Synergistic dual sites of Zn-Mg on hierarchical porous carbon as an advanced oxygen reduction electrocatalyst for Zn-air batteries.

The development of cost-effective and high-performance non-noble metal catalysts for the oxygen reduction reaction (ORR) holds substantial promise for real-world applications. Introducing a secondary metal to design bimetallic sites enables effective modulation of a metal-nitrogen-carbon (M-N-C) catalyst's electronic structure, providing new opportunities for enhancing ORR activity and stability. Here, we successfully synthesized an innovative hierarchical porous carbon material with dual sites of Zn and Mg (Zn/Mg-N-C) using polymeric ionic liquids (PILs) as precursors and SBA-15 as a template through a bottom-up approach. The hierarchical porous structure and optimized Zn-Mg bimetallic catalytic centers enable Zn/Mg-N-C to exhibit a half-wave potential of 0.89 V, excellent stability, and good methanol tolerance in 0.1 M KOH solution. Theoretical calculations indicated that the Zn-Mg bimetallic sites in Zn/Mg-N-C effectively lowered the ORR energy barrier. Furthermore, the Zn-air batteries assembled based on Zn/Mg-N-C demonstrated an outstanding peak power density (298.7 mW cm-2) and superior cycling stability. This work provides a method for designing and synthesizing bimetallic site catalysts for advanced catalysis.

Zn/N/S Co-doped hierarchical porous carbon as a high-efficiency oxygen reduction catalyst in Zn-air batteries.

Zn-N-C catalysts have garnered attention as potential electrocatalysts for the oxygen reduction reaction (ORR). However, their intrinsic limitations, including poor activity and a low density of active sites, continue to hinder their electrocatalytic performance. In this study, we have devised a dual-template strategy for the synthesis of Zn, N, S co-doped nanoporous carbon-based catalysts (Zn-N/S-C(S, Z)) with a substantial specific surface area and a graded pore structure. The introduction of S enhances electron localization around the Zn-Nx active centers, facilitating interactions with oxygen-containing substances. The resulting Zn-N/S-C(S, Z) sample exhibits outstanding performance in an alkaline solution, demonstrating a half-wave potential of 0.89 V. This value surpasses that of commercial Pt/C by 40 mV. Furthermore, when combined with RuO2 (Zn-N/S-C(S, Z) + RuO2), the catalyst demonstrates exceptional performance in a Zn-air battery, offering an open-circuit voltage (OCV) of 1.47 V and a peak power density of 290.8 mW cm-2. This study paves the way for the development of highly dispersed and highly active Zn-metal site catalysts, potentially replacing traditional Pt-based catalysts in various electrochemical devices.

Nitrogen-Doped Carbon-Encapsulated Ordered Mesoporous SiOx as Anode for High-Performance Lithium-Ion Batteries.

SiOx (0

High-Quality N-Doped Graphene with Controllable Nitrogen Bonding Configurations Derived from Ionic Liquids.

Controllable nitrogen doping is an effective way to regulate the electronic properties of graphene and further to facilitate its wider application. However, the synthesis of high-quality nitrogen-doped graphene (NG) with a controllable nitrogen configuration still faces considerable challenges. In this work, we present for the first time a simple method for the one-step synthesis of NG with ionic liquids (ILs) as precursors, which avoids the defects introduced by secondary doping and simplifies the process. Using 1-Ethyl-3-methylimidazolium dicyanamide (EMIM-dca) as the precursor, we obtained a high-quality NG with few defects (ID /IG is 0.83), nitrogen content (4.11 at%), and graphite-N proportion of 92% at a growth temperature of 1000 °C and field effect transistors (FETs) fabricated on SiO2 /Si substrates using the NG exhibited typical n-type semiconductor behavior in air. Our findings bring more inspiration for the controllable growth of high-quality graphitic N-doped graphene, thereby promoting its application possibilities in numerous fields.

Carbon Uniformly Distributed SiOx/C Composite with Excellent Structure Stability for High Performance Lithium-Ion Batteries.

Silicon oxides (SiOx, 0

Combining Organic Plastic Salts with a Bicontinuous Electrospun PVDF-HFP/Li7La3Zr2O12 Membrane: LiF-Rich Solid-Electrolyte Interphase Enabling Stable Solid-State Lithium Metal Batteries.

Solid-state electrolytes can guarantee the safe operation of high-energy density lithium metal batteries (LMBs). However, major challenges still persist with LMBs due to the use of solid electrolytes, that is, poor ionic conductivity and poor compatibility at the electrolyte/electrode interface, which reduces the operational stability of solid-state LMBs. Herein, a novel fiber-network-reinforced composite polymer electrolyte (CPE) was designed by combining an organic plastic salt (OPS) with a bicontinuous electrospun polyvinylidene fluoride-co-hexafluoropropylene (PVDF-HFP)/Li7La3Zr2O12 (LLZO) membrane. The presence of LLZO in the composite helps to promote the dissociation of FSI- from OPSs. Subsequently, the dissociated FSI- is then involved in the formation of a LiF-rich solid electrolyte interphase (SEI) layer on the lithium anode via a reductive decomposition reaction, which was affirmed by theoretical calculations and experimental results. Due to the LiF-rich SEI layer, the Li/Li symmetric cell was able to demonstrate a long cyclic life of over 2600 h at a current density of 0.1 mA cm-2. More importantly, the as-prepared CPE achieved a high ionic conductivity of 2.8 × 10-4 S cm-1 at 25 °C, and the Li/LiFePO4 cell based on the CPE exhibited a high discharge capacity and 83.3% capacity retention after 500 cycles at 1.0 C. Thus, the strategy proposed in this work can inspire the future development of highly conductive solid electrolytes and compatible interface designs toward high-energy density solid-state LMBs.

Constructing the Single-Phase Nanotubes with Uniform Dispersion of SiOx and Carbon as Stable Anodes for Lithium-Ion Batteries.

SiOx is an attractive anode material for lithium-ion batteries due to its considerable capacity. However, its obvious volume expansion and low conductivity result in poor electrochemical performance. Herein, a novel single-phase nanotube structure with uniform distribution of nanoscale SiOx units and amorphous carbon matrix was fabricated. The hollow nanotube and homogeneously distributed ultrafine SiOx units greatly alleviate volume changes. The amorphous carbon facilitates electron transport throughout the network and offers a buffer to further reduce the volume expansion of SiOx. Benefiting from this unique structure, as-prepared single-phase SiOx/C NTs demonstrate excellent durability and rate capability. Specifically, it delivers a high reversible specific capacity (713 mAh g-1 at 0.1 A g-1 after 200 cycles); negligible capacity decay is confirmed after 500 cycles at high density current (544 mAh g-1 at 1 A g-1 after 500 cycles).

A Novel High-Capacity Anode Material Derived from Aromatic Imides for Lithium-Ion Batteries.

A novel anode material for lithium-ion batteries derived from aromatic imides with multicarbonyl group conjugated with aromatic core structure is reported, benzophenolne-3,3',4,4'-tetracarboxylimide oligomer (BTO). It could deliver a reversible capacity of 829 mA h g-1 at 42 mA g-1 for 50 cycles with a stable discharge plateaus ranging from 0.05-0.19 V versus Li+ /Li. At higher rates of 420 and 840 mA g-1 , it can still exhibit excellent cycling stability with a capacity retention of 88% and 72% after 1000 cycles, delivering capacity of 559 and 224 mA h g-1 . In addition, a rational prediction of the maximum amount of lithium intercalation is proposed and explored its possible lithium storage mechanism.

Eco-friendly preparation of large-sized graphene via short-circuit discharge of lithium primary battery.

We proposed a large-sized graphene preparation method by short-circuit discharge of the lithium-graphite primary battery for the first time. LiCx is obtained through lithium ions intercalation into graphite cathode in the above primary battery. Graphene was acquired by chemical reaction between LiCx and stripper agents with dispersion under sonication conditions. The gained graphene is characterized by Raman spectrum, X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Atomic force microscope (AFM) and Scanning electron microscopy (SEM). The results indicate that the as-prepared graphene has a large size and few defects, and it is monolayer or less than three layers. The quality of graphene is significant improved compared to the reported electrochemical methods. The yield of graphene can reach 8.76% when the ratio of the H2O and NMP is 3:7. This method provides a potential solution for the recycling of waste lithium ion batteries.

Nitrogen-doped hierarchical porous carbon microsphere through KOH activation for supercapacitors.

A porous carbon microsphere with moderate specific surface area and superior specific capacitance for supercapacitors is fabricated from polyphosphazene microsphere as the single heteroatoms source by the carbonization and subsequent KOH activation under N2 atmosphere. With KOH activation, X-ray photoelectron spectroscopy analysis confirms that the phosphorus of polyphosphazene microsphere totally vanishes, and the doping content of nitrogen and its population of various functionalities on porous carbon microsphere surface are tuned. Compared with non-porous carbon microsphere, the texture property of the resultant porous carbon microsphere subjected to KOH activation has been remarkably developed with the specific surface area growing from 315 to 1341 m(2) g(-1)and the pore volume turning from 0.17 to 0.69 cm(3) g(-1). Prepared with the KOH/non-porous carbon microsphere weight ratio at 1.0, the porous carbon microsphere with moderate specific surface area of 568 m(2) g(-1), exhibits intriguing electrochemical behavior in 1 M H2SO4 aqueous electrolyte, with superior specific capacitance (278 F g(-1) at 0.1 A g(-1)), good rate capability (147 F g(-1) remained at 10 A g(-1)) and robust cycling durability (No capacitance loss after 5000 cycles). The promising electrochemical performance could be ascribed to the synergy of nitrogen heteroatom functionalities and the porous morphology.

Hierarchical activated mesoporous phenolic-resin-based carbons for supercapacitors.

A series of hierarchical activated mesoporous carbons (AMCs) were prepared by the activation of highly ordered, body-centered cubic mesoporous phenolic-resin-based carbon with KOH. The effect of the KOH/carbon-weight ratio on the textural properties and capacitive performance of the AMCs was investigated in detail. An AMC prepared with a KOH/carbon-weight ratio of 6:1 possessed the largest specific surface area (1118 m(2) g(-1)), with retention of the ordered mesoporous structure, and exhibited the highest specific capacitance of 260 F g(-1) at a current density of 0.1 A g(-1) in 1 M H2 SO4 aqueous electrolyte. This material also showed excellent rate capability (163 F g(-1) retained at 20 A g(-1)) and good long-term electrochemical stability. This superior capacitive performance could be attributed to a large specific surface area and an optimized micro-mesopore structure, which not only increased the effective specific surface area for charge storage but also provided a favorable pathway for efficient ion transport.

Facile synthesis of novel Si nanoparticles-graphene composites as high-performance anode materials for Li-ion batteries.

Improving the Li storage properties of a Si negative electrode is of great significance for Li-ion batteries. A major challenge is to fabricate Si-based active materials with good electronic conduction and structural integrity in the process of discharging and charging. In this study, novel Si nanoparticles-graphene composites have been synthesized by hybrid electrostatic assembly between positively charged aminopropyltriethoxysilane modified Si nanoparticles and negatively charged graphene oxide, followed by thermal reduction. Commercially available Si nanoparticles are well embedded and uniformly dispersed into the graphene sheets, and the typically wrinkled graphene sheets form a network and cover the highly dispersed Si nanoparticles well. No any obvious aggregation of the Si nanoparticles can be found and many nanospaces exist around the Si nanoparticles, which provide buffering spaces needed for volume changes of Si nanoparticles during insertion/extraction of Li. High capacity and long cycle life (822 mA h g(-1) after 100 cycles at a current density of 0.1 A g(-1)) have been realized in the novel Si nanoparticles-graphene composites for Li-ion batteries. The excellent electrochemical performance is ascribed to the uniform distribution of Si nanoparticles and graphene, which effectively prevents aggregation and pulverization of Si nanoparticles, keeps the overall electrode highly conductive, and maintains the stability of the structure.

Graphene/carbon-coated Si nanoparticle hybrids as high-performance anode materials for Li-ion batteries.

Si is regarded as one of the most promising anode materials for next generation Li-ion batteries, but it usually exhibits poor cycling stability due to the low intrinsic electrical conductivity and huge volume change induced by the alloying reaction with Li. In this study, we present a double protection strategy by fabricating graphene/carbon-coated Si nanoparticle hybrids to improve the electrochemical performance of Si in Li storage. The Si nanoparticles are wrapped between the graphene and the amorphous carbon coating layers in the hybrids. The graphene and the amorphous carbon coating layers work together to effectively suppress the aggregation and destruction of Si nanoparticles, keeping the overall electrode highly conductive and active in Li storage. As a result, the produced graphene/carbon-coated Si nanoparticle hybrids exhibit outstanding reversible capacity for Li storage (902 mAh g(-1) after 100 cycles at 300 mA g(-1)). This work suggests a strategy to improve the electrochemical performance of Li-ion batteries by using graphene as supporting sheets for loading of active materials and carbon as the covering layers.

Direct synthesis of porous organosilicas containing chiral organic groups within their framework and a new analytical method for enantiomeric purity of organosilicas.

Organosilica porous solids containing chiral organic moieties in the framework with an enantiomeric purity of 95% ee, estimated by eluting organic constituent units from chiral organosilicas, were synthesized from a newly designed chiral (R)-(+)-1,2-bis(trimethoxysilyl)phenylethane precursor via a surfactant-mediated self-assembly approach.

An ordered mesoporous organosilica hybrid material with a crystal-like wall structure.

Surfactant-mediated synthesis strategies are widely used to fabricate ordered mesoporous solids in the form of metal oxides, metals, carbon and hybrid organosilicas. These materials have amorphous pore walls, which could limit their practical utility. In the case of mesoporous metal oxides, efforts to crystallize the framework structure by thermal and hydrothermal treatments have resulted in crystallization of only a fraction of the pore walls. Here we report the surfactant-mediated synthesis of an ordered benzene-silica hybrid material; this material has an hexagonal array of mesopores with a lattice constant of 52.5 A, and crystal-like pore walls that exhibit structural periodicity with a spacing of 7.6 A along the channel direction. The periodic pore surface structure results from alternating hydrophilic and hydrophobic layers, composed of silica and benzene, respectively. We believe that this material is formed as a result of structure-directing interactions between the benzene-silica precursor molecules, and between the precursor molecules and the surfactants. We expect that other organosilicas and organo-metal oxides can be produced in a similar fashion, to yield a range of hierarchically ordered mesoporous solids with molecular-scale pore surface periodicity.