The fabrication of highly durable skin‐mimicking sensors remains challenging because of the unavoidable fatigue and physical damage that sensors are subjected to in practical applications. In this study, ultra‐durable ionic skins (I‐skins) with excellent healability and high sensitivity are fabricated by impregnating ionic liquids (ILs) into a mechanically robust poly(urea‐urethane) (PU) network. The PU network is composed of crystallized poly(ε‐caprolactone) and flexible poly(ethylene glycol) that are dynamically cross‐linked with hindered urea bonds and hydrogen bonds. Such a design endows the resultant ionogels with high mechanical strength, good elasticity, Young's modulus similar to that of natural skin, and excellent healability. The ionogel‐based I‐skins exhibit a high sensitivity to a wide range of strains (0.1–300%) and pressures (0.1–20 kPa). Importantly, the I‐skins show a highly reproducible electrical response over 10 000 uninterrupted strain cycles. The sensing performance of the I‐skins stored in open air for 200 days is almost the same as that of the freshly prepared I‐skin. The fractured I‐skins can be easily healed by heating at 65 °C that restores their original ultra‐durable sensing performance. The long‐term durability of the I‐skins is attributed to the combination of non‐volatility of the ILs, excellent healability, and well‐designed mechanical properties.

Hydrogel-based self-healing ionic skins possess high mechanical strength, excellent resilience, anti-freezing properties and high sensitivity and can heal fatigue and mechanical damage to restore the original sensing performance.

It is challenging to develop healable elastomers with combined high mechanical strength and good elasticity. Herein, a simple strategy to develop high-performance elastomers that integrate high mechanical strength, enormous stretchability, good resilience, and healability is reported. Through simply complexing poly(acrylic acid) and poly(ethylene oxide) based on hydrogen-bonding interactions, transparent composite materials that perform as elastomers are generated. The as-prepared elastomers exhibit mechanical strength (true strength at break) and toughness (fracture energy) as high as 61 MPa and 22.9 kJ/m, respectively, and they can be stretched to >35 times their initial length and are able to return to their original dimensions following the removal of stress. Further, the elastomers are capable of healing from physical cuts/damages in a humid environment because of reformation of the reversible hydrogen bonds between the polymer components. The high mechanical strength of the elastomers is ascribed to the high degree of polymer chain entanglements and multiple hydrogen-bonding interactions in the composites. The reversible hydrogen bonds, which act as cross-linkages, facilitate the unfolding and sliding of the polymer chains in the composites, thereby endowing the elastomers with good elasticity and healability. Furthermore, flexible conductors with water-enabled healability were developed by drop-casting Ag nanowires on top of the elastomers.

During the exploration of highly efficient noble-metal-free electrocatalysts for the hydrogen evolution reaction (HER), a promising and challenging strategy is to fabricate composite nanocatalysts by finely tuning metal and/or nonmetal element components. Herein, we report a new HER electrocatalyst, which is composed of molybdenum phosphide and molybdenum carbide composite nanoparticles (NPs) coated by few-layer N-doped graphitic carbon shells (denoted as MoP/MoC@C). Such a new combination mode of electrocatalysts is realized by a one-step annealing route with the mixture of a Mo/P-based polyoxometalate (POM) and dicyandiamide. On the basis of this method, the simultaneous phosphorization and carbonization in a nanoscale confined space can be easily achieved by the use of POM as the molecular-element-regulating platform. MoP/MoC@C exhibits more remarkable HER performance over the whole pH range than those of MoP, MoC, and the physical mixture of MoP and MoC. The low overpotentials of 89, 136, and 75 mV were obtained at a current density of 10 mA cm in the media of pH = 0, 7, and 14, respectively. Furthermore, MoP/MoC@C shows a long-term durability for 14 h over the entire pH range (0-14). Because of the protection of carbon shells, such composite electrocatalyst also possesses better transition-metal tolerance exemplified by Fe, Co, and Ni than that of 20% commercial Pt/C. This work demonstrates the advantage of POM precursors in adjusting the component and properties of nanoscale composite electrocatalysts for HER, which may suggest new options for the fabrication of highly efficient composite electrocatalysts.

degradation generally requires harsh and strictly controlled conditions. [5,8,9] Moreover, the number of plastic types that are capable of being fully and efficiently degraded by such methods is very less. Therefore, the most effective approach to solve the issue of plastic waste accumulation consists in substituting traditional plastics with novel plastics that can be fully degraded into environmentally friendly substances in natural environments. [10-18] Poly(lactic acid) (PLA) can be degraded into CO 2 and H 2 O by microorganisms under specific and controlled humidity and temperature conditions. [16,19,20] Currently, degradable PLA is widely used in biomedical equipment, food packaging, and disposable tableware. [16] Nevertheless, to meet a wide range of applications, the development of new types of degradable plastics remains crucial. [10,14,21] In particular, it is necessary to develop plastics that are capable of complete degradation under natural environmental conditions. Poly(vinyl alcohol) (PVA) production is cost-effective, and the material itself possesses desirable degradability, nontoxicity, high tensile strength, and excellent flexibility. [11,22-26] In natural environments, PVA can be fully degraded into CO 2 and H 2 O by microorganisms through the oxidation of PVA hydroxyl groups into diketones and the subsequent hydrolysis of carbon-carbon diketone bonds. [11,22,27,28] Therefore, PVA-based plastics are environmentally friendly and degradable, and they can be used for a wide range of potential applications. [29,30] PVA-based plastics have been fabricated by complexation of PVA with partner species such as inorganic nanofillers, [31] organic molecules, [32] and polymers [25,30] containing complementary noncovalent interactions. However, because of the water solubility of PVA, these PVA-based plastics absorb water from the environment and exhibit lower mechanical strength compared to those of PEbased plastics in watery environments. This limitation restricts the applications of PVA-based plastics and increases their storage cost. Commercially available poly(vinyl formal) (PVF) and poly(vinyl butyral) (PVB), which are synthesized via an acid-catalyzed acetal reaction between the PVA hydroxyl groups and the aldehyde groups of formaldehyde and n-butyraldehyde, respectively, exhibit good water resistance. However, PVF and PVB are difficult to be degraded in soil because of their high acetalization ratios (usually higher than ≈70%). [33,34] Therefore, it is necessary to fabricate PVA-based degradable plastics that can maintain sufficiently high mechanical strength in watery