Search

Ionic cross-linked hydrogels with flexibility, self-recovery and conductivity have attracted extensive attention for the diverse applications in flexible and wearable sensors as ionic conductive hydrogels. However, the hydrogels need to trade off the ionic conductivity for the mechanical property due to the significant decrease in ionic bond strength at high salt concentration. It remains a challenge to find a feasible strategy to realize both excellent mechanical property and ionic conductivity in ionic cross-linked hydrogels. Herein, hydrogels with high extensibility, fatigue, toughness resistance and ionic conductivity are prepared by the incorporating of trivalent metal cations as cross-linker in one-pot reaction. The improved mechanical property of Al3+ cross-linked hydrogel can be attributed to the labile ligand substitution of Al3+ compared with that of Cr3+, resulting in the rapid self-recovery of ionic bonds. Meanwhile, the hydrogels exhibit a high ionic conductivity, sensibility and stability as strain sensors. The hydrogel sensors can detect the motion of multiple body parts and distinguish different electrical signals. Our study will unfold the crucial role of the metal cation-ligand interaction in the design of soft materials with excellent mechanical performance.

Owing to the abundant uranium reserves in the oceans, the collection of uranium from seawater has aroused the widespread interest. Compared to the uranium extraction from ore, uranium collection from seawater is a more environmentally friendly strategy. The amidoxime (AO) functional group has been considered as one of the most efficient chelating groups for uranium capture. In this work, by drawing upon the photothermal character and antibacterial activity of cuttlefish ink, a cuttlefish ink loaded polyamidoxime (CI-PAO) membrane adsorbent is developed. Under one-sun illumination, the CI-PAO membrane shows a high extraction capacity of 488.76 mg-U/g-Ads in 500 mL 8 ppm uranium spiked simulated seawater, which is 1.24 times higher than PAO membrane. The adsorption rate of CI-PAO membrane is increased by 32.04%. Furthermore, exhibiting roughly 75% bacteriostatic rate in composite marine bacteria, the CI-PAO shows a dramatically antibacterial activity, which effectively prevents the functional sites on the adsorbent surface from being occupied by the biofouling blocks. After immersing in natural seawater for 4 weeks, light-irradiated CI-PAO gave high uranium uptake capacity of 6.17 mg-U/g-Ads. Hence, the CI-PAO membrane adsorbent can be considered as a potential candidate for the practical application for uranium extraction from seawater.

Summary Easy regenerability of core components such as electrode and electrolyte is highly required in advanced electrochemical devices. This work reports a reliable, regenerable, and stretchable hydrogel electrolyte based on ionic bonds between polyacrylic acid (PAA) and polyallylamine (PAH). PAA-PAH electrolyte (1M LiCl addition) exhibits high ionic conductivity (0.050 S·cm-1) and excellent mechanical property (fracture strain of 1,688%). Notably, the electrolyte can be regenerated to any desired shape under mild conditions and remains 96% and 90% of the initial ionic conductivity after the first and second regeneration, respectively. PAA-PAH/LiCl-based supercapacitor exhibits nearly 100% capacitance retention upon rolling, stretching, and 5,000 charge-discharge cycles, whereas the regenerated device holds 97.6% capacitance of the initial device and 90.9% after 5,000 cycles. This low-cost, high-efficiency, and regenerable hydrogel electrolyte reveals very promising use in solid-state/flexible supercapacitors and possibly becomes a standard commercial hydrogel electrolyte for sustainable electrochemical energy devices., Graphical Abstract, Highlights • Highly reliable PAA-PAH/LiCl electrolyte for flexible supercapacitor is developed • PAA-PAH/LiCl hydrogel electrolyte can be easily regenerated under mild conditions • Regenerated hydrogel shows high retention of ionic conductivity and extensibility • Regenerated device reserves >90% capacitance and durability of the original one, Energy Materials; Materials Science; Polymer Chemistry