Ultrafine red phosphorus confined in reasonably designed pitch-based carbon matrix built of well-interconnected carbon nanosheets for high-performance lithium and potassium storage

Red phosphorus has been well-recognized as promising anode materials for lithium-ion batteries(LIBs)and potassium-ion batteries(PIBs)due to its extremely high theoretical capacity and low cost.However,the huge volume change and poor electric conductivity severely limit its further practical application.Herein,the nanoscale ultrafine red phosphorus has been successfully confined in a three-dimensional pitch-based porous carbon skeleton composed of well-interconnected carbon nanosheets through the vaporization-condensation method.Except for the traditional requirement of high electric conductivity and stable mechanical stability,the micropores and small mesopores in the porous carbon matrix centered at 1 to 3 nm and the abundant amount of oxygen-containing functional groups are also beneficial for the high loading and dispersion of red phosphorus.As anode for LIBs,the composite exhibits high reversible discharge capacities of 968 mAh g^(-1),excellent rate capabilities of 593 mAh g^(-1)at 2 A g^(-1),and long cycle performance of 557 mAh g^(-1)at 2 A g^(-1).More impressively,as the anode for PIBs,the composite presents a high reversible capacity of 661 mAh g^(-1)and a stable capacity of 312 mAh g^(-1)at 0.5 A g^(-1)for 500 cycles with a capacity retention up to 84.3%.This work not only sheds light on the structure design of carbon hosts with specific pore structure but also open an avenue for high value-added utilization of coal tar pitch.

Newly Design Porous/Sponge Red Phosphorus@Graphene and Highly Conductive Ni2P Electrode for Asymmetric Solid State Supercapacitive Device With Excellent Performance

Supercapacitors have attracted much attention in the field of electrochemical energy storage.However,material preparation,stability,performance as well as power density limit their applications in many fields.Herein,a sponge-like red phosphorus@graphene(rP@rGO)negative electrode and a Ni2P positive electrode were prepared using a simple one-step method.Both electrodes showed excellent performances(294 F g^−1 and 1526.6 F g^−1 for rP@rGO and Ni2P,respectively),which seem to be the highest among all rP@rGO-and Ni2P-based electrodes reported so far.The asymmetric solid-state supercapacitor was assembled by sandwiching a gel electrolyte-soaked cellulose paper between rP@rGO and Ni2P as the negative and positive electrodes.Compared to other asymmetric devices,the device,which attained a high operating window of up to 1.6 V,showed high energy and power density values of 41.66 and 1200 W kg−1,respectively.It also has an excellent cyclic stability up to 88%after various consecutive charge/discharge tests.Additionally,the device could power commercial light emitting diodes and fans for 30 s.So,the ease of the synthesis method and excellent performance of the prepared electrode materials mat have significant potential for energy storage applications.

Preparation,Characterization,and Performance of Lignin-based Microencapsulated Red Phosphorus Flame Retardant for ABS

The inherent difficulty in preservation and processing of conventional red phosphorus flame retardant severely limits its growing applications in polymer materials,thus,there is an urgent need to exploit effective technology to modify red phosphorus.Functionalized lignin-based compounds can provide a great potential in improving the preservation and processing of red phosphorus.Here,we prepared melamine modified lignin/aluminum phosphate coated red phosphorus(LMAP@RP)and used it as the flame retardant of acrylonitrile-butadiene-styrene(ABS)resin.With 25wt%loading LMAP@RP,the ABS samples show excellent flame inhibiting capacity and reached UL-94 V-0 rating.Cone calorimetry test results show that the peak heat release rate,total heat release and total smoke release of ABS/25LMAP@RP are reduced strikingly by 64.6%,49.3%,and 30.1%,respectively.The char residue is 15.36wt%and the char layer is continuous and dense.The outstanding flame retardant and smoke-suppressant performances of LMAP@RP show its application prospect for ABS.

On-site conversion reaction enables ion-conducting surface on red phosphorus/carbon anode for durable and fast sodium-ion batteries

The practical applications of high-capacity alloy-type anode materials in sodium-ion batteries(SIBs)are challenged by their vast volume effects and resulting unstable electrode-electrolyte interphases during discharge-charge cycling.Taking red phosphorus(P)/carbon anode material as an example,we report an on-site conversion reaction to intentionally eliminate the volume effect-dominated surface P and yield an ionically conducting layer of Na3PS4solid-state electrolyte on the composite.Such a surface reconstruction can significantly suppress the electrode swelling and simultaneously enable the activation energy of interfacial Na+transfer as low as 36.7 k J mol^(-1),resulting in excellent electrode stability and ultrafast reaction kinetics.Consequently,excellent cycling performance(510 mA h g^(-1)at 5 A g^(-1)after 1000 cycles with a tiny capacity fading rate of 0.016%per cycle)and outstanding rate capability(484 mA h g^(-1)at 10 A g^(-1)are achieved in half cells.When coupled with Na_(3)V_(2)(PO4)3cathode,the full cells exhibit 100%capacity retention over 200 cycles at 5C with an average Coulombic efficiency of 99.93%and a high energy density of 125.5 W h kg^(-1)at a power density of 8215.6 W kg^(-1)(charge or discharge within~49 s).Remarkably,the full cell can steadily operate at a high areal capacity of 1.9 mA h cm^(-2),the highest level among red P-based full SIBs ever reported.

A review on nanoconfinement engineering of red phosphorus for enhanced Li/Na/K-ion storage performances

Secondary batteries are widely used in energy storage equipment.To obtain high-performance batteries,the development and utilization of electrode materials with cheap price and ideal theoretical gravimetric and volumetric specific capacities have become particularly important.Naturally abundant and low-cost red phosphorus(RP)is recognized as an anode material with great promise because it has a theoretical capacity of 2596 mA h g^(-1) in lithium-ion batteries(LIBs)and sodium-ion batteries(SIBs).However,owing to the inferior discharging,the capacity of pure RP has a fast decay.Nanoconfinement of RP nanoparticles within porous carbon framework is one of the efficient methods to overcome these problems.In this review,we introduce the recent progress of RP confinement into carbon matrix as an energy storage anode material in LIBs,SIBs and potassium-ion batteries(PIBs).The synthetic strategies,lithiation/sodia tion/potassiation mechanism,and the electrochemical performances of RP/carbon composites(RP/C)with kinds of designed structures and P-C and P-O-C bond by kinds of methods are included.Finally,the challenges and perspectives of RP faced in the application development as anodes for LIBs/SIBs/PIBs are covered.This review will strengthen the understanding of composites of RP nanoparticles in porous carbon materials and aid researchers to carry out future work rationally.

A facile fabrication of novel stuff with antibacterial property and osteogenic promotion utilizing red phosphorus and near-infrared light

Bone-implant materials are important for bone repairing and orthopedics surgery,which include bone plates and bone nails.These materials need to be designed not only considering its biostability and biocompatibility,but also their by-products induced infection after therapy or long-time treatment in vivo.Thus,the development of novel implant materials is quite urgent.Red phosphorus has great biocompatibility and exhibits efficient photothermal ability.Herein,a red phosphorus/IR780/arginine-glycine-asparticacid-cysteine(RGDC)coating on titanium bone-implant was prepared.The temperature sensitivity of Staphylococcus aureus biofilm is enhanced in the presence of ROS produced by IR780 with 808 nm light irradiation.With keeping the cells and tissues normal,a high antibacterial performance can be realized by near-infrared(808 nm)irradiated within 10 min at 50℃.Besides the high effective antibacterial efficacy provided by photothermal therapy(PTT)and photodynamic therapy(PDT),the RGDC decorated surface can also possess an excellent performance in osteogenesis in vivo.

Hierarchical red phosphorus incorporated TiO_(2) hollow sphere heterojunctions toward superior photocatalytic hydrogen production

Solar-to-hydrogen conversion through photocatalysis is a sustainable and promising strategy for storing solar energy.Recently,elemental red phosphorus(RP)with broad light absorption has been recognized as a potential candidate for photocatalytic hydrogen evolution,while challenges remain due to the rapid recombination of photogenerated carriers.In this work,RP modified TiO_(2)hollow spheres were designed and fabricated through the chemical vapor deposition method.The optimal hydrogen production rate reaching 215.5μmol/(g h)over TiO_(2)@RP heterostructure was obtained under simulated solar light irradiation.Experimental results evidenced that the hollow sphere structure and RP light absorber extended light absorption ability,and the heterostructure induced interfacial charge migration facilitated photoinduced charge separation,which benefited the photocatalytic hydrogen production performance.

Hierarchically porous carbon/red phosphorus composite for high-capacity sodium-ion battery anode

Red phosphorus has received remarkable attention as a promising anode material for sodium ion batteries(NIBs) due to its high theoretical capacity. However, its practical application has been impeded by its intrinsic low electronic conductivity and large volume variations during sodiation/desodiation process. Here, we design a composite to confine nanosized red phosphorus into the hierarchically porous carbon(HPC) walls by a vaporization-condensation strategy. The mass loading of P in the HPC/P composite is optimized to deliver a reversible specific capacity of 2,202 m Ah/gpbased on the mass of red P(836 m Ah/gcompositebased on the total composite mass), a high capacity retention over 77% after100 cycles, and excellent rate performance of 929 m Ah/gpat 2 C. The hierarchical porous carbon serves as the conductive networks, downsize the red phosphorus to nanoscale, and provide free space to accommodate the large volume expansions. The suppressed mechanical failure of the red phosphorus also enhances the stability of solid-electrolyte interface(SEI) layer, which is confirmed by the microscopy and impedance spectroscopy after the cycling tests. Our studies provide a feasible approach for potentially viable high-capacity NIB anode.

Amorphous red phosphorus anchored on carbon nanotubes as high performance electrodes for lithium ion batteries

Red phosphorus-carbon nanotube （P@CNT） composites were synthesized as anodes for advanced lithium ion batteries via a facile solution-based method at room temperature. In these composites, the entangled P@CNT nanostructure reduced the aggregation of both components and allowed their complete utilization in a synergetic manner. The highly conductive and porous CNT framework, along with the nanoscale red P particles intimately anchored on the CNT surface, conferred the composite with excellent ion/electron transport properties. Volume expansion within the red P particles was mitigated by their amorphous and nanoscale features, which can be well buffered by the soft CNTs, therefore maintaining an integrated electrode structure during cycling. When used as an anode in lithium ion batteries, the composite exhibited a reversible capacity of 960 mAh·g^-1 （based on the overall weight of the composite） after 120 cycles at 200 mA·g^-1. The composite also delivered excellent high-rate capability with capacities of 886, 847, and 784 mAh·g^-1 at current densities of 2,000, 4,000, and 10,000 mA·g^-1 respectively, which reveals its potential as a high performance anode for lithium ion batteries.

Single-step flash-heat synthesis of red phosphorus/ graphene flame-retardant composite as flexible anodes for sodium-ion batteries

Red phosphorus （RP） has attracted considerable attention as the anode for high-performance Na-ion batteries, owing to its low cost and high theoretical specific capacity of -2,600 mAh/g. In this study, a facile single-step flash-heat treatment was developed to achieve the reduction of graphene oxide （GO） and the simultaneous deposition of RP onto the reduced graphene oxide （rGO） sheets. The resulting RP/rGO composite was shown to be a promising candidate for overcoming the issues associated with the poor electronic conductivity and large volume variation of RP during cycling. The RP/rGO flexible film anode delivered an average capacity of 1,625 mAh/g during 200 cycles at a charge/ discharge current density of 1 A/g. Average charge capacities of 1,786, 1,597, 1,324, and 679 mAh/g at 1, 2, 4, and 6 A/g current densities were obtained in the rate capability tests. Moreover, owing to the RP component, the RP/rGO film presented superior flame retardancy compared to an rGO film. This work thus introduces a highly accessible synthesis method to prepare flexible and safe RP anodes with superior electrochemical performance toward Na-ion storage.

A novel battery scheme:Coupling nanostructured phosphorus anodes with lithium sulfide cathodes

Lithium-ion batteries are approaching their theoretical limit and can no longer keep up with the increasing demands of human society.Lithium-sulfur batteries,with a high theoretical specific energy,are promising candidates for next generation energy storage.However,the use of Li metal in Li-S batteries compromises both safety and performance,enabling dendrite formation and causing fast capacity degradation.Previous studies have probed alternative battery systems to replace the metallic Li in Li-S system,such as a Si/Li2S couple,with limited success in performance.Recently,there is a focus on red P as a favorable anode material to host Li.Here,we establish a novel battery scheme by utilizing a P/C nanocomposite anode and pairing it with a Li2S coated carbon nanofiber cathode.We find that red P anode can be compatible in ether-based electrolyte systems and can be successfully coupled to a Li2S cathode.Our proof of concept full-cell displays remarkable specific capacity,rate and cycling performances.We expect our work will provide a useful alternative system and valuable insight in the quest for next generation energy storage devices.

Effects of carbon on electrochemical performance of red phosphorus(P) and carbon composite as anode for sodium ion batteries

Red phosphorus/graphite(P/G) and red phosphorus/carbon nanotube(P/CNT) composites were prepared by ball milling red phosphorus with CNTs and graphite, respectively. The electrochemical results show superior electrochemical performances of the P/G and P/CNT composites compared with that of the reference sample milled with Super-P carbon. After 70 cycles, the P/G and P/CNT composites remained771.6 and 431.7 mA h g^(-1), with 68 % and 50 % capacity retention, respectively. With increasing the milling time(20 h), CNTs were cut into short pieces and then broken into carbon rings and sheets which were well mixed with red phosphorus. The morphology of the P/CNT composite can buffer the large volume changes from alloying and de-alloying during cycling, resulting in the enhanced cycling stability.

Eco-friendly and degradable red phosphorus nanoparticles for rapid microbial sterilization under visible light

Pathogens pose a serious challenge to environmental sanitation and a threat to public health.The frequent use of chemicals for sterilization in recent years has not only caused secondary damage to the environment but also increased pathogen resistance to drugs,which further threatens public health.To address this issue,the use of non-chemical antibacterial means has become a new trend for environmental disinfection.In this study,we developed red phosphorus nanoparticles(RPNPs),a safe and degradable photosensitive material with good photocatalytic and photothermal properties.The red phosphorus nanoparticles were prepared using a template method and ultrasonication.Under the irradiation of simulated sunlight for 20 min,the RPNPs exhibited an efficiency of 99.98%in killing Staphylococcus aureus due to their excellent photocatalytic and photothermal abilities.Transmission electron microscopy and ultraviolet–visible spectroscopy revealed that the RPNPs exhibited degradability within eight weeks.Both the RPNPs and their degradation products were nontoxic to fibroblast cells.Therefore,such RPNPs are expected to be used as a new type of low-cost,efficient,degradable,biocompatible,and eco-friendly photosensitive material for environmental disinfection.

Nano-structured red phosphorus/porous carbon as a superior anode for lithium and sodium-ion batteries

To enhance electrochemical performance of li- thium or sodium-ion batteries （LIBs or NIBs）, active materials are usually filled in porous conductive particles to produce anode composites. However, it is still challenging to achieve high performance anode composites with high specific capa- city, excellent rate performance, high initial Coulombic effi- ciency （ICE） and long cycle life. Based on these requirements, we design and fabricate activated carbon-coated carbon na- notubes （AC@CNT） with hierarchical structures containing micro- and meso-pores. A new structure of phosphorus/car- bon composite （P@AC@CNT） is prepared by confining red P in porous carbon through a vaporization-condensation-con- version method. The micro-pores are filled with P, while the meso-pores remain unoccupied, and the pore openings on the particle surface are sealed by P. Due to the unique structure of P@AC@CNT, it displays a high specific capacity of 1674 mA h g-i at 0.2 C, ultrahigh ICE of 92.2%, excellent rate per- formance of 1116 mA h g-i at 6 C, and significantly enhanced cycle stability for LIBs. The application of P@AC@CNT in NIBs is further explored. This method for the fabrication of the special composites with improved electrochemical per- formance can be extended to other energy storage applica- tions.

A metal-free composite photocatalyst of graphene quantum dots deposited on red phosphorus

A simple approach to enhance the photocatalytic activity of red phosphorus（P） was developed.A mechanical ball milling method was applied to reduce the size of red P and to deposit graphene quantum dots onto red P. The product was characterized by scanning electron microscopy, transmission electron microscopy, contact angle measurements, zeta-potential measurements, X-ray diffraction and UV–vis absorption spectroscopy. The product exhibited high visible-light-driven photocatalytic performance in the photodegradation of rhodamine B.

Ternary red phosphorus/CoP2/SiO2 microsphere boosts visible-light-driven photocatalytic hydrogen evolution from pure water splitting

Red phosphorus(RP) is a promising visible-light-driven semiconductor for photocatalytic hydrogen evolution,but the activity is restricted due to the rapid charge carrier recombination and sluggish surface reaction kinetics.Herein,cobalt phosphide(CoP_(2)) modified RP heterostructure was developed by in situ phosphorization of cobalt oxide from phosphorus vapor.By tuning the amounts of CoP_(2) in the heterostructure,the optimized hybrid exhibited a HER rate reaching 11.79 μmol h^(-1) under visible light illumination,which is 3.5 times higher than that of the RP with Pt as cocatalyst.It was experimentally indicated that the intimate interaction between CoP_(2) and RP gave rise to improved visible light absorption and accelerated photogenerated electron-holes separation.Moreover,the CoP_(2) as a noble-metal-free cocatalyst could promote the surface hydrogen evolution reaction,which synergetic benefited the photocatalytic hydrogen production activity.

Promoting the protonation step on the interface of titanium dioxide for selective photocatalytic reduction of CO_(2)to CH_(4)by using red phosphorus quantum dots

Enhancing the selectivity of hydrocarbon in CO_(2)is a great challenge.Herein,taking widely-used and highly-stable TiO_(2)as an example,we found that the protonation step,the key step for CH_(4)production,can change from endoergic to exoergic by using red phosphorus quantum dots.Consequently,the main product in CO_(2)reduction can be shifted from CO into CH_(4).The preparation method is very simple,which just ultrasonically treating the red P in the presence of TiO_(2).With an initial rate of CH_(4)production of 4.69μmol·g^(-1)·h^(-1),under simulated solar light,it manifests a significant 49.4-fold enhancement of CH_(4)yield over TiO_(2).Density functional calculation indicates that the red P optimizes the surface electronic structure.The Gibbs free energy for CHO^(*)formation(^(-1).12 eV)becomes lower than the desorption energy of the CO(-0.01 eV)when red P is introduced.This indicates that the CO intermediates on the surface are rapidly protonated to produce CHO^(*).Subsequently,the CHO^(*)will be converted into CH_(4)instead of being desorbed from the surface to produce CO.This study demonstrates that red P quantum dot is a promising candidate for the development of efficient photocatalyst for CO_(2)photoreduction to CH_(4)under solar light irradiation.

High-yield red phosphorus sponge mediated robust lithium-sulfur battery

Although lithium-sulfur(Li-S)batteries with high specific energy exhibit great potential for next-generation energy-storage systems,their practical applications are limited by the growth of Li dendrites and lithium polysulfides(LiPSs)shuttling.Herein,a highly porous red phosphorus sponge(HPPS)with well distributed pore structure was efficiently prepared via a facile and largescale hydrothermal process for polysulfides adsorption and dendrite suppression.As experimental demonstrated,the porous red phosphorus modified separator with increased active site greatly promotes the chemisorption of LiPSs to efficiently immobilize the active sulfur within the cathode section,while Li metal anode activated by Li_(3)P interlayer with abundant ionically conductive channels significantly eliminates the barrier for uniform Li^(+)permeation across the interlayer,contributing to the enhanced stability for both S cathode and Li anode.Mediated by the HPPS,long-term stability of 1,200 h with minor voltage hysteresis is achieved in symmetric cells with Li_(3)P@Li electrode while Li-S half-cell based on HPPS modified separator delivers an outperformed reversibility of 783.0 mAh·g^(−1)after 300 cycles as well as high-rate performance of 694.5 mAh·g^(−1)at 3 C,which further boosts the HPPS tuned full cells in practical S loading(3 mg·cm^(−2))and thin Li3P@Li electrode(100μm)with a capacity retention of 71.8%after 200 cycles at 0.5 C.This work provides a cost-effective and metal free mediator for simultaneously alleviating the fundamental issues of both S cathode and Li anode towards high energy density and long cycle life Li-S full batteries.

Deciphering the potassium storage phase conversion mechanism of phosphorus by combined solid-state NMR spectroscopy and density functional theory calculations

Phosphorus is the potential anode material for emerging potassium-ion batteries(PIBs)owing to the highest specific capacity and relatively low operation plateau.However,the reversible delivered capacities of phosphorus-based anodes,in reality,are far from the theoretical capacity corresponding to the formation of K3P alloy.And,their underlying potassium storage mechanisms remain poorly understood.To address this issue,for the first time,we perform high-resolution solid-state31P NMR combined with XRD measurements,and density functional theory calculations to yield a systemic quantitative understanding of(de)potassiation reaction mechanism of phosphorus anode.We explicitly reveal a previously unknown asymmetrical nanocrystalline-to-amorphous transition process via rP←→(K_(3)P_(11),K_(3)P_(7),beta-K_(4)P_(6))←→(alpha-K4P6)←→(K_(1-x)P,KP,K_(4-x)P3,K_(1+x)P)←→(amorphous K4P3,amorphous K3P)that are proceed along with the electrochemical potassiation/depotassiation processes.Additionally,the corresponding KP alloys intermediates,such as the amorphous phases of K_(4)P_(3),K_(3)P,and the nonstoichiometric phases of“K_(1-x)P”,“K_(1+x)P”,“K_(4-x)P_(3)”are experimentally detected,which indicating various complicated K-P alloy species are coexisted and evolved with the sluggish electrochemical reaction kinetics,resulting in lower capacity of phosphorus-based anodes.Our findings offer some insights into the specific multi-phase evolution mechanism of alloying anodes that may be generally involved in conversion-type electrode materials for PIBs.

B, N-Co-doped Carbon Tubes with P Encapsulated in 3D Graphene Aerogel for High-stable Lithium-ion Batteries

Li-related anodes with stable ability and excellent rate performance are urgently being pursued to overcome the slow kinetic of current lithium ion storage devices.In this work,an annealing-hydrothermal method is developed to fabricate the anode of a three-dimension nano-construction with robust charge transfer networks,which is composed of elements B,N co-doped carbon tube(BN-CT)as the carrier of red phosphorous to(3D BN-CT@P).Then,3D BN-CT@P is embedded in the graphene aerogel network to obtain (3D BN-CT@P@GA).Impressively,the 3D BN-CT@P@GA shows high capacity and good cycle stability in the potential rage of 0.01-2.5V.Especially,the discharge capacity is~800 mAh g^(-1) at 500 mA g^(-1) after 500 cycles when evaluated as anode materials for lithium-ion batteries(LIBs).The improved electrochemical performances result from the unique structure of the 3D BN-CT@P@GA.With the hetero atoms doping,the active P can load up to the BN-CT,which can realize the high capacity as well as the low potential for the anode.At the same time,the graphene aerogel network provides the protection for the BN-CT@P species and good conductivity to enhance ion diffusion.This work fundamentally presents an effective structural engineering way for improving the performance of P-based anodes for advanced LIBs.