistically impeding their applications. [ 8–11 ] Eutectogels, a new class of soft materials that have just emerged in the gel family in recent years, are composed of cross‐linked polymer networks and deep eutectic solvents (DESs). Benefiting from the inherent high‐electrical conductivity, weak volatility, extensive thermal stability, and low cost of DESs, [ 12–14 ] eutectogels are well placed to replace temperature‐resistant hydrogels and expensive ionogels as flexible ionic conductors, with immeasurable prospects in energy, electronics, and environmental science.…”

“…[1][2][3][4][5][6][7] At present, traditional gels using water, organic solvents, or ionic liquids as continuous phases are facing the problems of poor temperature-resistance, low conductivity, bio-incompatibility, and high cost, realistically impeding their applications. [8][9][10][11] Eutectogels, a new class of soft materials that have just emerged in the gel family in recent years, are composed of cross-linked polymer networks and deep polymers is essential to realize the optimization of polymer networks and obtain strong and acceptable eutectogels.…”

Two-dimensional mineral hydrogel-derived single atoms-anchored heterostructures for ultrastable hydrogen evolution

“…Mineral hydrogel is made by inorganic matter, inorganic salt and water, and can self-assemble into gel networks with various morphologies via a rapid and straightforward process of mixing and gelation under mild conditions 19 , 20 . The coordinated metal ions, which are singly dispersed in the gel networks, can convert into a heterostructure of metal oxides/phosphides/sulphides following a post-heating treatment.…”

Significant Roles of Ions in Enhancing and Functionalizing Anisotropic Hydrogels

“…Although the proportion of inorganic salts in the human body is extremely low, they are essential micronutrients involved in a variety of physiological activities. − Common inorganic salts ionize in aqueous solutions into cations and anions and often play multiple roles in maintaining human health. For example, sodium chloride, an essential condiment that is often used to enhance food taste and preserve food, exhibits a series of functions when involved in metabolism. − Sodium ions are important for water metabolism, regulation of neuromuscular excitability, etc., while chloride ions participate in the formation of gastric acid, the transport of carbon dioxide in the blood, etc.…”