Development prospects of metal-based two-dimensional nanomaterials in lithium- sulfur batteries

Linking D-Band Center Modulation with Rapid Reversible Sulfur Conversion Kinetics via Structural Engineering of VS₂

The rapid catalytic conversion toward polysulfides is considered to be an advantageous approach to boost the reaction kinetics and inhibit the shuttle effect in lithium-sulfur (Li─S) batteries. However, the prediction of high catalytic activity Li─S catalysts has become challenging given the carelessness in the relationship between important electronic characteristics of catalysts and catalytic activity. Herein, the relationships between the D-band regulation of catalysts with reaction kinetics toward polysulfides are described. Through the combination of experimental and theoretical analysis, the opportune upward shift of the D-band center results in a favorable interaction with polysulfides, controlling the adsorption behavior of polysulfides. In addition, the electron regulation achieved by moderately moving up the D-band center further reduces the reaction energy barrier through hybridization with polysulfides. Based on this, a composite catalyst Mo doped VS2/rGO as a host material is proposed, which provides impressive long-term cycling stability and superior rate performance. This fundamental knowledge of the inherent connection between the D-band center of the catalyst and the reaction Kinetics of polysulfides offers a rationale for the development of the Li─S catalyst and the modification of its activity.

Experimental and computational studies on the corrosion inhibition potential of a novel synthesized thiophene and pyridine-based 1,3,4-oxadiazole hybrid against mild steel corrosion in 1 N HCl

A convenient synthesis of a novel 1,3,4-oxadiazole derivative, specifically known as, 2-(5-methylthiophen-2-yl)-5-(pyridin-3-yl)-1,3,4-oxadiazole (MTPO), is reported along with a comprehensive evaluation of its ability to inhibit the corrosion of mild steel (MS) in a 1 N HCl environment using weight loss, EIS, PDP, SEM, EDX, and UV-Vis spectroscopy. The investigated inhibitor expressed excellent inhibition efficiency (99.05% at 500 ppm, 298 K) with a mixed-type inhibitory mechanism as demonstrated by the PDP technique. Furthermore, MTPO followed Langmuir adsorption isotherm, which provides insights into the adsorption phenomena, demonstrating that it exhibits superior adsorption behavior on the MS surface compared. In silico investigations, using DFT computation and MD simulation complements the experimental outcomes revealing strong adsorbing attributes of the MTPO hybrid with the ω - and ω + values of 8.8882 eV and 4.4787 eV, respectively. In addition, the radial distribution function also addressed the chemisorption behavior of MTPO. This article also takes into consideration the various ways in which the inhibitor interacts with the mild steel, offering potential insights for developing strategies to mitigate metal dissolution in acidic environments.

Rapid construction of Co/CoO/CoCH nanowire core/shell arrays for highly efficient hydrogen evolution reaction

The Co/CoO/CoCH (P-CoCH) nanowire core/shell arrays were prepared by a one step hydrothermal method and rapid reduction of cobalt carbonate hydroxide (CoCH) in Ar/H2 plasma for the first time. The rapid reduction process endows the P-CoCH with a unique porous structure, larger electrochemical active surface area and abundant activity sites. Therefore, the as-prepared P-CoCH nanowire core/shell arrays show superior HER performance with a low overpotential of 69 mV and a small Tafel slope of 47 mV dec-1 at a current density of 10 mA cm-2. In addition, the P-CoCH electrocatalyst demonstrates an excellent cycling stability without any obvious decay after 24 h continuous operation at 100 mA cm-2 current density. This study might provide a new insight into the rapidly construction of efficient HER Co-based electrocatalysts and beyond.

Electrolytic Graphene Encapsulated CeO2 for Lithium-Sulfur Battery Interlayer Separator

Rare earth elements and graphene composites exhibit better catalytic properties in energy storage materials. The introduction of rare earth oxide and graphene composites as functional layers into the separator to seal the "shuttle effect" formed by polysulfides during the discharge process has proven to be effective. In this study, we prepared CeO2/graphene composites (labeled as CeG) by intercalation exfoliation and in situ electrodeposition methods simultaneously, in which CeO2 was encapsulated in large folds of graphene, which exhibited good defect levels (ID/IG < 1) and its intrinsically superior physical structure acted as a shielding layer to hinder the shuttle of polysulfides, improving the cycling stability and rate of cell performance. The separator cell with CeG achieves an initial discharge specific capacity of 1133.5 mAh/g at 0.5C, excellent rate performance (978.5 mAh/g at 2C), and long cycling (790 mAh/g after 400 cycles).

Heavy Metal Removal from Aqueous Effluents by TiO2 and ZnO Nanomaterials

The presence of heavy metals in wastewater, such as Ni, Pb, Cd, V, Cr, and Cu, is a serious environmental problem. This kind of inorganic pollutant is not biodegradable for several years, and its harmful effect is cumulative. Recently, semiconductor nanomaterials based on metal oxides have gained interest due to their efficiency in the removal of heavy metals from contaminated water, by inducing photocatalytic ion reduction when they absorb light of the appropriate wavelength. The most commonly applied semiconductor oxides for these purposes are titanium oxide (TiO2), zinc oxide (ZnO), and binary nanomaterials composed of both types of oxides. The main purpose of this work is to critically analyse the existent literature concerning this topic focusing specially in the most important factors affecting the adsorption or photocatalytic capacities of this type of nanomaterials. In particular, photocatalytic activity is altered by various factors, such as proportion of polymorphs, synthesis method, surface area, concentration of defects and particle size, among others. After a survey of the actual literature, it was found that, although these metal oxides have low absorption capacity for visible light, it is possible to obtain an acceptable heavy metal reduction performance by sensitization with dyes, doping with metallic or nonmetallic atoms, introduction of defects, or the coupling of two or more semiconductors.

Edge-oriented N-Doped WS2 Nanoparticles on Porous Co3 N Nanosheets for Efficient Alkaline Hydrogen Evolution and Nitrogenous Nucleophile Electrooxidation

Earth-abundant layered tungsten disulfide (WS₂ ) is a well-known electrocatalyst for acidic hydrogen evolution, but it becomes rather sluggish for alkaline hydrogen or oxygen evolution due to the low-density edge sites, poor conductivity, and unfavorable water dissociation behavior. Here, an interfacial engineering strategy to construct an efficient bifunctional electrocatalyst by in situ growing N-doped WS₂ nanoparticles on highly conductive cobalt nitride (N-WS₂ /Co₃ N) for concurrent hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) is demonstrated. Benefiting from the good conductivity of Co₃ N, rich well-oriented edge sites and water-dissociation sites at the nanoscale interfaces between N-WS₂ and Co₃ N, the resultant N-WS₂ /Co₃ N exhibits remarkable HER activity in 1 m potasium hydroxide (KOH) requiring a small overpotential of 67 mV at 10 mA cm^-2 with outstanding long-term durability at 500 mA cm^-2 , representing the best alkaline hydrogen-evolving activity among reported WS₂ catalysts. In particular, this hybrid catalyst also shows exceptional catalytic activities toward theurea oxidation reaction featured by very low potentials of 1.378 and 1.41 V to deliver 100 and 500 mA cm^-2 along with superb large-current stability in 1 m KOH + 0.5 m urea. Moreover, the assembled two-electrode cell delivers the industrially practical current density of 500 mA cm^-2 at a low cell voltage of 1.72 V with excellent durability in alkaline urea-containing solutions, outperforming most MoS₂ -like bifunctional electrocatalysts for overall water splitting reported hitherto. This work provides a promising avenue for the development of high-performance WS₂ -based electrocatalysts for alkaline water splitting.