Precise Atomic Structure Regulation of Single-Atom Platinum Catalysts toward Highly Efficient Hydrogen Evolution Reaction.

Noble metal single-atom-catalysts (SACs) have demonstrated significant potential to improve atom utilization efficiency and catalytic activity for hydrogen evolution reaction (HER). However, challenges still remain in rationally modulating active sites and catalytic activities of SACs, which often results in sluggish kinetics and poor stability, especially in neutral/alkaline media. Herein, precise construction of Pt single atoms anchored on edge of 2D layered Ni(OH)2 (Pt-Ni(OH)2-E) is achieved utilizing in situ electrodeposition. Compared to the single-atom Pt catalysts anchored on the basal plane of Ni(OH)2 (Pt-Ni(OH)2-BP), the Pt-Ni(OH)2-E possesses superior electron affinity and high intrinsic catalytic activity, which favors the strong adsorption and rapid dissociation toward water molecules. As a result, the Pt-Ni(OH)2-E catalyst requires low overpotentials of 21 and 34 mV at 10 mA cm-2 in alkaline and neutral conditions, respectively. Specifically, it shows the high mass activity of 23.6 A mg-1 for Pt at the overpotential of 100 mV, outperforming the reported catalysts and commercial Pt/C. This work provides new insights into the rational design of active sites for preparing high-performance SACs.

Twisted Bilayer Graphene Induced by Intercalation.

Twisted bilayer graphene (tBLG) has gained significant attention due to its unique physical and electronic properties. However, efficient fabrication of high-quality tBLG with diverse twist angles is crucial to expedite research on angle-dependent physics and potential applications. In this study, an intercalation strategy utilizing organic molecules, such as 1,2-dichloroethane, is developed to weaken the interlayer interaction and induce slide or rotation of the topmost graphene layer for tBLG fabrication. The proportion of tBLGs in the resulting 1,2-dichloroethane-treated BLG (dtBLG) reaches up to 84.4% for twist angles ranging from 0° to 30°, surpassing previously reported methods using chemical vapor deposition (CVD). Moreover, the twist angle distribution is not uniform and tends to concentrate in the ranges of 0-10° and 20-30°. This facile and rapid intercalation-based methodology provides a practical solution for studying angle-dependent physics and advancing the utilization of twisted two-dimensional materials.

Ultrathin Fe-ReS2 Nanosheets as Electrocatalysts for Accelerating Sulfur Reduction in Li-S Batteries.

Lithium-sulfur batteries are promising next-generation energy storage systems with high theoretical specific capacity. Despite extensive research efforts, it is still challenging to rationally design electrocatalysts with fast kinetics and effective adsorption of polysulfides. Herein, Fe-doped ReS2 (Fe-ReS2) ultrathin nanosheets are prepared as an electrocatalyst to trap the intermediates and accelerate the sulfur reduction reaction kinetics. Density functional theory calculations combined with activation energies in the multistep sulfur reduction reaction reveal that the Fe-ReS2 considerably reduces the activation energy and optimizes the optimum adsorption strength of polysulfides and catalytic activity. The Fe-ReS2/S exhibits a highly reversible discharge capacity of 882.3 mA h g-1 at 1 C. For 500 cycles, the capacity fade rate is 0.013% per cycle. Moreover, in situ Raman spectroscopy measurements further confirmed that both sulfur reduction and oxidation processes were significantly enhanced by Fe-ReS2.

Ni(OH)2 Templated Synthesis of Ultrathin Ni3 S2 Nanosheets as Bifunctional Electrocatalyst for Overall Water Splitting.

Ultrathin nickel (Ni)-based sulfide nanosheets have been reported as excellent electrocatalysts for overall water splitting; however, the uncontrollability over thickness due to the nonlayered structure still hampers its practical application. Herein, a simple topochemical conversion strategy is employed to synthesize cobalt-doped Ni3 S2 (Co-Ni3 S2 ) ultrathin nanosheets on Ni foam. The Co-Ni3 S2 nanosheets are controlled synthesized by using Co-Ni(OH)2 ultrathin nanosheets as templates with anneal and sulfurization treatment, showing exceptional electrocatalytic activity. This template-assisted method can also be applied to obtain Ni, NiO, and NiPx nanosheets, providing a universal strategy to synthesize ultrathin nanosheets of nonlayered materials. The overall water splitting of this Co-Ni3 S2 ultrathin nanosheets achieves a low voltage of 1.54 V at a current density of 10 mA cm-2 and high durability in 1 m KOH, comparable to the best performance of electrochemical water splitting ever reported. The detailed structural transformation of Ni-based sulfides in the catalytic process and its mechanism are further explored both experimentally and theoretically.

In-Situ Formed Protecting Layer from Organic/Inorganic Concrete for Dendrite-Free Lithium Metal Anodes.

In this work, a separator modified by composite material of graphite fluoride nanosheets and poly(vinylidene difluoride) (GFNs-PVDF) is fabricated to in-situ construct a protective layer on Li metal anodes. The much-improved mechanical properties of this organic/inorganic protecting layer ensure efficient restriction on the growth of Li dendrites. The LiF and graphene nanosheets generated by the reaction of GFNs with lithium metal can not only provide fast transport channels for Li ions but also protect the Li metal anode from continuous corrosion of electrolytes. In addition, GFNs' lithiophilic nature guarantees the uniform Li nucleation site and perfect contact between li metal and the protecting layer without void space, leading to a low interfacial impedance and layer-by-layer lithium deposition. Together with the scalable method and cheap raw materials, this strategy provides new insights toward practical applications of Li metal batteries.

Perylene diimide-functionalized CeO2 nanocomposite as a peroxidase mimic for colorimetric determination of hydrogen peroxide and glutathione.

A novel perylene diimide (PDI) functionalized CeO2 nanocomposite (NC) was successfully fabricated via one-pot hydrothermal method. Compared with pure CeO2 nanoparticles (CeO2 NPs), the NC catalyst presents more Ce3+ and active oxygen species and exhibits a higher peroxidase mimicking activity towards the oxidation 3,3',5,5'-tetramethylbenzidine by H2O2 to form a blue product with an absorption maximum at 652 nm. The composite catalyst shows high sensitivity and selectivity toward H2O2 determination in the range of 20 to 80 µM with a limit of detection (LOD) of 2.59 µM. Based on the colorimetric method, a sensitive method for detecting the reduced glutathione (GSH) was also established over arrange of 1~4 µM with a LOD of 0.92 µM. Electron spin resonance (ESR) experiments suggest that the active radicals during the catalytic processes are •OH and •O2-. A possible synergistic catalytic mechanism is discussed. Graphical abstract Schematic presentation of the possible catalytic mechanism for colorimetric determination of hydrogen peroxide and glutathione based on the peroxidase-like activity perylene-diimide (PDI) functionalized CeO2 nanocomposite.