Construction of Bimetallic-Anchored Two-Dimensional Nanosheets on COF for Rechargeable Zinc-Air Batteries

The preparation of carbon materials by doping bimetallic oxides into triazine frameworks (COFs) is a promising electrocatalyst with the potential to replace precious metals in energy storage systems. In this experiment, a covalent triazine framework (COF) was synthesized by 1,4-dicyanobenzene (DCB) and zinc chloride, in which the COF and transition metals were used as carbon, nitrogen, cobalt, and iron sources. According to the properties of this COF, the destruction of the catalyst during pyrolysis can be prevented. The enhanced catalytic performance of the catalysts can be seen by testing all of the samples of catalysts in an alkaline medium. The high half-wave potential (E1/2) of 0.86 V is comparable to Pt/C and also shows excellent durability by testing. Zinc-air batteries were assembled using the prepared catalysts, and the batteries were tested for specific capacity (548 mAh g–1) and power density (189 mW cm–2). This work provides a new direction for COF-derived catalysts for carbon materials

Graphene-Loaded Bimetallic Oxide Nanoparticle Oxygen Electrode Materials for Rechargeable Zinc–Air Batteries

Currently, precious metal catalysts Pt/C and RuO2/IrO2 are considered efficient catalysts for oxygen reduction reaction (ORR). However, their high cost, scarcity, and poor stability hinder their wide application. Therefore, a simple method to prepare bimetallic oxide nanoparticles as electrodes instead of precious metals is of significant importance for electrocatalysis at present. Here, we use graphene nanosheets as carbon precursors, which can exhibit excellent ORR performance by taking advantage of the empty orbitals of the samarium f-layer, which will result in a high specific surface area due to the use of templates. Therefore, in the preparation process, samarium oxide- and iron oxide-encapsulated nanosheets are formed from samarium and iron coordination polymers, respectively. Moreover, the specific Brunauer–Emmett–Teller effective active sites and the synergistic interaction between samarium oxide and iron oxide also promote ORR kinetics This novel rare earth transition-metal nanoparticle-encapsulated ORR catalyst with a conductive carbon matrix (SmFeOx@CN-5) is attractive for zinc–air battery applications

Air-Calcined Fe/Ni-Based Metal–Organic Framework Nanosheets for Oxygen Evolution Reactions

The oxygen evolution reaction (OER) plays a pivotal role in the hydrolysis process of zinc–air batteries. Consequently, it is essential to develop cathode catalysts with both cost-effectiveness and high oxygen evolution activity. In this study, we synthesized the FeFFIVE-1-Ni two-dimensional (2D) metal–organic framework (MOF) nanosheets via a straightforward solvothermal approach and oxidized them in an air atmosphere. During the calcination process in an air atmosphere, the heteroatoms (O, F) within the FeFFIVE-1-Ni 2D MOF nanosheets combine with iron and nickel metal ions, forming FeOF and NiF2 compounds. The synergy between these compounds and the creation of surface cracks during calcination yield catalytic active power and catalytic active sites essential for the oxygen evolution reaction. Notably, the overpotential of FeFFIVE-1-Ni 2D MOF nanosheets calcined in air under alkaline test conditions (η10 = 286 mV) was lower than that of commercial RuO2 catalysts (η10 = 355 mV). This work presents an effective strategy for replacing noble metal catalysts such as RuO2 by simply treating fluorinated metal–organic frameworks

Nitrogen-Doped Graphitic Carbon-Supported Ultrafine Co Nanoparticles as an Efficient Multifunctional Electrocatalyst for HER and Rechargeable Zn–Air Batteries

The construction of high-efficiency electrocatalysts for hydrogen evolution, oxygen reduction, and oxygen evolution reactions (HER/ORR/OER) is critical for the overall water splitting system, fuel cells, and rechargeable metal–air batteries. Here, we report a viable strategy for tuning the size of a Co-based zeolitic imidazolate framework (ZIF). As a result, a nitrogen-doped graphitic carbon-supported ultrafine Co nanoparticle electrocatalyst (Co/NGC-3) with multifunctional activity was developed. Owing to the smaller ZIF-67 polyhedrons with relatively uniform distribution, more effective active sites, and a strong coupling effect of Co-pyridinic-N, the proposed Co/NGC-3 catalyst exhibited an impressive HER activity. It also showed brilliant catalytic activity in both the ORR and OER, delivering a more positive half-wave potential and a lower overpotential than that of the Pt/C catalyst, respectively. Moreover, the Co/NGC-3 involved the Zn–air battery displayed satisfactory power density, excellent energy density, and superior stability. This approach provides an efficient strategy for the preparation of high-performance multifunctional electrocatalysts for energy-related applications

Cl-Doped Li₁₀SnP₂S₁₂ with Enhanced Ionic Conductivity and Lower Li-Ion Migration Barrier

All-solid-state lithium batteries based on sulfide solid electrolytes have attracted much attention because of their high ionic conductivity. Li10SnP2S12 (LSPS) has the same structure as Li10GeP2S12, and there is little difference in ionic conductivity between them, but the preparation cost of LSPS is lower. Here, Cl doping is used to improve the electrochemical stability of the LSPS to the anode and the Li-ion transport performance. Among them, Li9.9SnP2S11.9Cl0.1 had a high ion conductivity of 2.62 mS cm–1 after cold pressure. On the crystal structure, X-ray diffraction Rietveld refinement indicated that the Cl-substituted portion S is successfully incorporated into the lattice of the LSPS, increasing Li-ion vacancies and reducing the distance between adjacent Li-ion distributed along the c-axis, these are conducive to Li-ion transmission. The temperature-dependent AC impedance experiment and density functional theory calculation show that doping with Cl makes Li9.9SnP2S11.9Cl0.1 have a lower activation energy. The assembled lithium symmetric batteries show that the doping of Cl promotes the stability of the interface between LSPS and the lithium metal anode. The charge–discharge tests of all-solid-state batteries using Li9.9SnP2S11.9Cl0.1 as electrolyte have confirmed that Cl doping can improve the electrochemical performance of LSPS, which have a higher specific capacity and cycle life

One-Step Spray-Coating Process for the Fabrication of Colorful Superhydrophobic Coatings with Excellent Corrosion Resistance

A simple method was used to generate colorful hydrophobic stearate particles via chemical reactions between inorganic salts and sodium stearate. Colored self-cleaning superhydrophobic coatings were prepared through a facile one-step spray-coating process by spraying the stearate particle suspensions onto stainless steel substrates. Furthermore, the colorful superhydrophobic coating maintains excellent chemical stability under both harsh acidic and alkaline circumstances. After being immersed in a 3.5 wt % NaCl aqueous solution for 1 month, the as-prepared coatings remained superhydrophobic; however, they lost their self-cleaning property with a sliding angle of about 46 ± 3°. The corrosion behavior of the superhydrophobic coatings on the Al substrate was characterized by the polarization curve and electrochemical impedance spectroscopy (EIS). The electrochemical corrosion test results indicated that the superhydrophobic coatings possessed excellent corrosion resistance, which could supply efficient and long-term preservation for the bare Al substrate

Co-Inlaid Carbon-Encapsulated SiO_<i>x</i> Anodes via a Self-Assembly Strategy for Highly Stable Lithium Storage

SiOx is a promising anode material for next-generation lithium-ion batteries, with high energy density and low cost. However, several issues, such as poor cycling stability, should be overcome before practical application. Here, gum arabic, a well-known natural gum with low cost, is used as a carbon source to form a uniform Co-inlaid carbon coating on SiOx by a facile and scalable self-assembly method using Co2+ as a “bridge”, during which Co2+ plays a key role. After carbonization treatment, the Co-inlaid carbon coating can effectively mitigate volume effects, enhance electrical conductivity, boost deep delithiation processes, and guarantee the structural integrity of SiOx-Co@C. Because of the unique Co-inlaid carbon coating, the SiOx-Co@C electrode displays much improved lithium-storage properties. The charging capacity of the SiOx-Co@C electrode at the 250th cycle is 1010.8 mA h g–1 with 84% capacity retention at 200 mA g–1. This work presents a facile and efficient strategy to construct a uniform multifunctional coating for improved electrochemical properties

Enhancement of Electrocatalytic Oxygen Reduction Reaction and Oxygen Evolution Reaction by Introducing Lanthanum Species in the Carbon Shell

The development of cost-effective non-noble metal electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) opens up the possibility for sustainable energy systems. Herein, we report a surface overcoating strategy with lanthanum organic complex (La-OC) as the precursor to prepare lanthanum species (La-SPc) encapsulated in nitrogen, fluorine, and sulfur self-doped porous carbon (NFS-PC) composites (La-SPc@NFS-PC) for efficient ORR and OER. The La-SPc is introduced not only as a promoter to increase the electrochemical stability of the La-SPc@NFS-PC catalysts but also to tailor the electronic structure of NFS-PC due to the unique electrochemical properties of La-SPc. In addition, the integration of La-SPc and NFS-PC can improve the electronic conductivity of composites by inducing electron redistribution and lowering the band gap, which is advantageous in enhancing the kinetics of charge transfer. Simultaneously, benefiting from the optimized porous structure and positive cooperation of La-SPc with NFS-PC shells, the obtained La-SPc@NFS-PC-3 delivers robust bifunctional ORR/OER activities and stabilities. More importantly, the Zn–air battery (ZAB) assembled with La-SPc@NFS-PC-3 demonstrates an outstanding power density (181.1 mW cm–2) and long cycling life, outperforming the commercial Pt/C. This work offers a rational approach to preparing high-efficiency rare-earth-based catalysts and provides potential applications in ZABs

Facile Spray-Coating Process for the Fabrication of Tunable Adhesive Superhydrophobic Surfaces with Heterogeneous Chemical Compositions Used for Selective Transportation of Microdroplets with Different Volumes

In this paper, tunable adhesive superhydrophobic ZnO surfaces have been fabricated successfully by spraying ZnO nanoparticle (NP) suspensions onto desired substrates. We regulate the spray-coating process by changing the mass percentage of hydrophobic ZnO NPs (which were achieved by modifying hydrophilic ZnO NPs with stearic acid) in the hydrophobic/hydrophilic ZnO NP mixtures to control heterogeneous chemical composition of the ZnO surfaces. Thus, the water adhesion on the same superhydrophobic ZnO surface could be effectively tuned by controlling the surface chemical composition without altering the surface morphology. Compared with the conventional tunable adhesive superhydrophobic surfaces, on which there were only three different water sliding angle values: lower than 10°, 90° (the water droplet is firmly pinned on the surface at any tilted angles), and the value between the two ones, the water adhesion on the superhydrophobic ZnO surfaces has been tuned effectively, on which the sliding angle is controlled from 2 ± 1° to 9 ± 1°, 21 ± 2°, 39 ± 3°, and 90°. Accordingly, the adhesive force can be adjusted from extremely low (∼2.5 μN) to very high (∼111.6 μN). On the basis of the different adhesive forces of the tunable adhesive superhydrophobic surfaces, the selective transportation of microdroplets with different volumes was achieved, which has never been reported before. In addition, we demonstrated a proof of selective transportation of microdroplets with different volumes for application in the droplet-based microreactors via our tunable adhesive superhydrophobic surfaces for the quantitative detection of AgNO3 and NaOH. The results reported herein realize the selective transportation of microdroplets with different volumes and we believe that this method would potentially be used in many important applications, such as selective water droplet transportation, biomolecular quantitative detection and droplet-based biodetection

Preparation of a Low-cost and Eco-friendly Superabsorbent Composite Based on Wheat Bran and Laterite for Potential Application in Chinese Herbal Medicine Growth

A low-cost and eco-friendly superabsorbent composite is prepared through the free-radical graft co-polymerization of wheat bran (WB), acrylic acid (AA) and laterite (LA) in an aqueous solution. Elemental map, scanning electron microscopy and Fourier transform infrared spectra revealed that the LA evenly distributed in the superabsorbent composite and wheat bran-g-poly(acrylic acid)/laterite (WB-g-PAA/LA) formed successfully. Thermogravimetric analysis confirmed that the WB-g-PAA/LA had high thermal stability. Furthermore, the properties of the WB-g-PAA/LA, such as swelling in saline solutions and degradation, are also assessed. The final WB-g-PAA/LA (5 wt%) superabsorbent composite attained an optimum water absorbency of 1425 g g⁻¹ in distilled water and 72 g g⁻¹ in 0.9 wt% NaCl solution. The water absorbency of WB-g-PAA/LA (10 wt%) is even greater than that of the WB-g-PAA. Moreover, the water-retention capacity of WB-g-PAA/LA (5 wt%) is high, and the water-retention process followed a zero-order reaction. The reaction rate constant is 8.2428 × 10⁵ exp(−<i>E</i>_a<i>/RT</i>) and the apparent activation energy (<i>E</i>_a) is 35.11 kJ mol⁻¹. Furthermore, WB-g-PAA/LA (5 wt%) may regulate the release of urea, indicating that the superabsorbent composite could provide a promising application as a urea fertilizer carrier. Additionally, it increased the germination and growth rates of <i>Glycyrrhiza uralensis</i> Fisch, suggesting it could influence the growth of Chinese herbal medicine