Showing papers by "Qian Wang published in 2022"

Voltage-Gated Membranes Incorporating Cucurbit[n]uril Molecular Containers for Molecular Nanofiltration.

Abstract: Smart voltage-gated nanofiltration membranes have enormous potential for on-demand and precise separation of similar molecules, which is an essential element of sustainable water purification and resource recovery. However, the existing voltage-gated membranes are hampered by limited selectivity, stability, and scalability due to electroactive monomer dimerization. Here, for the first time, the host-guest recognition properties of cucurbit[7]uril (CB[7]) are used to protect the viologen derivatives and promote their assembly into the membrane by interfacial polymerization. Viologen functions as a voltage switch, whereas CB[7] complexation prevents its dimerization and improves its redox stability. The inhibited diffusion of the CB[7]-viologen complex enables the precise patterning of the surface structure. The resultant voltage-gated membrane displays 80% improved rejection performance, excellent recovery accuracy for similar molecules, and anti-fouling properties. This work not only provides an innovative strategy for the preparation of voltage-gated smart nanofiltration membranes but also opens up new avenues for ion-selective transmission in water treatment, bionic ion channels, and energy conversion.

Ionically Conductive Tunnels in h‐WO3 Enable High‐Rate NH4 + Storage

Abstract: Compared to the commonly applied metallic ion charge carriers (e.g., Li+ and Na+), batteries using nonmetallic charge carriers (e.g., H+ and NH4+) generally have much faster kinetics and high‐rate capability thanks to the small hydrated ionic sizes and nondiffusion control topochemistry. However, the hosts for nonmetallic charge carriers are still limited. In this work, it is suggested that mixed ionic–electronic conductors can serve as a promising host for NH4+ storage. Using hexagonal tungsten oxide (h‐WO3) as an example, it is shown that the existence of ionic conductive tunnels greatly promotes the high‐rate NH4+ storage. Specifically, a much higher capacity of 82 mAh g–1 at 1 A g–1 is achieved on h‐WO3, in sharp contrast to 14 mAh g–1 of monoclinic tungsten oxide (m‐WO3). In addition, unlike layered materials, the insertion and desertion of NH4+ ions are confined within the tunnels of the h‐WO3, which minimizes the damage to the crystal structure. This leads to outstanding stability of up to 200 000 cycles with 68% capacity retention at a high current of 20 A g–1.

Ultralong organic phosphorescence from isolated molecules with repulsive interactions for multifunctional applications

Abstract: Abstract Intermolecular interactions, including attractive and repulsive interactions, play a vital role in manipulating functionalization of the materials from micro to macro dimensions. Despite great success in generation of ultralong organic phosphorescence (UOP) by suppressing non-radiative transitions through attractive interactions recently, there is still no consideration of repulsive interactions on UOP. Herein, we proposed a feasible approach by introducing carboxyl groups into organic phosphors, enabling formation of the intense repulsive interactions between the isolated molecules and the matrix in rigid environment. Our experimental results show a phosphor with a record lifetime and quantum efficiency up to 3.16 s and 50.0% simultaneously in film under ambient conditions. Considering the multiple functions of the flexible films, the potential applications in anti-counterfeiting, afterglow display and visual frequency indicators were demonstrated. This finding not only outlines a fundamental principle to achieve bright organic phosphorescence in film, but also expands the potential applications of UOP materials.

A Review: Adsorption and Removal of Heavy Metals Based on Polyamide-amines Composites

Abstract: In recent years, the problem of heavy metal pollution has become increasingly prominent, so it is urgent to develop new heavy metal adsorption materials. Compared with many adsorbents, the polyamide-amine dendrimers (PAMAMs) have attracted extensive attention of researchers due to its advantages of macro-molecular cavity, abundant surface functional groups, non-toxicity, high efficiency and easy modification. But in fact, it is not very suitable as an adsorbent because of its solubility and difficulty in separation, which also limits its application in environmental remediation. Therefore, in order to make up for the shortcomings of this material to a certain extent, the synthesis and development of polymer composite materials based on PAMAMs are increasingly prominent in the direction of solving heavy metal pollution. In this paper, the application of composites based on PAMAMs and inorganic or organic components in the adsorption of heavy metal ions is reviewed. Finally, the prospects and challenges of PAMAMs composites for removal of heavy metal ions in water environment are discussed.

Stretchable supercapacitor based on a hierarchical PPy/CNT electrode and hybrid hydrogel electrolyte with a wide operating temperature

Abstract: Hydrogel is frequently used as a solid electrolyte for all solid-state supercapacitors (SCs) because of its liquid-like ion-transport property and high conformability. However, due to the higher water content, the hydrogel electrolyte undergoes inevitable freezing and/or dehydration with climate change. Herein, polypyrrole/carbon all-solid-state SCs (PCSCs) were developed based on a hierarchical polypyrrole/carbon nanotube electrode and a highly stretchable double-network polymer hydrogel electrolyte with LiCl/ethylene glycol as a mixed solvent. The PCSCs showed excellent electrochemical performance and cycle stability with a wide operating temperature. The specific capacitances could reach 202.2 and 112.3 mF cm−2 at current densities of 0.5 and 3.0 mA cm−2, respectively. Meanwhile, the PCSCs showed outstanding mechanical properties in maintaining a high areal capacitance under deformations of bending and tension. The excellent water retention of the device also ensured the stable electrochemical performance of PCSCs in a wide temperature range (30–80°C), which could potentially represent a reliable application in various harsh environments.

Adsorption and Removal of Mercury(II) by a Crosslinked Hyperbranched Polymer Modified via Sulfhydryl

Abstract: In this study, the highly crosslinked hyperbranched polyamide-amines (H-PAMAMs) were first prepared via one-pot methods and then modified with thiourea to synthesize a novel adsorbent containing sulfhydryl groups (CHAP-SH), which was used to adsorb Hg(II) ions from aqueous solutions. The adsorption characteristics and mechanism of CHAP-SH for Hg(II) ions were systematically studied. As expected, CHAP-SH exhibited a rapid removal performance toward Hg(II), and the maximum adsorption capacity was 282.74 mg/g at 318 K and pH = 4.5. The whole adsorption behavior could be well described by the pseudo-second-order kinetic model and Langmuir and Redlich–Peterson adsorption isotherm models, which reflected that the adsorption process was mainly monolayer chemisorption. Meanwhile, CHAP-SH had strong selectivity for Hg(II) in the presence of multimetal ions, and it had excellent recoverability after five cycles. In order to further elucidate the adsorption mechanism, the adsorbents before and after adsorption were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, and energy-dispersive X-ray spectroscopy, and the results showed that the nitrogen-containing, oxygen-containing, and sulfur-containing groups in the adsorbent molecule had synergistic complexation with Hg(II). These results indicated that the adsorbents had great potential in the future treatment of aqueous solutions containing Hg(II).

Poly(vinylidene fluoride) (PVDF) membrane fabrication with an ionic liquid via non-solvent thermally induced phase separation (N-TIPs)

Abstract: Abstract In this paper, ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate was the first time successfully utilized as single solvent in preparing the PVDF membrane with a good performance by N-TIPs method. The effects of quenching temperature and hydrophilic additive content on the morphology, permeability, and strength of the membranes were studied. All the prepared PVDF membranes were proved to be a pure β phase by FTIR and XRD, possessing a narrow pore size distribution. By adjusting quenching temperature and additive content, membranes with a flux of 383.2 L/m 2 h and concentrated pore diameter of 26 nm obtained.

Ultrasonic-Induced Synthesis of Underwater Adhesive and Antiswelling Hydrogel for Strain Sensor.

Abstract: To perceive the human body's multienvironmental mobility, intelligent flexible electronic equipment with an underwater motion monitoring function has potential research value in the field of intelligent detection. Hydrogels are widely used in the field of flexible electronics for their unique three-dimensional polymer networks. Due to the instinctive hydrophilicity of hydrogels, the swelling of hydrogels underwater and the formation of hydration coating on the surface become the primary obstacles to underwater applications. Herein, a hydrogel sensor that can achieve underwater utilization was prepared through copolymerization between hydrophobic and hydrophilic polymer monomers. The synergistic impact of electrostatic interaction, metal coordination, and hydrogen bonding ensured the hydrogel's remarkable underwater adhesive ability to a variety of substrates. The hydrophobic micelles and self-hydrophobization process induced from ultrasonic dispersion in the polymer matrix gave an outstanding hydrophobic performance (water contact angle of 130.4°) and antiswelling property (swelling ratio of 26% after 72 h of immersion), presenting unprecedented underwater adaptability. The above-mentioned hydrogel could be assembled into a flexible hydrogel sensor with satisfactory sensitivity (gauge factor of 0.44), ultrafast response rate (106 ms), and excellent cyclic stability, demonstrating accurate monitoring of complex human motions in water and air.

Underwater Adhesion and Anti‐Swelling Hydrogels

Abstract: Wearable devices, biomaterials, and tissue engineering have all gained from the development of flexible materials. Hydrogels are made up of the polymer matrix in an amount of water and are now being explored extensively. Ascribed to their high hydrophilicity, conventional hydrogels are difficult to deal with high humidity, being easily swell and even decompose. The utilization of hydrogel underwater is influenced by two key factors: the hydrogel absorbs water and swells easily to depress the mechanical characteristics, and the hydration layer at the contact interface also prevents the hydrogel from making close contact with the target surface, preventing conformal and accurate smart perception. So far, many researchers have proposed satisfying improvements for underwater applications from these two perspectives. This review first summarizes the general mechanisms of underwater adhesion hydrogels. Then, various anti‐swelling strategies of the reported hydrogel are described. Finally, the existing challenges and prospects of underwater adhesion and anti‐swelling hydrogels are provided.

Bioinspired wet-resistant organogel for highly sensitive mechanical perception

Abstract: Smart flexible electronics with underwater motion detection have become a promising research aspect in intelligent perception. Inspired by the strong adaptability of marine creatures to complex underwater environments, conventional biocompatible hydrogels are worth developing into organogels with preferred underwater adhesive properties, hydrophobic and antiswelling performance, and motion perception ability. Herein, a highly sensitive organogel sensor exhibiting good hydrophobicity, electromechanical properties, and adhesion properties was prepared for underwater utilization by regulating the chemical components and internal interactions. The synergistic effect of massive reversible non-covalent bonds ensures the organogel’s excellent underwater adhesion to multifarious substrates. Meanwhile, the interactions of hydrophobic conductive fillers and the dynamic hydrophobic associations in the organogel endow it with satisfactory hydrophobic performance (contact angle of 111.8°) and antiswelling property (equilibrium swelling ratio of −31% after 15-day immersion). The fabricated flexible organogel strain sensor exhibits high sensitivity (gauge factor of 1.96), ultrafast response rate (79.1 ms), low limit of detection (0.45 Pa), and excellent cyclic stability (1044 tensile cycles followed by 3981 compressive cycles). Results demonstrate the proposed organogel’s precise perception of sophisticated human motions in air and underwater, which expands its application scenarios.

Quadrangular Prism Porous Shells Constructed by Parallelly Interconnected and Lattice‐Strained NiCoP Nanoflakes for Maximized Energy Storage

Abstract: One of the challenges with pseudocapacitive energy storage is maximizing the utilization of active materials while assuring their cycling stability due to diffusion confinement and low electron transferability. Herein, a new insight into the design of architectures with combined advantages of ultrathin 2D materials’ oriented distribution and structural modulation at the atomic scale is proposed. Porous quadrangular prism shells (PQPSs) constructed by parallelly and interconnected lattice‐strained NiCoP nanoflakes are achieved via quadrangular prism‐assisted surface anisotropic growth, template removal, and ion exchange. An aqueous asymmetric supercapacitor with the NiCoP PQPSs and activated carbon (AC) delivers outstanding cycle stability with 103.1% capacity retention even after 30 000 cycles at 20 A g−1, much superior electrochemical performance over that reported for single‐metal phosphides. The NiCoP//AC exhibits a prominent high energy density of 47.7 Wh kg−1 at 800 W kg−1, superior over most state‐of‐the‐art devices. This is mainly attributed to the fact that the nanoflake‐built shells effectively avoid “dead volume,” thus providing abundant ion‐accessible active sites and straight ion transport channels as well as the lattice tensile strain demonstrated by geometrical phase analysis facilitates charge transportation. This work provides an innovative route to the controlled synthesis of space‐oriented phosphides’ arrays for improved energy storage.

ECTFE Membrane Fabrication Using Green Binary Diluents TEGDA/TOTM and Its Performance in Membrane Condenser

Abstract: Poly(ethylene-chlorotrifluoroethylene) (ECTFE) membrane is a hydrophobic membrane material that can be used to recover water from high-humidity gases in the membrane condenser (MC) process. In this study, ECTFE membranes were prepared by the thermally induced phase separation (TIPS) method using the green binary diluents triglyceride diacetate (TEGDA) and trioctyl trimellitate (TOTM). Thermodynamic phase diagrams of the ECTFE/TEGDA: TOTM system were made. The effects of the diluent composition and cooling rate on the structure and properties of the ECTFE membranes were investigated by characterizing the SEM, contact angle, mechanical properties, pore size and porosity. The results showed that ECTFE membranes with cellular structure were successfully prepared and exhibit good mechanical properties. Moreover, increasing the TOTM content in the binary diluents and decreasing the cooling rate could effectively improve the mean pore size of the ECTFE membranes, but the increase in TOTM content reduced the mechanical properties. During the MC process, the water recovery performance of ECTFE membranes increased with the increase in the mean pore size of the membranes, and the condensation flow and water recovery of membrane prepared at 20% TOTM were 1.71 kg·m−2·h−1 and 54.84%, respectively, which were better than the performance of commercial hydrophobic PVDF membranes in the MC. These results indicated that there is good potential for the application of ECTFE membranes during the MC process.