Optimizing Eg Orbital Occupancy of Transition Metal Sulfides by Building Internal Electric Fields to Adjust the Adsorption of Oxygenated Intermediates for Li-O2 Batteries

Li-O2 batteries are acknowledged as one of the most promising energy systems due to their high energy density approaching that of gasoline, but the poor battery efficiency and unstable cycling performance still hinder their practical application. In this work, hierarchical NiS2 -MoS2 heterostructured nanorods are designed and successfully synthesized, and it is found that heterostructure interfaces with internal electric fields between NiS2 and MoS2 optimized eg orbital occupancy, effectively adjusting the adsorption of oxygenated intermediates to accelerate reaction kinetics of oxygen evolution reaction and oxygen reduction reaction. Structure characterizations coupled with density functional theory calculations reveal that highly electronegative Mo atoms on NiS2 -MoS2 catalyst can capture more eg electrons from Ni atoms, and induce lower eg occupancy enabling moderate adsorption strength toward oxygenated intermediates. It is evident that hierarchical NiS2 -MoS2 nanostructure with fancy built-in electric fields significantly boosted formation and decomposition of Li2 O2 during cycling, which contributed to large specific capacities of 16528/16471 mAh g-1 with 99.65% coulombic efficiency and excellent cycling stability of 450 cycles at 1000 mA g-1 . This innovative heterostructure construction provides a reliable strategy to rationally design transition metal sulfides by optimizing eg orbital occupancy and modulating adsorption toward oxygenated intermediates for efficient rechargeable Li-O2 batteries.

In-situ constructing self-supported NiO/RuO2 heterostructure for reinforced alkaline hydrogen evolution reaction

Rationally designing a strongly coupled heterostructure with rich functional sites and high catalytic stability is essential for efficient energy conversion. This work synthesizes a self-supported NiO/RuO₂ heterostructure for hydrogen production via facile dealloying following an in-situ electrochemical oxidation method. It only requires 88 ± 1 mV to drive a current density of -100 mA/cm² in the alkaline electrolyte during hydrogen evolution reaction (HER), outperforming NiO, RuO₂, and Pt foil. The higher anodic potential applied to the dealloyed ribbons results in lower overpotentials and faster reaction kinetics. Meanwhile, the catalytic activity and stability of the individual NiO can be significantly improved once coupled with a small amount of heterogeneous RuO₂. The strong synergistic effect between NiO and RuO₂ contributes to exposing abundant active sites, optimizing electronic structure, facilitating charge transfer at the interface, and most importantly, maintaining structural stability. These advantages make the self-supported NiO/RuO₂ heterostructure a promising candidate for replacing the Pt-based catalysts.

Synthesis of mesoporous-structured MIL-68(Al)/MCM-41-NH2 for methyl orange adsorption: Optimization and Selectivity

Here, we report a novel amino-modified mesoporous-structured aluminum-based metal-organic framework adsorbent, MIL-68(Al)/MCM-41-NH₂, for dye sewage treatment. The introduction of molecular sieves overcomes the inherent defects of microporous MOFs in contaminant transfer and provides more active sites to enhance adsorption efficiency. Compared with using organic amino ligands directly, this strategy is ten times cheaper. The composite was well characterized and analyzed in terms of morphology, structure and chemical composition. Batch experiments were carried out to study the influences of essential factors on the process, such as pH and temperature. In addition, their interactions and the optimum conditions were examined using response surface methodology (RSM). The adsorption kinetics, isotherms and thermodynamics were systematically elucidated. In detail, the adsorption process conforms to pseudo-second-order kinetics and follows the Sips and Freundlich isothermal models. Moreover, the maximum adsorption capacity Q_s of methyl orange (MO) was 477 mg g^-1. It could be concluded that the process was spontaneous, exothermic, and entropy-reducing. Several binary dye systems have been designed for selective adsorption research. Our material has an affinity for anionic pigments. The adsorption mechanisms were discussed in depth. The electrostatic interaction might be the dominant effect. Meanwhile, hydrogen bonding, π-π stacking, and pore filling might be important driving forces. The excellent thermal stability and recyclability of the adsorbent are readily noticed. After five reuse cycles, the composite still possesses a removal efficiency of 90% for MO. Overall, the efficient and low-cost composite can be regarded as a promising adsorbent for the selective adsorption of anionic dyes from wastewater.

Construction of an S-Scheme Ag2MoO4/ZnFe2O4 Nanofiber Heterojunction for Enhanced Photoelectrocatalytic Activity under Visible Light Irradiation

The removal of organic dyes and pathogenic bacteria from contaminated water remains a significant challenge. In the present study, S-type heterojunction Ag₂MoO₄/ZnFe₂O₄ (AMO/ZFO) composite nanofibers were synthesized by electrospinning and co-precipitation and fabricated into photoanodes. It is found that the constructed S-type heterojunction of AMO/ZFO composites effectively inhibits the recombination of photogenerated carriers, in addition to the benefits of more exposed active sites and a greater specific surface area. When several properties are improved, AMO/ZFO composites exhibit excellent photoelectrocatalytic performance. The results demonstrate that under visible light irradiation, the photoelectrocatalytic degradation rate of AMO/ZFO-3 to methylene blue reached 76.2% within 50 min, and the killing rate of Salmonella was 83.6% within 80 min. The enhanced photoelectrocatalytic activity was due to the synergy of both electrochemical and photocatalytic effects. More importantly, after four testing cycles, AMO/ZFO-3 still has a better ability to kill pathogenic bacteria and degrade organic dyes due to its high stability. This work provides a feasible method for oxidizing organic dyes and pathogenic bacteria.

Key Factors of Mechanical Strength and Toughness in Oriented Poly(l-lactic acid) Monofilaments for a Bioresorbable Self-Expanding Stent

The investigation of the strength and toughness of poly(l-lactic acid) (PLLA) monofilaments is essential as the fundamental element of a biodegradable braided stent. However, the determining factor remains poorly addressed with respect to influencing the mechanical behavior of PLLA monofilaments. In this work, the electron beam (EB) with different radiation doses was utilized to sterilize PLLA monofilaments. Properties of the monofilaments, including the breaking strength, elongation at break, molecular weight, orientation, and microstructure of the fracture, were characterized. Results showed that a random chain scission of PLLA resulting from EB during this process could cause the decrease in molecular weight, which led to the decline in breaking strength. Meanwhile, the irradiated monofilaments were found to have almost the same elongation at break below a dose of 30 kGy and declined by 71.41% up to a dose of 48 kGy. It was also found that the ductile fracture connection of the monofilament translated to the brittle fracture by comparing the microstructure without and with sterilization. These phenomena could originate from the destruction of the long molecular chains connecting the crystal plates into shorter ones by radiation. PLLA monofilaments with 0, 30, and 48 kGy were used to braid carotid stents. Compared with a carotid Wallstent, the PLLA stent can better provide radial supporting to the carotid lesion. This study provides preliminary experimental references to evaluate and predict the mechanical performance of PLLA braided stents.

Improved catalytic properties of Candida antarctica lipase B immobilized on cetyl chloroformate-modified cellulose nanocrystals

The catalytic activity of Candida antarctica lipase B (CALB) immobilized on modified cellulose nanocrystals (CNC) with different hydrophobicity was investigated using experimental and theoretical approaches. Firstly, the modified CNC were characterized by multi-spectroscopic methods, water contact angle, scanning electron microscopy and thermogravimetric analysis. Moderately hydrophobic CNC were found to be an optimal support for CALB immobilization. Secondly, model systems contained a CALB molecule and different numbers of modified CNC molecules (CALB@3CNC-C16, CALB@10CNC-C16 and CALB@15CNC-C16) were prepared for molecular dynamics (MD) simulation. Root-mean-square fluctuation values (0.61-2.61 Å) of lid region were relatively high in CALB@10CNC-C16, indicating that modified CNC with moderate hydrophobicity favored forming a lid-open conformation of CALB. Finally, the esterification of oleic acid catalyzed by the immobilized CALB showed higher conversion (54.68 %) than free CALB (12.98 %). Insights into modified CNC with tunable properties provided by this study may be a potential support for improving the catalytic performance of lipases.

A Review of the Application of Modified Separators in Inhibiting the "shuttle effect" of Lithium-Sulfur Batteries

Lithium-sulfur batteries with high theoretical specific capacity and high energy density are considered to be one of the most promising energy storage devices. However, the "shuttle effect" caused by the soluble polysulphide intermediates migrating back and forth between the positive and negative electrodes significantly reduces the active substance content of the battery and hinders the commercial applications of lithium-sulfur batteries. The separator being far from the electrochemical reaction interface and in close contact with the electrode poses an important barrier to polysulfide shuttle. Therefore, the electrochemical performance including coulombic efficiency and cycle stability of lithium-sulfur batteries can be effectively improved by rationally designing the separator. In this paper, the research progress of the modification of lithium-sulfur battery separators is reviewed from the perspectives of adsorption effect, electrostatic effect, and steric hindrance effect, and a novel modification of the lithium-sulfur battery separator is prospected.

Nanomaterial based PVA nanocomposite hydrogels for biomedical sensing: Advances toward designing the ideal flexible/wearable nanoprobes

In today's world, the progress of wearable tools has gained increasing momentum. Notably, the demand for stretchable strain sensors has considerably increased owing to various potential and emerging applications like human motion monitoring, soft robotics, prosthetics, and electronic skin. Hydrogels possess excellent biocompatibility, flexibility, and stretchability that render them ideal candidates for flexible/wearable substrates. Among them, enormous efforts were focused on the progress of polyvinyl alcohol (PVA) hydrogels to realize multifunctional wearable sensing through using additives/nanofillers/functional groups to modify the hydrogel network. Herein, this review offers an up-to-date and comprehensive summary of the research progress of PVA hydrogel-based wearable sensors in view of their properties, strain sensory efficiency, and potential applications, followed by specifically highlighting their probes using metallic/non-metallic, liquid metal (LM), 2D materials, bio-nanomaterials, and polymer nanofillers. Indeed, flexible electrodes and strain/pressure sensing performance of designed PVA hydrogels for their effective sensing are described. The representative cases are carefully selected and discussed regarding the construction, merits and demerits, respectively. Finally, the necessity and requirements for future advances of conductive and stretchable hydrogels engaged in the wearable strain sensors are also presented, followed by opportunities and challenges.

High-Porosity Lamellar Films Prepared by a Multistage Assembly Strategy for Efficient Photothermal Water Evaporation and Power Generation

The frame structure combined with water- and heat-transfer capabilities fully satisfies the requirements of photothermal conversion materials in seawater evaporation applications. Meanwhile, it must integrate the characteristics of a high photothermal conversion rate, thermal management, and water transportation. Herein, lamellar porous films were successfully designed and synthesized by a simple ultrasonic-assisted vacuum filtration method. In this process, polystyrene sulfonate@carbon nanotubes/reduced graphene oxide (PSS@CNT/rGO) lamellar films were constructed by the one-dimensional synthesis of PSS@CNT self-assembled at the molecular scale and the two-dimensional matrix material rGO. It is worth noting that the lamellar film exhibits a high specific surface area (285.5 m²·g^-1), which is reflected in its abundant nanopores. Among them, the porous network system composed of nanochannels can provide efficient water supply and steam-transfer ability and strengthen the heat insulation performance of thermal localization, which is beneficial to photothermal evaporation. The obtained PSS@CNT/rGO lamellar films achieved a condensed water yield of 1.825 kg·m^-2·h^-1 under 1 sun illumination (1 kW·m^-2), and their solar-vapor conversion efficiency was 97.1%. Simultaneously, the interaction between the water flow and the carbon material interface was also used to generate additional electric energy output. The maximum open-circuit voltage of 0.46 V was generated at both termini of the PSS@CNT/rGO lamellar film, which successfully realized the multieffect utilization of energy. These results show that the multistage assembly strategy is a facile and effective means for the development of an efficient evaporation photothermal film, which offers significant value in the field of photothermal seawater evaporation and power generation.

Inorganic crosslinked supramolecular binder with fast Self-Healing for high performance silicon based anodes in Lithium-Ion batteries

Capacity retention is one of the key factors affecting the performance of silicon (Si)-based lithium-ion batteries and other energy storage devices. Herein, a three dimension (3D) network self-healing binder (denoted as PVA + LB) consisting of polyvinyl alcohol (PVA) and lithium metaborate (LiBO₂) solution is proposed to improve the cycle stability of Si-based lithium-ion batteries. The reversible capacity of the silicon electrode is maintained at 1767.3 mAh g^-1 after 180 cycles when employing PVA + LB as the binder, exhibiting excellent cycling stability. In addition, the silicon/carbon (Si/C) anode with the PVA + LB binder presents superior electrochemical performance, achieving a stable cycle life with a capacity retention of 73.7% (858.3 mAh g^-1) after 800 cycles at a current density of 1 A g^-1. The high viscosity and flexibility, 3D network structure, and self-healing characteristics of the PVA + LB binder are the main reasons to improve the stability of the Si or Si/C contained electrodes. The novel self-healing binder shows great potential in designing the new generation of silicon-based lithium-ion batteries and even electrochemical energy storage devices.

Balance of antiperitoneal adhesion, hemostasis, and operability of compressed bilayer ultrapure alginate sponges

In surgery, both antiperitoneal adhesion barriers and hemostats with high efficiency and excellent handling are necessary. However, antiadhesion and hemostasis have been examined separately. In this study, six different ultrapure alginate bilayer sponges with thicknesses of 10, 50, 100, 200, 300, and 500 μm were fabricated via lyophilization and subsequent mechanical compression. Compression significantly enhanced mechanical strength and improved handling. Furthermore, it had a complex effect on dissolution time and contact angle. Therefore, the 100 μm compressed sponge showed the highest hemostatic activity in the liver bleeding model in mice, whereas the 200 μm sponge demonstrated the highest antiadhesion efficacy among the compressed sponges in a Pean crush hepatectomy-induced adhesion model in rats. For the first time, we systematically evaluated the effect of sponge compression on foldability, fluid absorption, mechanical strength, hemostatic effect, and antiadhesion properties. The optimum thickness of an alginate bilayer sponge by compression balances antiperitoneal adhesion and hemostasis simultaneously.