Nickel Nanowire@Porous NiCo2O4 Nanorods Arrays Grown on Nickel Foam as Efficient Pseudocapacitor Electrode

A three dimensional hierarchical nanostructure composed of nickel nanowires and porous NiCo2O4 nanorods arrays on the surface of nickel foam is successfully fabricated by a facile route. In this structure, the nickel nanowires are used as core materials to support high-pseudocapacitance NiCo2O4 nanorods and construct the well-defined NiCo2O4 nanorods shell/nickel nanowires core hierarchical structure on nickel foam. Benefiting from the participation of nickel nanowires, the nickel nanowire@NiCo2O4/Ni foam electrode shows a high areal specific capacitance (7.4 F cm−2 at 5 mA cm−2), excellent rate capability (88.04% retained at 100 mA cm−2), and good cycling stability (74.08% retained after 1,500 cycles). The superior electrochemical properties made it promising as electrode for supercapacitors

Table_1_Causal effects of gut microbiome on hypertension: a Mendelian randomization study.xlsx

BackgroundPrevious observational studies have shown that there is an important relationship between gut microbiota and hypertension, we performed a two-sample Mendelian randomization analysis to examine whether the gut microbiota is causally related to hypertension in order to find a basis for potential diagnostic or intervention approaches for hypertension.MethodsWe obtained significant single nucleotide polymorphisms related to gut microbiota and hypertension from publicly available genome-wide association studies for a two-sample Mendelian randomization study. A total of 18,340 individual genome-wide genotype data were included from 24 population-based cohorts. The inverse-variance weighted meta-analysis is the main analytical method for evaluating causal relationships, and the Mendelian randomization research results have been validated through a series of sensitivity analyses.ResultsThe inverse-variance weighted analysis results indicated that phylum Verrucomicrobia (OR:0.831, 95%CI: 0.710–0.972; p = 0.021), family BacteroidalesS24.7group (OR:0.672, 95%CI: 0.496–0.911; p = 0.01), family Bifidobacteriaceae (OR:0.709, 95%CI:0.569–0.884, p = 0.002), genus Adlercreutzia (OR: 0.991, 95%CI: 0.982–0.999, p = 0.035), genus Phascolarctacterium (OR:0.819, 95%CI:0.685–0.981; p = 0.03), genus LachnospiraceaeNK4A136group (OR:0.990, 95%CI:0.981–0.999; p = 0.025), and genus Ruminococcus2 (OR:0.988, 95%CI: 0.979–0.997; p = 0.008) had protective causal effects on hypertension. The Family Alcaliginaceae (OR:1.011, 95%CI:1.000–1.021, p = 0.04), Genus Anaerostipes (OR:1.375, 95%CI:1.096–1.653; p = 0.025), Genus Collinsella (OR:1.899, 95%CI:1.361–2.348; p = 0.02), and Genus Lachnospiraceae_UCG_010 (OR:1.536, 95%CI:1.072–2.202; p = 0.019) were associated with a higher risk of HTN. The reverse Mendelian randomization analysis results showed no reverse causal relationship between HTN and these bacterial taxa.ConclusionOur Mendelian randomization analysis results indicate a potential causal relationship between these bacterial taxa and hypertension, providing a new perspective for the treatment and prevention of hypertension.</p

Ag Decorated Co₃O₄-Nitrogen Doped Porous Carbon as the Bifunctional Cathodic Catalysts for Rechargeable Zinc-Air Batteries

The use of transition metals as bifunctional catalysts for rechargeable zinc-air batteries has recently attracted much attention. Due to their multiple chemical valence states, the cobalt oxides are considered to be promising catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this work, bifunctional Ag-decorated Co3O4-nitrogen doped porous carbon composite (Co3O4-NC&Ag) catalysts were synthesized by annealing ZIF-67 in N2 and O2, respectively, followed by Ag deposition using chemical bath deposition. Due to the decoration of Ag nanoparticles and high specific surface area (46.9 m2 g−1), the electrochemical activity of Co3O4 increased significantly. The optimized Co3O4-NC&Ag catalysts possessed superior ORR performance with a half-wave potential of 0.84 V (vs. RHE) and OER activity with an overpotential of 349 mV at 10 mA cm−2. The open circuit voltage of the Co3O4-NC&Ag-based zinc-air battery was 1.423 V. Meanwhile, the power density reached 198 mW cm−2 with a specific discharge capacity of 770 mAh g−1 at 10 mA cm−2, which was higher than that of Pt/C-based zinc-air battery (160 mW cm−2 and 705 mAh g−1). At a current density of 10 mA cm−2, the charge-discharge performance was stable for 120 h (360 cycles), exhibiting better long-term stability than the Pt/C&RuO2 counterpart

Core/shell Cu/FePtCu nanoparticles with face-centered tetragonal texture: An active and stable low-Pt catalyst for enhanced oxygen reduction

International audienceLow-Pt based nanocrystals demonstrate potential as highly active catalysts for the oxygen reduction reaction (ORR), but they suffer from undesirable structural degradation. Therefore, it is highly challenging to optimize their surface and interfacial structures to tune their catalytic properties for both activity and stability. Here core–shell Cu/FePtCu nanoparticles with a face-centered-tetragonal phase are prepared by a facile one–pot polyol method at 320 °C. The optimized core–shell Fe45Pt35Cu20 catalyst with Pt-enriched surface exhibits 0.5 A/mgPt mass activity, which is a factor of 4 better than that of commercial Pt/C (0.13 A/mgPt). In addition, the current density of the catalyst drops only 3.0% after 1000 cycles, which is much better than Pt/C (34.2% decay). Using aberration-corrected scanning transmission electron microscopy and atomically resolved elemental mapping, the morphology and structure evolving between the FePtCu alloy and core–shell Cu/FePtCu could clearly be explained. This work demonstrates that an ordered and core–shell FePtCu catalyst is highly promising for ORR and other electrochemical processes

Ag Decorated Co3O4-Nitrogen Doped Porous Carbon as the Bifunctional Cathodic Catalysts for Rechargeable Zinc-Air Batteries

The use of transition metals as bifunctional catalysts for rechargeable zinc-air batteries has recently attracted much attention. Due to their multiple chemical valence states, the cobalt oxides are considered to be promising catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this work, bifunctional Ag-decorated Co3O4-nitrogen doped porous carbon composite (Co3O4-NC&amp;Ag) catalysts were synthesized by annealing ZIF-67 in N2 and O2, respectively, followed by Ag deposition using chemical bath deposition. Due to the decoration of Ag nanoparticles and high specific surface area (46.9 m2 g&minus;1), the electrochemical activity of Co3O4 increased significantly. The optimized Co3O4-NC&amp;Ag catalysts possessed superior ORR performance with a half-wave potential of 0.84 V (vs. RHE) and OER activity with an overpotential of 349 mV at 10 mA cm&minus;2. The open circuit voltage of the Co3O4-NC&amp;Ag-based zinc-air battery was 1.423 V. Meanwhile, the power density reached 198 mW cm&minus;2 with a specific discharge capacity of 770 mAh g&minus;1 at 10 mA cm&minus;2, which was higher than that of Pt/C-based zinc-air battery (160 mW cm&minus;2 and 705 mAh g&minus;1). At a current density of 10 mA cm&minus;2, the charge-discharge performance was stable for 120 h (360 cycles), exhibiting better long-term stability than the Pt/C&amp;RuO2 counterpart

Zincophobic electrolyte achieves highly reversible zinc-ion batteries

Zinc metal batteries show tremendous applications in wide-scale storages still impeded by aqueous electrolytes corrosion and interfacial water splitting reaction. Herein, a zincophobic electrolyte containing succinonitrile (SN) additive is proposed, the SN electrolyte shows a lower affinity for zinc but a stronger affinity for solid-state interphase (SEI). In the SN electrolyte, zinc hydroxide sulfate (ZHS) is more inclined to accumulate horizontally, forming a dense SEI protective layer on the surface of the Zn anode, effectively slowing down the corrosion of Zn and dendrite growth. The zincophobic SN electrolyte enables excellent performance: zinc plating/stripping Coulombic efficiency of 99.71% for an average of 400 cycles; stable cycles in a symmetric cell for 4000 h (0.9% zinc utilization) and 325 h (86.1% zinc utilization). The soft pack battery using limited zinc delivers maximum energy density of 57.0 Wh kg−1 (based on mass loading of cathode materials and anode materials). Such a simple additive strategy provides a theoretical reference for zinc chemistry in a mild electrolyte environment in practical applications.This research was supported by the National Natural Science Foundation of China (no. 52272198), the Project funded by China Postdoctoral Science Foundation (no. 2021M690947)

Intercalation of glucose in NiMn-layered double hydroxide nanosheets: An effective path way towards battery-type electrodes with enhanced performance

Glucose intercalated NiMn <i>layered double hydroxide</i> (LDH) is successfully fabricated with a facile one-pot hydrothermal method, which expands interlayer distances to enhance cycling stability and break the bottleneck of Ni-based hydroxide in applications. Electrochemical measurements show that the annealing-treated glucose intercalated NiMn LDH (LDH-GA) delivers a high specific capacity of 1464 F g⁻¹at a current density of 0.5 A g⁻¹ (852 F g⁻¹ for pristine NiMn LDH). The enhanced performance is contributed to the small sized architectures, lower charge transfer resistance and faster reversible redox reactions. Through enlarging interlayer distance and robustly stabilizing LDH, the cycling stability is dramatically enhanced from 45% to 90% for over 1000 cycles. To further disclose the reason of the enhanced electrochemical performance of NiMn LDH, a molecular dynamics (MD) simulation is implemented to calculate the diffusion of the electrolyte ions, the ionic diffusion coefficient and the ionic conductivity inside the NiMn LDH nanopores for different interlayer distances. Based on the experimental and theoretical results, it suggests that the intercalation of glucose in NiMn LDH could be an effective approach to enhance electrochemical performance, of which it also could be generalized to intercalation of other molecules to stabilize the α-phase of LDH

Tailoring the electrocatalytic activity of bimetallic nickel-iron diselenide hollow nanochains for water oxidation

Exploring low-cost, high-efficient and durable electrocatalysts to substitute for Ru, Ir-based noble metal catalysts is of great significance for oxygen evolution reaction (OER), which is in particular a sluggish anodic process in water oxidation and remains to be a major challenge that we are confronted with. Herein, we report nickel-iron diselenide hollow nanochains (denoted as NFSHNCs) synthesized via a two-step hydrothermal method working as the high performance OER catalyst. The formation of well-shaped NFSHNCs is due to the Kirkendall effect, in which NiFe alloy solid nanochains were employed as the precursors. The as-prepared NFSHNCs not only exhibit outstanding OER performance with low overpotential of 267 mV (at a current density of 10 mA cm−2) and small Tafel slope of 67 mV dec−1, superior to the state-of-the-art commercial RuO2, but also deliver high durability with a dinky degradation of 5.3% after 12 h fierce test. To identify the electrocatalytic active sites, the Gibbs free energy differences (ΔG) related to the O* and OH* adsorption on NiFe selenides were calculated with density functional theory. The theoretical results corroborate the fact that the O* and OH* adsorption prefers to occur on both iron sites and the nickel sites (the one that in the vicinity of iron sites) because of the synergistic effects of electron configuration

Critical Solvation Structures Arrested Active Molecules for Reversible Zn Electrochemistry

Highlights Critical solvation structure changes the hydrogen bond network through “catchers”. Catcher further arrests the active molecules to promote Zn2+ deposition. The Zn||Zn symmetric battery can stably cycle for 2250 h. Zn||V6O13 full battery achieved a capacity retention rate of 99.2% after 10,000 cycles