Heteroatom tuning in agarose derived carbon aerogel for enhanced potassium ion multiple energy storage

The incorporation of heteroatoms into carbon aerogels(CAs)can lead to structural distortions and changes in active sites due to their smaller size and electronegativity compared to pure carbon.However,the evolution of the electronic structure from single-atom doping to heteroatom codoping in CAs has not yet been thoroughly investigated,and the impact of codoping on potassium ion(K+)storage and diffusion pathways as electrode material remains unclear.In this study,experimental and theoretical simulations were conducted to demonstrate that heteroatom codoping,composed of multiple heteroatoms(O/N/B)with different properties,has the potential to improve the electrical properties and stability of CAs compared to single-atom doping.Electronic states near the Fermi level have revealed that doping with O/N/B generates a greater number of active centers on adjacent carbon atoms than doping with O and O/N atoms.As a result of synergy with enhanced wetting ability(contact angle of 9.26°)derived from amino groups and hierarchical porous structure,ON-CA has the most optimized adsorption capacity(−1.62 eV)and diffusion barrier(0.12 eV)of K^(+).The optimal pathway of K^(+)in ON-CA is along the carbon ring with N or O doping.As K^(+)storage material for supercapacitors and ion batteries,it shows an outstanding specific capacity and capacitance,electrochemical stability,and rate performance.Especially,the assembled symmetrical K^(+)supercapacitor demonstrates an energy density of 51.8 Wh kg^(−1),an ultrahigh power density of 443Wkg^(−1),and outstanding cycling stability(maintaining 83.3%after 10,000 cycles in 1M KPF6 organic electrolyte).This research provides valuable insights into the design of highperformance potassium ion storage materials.

NiFe-based nanostructures on nickel foam as highly efficiently electrocatalysts for oxygen and hydrogen evolution reactions

Water splitting,as an advanced energy conversion technology,consists of two half reactions,including oxygen evolution reaction(OER)and hydrogen evolution reaction(HER).However,the ideal electrocatalysts are noble metal based catalysts.Their high cost and scarcity in earth seriously restrict the large deployments.Ni Fe-based materials have attracted great attention in recent years due to their excellent catalytic properties for OER and HER.Nevertheless,their conductivity and electrochemical stability at high current density are unsatisfactory,resulting in ineffective water splitting due to high impedance and low stability.Recently,a series of catalysts coating Ni Fe-based materials on 3 D nickel foam were found to be extremely stable under the circumstance of high current density.In this review,we summarized the recent advances of NiFe-based materials on nickel foam for OER and HER,respectively,and further provided the perspectives for their future development.

Research progress of nanocellulose for electrochemical energy storage:A review

Recently, in response to the major challenges in energy development and environmental issues, tremendous efforts are being devoted to developing electrochemical energy storage devices based on green sustainable resources. As a class of green materials, nanocellulose(NC) has received extensive attention. In this review, we summarize the research progress of NC derived materials in electrochemical energy storage. Specifically, we first introduce various synthesis methods based on NC and the pretreatment process to increase the conductivity. Then we focus on the specific application of NC in electrochemical energy storage devices. Finally, we summarize the previously reported work and put forward views on the further development of NC in the field of electrochemical energy storage.

Ultrafine polycrystalline titania nanofibers for superior sodium storage

Sodium ion batteries have a huge potential for large-scale energy storage for the low cost and abundance of sodium resources. In this work, a novel structure of ultrafine polycrystalline TiO2 nanofibers is prepared on nickel foam/carbon cloth by a simple vapor deposition method. The as-prepared TiO2 nanofibers show excellent performance when used as anodes for sodium-ion batteries. Specifically, the TiO2 nanofibers@nickel foam electrode delivers a high reversible capacity of 263.2 m Ahg^-1 at 0.2 C and maintains a considerable capacity of 144.2 m Ahg^-1 at 10 C. The TiO2 nanofibers@carbon cloth electrode also shows excellent high-rate capability, sustaining a capacity of 148 m Ahg^-1 after 20 0 0 cycles at 10 C. It is believed that the novel nanofibrous structure increases the contact area with the electrolyte and greatly shortens the sodium ion diffusion distance, and meanwhile, the polycrystalline nature of nanofibers exposes more intercalation sites for sodium storage. Furthermore, the density functional theory calculations exhibit strong ionic interactions between the exposed TiO2(101) facets and sodium ions, leading to a preferable sodiation/desodiation process. The unique structural features endow the TiO2 nanofibers electrodes great advantages in rapid sodium storage with an outstanding high-rate capability.

Boosting electrocatalytic hydrogen generation by a renewable porous wood membrane decorated with Fe-doped NiP alloys

Porous biomass electrodes have emerged as a critical material for electrocatalytic hydrogen evolution reaction(HER).However,most approaches for synthesizing porous electrodes from biomass require high energy consumption,which is resulted from the smash of biomass and the undergoing of serial assembly.Herein,a self-supported wood-derived"breathable"membrane is utilized directly as electrodes for highefficient HER via an assembly of Fe-doped NiP alloys.The well-designed hierarchical porous structures in natural wood membrane(NWM)are unusually beneficial for electrolytes accessibility and hydrogen gas removal.The obtained wood-derived membrane exhibits a high electrocatalytic activity and good cycling durability in acidic and alkaline electrolytes.Remarkably,the Fe_(0.074) NiP alloys/NWM electrode affords a large current density of 100 m A cm^(-2) at extremely low overpotentials of 168 mV in acidic electrolyte and174 m V in alkaline electrolyte.Density functional theory calculations unveil that the Fe atom doped in NiP alloys can create much more charge accumulation around Fe and Ni active sites,which helps decrease the △GH_(*)and △G_(H2O)and significantly promote the HER process.This new insight will promote further explorations of economic,high-efficient,and biodegradable wood-derived electrocatalysts for HER.

CoFe_2O_4/carbon nanotube aerogels as high performance anodes for lithium ion batteries

High-performance lithium ion batteries(LIBs) require electrode material to have an ideal electrode construction which provides fast ion transport, short solid-state ion diffusion, large surface area, and high electric conductivity. Herein, highly porous three-dimensional(3D)aerogels composed of cobalt ferrite(CoFe_2O_4, CFO) nanoparticles(NPs) and carbon nanotubes(CNTs) are prepared using sustainable alginate as the precursor. The key feature of this work is that by using the characteristic egg-box structure of the alginate, metal cations such as Co^(2+)and Fe^(3+) can be easily chelated via an ion-exchange process, thus binary CFO are expected to be prepared. In the hybrid aerogels, CFO NPs interconnected by the CNTs are embedded in carbon aerogel matrix, forming the 3D network which can provide high surface area, buffer the volume expansion and offer efficient ion and electron transport pathways for achieving high performance LIBs. The as-prepared hybrid aerogels with the optimum CNT content(20 wt%) delivers excellent electrochemical properties, i.e., reversible capacity of 1033 mAh g^(-1) at 0.1 A g^(-1) and a high specific capacity of 874 mAh g^(-1) after 160 cycles at 1 A g^(-1). This work provides a facile and low cost route to fabricate high performance anodes for LIBs.

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.

Selective CO_(2)-to-formic acid electrochemical conversion by modulating electronic environment of copper phthalocyanine with defective graphene

In the carbon dioxide reduction reaction(CO_(2)RR),the activity of transition metal center depends largely on its electronic structure,since the electronic rich region enhances the adsorption of intermediates at active sites,thus improving the selectivity to reduction products.In this work,we prepared CuPc/DG composite(CuPc:copper phthalocyanine;DG:defective graphene)to achieve selective CO_(2)-to-formic acid(HCOOH)electrochemical conversion through modulating the electronic structure of Cu active centers with DG via π-π stacking.Evaluated as the electrocatalyst,the CuPc/DG composite displays a high faradaic efficiency(FE)of 44.6%−0.78 V vs.RHE for CO_(2)RR to HCOOH.Partial current density is 5.28 mA cm^(−2) for HCOOH together with an exceptional stability throughout at least 20 h of reaction.On the basis of density functional theory(DFT)calculation results,defects in DG can effectively promote the charge redistribution of dispersed CuPc,where electrons transfer to CuPc from defects,forming rich electronic environment around Cu sites.The abundance of electrons makes the d-band center of Cu approach to the Fermi level and decrease the energy barrier of CuPc/DG composite for the intermediate of ∗OCHO,thus accelerating the reduction of CO_(2) to HCOOH.

Enhanced photodynamic therapy of mixed phase TiO2（B）/anatase nanofibers for killing of HeLa cells

光力学的治疗(太平洋夏季时间) 是使用使药具有感光性有选择地使用治疗指向地点的一个过程，被证明了是为可以发展成癌症的癌症和条件的安全治疗。缩放 Nano 的 TiO < 潜水艇 class= “ a-plus-plus ” > 2 为紫外轻驾驶太平洋夏季时间被认为是潜在的 photosensitizer。在这研究， TiO 的四种类型<潜水艇class=“ a-plus-plus ”> 2 nanofibers 从质子 tri-titanate 被准备( H <潜水艇class=“ a-plus-plus ”> 2 T <潜水艇class=“ a-plus-plus ”> 3 O <潜水艇class=“ a-plus-plus ”> 7 ) nanofiber 。同样获得的 nanofibers 为太平洋夏季时间杀死 HeLa 房间作为有效 photosensitizers 被表明。MTT 试金和流动 cytometry (FCM ) 被执行评估 biocompatibility， apoptotic 房间的百分比，和房间生存能力。同样准备的 TiO 的 non-cytotoxicity < 潜水艇 class= “ a-plus-plus ” > 当紫外照耀不在时的 2 nanofibers 也被表明了。在紫外轻照耀下面， TiO < 潜水艇 class= “ a-plus-plus ” > 2 nanofibers，特别地混合阶段 nanofibers，比 Pirarubicin (THP ) 显示了高得多的杀死房间的效率，它是普通的药导致 HeLa 房间的 apoptosis。我们归功于混合阶段 nanofibers 的高 cellkilling 效率到在 TiO 之间的 bandgap 边比赛和稳定的接口 < 候补选手 class= “ a-plus-plus ” > 2 (B) 和锐钛矿在单个 nanofiber 分阶段执行，它能禁止 photogenerated 电子和洞的再结合。这支持费用分离和转移过程和罐头生产负责杀死 HeLa 房间的更多的反应的氧种类(ROS ) 。

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.

How heteroatoms(Ge,N,P) improve the electrocatalytic performance of graphene:theory and experiment

The oxygen reduction reactions(ORR)play a crucial role in the electrochemical energy storage devices,such as fuel cell,metal-air batteries[1–3].However,their larger scale applications are hindered by the sluggish slow kinetics of the ORR.Up to now,platinum(Pt)-based catalysts are still known as the best

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.

Biochar aerogel-based electrocatalyst towards efficient oxygen evolution in acidic media

The controllable synthesis of oxygen evolution reaction(OER)electrocatalyst is an urgent need to advance the develop-ment of sustainable energy conversion and storage.However,the OER efficiency in acidic media is seriously hindered by slow reaction kinetics.The traditional acidic OER electrocatalysts are more prone to be oxidized and corroded as results of unstable carrier structures and variable electronic states of active species.Herein,a high-performing biochar aerogel(BA)based electrocatalyst were realistically designed and synthetized via joint utilization of the terrestrial lignin and seaweed polysaccharide as carbon sources.Originating from the induction effect of"egg-box"structure in alginate and the self-template effect of lignosulfonate,the BA decorated with Ru/RuS_(2)particles was synthesized triumphantly.The as-synthesized electrocatalyst required a low overpotential of 228 mV to attain 10 mA cm^(−2)in 0.5 M H_(2)SO_(4)and exhibited a good stability for over 12,000 s.The good activity was strongly dependent on the assembled unique two-dimensional/three-dimensional(2D/3D)channels in carbon aerogels.Notably,the numerous defective sites at carbon could strongly interact with the Ru/RuS_(2)heterojunction for remarkably enhancing the catalytic activity and stability of whole catalytic system in acidic media.This work puts forward a novel and effective strategy towards the enhancement of the acidic OER process by rational regu-lations of the BA and the coupling effect in micro-interface.

Hierarchically Porous and Defective Carbon Fiber Cathode for Efficient Zn‑Air Batteries and Microbial Fuel Cells

Developing low-cost,efficient oxygen reduction reaction(ORR)catalysts to replace Pt-based materials is urgently required for the application of Zn-air batteries(ZABs)and microbial fuel cells(MFCs).In this work,meso-microporous carbon fibers with tunable defect density were synthesized by carrageenan fibers.A highly defective carbon fiber(HDCFs)was produced which exhibited an outstanding ORR catalytic activity,reaching to the half-wave potential of 0.841 and 0.44 V in alkaline and neutral electrolytes,respectively.These HDCFs can also act as highly efficient air cathodes for ZABs(delivered potential of 0.69 V and power density of 220 mW cm^(–2) at 300 mA cm^(–2))and MFCs(high power density of 69.7 mW cm^(–2)).Simulation by the density functional theory indicated that a high density of defections in a carbon based framework can remarkably modulate the electrical properties.For instance the charge entrapments in the carbon active sites may reduce the energy barrier of ORR.

Environmental life cycle assessment of supercapacitor electrode production using algae derived biochar aerogel

Porous carbon aerogel material has gained an increasing attraction for developing supercapacitor electrodes due to its cost-effective synthesis process and relatively high electrochemical performance.However,the environmental performances of supercapacitor electrodes produced from different carbon aerogel materials are never comparatively studied,hindering our knowledge of supercapacitor electrode production in a sustainable pattern.In this study,nitrogen-doped biochar aerogel-based electrode(BA-electrode)produced from Entermorpha prolifera was simulated to investigate the environmental performance by using life cycle assessment method.For comparison,the assessment of graphene oxide aerogel-based electrode(GOA-electrode)was also carried out.It can be observed that the life cycle global warming potential for the BA-electrode was lower than that of GOA-electrode with a reduction of 53.1‒68.1%.In comparison with GOA-electrode,the BA-electrodes endowed smaller impacts on environment in majority of impact categories.Moreover,in comparison with GOA-electrode,the environmental damages of BA-electrode were greatly decreased by 35.8‒56.4%(human health),44.9‒62.6%(ecosystems),and 87.0‒91.2%(resources),respectively.The production stages of GOA and graphene oxide and stages of nitrogen-doped biochar aerogel production and Entermorpha prolifera drying were identified as the hotspots of environmental impact/dam-age for the GOA-electrode and BA-electrode,respectively.Overall,this finding highlights the efficient utilization of algae feedstock to construct a green and sustainable technical route of supercapacitor electrode production.