Research progress in rare earths and their composites based electrode materials for supercapacitors

Supercapacitor is an imminent potential energy storage system,and acts as a booster to the batteries and fuel cells to provide necessary power density.In the last decade,carbon and carbonaceous materials,conducting polymers and transition metal oxide/hydroxide based electrode materials have been made to show a remarkable electrochemical performance.Rare-earth materials have attracted significant research attention as an electrode material for supercapacitor applications based on their physicochemical properties.In this review,rare earth metals,rare earth metal oxides/hydroxides,rare-earth metal chalcogenides,rare-earth metal/carbon composites and rare-earth metal/metal oxide composites based electrode materials are discussed for supercapacitors.We also discuss the energy chemistry of rare-earth metal-based materials.Besides the factors that affect the performance of the electrode materials,their evaluation methods and supercapacitor performances are discussed in details.Finally,the future outlook in rare-earth-based electrode materials is revealed towards its current developments for supercapacitor applications.

Ni Flower/MXene-Melamine Foam Derived 3D Magnetic/Conductive Networks for Ultra-Efficient Microwave Absorption and Infrared Stealth

The development of multifunctional and efficient electromagnetic wave absorbing materials is a challenging research hotspot.Here,the magnetized Ni flower/MXene hybrids are successfully assembled on the surface of melamine foam(MF)through electrostatic self-assembly and dip-coating adsorption process,realizing the integration of microwave absorption,infrared stealth,and flame retardant.Remarkably,the Ni/MXene-MF achieves a minimum reflection loss(RLmin)of−62.7 dB with a corresponding effective absorption bandwidth(EAB)of 6.24 GHz at 2 mm and an EAB of 6.88 GHz at 1.8 mm.Strong electromagnetic wave absorption is attributed to the three-dimensional magnetic/conductive networks,which provided excellent impedance matching,dielectric loss,magnetic loss,interface polarization,and multiple attenuations.In addition,the Ni/MXene-MF endows low density,excellent heat insulation,infrared stealth,and flame-retardant functions.This work provided a new development strategy for the design of multifunctional and efficient electromagnetic wave absorbing materials.

Interface Engineered Microcellular Magnetic Conductive Polyurethane Nanocomposite Foams for Electromagnetic Interference Shielding

Lightweight microcellular polyurethane(TPU)/carbon nanotubes(CNTs)/nickel-coated CNTs(Ni@CNTs)/polymerizable ionic liquid copolymer(PIL)composite foams are prepared by non-solvent induced phase separation(NIPS).CNTs and Ni@CNTs modified by PIL provide more heterogeneous nucleation sites and inhibit the aggregation and combination of microcellular structure.Compared with TPU/CNTs,the TPU/CNTs/PIL and TPU/CNTs/Ni@CNTs/PIL composite foams with smaller microcellular structures have a high electromagnetic interference shielding effectiveness(EMI SE).The evaporate time regulates the microcellular structure,improves the conductive network of composite foams and reduces the microcellular size,which strengthens the multiple reflections of electromagnetic wave.The TPU/10CNTs/10Ni@CNTs/PIL foam exhibits slightly higher SE values(69.9 dB)compared with TPU/20CNTs/PIL foam(53.3 dB).The highest specific EMI SE of TPU/20CNTs/PIL and TPU/10CNTs/10Ni@CNTs/PIL reaches up to 187.2 and 211.5 dB/(g cm^(−3)),respectively.The polarization losses caused by interfacial polarization between TPU substrates and conductive fillers,conduction loss caused by conductive network of fillers and magnetic loss caused by Ni@CNT synergistically attenuate the microwave energy.

Correction to: Ni Flower/MXene-Melamine Foam Derived 3D Magnetic/Conductive Networks for Ultra-Efficient Microwave Absorption and Infrared Stealth

The original version of this article unfortunately contained some mistakes.The corrections are updated as follows:Error 1:We found that Equations 3,4 and 6 were wrong in the published paper:Error 2:In the page 7,“Since N Ni/MXene-MF possessed numer-ous heterogeneous interfaces and abundant functional groups,the dielectric loss mechanism was explored.”

Effect of K_(2)CO_(3) doping on CO_(2) sorption performance of silicate lithium-based sorbent prepared from citric acid treated sediment

In this paper,a low-cost and environmental-friendly leaching agent citric acid(C_(6)H_(8)O_(7))was used to treat the sediment of Dianchi Lake(SDL)to synthesize lithium silicate(Li_(4)SiO_(4))based CO_(2)sorbent.The results were compared with that treated with strong acid.Moreover,the effects of preparation conditions,sorption conditions and desorption conditions on the CO_(2)sorption performance of prepared Li_(4)SiO_(4)were systematically studied.Under optimal conditions,the Li_(4)SiO_(4)sorbent was successfully synthesized and its CO_(2)sorption capacity reached 31.37%(mass),which is much higher than that synthesized from SDL treated with strong acid.It is speculated that the presence of some elements after C_(6)H_(8)O_(7)treatment may promote the sorption of synthetic Li_(4)SiO_(4)to CO_(2).In addition,after doping with K_(2)CO_(3),the CO_(2)uptake increases from the original 12.02%and 22.12%to 23.96%and 32.41%(mass)under the 20%and 50%CO_(2)partial pressure,respectively.More importantly,after doping K_(2)CO_(3),the synthesized Li_(4)SiO_(4)has a high cyclic stability under the low CO_(2)partial pressure.

Self-regulation in chemical and bio-engineering materials for intelligent systems

Herein, the authors review the self-regulation system secured by well-designed hybrid materials, composites, and complex system. As a broad concept, the self-regulated material/system has been defined in a wide research field and proven to be of great interest for use in a biomedical system, mechanical system, physical system, as the fact of something such as an organisation regulating itself without intervention from external perturbation. Here, they focus on the most recent discoveries of self-regulation phenomenon and progress in utilising the self-regulation design. This paper concludes by examining various practical applications of the remarkable materials and systems including manipulation of the oil/water interface, cell out-layer structure, radical activity, electron energy level, and mechanical structure of nanomaterials. From material science to bioengineering, self-regulation proves to be not only viable, but increasingly useful in many applications. As part of intelligent engineering, self-regulatory materials are expected to be more used as integrated intelligent components.

Magnetic NiFe_(2)O_(4)/Polypyrrole nanocomposites with enhanced electromagnetic wave absorption

NiFe_(2)O_(4)/polypyrrole(NiFe_(2)O_(4)/PPy)nanocomposites are prepared by a simple surface-initiated polymerization method and demonstrate negative permittivity in the low frequency regions.These nanocomposites also exhibit significantly enhanced electromagnetic wave(EMW)absorption property in the high frequency regions.Compared with pure PPy,the enhanced negative permittivity is observed in the NiFe_(2)O_(4)/PPy nanocomposites with a NiFe_(2)O_(4)loading of 5.0,10.0,20.0 and 40.0 wt%,indicating the formation of metal-like electrical conducting network in NiFe_(2)O_(4)/PPy nanocomposites.Moreover,the negative permittivity could be tuned by changing the NiFe_(2)O_(4)loading.The minimum reflection loss(RL)of-40.8 dB is observed in the 40.0 wt%NiFe_(2)O_(4)/PPy composites with a thickness of only 1.9 mm.The effective absorption bandwidth below-10.0 and-20.0 dB reaches 6.08 and 2.08 GHz,respectively.The enhanced EMW absorption performance benefits from the improved independence matching,EMW attenuation capacity,and synergistic effects of conduction loss,dielectric loss(interfacial and dipole polarizations)and magnetic loss(exchange and natural resonances).This research work provides a guidance for the fabrication of nanocomposites with an excellent EMW absorption.

Morphology controllable urchin-shaped bimetallic nickel-cobalt oxide/carbon composites with enhanced electromagnetic wave absorption performance

The microscopic morphology of electromagnetic wave absorbers influences the multiple reflections of electromagnetic waves and impedance matching,determining the absorption properties.Herein,the urchin-shaped bimetallic nickel-cobalt oxide/carbon(NiCo_(2)O_(4)/C)composites are prepared via a hy-drothermal route,whose absorption properties are investigated by different morphologies regulated by changing calcination temperature.A minimum reflection loss(RL_(min))of-75.26 dB is achieved at a match-ing thickness of 1.5 mm,and the effective absorption bandwidth(EAB)of 8.96 GHz is achieved at 2 mm.Multi-advantages of the synthesized NiCo_(2)O_(4)/C composites contribute to satisfactory absorption proper-ties.First,the interweaving of the needle-like structures increases the opportunities for scattering and multiple reflections of incident electromagnetic waves,and builds up a conductive network to facilitate the enhancement of conductive losses.Second,the carbon component in the NiCo_(2)O_(4)/C composites en-hances the interfacial polarization and reduces the density of the absorber.Besides,generous oxygen va-cancy defects are introduced into the NiCo_(2)O_(4)/C composites,which induces defect polarization and dipole polarization.In summary,the ternary coordination of components,defects and morphology led to out-standing electromagnetic wave absorption,which lightened the path for improving the electromagnetic wave absorption property and enriching the family of NiCo_(2)O_(4) absorbers with excellent performance.

Simple fabrication of superhydrophobic PLA with honeycomb-like structures for high-efficiency oil-water separation

Polylactic acid(PLA) is one of the most suitable candidates for environmental pollution treatment because of its biodegradability which will not cause secondary pollution to the environment after application.However,there is still a lack of a green and facile way to prepare PLA oil-water separation materials.In this work,a water-assisted thermally induced phase separation method for the preparation of superhydrophobic PLA oil-water separation material with honeycomb-like structures is reported.The PLA material shows great ability in application and could adsorb 27.3 times oil to its own weight.In addition,it could also be applicated as a filter with excellent efficiency(50.9 m^3 m^(-2) h^(-1)).

Superhydrophobic conductive rubber band with synergistic dual conductive layer for wide-range sensitive strain sensor

Wearable electronic devices have received increasing interests because of their excellent flexibility,stretchability,and human friendliness.As the core components,flexible strain sensors integrated with wide working range,high sensitivity,and environment stability,especially in moisture or corrosive environments,remain a huge challenge.Herein,synergistic carbon nanotubes(CNTs)/reduced graphene oxide(rGO)dual conductive layer decorated elastic rubber band(RB)was successfully developed and treated with hydrophobic fumed silica(Hf-SiO_(2))for preparing superhydrophobic strain sensor.As expected,stable entangled CNTs layer and ultrasensitive microcracked rGO layer endow the sensor with extremely low detection limit(0.1%),high sensitivity(gauge factor is 685.3 at 482%strain),wide workable strain range(0–482%),fast response/recovery(200 ms/200 ms)and favorable reliability and reproducibility over 1000 cycles.Besides,the constructed Hf-SiO_(2) coating also makes the sensor exhibit excellent superhydrophobicity,self-cleaning property,and corrosion-resistance.As a proof of concept,our prepared high-performance strain sensor can realize the full-range monitoring of human motions and physiological signals even in the water environment,including pulse,vocalization,joint bending,running,and gesture recognition.Interestingly,it can also be knitted into a tactile electronic textile for spatial pressure distribution measurement.Thus,this study provides a universal technique for the preparation of high-performance strain sensors with great potential applications in the field of next-generation intelligent wearable electronics.

Highly transmitted silver nanowires-SWCNTs conductive flexible film by nested density structure and aluminum-doped zinc oxide capping layer for flexible amorphous silicon solar cells

Indium tin oxide(ITO)is widely used in transparent conductive films(TCFs);however,several disadvan-tages,such as high cost and toxicity of indium,limit its applications.Therefore,it is necessary to develop other materials that can replace ITO.Silver nanowires or single walled carbon nanotubes(SWCNTs)have attracted considerable interest owing to their unique electrical,optical,and thermal stabilities,and thus,they are ideal for transparent electrodes for flexible or stretchable devices.In this study,we develop a novel architecture of composite TCFs on a polyethylene naphthalate(PEN)flexible substrate.Herein,the silver nanowires-SWCNTs films with nested density structure were fabricated through ultrasonic spraying technology by varying the spraying width.For achieving enhanced transmittance,we combined the larger irregular grids and holes with fewer nanowires stacked in the longitudinal direction,more optical chan-nels,and good carrier transport.Thereafter,aluminum-doped zinc oxide(AZO)was used as capping to the structure for enhancing the optical properties of the TCFs.The silver nanowires-SWCNTs/AZO(ASA)bilayer was obtained in the optimized architecture,which showed superior optoelectronic performance to that shown by commercial ITO with a high optical transmittance of 92%at the wavelength of 550 nm and low sheet resistance of 17/sq.In the specially structured conductive film,the significant improvement in the transmittance and uniformity of the sheet resistance was attributed to the effective nanowire junc-tion contact compared to that in ordinary structure of silver nanowires,which reduced the mean density of small clusters of nanowires.Compared with the silver nanowires-SWCNTs films,the ASA bilayer film exhibited excellent resistance to boiling,mechanical bending(10,000 cycles),and CO_(2)plasma.Moreover,the sheet resistance of ASA changed slightly after the tape tests,thereby illustrating a strong adhesion to the PEN substrate after the enclosure of AZO.Meanwhile,the AZO capping layer can enhance the op-tical transmittance between 600 and 1500 nm.In addition,the amorphous silicon photovoltaic devices with flexible ASA TCFs exhibited a power conversion efficiency(PCE)of 8.67%.After bending for 3000 times,the PCE was decreased to 8.20%,thereby demonstrating the potential of developed films to replace traditional ITO.

Engineering hierarchical heterostructure material based on metal-organic frameworks and cotton fiber for high-efficient microwave absorber

Rational construction of hierarchical multi-component materials with abundant heterostructure is evolving as a promising strategy to achieve excellent metal-organic frameworks(MOFs)based electromagnetic wave(EMW)absorbers.Herein,hierarchical heterostructure WS_(2)/CoS_(2)@carbonized cotton fiber(CCF)was fabricated using the ZIF-67 MOFs nanosheets anchored cotton fiber(ZIF-67@CF)as a precursor through the tungsten etching,sulfurization,and carbonization process.Apart from the synergetic effect of dielectric-magnetic dual-loss mechanism,the hierarchical heterostructure and multicomponent of WS_(2)/CoS_(2)@CCF also display improved impedance matching.Furthermore,numerous W-S-Co bands and heterojunction interfaces of heterogeneous WS_(2)/CoS_(2)are beneficial to promoting additional interfacial/dipole polarization loss and conductive loss,thereby enhancing the EMW attenuation performance.Based on the percolation theory,a good balance between impedance matching and EMW absorption capacity was achieved for the WS_(2)/CoS_(2)@CCF/paraffin composite with 20 wt.%filler loading,exhibiting strong EMW absorption capability with a minimum reflection loss(RLmin)value of−51.26 dB at 17.36 GHz with 2 mm thickness and a maximum effective absorption bandwidth(EABmax)as wide as 6.72 GHz.Our research will provide new guidance for designing high-efficient MOFs derived EMW absorbers.

Fabric-based all-weather-available photo-electro-thermal steam generator with high evaporation rate and salt resistance

Solar-driven steam generation is a practical strategy to harness solar energy for desalination and production of clean water with a minimized carbon footprint.However,this strategy suffers from a low evaporation rate under weak illumination on cloudy days or at night.Herein,we present a fabric-based all-weather-available photo-electrothermal steam generator(P/ET-SG)capable of regulating the surface temperature and evaporation rate by the coupling effect of photo-thermal and electro-thermal heating depending on the light conditions.An unprecedented high surface temperature of 52℃ in the wet state and an evaporation rate of 2.61 kg m^(-2) h^(-1) were achieved by the P/ET-SG under 1 sun with only 1 V input voltage owing to the uniform heat distribution and the coupled electro-thermal source.The oneway fluidic design of the P/ET-SG effectively prevented salt precipitation during continuous desalination in 24 h and was able to remove salt granules from the evaporation surface.Furthermore,the P/ET-SG demonstrated a high evaporation rate of 2.58 kg m^(-2) h^(-1) in the purification of concentrated saline water and dye-contaminated water with high efficiency(>99.9%).This study offers new thoughts for the design of allweather-available solar steam generators with high efficiency and makes a step forward towards fast purification of concentrated saline water and wastewater.

“Several birds with one stone”strategy of pH/thermoresponsive flame-retardant/photothermal bactericidal oil-absorbing material for recovering complex spilled oil

Although many material designs or strategic methods have been proposed for treating oil spills and oily wastewater,the complex oily state,dealing with the harsh operating conditions of oil–water separation(such as the recovery of viscous spilled crude oil,bacteria-containing oily wastewater,and removal of spilled oil under fire),and the autorecycling of oil and absorption materials remain a great challenge.This work proposed an ingenious design strategy of“several birds with one stone”to prepare p H/thermoresponsive flame-retardant/photothermal bactericidal P-Fe_(3)O_(4)-polydopamine(PDA)@melamine–formaldehyde(MF)foams.This design makes the foams remarkably effective in the recovery of spilled viscous crude oil as well as in the separation of bacteria-containing oily emulsions,particularly for instant fire extinguishing by magnetically controlled oil absorption as well as for fire alarms.The photothermal effect and p H response induce a change in the surface wettability of the foams,facilitating excellent autoadsorption/desorption of the spilled oil.The photothermal bactericidal activity and fouling resistance of the foam are beneficial to the separation of bacteria-containing oily wastewater.Outstanding flame-retardant properties and maneuverable magnetic control enable the foam to rapidly recover the spilled oil in a large range of fires,extinguish fires instantly,and facilitate early fire warning.The proposed strategy is expected to inspire further research on treating oil spills under complex conditions.

Preparation of Mg,N-co-doped lignin adsorbents for enhanced selectivity and high adsorption capacity of As(Ⅴ) from wastewater

Among various environmental problems,water pollution has drawn more and more attention.To develop an adsorbent with enhanced selectivity and high capacity for As(V)oxyanion,a novel lignin-based adsorbent was prepared by doping with N and modifying with Mg^(2+),using thiethylenetetramine(TETA)and MgCl_(2) as the source of N and Mg^(2+),respectively.N-doped lignin(NL)shows a high selectivity for As(Ⅴ),which is further enhanced by modifying with Mg^(2+)(MNL).MNL shows an excellent reusability.The adsorption isotherms and kinetics of MNL for As(Ⅴ)follow Langmuir isotherms model and pseudo-second-order kinetics model,respectively.The adsorption of MNL for As(Ⅴ)achieved a maximum adsorption capacity of 687.46 mg g^(−1) and the equilibrium was established within 30 min.This study offers a novel idea on the recycle of the waste of paper industry and provides a new technology for As(Ⅴ)adsorption from wastewater.

Highly efficient removal of trace lead(Ⅱ)from wastewater by 1,4-dicarboxybenzene modified Fe/Co metal organic nanosheets

A novel Fe/Co metal organic complex nanosheet modified by 1,4-dicarboxybenzene(BDC),i.e.,FeCo@BDC,was prepared,and highly efficient removal performance for trace lead(Ⅱ)(Pb^(2+))was demonstrated in the neutral aqueous solutions.The removal rates were higher than 95%and the adsorption was equilibrated in 15 min.The isotherms and kinetics for the adsorption Pb^(2+)by the FeCo@BDC adsorbents followed Langmuir model and pseudo-second-order model,respectively.The maximum adsorption capacity was 220.48 mg g^(-1).The FeCo@BDC adsorbents also own a prominent regeneration performance.The prominent performance of in the removal of trace Pb^(2+)makes FeCo@BDC an ideal candidate as commercial adsorbent materials.

Influence of mass ratio and calcination temperature on physical and photoelectrochemical properties of ZnFe-layered double oxide/cobalt oxide heterojunction semiconductor for dye degradation applications

A visible light-active photoelectrocatalyst,ZnFe-layered double oxide(LDO)/cobalt(II,III)oxide(Co_(3)O_(4))composites were obtained by calcining the Co loaded ZnFe-layered double hydroxide(LDH)prepared by a hydrothermal and microwave hydrothermal method.The morphological studies revealed that the ZnFe-LDO/Co_(3)O_(4) composites exhibited a flower-like structure comprising Co_(3)O_(4) nanowires and ZnFe-LDO nanosheets.Further,when the mass ratio of Co(NO_(3))_(2)·6H_(2)O/LDH was 1:1.8 and the calcination temperature was 550℃,the ZnFe-LDO/Co_(3)O_(4) composite exhibited 93.3%degradation efficiency for methylene blue(MB)at the applied voltage of 1.0 V under visible light after 3 h.Furthermore,the Mott-Schottky model experiments showed that the formation of a p-n heterojunction between ZnFe-LDO and Co_(3)O_(4) could effectively inhibit the recombination of electrons and holes in the photoelectrocatalytic process.Meanwhile,free radical scavenging experiments showed that the active radicals of⋅OH played an important role in the degradation of MB.Therefore,the photoelectrocatalytic effect of ZnFe-LDO/Co_(3)O_(4) provides a simple and effective strategy for the removal of organic pollutants.

Boosted lithium storage performance by local build-in electric field derived by oxygen vacancies in 3D holey N-doped carbon structure decorated with molybdenum dioxide

Three-dimensional holey nitrogen-doped carbon matrixes decorated with molybdenum dioxide(MoO_(2))nanoparticles have been successfully synthesized via a NaCl-assisted template strategy.The obtained MoO_(2)/C composites offered multi-advantages,including higher specific surface area,more active sites,more ions/electrons transmission channels,and shorter transmission path due to the synergistic effect of the uniformly distributed MoO_(2) nanoparticles and porous carbon structure.Especially,the oxygen vacancies were introduced into the prepared composites and enhanced the Li^(+)intercalation/deintercalation process during electrochemical cycling by the Coulomb force.The existence of the local built-in electric field was proved by experimental data,differential charge density distribution,and density of states calculation.The uniquely designed structure and introduced oxygen vacancy defects endowed the MoO_(2)/C composites with excellent electrochemical properties.In view of the synergistic effect of the uniquely designed morphology and introduced oxygen vacancy defects,the MoO_(2)/C composites exhibited superior electrochemical performance of a high capacity of 918.2 mAh g^(-1) at 0.1 A g^(-1) after 130 cycles,562.1 mAh g^(-1) at 1.0 A g^(-1) after 1000 cycles,and a capacity of 181.25 mAh g^(-1) even at 20.0 A g^(-1).This strategy highlights the path to promote the commercial application of MoO_(2)-based and other transition metal oxide electrodes for energy storage devices.

An active bacterial anti-adhesion strategy based on directional transportation of bacterial droplets driven by triboelectric nanogenerators

An active bacterial anti-adhesion strategy based on directional transportation of bacterial droplets driven by a triboelectric nanogenerator(TENG)has not been reported to date,although passive defense approaches can prevent bacterial adhesion by regulating superwetting surfaces combined with incorporated antibacterial substances.Here a triboelectric nanogenerator driving droplet system(TNDDS)was built to drive directional transportation of bacterial droplets to be eliminated,which comprises TENG with periodical frictional Kapton film and aluminum foils and a superhydrophobic driving platform(SDP)with paralleled driving electrodes.The current generated by the TENG triboelectricity is transmitted to the paralleled driving electrodes to form an electric field driving the directional transportation of charged droplets.The critical value of the driven droplet volume on SDP is closely related to the distributed electrodes’distance and width,and the driving distance of droplets is related to the number of electrodes.More crucially,TNDDS can actively drive the charged droplets of prepared triangular silver nanoprisms(Ag NPs)forward and back to mix with and remove a tiny bacterial droplet on an open SDP or in a tiny semi-enclosed channel.Bacteria could be killed by releasing Ag+and effectively removed by TNDDS by regulating the motion direction.Generally,this approach offers a promising application for removing bacteria from material surfaces driven by TENG and opens a new avenue for bacterial anti-adhesion.

Tellurium intervened Fe-N codoped carbon for improved oxygen reduction reaction and high-performance Zn-air batteries

Pyrolysis-acquired iron and nitrogen codoped carbon(Fe-N-C)has been comprehensively investigated for its promising oxygen reduction reaction(ORR)catalytic performance and structural complexity.The modification of non-metal elements with larger atomic radius and the corresponding intrinsic microstructure-property relations are rarely reported.In this study,tellurium(Te)intervened Fe-N-C was prepared by micelles-induced polymerization with Te nanowires as an in-situ intervening agent.The out-plane bonding of Te with Fe induced the increase of both N content and proportion of pyridinic N on the material surface,thus improving the ORR catalytic performance.The assembled Zn-air battery demonstrated a maximum power density of 250 mW/cm^(2)and excellent rate capability under various discharge current densities,which was much better than the Pt/C.Overall,the current work demonstrates a novel Te/Fe-N-C material and reveals an original Te intervened Fe-N-C strategy and N reconfiguration mechanism,which is of great significance for the design of key materials in energy-related fields.