Spent Li-ion battery (LIB) recovery has become the hot research area due to its surge in quantity and release of heavy metals and toxic substances harmful to the environment. Green and efficient recovery methods are of great significance for the recovery of valuable metals. Herein, an oxalic acid-based deep eutectic solvent (DES) with the weak acidic character and reducibility of oxalic acid was designed for the recovery of valuable metals from spent LIBs via a sustainable and convenient process. Nearly 96.1% of Li and 96.3% of Co can be extracted from lithium cobalt oxide at 120 °C. The DES can extract valuable metals from cathode materials and separate metal ions by itself after extraction without destroying its own structure in a one-pot extraction process. The composition and the structure of DES have been maximum retained and could be intact recycled for another recovery process. After five cycles, the Li and Co extraction efficiencies were maintained above 92.9 and 74.5%, respectively. This work provides a sustainable one-pot recovery process with inexpensive and simple operations for valuable metal recovery from spent LIBs.

Flexible organic light-emitting diode (OLED) devices based on polymer substrates have attracted worldwide attention. However, the current OLED polymer substrates are limited due to weak thermal stability, which is not compatible with the high temperature in OLED fabrication. Here, we developed a novel nanocellulose/polyarylate (PAR) hybrid polymer substrate with both high transparency and excellent thermal properties. Benefiting from the nanometer scale of the cellulose nanofibrils (CNFs) and the efficient interfacial interaction with PAR, the substrate exhibited greatly improved thermal stability, with a glass transition temperature of 192 °C, the thermal decomposition temperature of 501 °C, and upper operating temperature up to over 220 °C. Meanwhile, the hybrid substrate exhibits outstanding mechanical properties. Notably, no apparent transparency loss was observed after the CNF addition, and the hybrid substrate maintains a high transmittance of 85% and a low haze of 1.75%@600 nm. Moreover, OLED devices fabricated on the hybrid substrates exhibit a much improved optoelectrical performance than that of the devices fabricated on the conventional poly(ethylene terephthalate) (PET) substrates. We anticipate this research will open up a new route for fabricating flexible high-performance OLEDs.

A g-C3N4/nanocarbon/ZnIn2S4 (CN/C/ZIS) nanocomposite with enhanced photocatalytic H2 production performance has been successfully synthesized. Based on the experimental results, for the first time, it has been demonstrated that nanocarbon could be integrated into a Z-scheme photocatalytic system and acted as an excellent solid electron mediator.

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Flexible organic light‐emitting diode (OLED) displays have attracted worldwide attention and colorless polyimides (CPIs) are their key substrate materials. However, desirable CPIs are difficult to obtain since the thermal and mechanical properties are sacrificed during CPI production through modification of colored polyimide. Here, a cellulose nanocrystal (CNC)/CPI hybrid substrate with high optical, mechanical, and thermal properties is introduced. Due to the outstanding mechanical and thermal properties of CNCs as well as their strong interfacial interaction with CPI matrix, the sacrificed properties are made up and hybrid substrate is demonstrated strikingly improved thermal properties and mechanical properties with thermal decomposition temperature of 555 °C, upper operating temperature of 320 °C, glass transition temperature of 289 °C, coefficient of thermal expansion of 31.62 ppm K−1, tensile strength of 128 MPa, elastic modulus of 3.72 GPa, and folding capacity of 160 000 times. Particularly, the substrate keeps an excellent transmittance of 86% at 600 nm and it is colorless. The OLED devices built on the hybrid substrates show outstanding performance, which is superior to that of OLED@CPI, and comparable to that of OLED@glass. It is expected that this work will open new avenues for fabricating high‐performance and low‐cost flexible OLED devices.

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