Carbonaceous materials are regarded as one of the most promising anodes for potassium-ion batteries (PIBs), but their rate capabilities are largely limited by the slow solid-state potassium diffusion kinetics inside anode and sluggish interfacial potassium ion transfer process. Herein, high-rate and high-capacity PIBs are demonstrated by facile topological defect-regulation of the microstructure of carbon anodes. The carbon lattice of the as-obtained porous carbon nanosheets (CNSs) with abundant topological defects (TDPCNSs) holds relatively high potassium adsorption energy yet low potassium migration barrier, thereby enabling efficient storage and diffusion of potassium inside graphitic layers. Moreover, the topological defects can induce preferential decomposition of anions, leading to the formation of high potassium ion conductive solid electrolyte interphase (SEI) film with decreased potassium ion de-solvation and transfer barrier. Additionally, the dominant sp2-hybridized carbon conjugated skeleton of TDPCNSs enables high electrical conductivity (39.4 S cm-1) and relatively low potassium storage potential. As a result, the as-constructed TDPCNSs anode demonstrates high potassium storage capacity (504 mA h g-1 at 0.1 A g-1), remarkable rate capability (118 mA h g-1 at 40 A g-1), as well as long-term cycling stability.
Quasi solid-state polymer electrolytes (QSPEs) are particularly attractive due to their high ionic conductivity and excellent safety for lithium metal batteries (LMBs). However, it is still a great challenge for QSPEs to achieve strong mechanical strength and high electrochemical performance simultaneously. Herein, a QSPE (SCOF-PEP-PEA) using a covalent organic framework (COF) containing abundant allyl groups (SCOF) as a rigid porous filler as well as a cross-linker to reinforce the polymer network is reported. Benefitting from the unique 3D nanonetwork structure and abundant lithiophilic functional groups, SCOF-PEP-PEA QSPE exhibits high ionic conductivity (4.0 × 10-4 S cm-1) and high lithium-ion transference number (0.82) at room temperature. Moreover, SCOF-PEP-PEA QSPE displays much improved mechanical strength compared to PEP-PEA QSPE (AFM Young's modulus: 453 vs 36 MPa). As a result, the Li/LFP full cell with SCOF-PEP-PEA QSPE shows great rate performance of 141 mAh g-1 at 1C and delivers a high specific capacity retention of 92% after 220 cycles at 0.5 C (60 °C). This work provides a new strategy to design and prepare high-performance QSPEs with COFs as porous organic filler, and further expand the application of COFs for energy storage applications.
The controlled conformational changes of planar graphene nanosheets are of great importance to the realization of their practical applications. Despite substantial effort in the area, the controlled folding of two-dimensional (2D) graphene sheets into one-dimensional (1D) structures still remains a significant challenge. Here, for the first time, we report an ice crystal guided folding strategy to fabricate 1D folded graphene nanobelts (FGBs), where the formation and growth of ice crystals in a confined space function to guide the folding of 2D graphene oxide (GO) nanosheets into 1D nanobelts (i.e. folded graphene oxide belts, FGOBs), which were subsequently converted to FGBs after annealing. Thin aqueous GO containing films were obtained by blowing air through a GO dispersion in the presence of a surfactant, polyoxypropylenediamine (D400), resulting in a foam containing uniform air bubbles. Subsequent shock cooling of the foam using liquid nitrogen resulted in the facile fabrication of FGOBs. This technique provides a general approach to encapsulate catalytic nanomaterials such as Fe3O4 nanorods, TiO2 and Co3O4 nanoparticles into the folded graphene structure for practical applications such as Li-ion batteries.
Herein, we develop a new intelligent moisture-sensitive hybrid aerogel by evenly embedding a proton-conductive covalent organic framework (COF-2SO3H) into a carboxylated cellulose nanofiber network (CNF-C) for water harvesting and spontaneous sustained electricity production from ambient humidity and human respiration. Our strategy first exploits the "suspending agent" role of CNF-C to stably disperse COF materials in water for forming uniform hierarchical hybrid structures. By utilizing the synergy of COF-2SO3H and CNF-C together with their inherent structure merits and surface group effects, the hybrid aerogel displays increased water uptake and ion conductivity. Upon asymmetric moisturization, it can create a self-maintained moisture gradient to engender a concentration difference for mobile Na+ and H+, resulting in efficient charge separation and diffusion. Thus, the hybrid aerogel-based coin-type generator achieves a continuous output voltage of â¼0.55 V for at least 5 h in ambient environments in contrast to that using pure CNF-C and carbon-based generators with transient voltage response. Intriguingly, the wearable generator with an aerogel in a mask is more sensitive to human respiration and achieves repeatable and reliable self-charge for persistent electricity along with an increased output voltage of up to 1.0 V and much faster self-charge (only 3 min), both of which surpass most reported moisture-enabled generators.
Electricity , Protons , Humans , Electric Conductivity , Cellulose , Respiration
Ruthenium (Ru) is a refractory metal that has applications in the semiconductor industry as a sputtering target material. However, conventional powder metallurgy methods cannot produce dense and fine-grained Ru targets with preferred orientation. Here, we present a novel method of hot-pressing deformation to fabricate Ru targets with high relative density (98.8%), small grain size (~4.4 µm) and strong (002) texture. We demonstrate that applying pressures of 30-40 MPa at 1400 °C transforms cylindrical Ru samples into disk-shaped targets with nearly full densification in the central region. We also show that the hardness and the (002)/(101) peak intensity ratio of the targets increase with the pressure, indicating enhanced mechanical and crystallographic properties. Our study reveals the mechanisms of densification and texture formation of Ru targets by hot-pressing deformation.
Carbonaceous materials are widely investigated as anodes for potassium-ion batteries (PIBs). However, the inferior rate capability, low areal capacity, and limited working temperature caused by sluggish K-ions diffusion kinetics are still primary challenges for carbon-based anodes. Herein, a simple temperature-programmed co-pyrolysis strategy is proposed for the efficient synthesis of topologically defective soft carbon (TDSC) based on inexpensive pitch and melamine. The skeletons of TDSC are optimized with shortened graphite-like microcrystals, enlarged interlayer spacing, and abundant topological defects (e.g., pentagons, heptagons, and octagons), which endow TDSC with fast pseudocapacitive K-ion intercalation behavior. Meanwhile, micrometer-sized structure can reduce the electrolyte degradation over particle surface and avoid unnecessary voids, ensuring a high initial Coulombic efficiency as well as high energy density. These synergistic structural advantages contribute to excellent rate capability (116 mA h g-1 at 20 C), impressive areal capacity (1.83 mA h cm-2 with a mass loading of 8.32 mg cm-2 ), long-term cycling stability (capacity retention of 91.8% after 1200 h cycling), and low working temperature (-10 °C) of TDSC anodes, demonstrating great potential for the practical application of PIBs.
With the overconsumption of disposable plastics, there is a considerable emphasis on the recycling of waste plastics to relieve the environmental, economic, and health-related consequences. Here, a sulfur-assisted pyrolysis strategy is demonstrated for versatile upcycling of plastics into high-value carbons with an ultrahigh carbon-atom recovery (up to 85%). During the pyrolysis process, the inexpensive elemental sulfur molecules are covalently bonded with polymer chains, and then thermally stable intermediates are produced via dehydrogenation and crosslinking, thereby inhibiting the decomposition of plastics into volatile small hydrocarbons. In this manner, the carbon products obtained from real-world waste plastics exhibit sulfur-rich skeletons with an enlarged interlayer distance, and demonstrate superior sodium storage performance. It is believed that the present results offer a new solution to alleviate plastic pollution and reduce the carbon footprint of plastic industry.
Carbon-based polymer brushes (CBPBs) are an important class of functional polymer materials, which synergistically combine the advantageous properties of both carbons and polymers. However, the conventional fabrication procedures of CBPBs involve tedious multistep modification, including preoxidation of carbon substrates, introduction of initiating groups, and subsequent graft polymerization. In this study, a simple yet versatile defect-engineering strategy is proposed for the efficient synthesis of high-grafting-density CBPBs with highly stable CC linkages via free radical polymerization. This strategy involves the introduction and removal of nitrogen heteroatoms in the carbon skeletons via a simple temperature-Fmed heat treatment, leading to the formation of numerous carbon defects (e.g., pentagons, heptagons, and octagons) with reactive C=C bonds in the carbon substrates. The as-proposed methodology enables the facile fabrication of CBPBs with various carbon substrates and polymers. More importantly, the highly grafted polymer chains in the resulting CBPBs are tethered with the carbon skeletons by robust CC bonds, which can endure strong acid and alkali environments. These interesting findings will shed new light on the well-orchestrated design of CBPBs and broaden their applications in various areas with fascinating performances.
Polymeric membranes are considered as promising materials to realize safe and long-life lithium metal batteries (LMBs). However, they are usually based on soft 1D linear polymers and thus cannot effectively inhibit piercing of lithium dendrites at high current density. Herein, single lithium-ion conducting molecular brushes (GO-g-PSSLi) are successfully designed and fabricated with a new 2D "soft-hard-soft" hierarchical structure by grafting hairy lithium polystyrenesulfonate (PSSLi) chains on both sides of graphene oxide (GO) sheets. The ultrathin GO-g-PSSLi membrane is further constructed by evaporation-induced layer-by-layer self-assembly of GO-g-PSSLi molecular brushes. Unlike conventional soft 1D linear polymeric structure, the rigid 2D extended aromatic structure of intralayer GO backbones can bear the shield effect of preventing the dendrites possibly generated at high current density from piercing. More importantly, such a shield effect can be significantly strengthened by layer-by-layer stacking of 2D molecular brushes. On the other hand, the 3D interconnected interlayer channels and the soft single lithium-ion conducting PSSLi side-chains on the surface of channels provide rapid lithium-ion transportation pathways and homogenize lithium-ion flux. As a result, LMBs with GO-g-PSSLi membrane possess long-term reversible lithium plating/striping (6 months) at high current density.
The low cycling efficiency and uncontrolled dendrite growth resulting from an unstable and heterogeneous lithium-electrolyte interface have largely hindered the practical application of lithium metal batteries. In this study, a robust all-organic interfacial protective layer has been developed to achieve a highly efficient and dendrite-free lithium metal anode by the rational integration of porous polymer-based molecular brushes (poly(oligo(ethylene glycol) methyl ether methacrylate)-grafted, hypercrosslinked poly(4-chloromethylstyrene) nanospheres, denoted as xPCMS-g-PEGMA) with single-ion-conductive lithiated Nafion. The porous xPCMS inner cores with rigid hypercrosslinked skeletons substantially increase mechanical robustness and provide adequate channels for rapid ionic conduction, while the flexible PEGMA and lithiated Nafion polymers enable the formation of a structurally stable artificial protective layer with uniform Li+ diffusion and high Li+ transference number. With such artificial solid electrolyte interphases, ultralong-term stable cycling at an ultrahigh current density of 10 mA cm-2 for over 9,100 h (>1 year) and unprecedented reversible lithium plating/stripping (over 2,800 h) at a large areal capacity (10 mAh cm-2) have been achieved for lithium metal anodes. Moreover, the protected anodes also show excellent cell stability when paired with high-loading cathodes (~4 mAh cm-2), demonstrating great prospects for the practical application of lithium metal batteries.
Ag/Y2O3 has excellent potential to replace Ag/CdO as the environmentally friendly electrical contact material. Using spherical Y2O3 as the starting material, Ag/Y2O3 contacts with a quasi-continuous network structure were successfully fabricated by a low-energy ball milling treatment. The mean size of Y2O3 used ranged from 243 to 980 nm. Due to the differences in the size of Y2O3, Ag/Y2O3 contacts had different primitive microstructures, thereby exhibiting distinctive anti-arc-erosion capabilities. Ag/Y2O3 contact prepared using 243 nm Y2O3 showed the best anti-arc-erosion capability and the most outstanding electrical performance measures, such as low contact resistance, less mass transfer, and no failure up to 105 cycle times. The quasi-continuous network structure formed in the micro-scale was responsible for the excellent electrical performance. The short distance between Y2O3 particles in the network promoted the cathode arc motion, and thus alleviated the localized erosion. The results obtained herein may inspire further attempts to design electrical contacts rationally.
LuAG:Ce (Lu3Al5O12:Ce) is one of the most important color converters in white lighting industry. Especially, LuAG:Ce film attracts more attention due to the outstanding advantages, such as the efficient heat dissipation, the saving of rare earth, and so on. Here, LuAG:Ce film on sapphire was successfully prepared by the ultrasonic spray pyrolysis process. The phase, microstructure and photoluminescence of LuAG:Ce films were investigated. LuAG:Ce films had a thickness of around 5 µm, which were well crystallized at 1000 °C in air atmosphere to form the typical garnet structure. Under the protection of CO atmosphere, increasing the annealing temperature greatly enhanced the photoluminescence performance. After annealing at 1500 °C for 5 h in CO atmosphere, 3.0 mol.% Ce3+ doped LuAG:Ce film exhibited the highest emission and excitation intensity. The emission intensity of 3.0 mol.% Ce3+ doped LuAG:Ce film annealed at 1500 °C in CO atmosphere increased up to five times, when compared with the best LuAG:Ce film annealed at 1000 °C in air atmosphere. The effects of Ce3+ doping concentration on the photoluminescence were also examined. As the Ce3+ doping concentration increased from 0.2 mol.% to 7.0 mol.%, the color of LuAG:Ce films changed from yellowish green to greenish yellow. When coupling the 3.0 mol.% Ce3+ doped LuAG:Ce film with a 0.5 W 450 nm blue laser, the formed device successfully emitted white light.
Developing efficient electrocatalysts to promote the hydrogen evolution reaction (HER) is essential for a green and sustainable future energy supply. For practical applications, it is a challenge to achieve the self-assembly of electrocatalyst from microscopic to macroscopic scales. Herein, a facile strategy is proposed to fabricate a self-supporting electrocatalyst film (CNT-g-PSSCo/PW12 ) for HER by electrostatic interaction-induced self-assembly of cobalt polystyrene sulfonate-grafted carbon nanotube heterogeneous bottlebrush (CNT-g-PSSCo) and polyoxometalate (PW12 ). Co2+ ions of CNT-g-PSSCo can function as junctions for interconnecting neighboring bottlebrushes to form the 3D nanonetwork structure and enable electrostatic capture of negatively charged PW12 nanodots. Moreover, CNT backbones can provide highly conductive pathways to CNT-g-PSSCo/PW12 . Such a self-assembled CNT-g-PSSCo/PW12 displays a low overpotential of 31 mV at a current density of 10 mA cm-2 and a small Tafel slope of 25 mV dec-1 , showing high efficiency toward HER. Furthermore, CNT-g-PSSCo/PW12 with a stable self-supporting film morphology exhibits long-term electrocatalytic stability over 1000 CV cycles without noticeable overpotential change in acidic media. The findings may provide a new avenue for constructing self-assembled functional nanonetwork materials with well-orchestrated structural hierarchy for many applications in energy, environment, catalysis, medicine, and others.
Acids , Hydrogen , Acids/chemistry , Anions , Catalysis , Hydrogen/chemistry , Polyelectrolytes
Carbon-based nanomaterials have been regarded as promising non-noble metal catalysts for renewable energy conversion system (e.g., fuel cells and metal-air batteries). In general, graphitic skeleton and porous structure are both critical for the performances of carbon-based catalysts. However, the pursuit of high surface area while maintaining high graphitization degree remains an arduous challenge because of the trade-off relationship between these two key characteristics. Herein, a simple yet efficient approach is demonstrated to fabricate a class of 2D N-doped graphitized porous carbon nanosheets (GPCNSs) featuring both high crystallinity and high specific surface area by utilizing amine aromatic organoalkoxysilane as an all-in-one precursor and FeCl3 ·6H2 O as an active salt template. The highly porous structure of the as-obtained GPCNSs is mainly attributed to the alkoxysilane-derived SiOx nanodomains that function as micro/mesopore templates; meanwhile, the highly crystalline graphitic skeleton is synergistically contributed by the aromatic nucleus of the precursor and FeCl3 ·6H2 O. The unusual integration of graphitic skeleton with porous structure endows GPCNSs with superior catalytic activity and long-term stability when used as electrocatalysts for oxygen reduction reaction and Zn-air batteries. These findings will shed new light on the facile fabrication of highly porous carbon materials with desired graphitic structure for numerous applications.
Due to the recent technological revolution that is centered around information technology, the Internet of Medical Things (IoMT) has become an important research domain. IoMT is a combination of Internet of Things (IoT), big data, cloud computing, ubiquitous network, and three-dimensional holographic technology, which is used to build a smart medical diagnosis and treatment system. Additionally, this system should automate various activities, such as the patient's health record and health monitoring, which is an important issue in the development of modern and smart healthcare system. In this paper, we have thoroughly examined the role of a smart healthcare system architecture and other key supporting technologies in improving the health status of both indoor and outdoor patients. The proposed system has the capacity to investigate and predict (if feasible) the clinical application and nursing effects of totally implantable intravenous port (TIVAP) in pediatric hematological tumors. For this purpose, seventy children with hematologic tumors were treated with TIVAP, and IoMT-enabled care was provided to them, where the occurrence of adverse events, specifically after the treatment, was observed. The experimental results collected after the 70 children were treated and cared for by TIVAP show that there were five cases of adverse events, whereas the incidence rate of the adverse events was 7.14%. Moreover, TIVAP has significant efficacy in the treatment of hematologic tumors in children, and it equally reduces the vascular injury caused by chemotherapy in younger patients. Likewise, targeted care reduces the incidence of adverse events in children with expected ratio.
Internet of Things , Neoplasms , Child , Cloud Computing , Humans , Infusions, Intravenous , Internet , Neoplasms/drug therapy , Technology
Cobalt disulfide (CoS2 ) has been explored as attractive electrocatalyst for oxygen evolution reaction (OER). However, bulk CoS2 sheets have limited catalytic activity due to low exposure of active sites. Herein, through an in-situ vulcanization approach, CoS2 nanoparticles are embedded into bipyridine-containing covalent organic polymer (BP-COP). The as-prepared nanocomposite CoS2 @BP-COP exhibits high catalytic activity toward OER with an ultra-low overpotential of 270â mV (vs. RHE) at a current density of 10â mA cm-2 , a small Tafel slope of 36â mV dec-1 , and an excellent durability for 24â h without decay. The surface of CoS2 is partially converted into CoOOH to form CoS2 /CoOOH as active sites under OER conditions. CoS2 @BP-COP displays superior OER catalytic activity to CoS2 nanosheets and commercially available RuO2 under the same conditions. The outstanding OER performance activity of CoS2 @BP-COP could be attributed to the uniform and small particle sizes of CoS2 /CoOOH distributed in BP-COP.
Quasi-solid-state polymer electrolytes are one of the most promising candidates for long-life lithium-metal batteries. However, introduction of plasticizers for high ion conductivity at room temperature inevitably gives rise to poor mechanical strength and requires a very thick electrolyte membrane, which is detrimental to safety and energy density of the batteries. Herein, inspired by tube brushes coupling hardness with softness, a novel superstructured polymer bottlebrush BC-g-PLiSTFSI-b-PEGM (BC = bacterial cellulose; PLiSTFSI = poly(lithium 4-styrenesulfonyl-(trifluoromethylsulfonyl) imide); PEGM = poly(diethylene glycol monomethyl ether methacrylate)) with a hard nanofibril backbone and soft functional polymer side-chains is reported as an effective strategy to well balance the mechanical strength and ion conductivity of quasi-solid-state polymer electrolytes. The resulting single lithium-ion conducting quasi-solid-state polymer-brush electrolytes (SLIC-QSPBEs) integrate the features of the ultrathin membrane thickness (10 µm), the nanofibril backbone-strengthened porous nanonetwork (Young's modulus = 1.9 GPa), and the high-rate single lithium-ion conducting diblock copolymer brushes. As a result, the ultrathin yet robust SLIC-QSPBEs enable ultralong-term (over 3300 h) reversible and stable lithium plating/stripping in Li/Li symmetrical cell at a current density of 1 mA cm-2 for lithium anode. This work affords a promising strategy to develop advanced electrolytes for solid-state lithium-metal batteries.
Nitrogen-doped porous carbon spheres have attracted great interest in diversified fields owing to their unique physical and chemical properties. However, the synthesis of nitrogen-doped porous carbon spheres with hierarchical superstructures and refined micropore structures is still a challenge. Herein, we develop a molecular-scale silica templating strategy to prepare nitrogen-doped microporous carbon spheres (MCSSs) with high porosity and a well-defined micropore structure. Octa(aminophenyl) polyhedral oligomeric silsesquioxane is used as a building block in MCSS precursors to provide precise molecular-scale templating and nitrogen doping. The morphology of MCSSs can be easily tuned by choosing the proper solvent. The as-synthesized MCSS with a large surface area (2036 m2 g-1), narrow micropore size distribution, nitrogen doping, and hierarchical geometry can serve as an efficient selective adsorbent for CO2 and organic pollutants. Furthermore, the MCSS decorated with Fe-N-C active sites (MCSS-Fe) shows enhanced electrocatalytic ORR activity in alkaline solution. This novel approach may open a new avenue for controllable fabrication of porous carbon spheres with desired geometry and well-designed pore structure and show potential applications in selective adsorption and catalysis.
A generalized and facile strategy toward 2D hybrid porous carbons (2DHPCs) with various highly active functional species (e.g. Co, B, and P) is developed via 2D molecular brushes as biomimetic building blocks. The resulting 2DHPCs present superior electrochemical energy conversion and storage properties.
A novel strategy is developed to produce an FeS-FeNC-decorated hierarchical porous N,S-co-doped carbon (FeS-FeNC@NSC) electrocatalyst via introducing volatile FeCl3 into a porphyrin polymer framework followed by carbonization. The synergistic effect between the FeS nanoparticles and FeNC active sites in FeS-FeNC@NSC is beneficial for enhancing the ORR activity.
