The rational design of cost-effective and efficient electrocatalysts for electrochemical water splitting is essential for green hydrogen production. Utilizing nanocatalysts with abundant active ...sites, high surface area, and deliberate stacking faults is a promising approach for enhancing catalytic efficiency. In this study, we report a simple strategy to synthesize a highly efficient electrocatalyst for the hydrogen evolution reaction (HER) using carbonized luffa cylindrica as a conductive N-doped carbon skeleton decorated with Ag nanorings that are activated by introducing stacking faults. The introduction of stacking faults and the resulting tensile strain into the Ag nanorings results in a significant decrease in the HER overpotential, enabling the use of Ag as an efficient HER electrocatalyst. Our findings demonstrate that manipulating the crystal properties of electrocatalysts, even for materials with intrinsically poor catalytic activity such as Ag, can result in highly efficient catalysts. Further, applying a conductive carbon backbone can lower the quantities of metal needed without compromising the HER activity. This approach opens up new avenues for designing high-performance electrocatalysts with very low metallic content, which could significantly impact the development of sustainable and cost-effective electrochemical water-splitting systems.
Nanocomposites with enhanced mechanical properties and efficient self‐healing characteristics can change how the artificially engineered materials’ life cycle is perceived. Improved adhesion of ...nanomaterials with the host matrix can drastically improve the structural properties and confer the material with repeatable bonding/debonding capabilities. In this work, exfoliated 2H‐WS2 nanosheets are modified using an organic thiol to impart hydrogen bonding sites on the otherwise inert nanosheets by surface functionalization. These modified nanosheets are incorporated within the PVA hydrogel matrix and analyzed for their contribution to the composite's intrinsic self‐healing and mechanical strength. The resulting hydrogel forms a highly flexible macrostructure with an impressive enhancement in mechanical properties and a very high autonomous healing efficiency of 89.92%. Interesting changes in the surface properties after functionalization show that such modification is highly suitable for water‐based polymeric systems. Probing into the healing mechanism using advanced spectroscopic techniques reveals the formation of a stable cyclic structure on the surface of nanosheets, mainly responsible for the improved healing response. This work opens an avenue toward the development of self‐healing nanocomposites where chemically inert nanoparticles participate in the healing network rather than just mechanically reinforcing the matrix by slender adhesion.
On the supposedly hard‐to‐modify 2D transition metal dichalcogenides, a technique for adding chemical functional groups is introduced. In addition to significantly strengthening polymer‐based nanocomposites, the resulting material also encourages autonomous self‐healing when damaged. The composite attained a 90% healing efficiency by creating a stable cyclic structure on the surface of nanosheets.
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Utilising the solid-state synthesis method is an easy and effective way to recycle spent lithium-ion batteries. However, verifying its direct repair effects on completely exhausting ...cathode materials is necessary. In this work, the optimal conditions for direct repair of completely failed cathode materials by solid-state synthesis are explored. The discharge capacity of spent LiCoO2 cathode material is recovered from 21.7 mAh g−1 to 138.9 mAh g−1 under the optimal regeneration conditions of 850 °C and n(Li)/n(Co) ratio of 1:1. The regenerated materials show excellent electrochemical performance, even greater than the commercial LiCoO2. In addition, based on the whole closed-loop recycling process, the economic and environmental effects of various recycling techniques and raw materials used in the battery production process are assessed, confirming the superior economic and environmental feasibility of direct regeneration method.
•Current review on Self-healing polymers based on Diels-Alder cycloaddition.•Discussing healing thermodynamics for physical and chemical changes during healing.•Deeper insight on use of advanced ...analytical/spectroscopic/modelling techniques.•Use of multifunctional healing mechanisms for advanced engineering applications.•Future scope of DA polymers based on better commerciality and green chemistry.
The ability of artificial materials to be healed efficiently, mimicking the living organisms, exhibits a great deal of potential advantages that can revolutionise the operation and maintenance of materials used in various applications. Such self-healable smart materials have been extensively researched in the last few decades, leading to the development of different physical and chemical synthesis approaches. Among these methods, chemical techniques based on reversible cycloadditions or disulfide bonding provide obvious advantages in terms of repeatability, which holds prime importance in determining the commerciality of the healing approach. This review compiles the recent advances in the field of self-healing polymers where the healing ability is introduced by reversible cycloaddition reactions while focusing mainly on the Diels-Alder (DA) reaction. DA is a 4 + 2 cycloaddition reaction where diene and dienophile pairs are used to fabricate thermally reversible crosslinked networks. These covalent bonds provide the necessary reversibility to the healing matrix and impart the desired strength to the polymeric material. There is a considerable body of recent literature where DA bonding has been employed either on its own or along with other healing mechanisms to impart self-healing to polymers. However, lack of a systematic review discussing these works makes it difficult for a beginner to cope with advancements in this field. Most early studies have focused on the healing stimuli and efficiency of healing in polymers but with this review, we would like to explore the healing thermodynamics governing the rupture–repair process in DA polymers along with the use of advanced spectroscopic techniques to study them and their applicability in thermosets, epoxy resins, biopolymers, and polymer nanocomposites. Novel applications for such advanced functional polymers, multifunctional healable polymers, and the outlook for future research, opportunities and challenges in the area are also discussed.
The search for improved surface properties of engineering alloys is always a matter of interest. Herein, we introduce a surface treatment based on depositing a non-continuous layer of two-dimensional ...(2D) nanomaterials via a simple and scalable method. 2D nanosheets of hexagonal boron nitride (h-BN) and graphene nanoplatelets (GNP) were sprayed on mild steel, followed by mild heat treatment. The nanosheets are strongly attached to the surfaces and even diffused to submicron under the surface, as proved by various analytical techniques. The mechanical, tribological and corrosion evaluations show significant simultaneous enhancement in a set of surface properties. From the friction tests with sliding steel-steel tribo-pairs under dry conditions, the graphene treatment decreases the friction coefficient and wear area by 21% and 31%, respectively. Interestingly, it is revealed that under dry and lubricated conditions, graphene-doped h-BN exhibits outstanding anti-wear properties synergistically compared to stand-alone 2D materials. The possible wear mechanism is investigated and found to be based on the formation of a tribofilm.
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•Mild steel surfaces were treated by a method based on the partial diffusion of 2D graphene nanoplatelets (GNP) and h-BN.•Different GNP and h-BN surface treatments on steel were tribologically studied.•Graphene treatment decreases the friction coefficient and wear area of bare steel by 21% and 31%, respectively.•Corrosion resistance of the steel treated by h-BN was improved by 41% compared to bare metal.
Binary metal oxides exhibit a compelling combination of features that make them highly attractive electrode materials for supercapacitors. Herein, a facile hydrothermal method is employed for the ...preparation of defect-rich hierarchical nanostructured NiCo2O4 with various morphologies, including urchin-like nanostructure, nanoflowers, and 2D nanosheets; and their electrochemical performances as electrodes for hybrid supercapacitor are studies. Notably, the supercapacitor based on the urchin-like nanostructure with high oxygen vacancies delivers a high gravimetric energy density of 45.2 Wh/kg at the power density of 750 W/kg, maintaining remarkable cycling stability. The electrode exhibits specific capacitance of 423.9 and 292.0 F/g at the current density of 1.5 and 7.5 A/g, respectively, with high capacitive retention of ≈ 94 % after 1500 cycles. Crystalline defects identified in nanostructured NiCo2O4 are suggested to significantly contribute to the high ionic/electrical conductivity and the electrochemical stability of the electrodes.
•Various NiCo2O4 Nanostructures have been prepared and tested for hydride supercapacitor application.•The role of the crystal defects in enhancing the electrochemical performance was investigated•Urchin-like nanostructure showed excellent performance as electrodes for hybrid supercapacitors.
Utilising the solid-state synthesis method is an easy and effective way to recycle spent lithium-ion batteries. However, verifying its direct repair effects on completely exhausting cathode materials ...is necessary. In this work, the optimal conditions for direct repair of completely failed cathode materials by solid-state synthesis are explored. The discharge capacity of spent LiCoO
cathode material is recovered from 21.7 mAh g
to 138.9 mAh g
under the optimal regeneration conditions of 850 °C and n(Li)/n(Co) ratio of 1:1. The regenerated materials show excellent electrochemical performance, even greater than the commercial LiCoO
. In addition, based on the whole closed-loop recycling process, the economic and environmental effects of various recycling techniques and raw materials used in the battery production process are assessed, confirming the superior economic and environmental feasibility of direct regeneration method.
