Emerging catalytic materials for practical lithium-sulfur batteries

High-energy lithium-sulfur batteries(LSBs)have experienced relentless development over the past decade with discernible improvements in electrochemical performance.However,a scrutinization of the cell operation conditions reveals a huge gap between the demands for practical batteries and those in the literature.Low sulfur loading,a high electrolyte/sulfur(E/S)ratio and excess anodes for lab-scale LSBs significantly offset their high-energy merit.To approach practical LSBs,high loading and lean electrolyte parameters are needed,which involve budding challenges of slow charge transfer,polysulfide precipitation and severe shuttle effects.To track these obstacles,the exploration of electrocatalysts to immobilize polysulfides and accelerate Li-S redox kinetics has been widely reported.Herein,this review aims to survey state-of-the-art catalytic materials for practical LSBs with emphasis on elucidating the correlation among catalyst design strategies,material structures and electrochemical performance.We also statistically evaluate the state-of-the-art catalyst-modified LSBs to identify the remaining discrepancy between the current advancements and the real-world requirements.In closing,we put forward our proposal for a catalytic material study to help realize practical LSBs.

Recent Advances on MOF Derivatives for Non-Noble Metal Oxygen Electrocatalysts in Zinc-Air Batteries

Oxygen electrocatalysts are of great importance for the air electrode in zinc-air batteries(ZABs).Owing to the high specific surface area,controllable pore size and unsaturated metal active sites,metal-organic frameworks(MOFs)derivatives have been widely studied as oxygen electrocatalysts in ZABs.To date,many strategies have been developed to generate efficient oxygen electrocatalysts from MOFs for improving the performance of ZABs.In this review,the latest progress of the MOF-derived non-noble metal-oxygen electrocatalysts in ZABs is reviewed.The performance of these MOF-derived catalysts toward oxygen reduction,and oxygen evolution reactions is discussed based on the categories of metal-free carbon materials,single-atom catalysts,metal cluster/carbon composites and metal compound/carbon composites.Moreover,we provide a comprehensive overview on the design strategies of various MOF-derived non-noble metal-oxygen electrocatalysts and their structure-performance relationship.Finally,the challenges and perspectives are provided for further advancing the MOF-derived oxygen electrocatalysts in ZABs.

Concentrated dual-salt electrolytes for improving the cycling stability of lithium metal anodes

Lithium（Li） metal is an ideal anode material for rechargeable Li batteries, due to its high theoretical specific capacity（3860 mAh/g）, low density（0.534 g/cm3）, and low negative electrochemical potential（-3.040 V vs. standard hydrogen electrode）. In this work, the concentrated electrolytes with dual salts, composed of Li[N（SO2F）2]（Li FSI） and Li[N（SO2CF3）2]（Li TFSI） were studied. In this dual-salt system, the capacity retention can even be maintained at 95.7%after 100 cycles in Li｜Li FePO4 cells. A Li｜Li cell can be cycled at 0.5 mA/cm2 for more than 600 h, and a Li｜Cu cell can be cycled at 0.5 m A/cm2 for more than 200 cycles with a high average Coulombi efficiency of 99%. These results show that the concentrated dual-salt electrolytes exhibit superior electrochemical performance and would be a promising candidate for application in rechargeable Li batteries.

Molecular engineering binuclear copper catalysts for selective CO_(2) reduction to C_(2) products

Molecular copper catalysts serve as exemplary models for correlating the structure-reaction-mechanism relationship in the electrochemical CO_(2) reduction(eCO_(2)R),owing to their adaptable environments surrounding the copper metal centres.This investigation,employing density functional theory calculations,focuses on a novel family of binuclear Cu molecular catalysts.The modulation of their coordination configuration through the introduction of organic groups aims to assess their efficacy in converting CO_(2) to C_(2)products.Our findings highlight the crucial role of chemical valence state in shaping the characteristics of binuclear Cu catalysts,consequently influencing the eCO_(2)R behaviour,Notably,the Cu(Ⅱ)Cu(Ⅱ)macrocycle catalyst exhibits enhanced suppression of the hydrogen evolution reaction(HER),facilitating proton trans fer and the eCO_(2)R process.Fu rthermore,we explo re the impact of diverse electro n-withdrawing and electron-donating groups coordinated to the macrocycle(R=-F,-H,and-OCH_3)on the electron distribution in the molecular catalysts.Strategic placement of-OCH_3 groups in the macrocycles leads to a favourable oxidation state of the Cu centres and subsequent C-C coupling to form C_(2) products.This research provides fundamental insights into the design and optimization of binuclear Cu molecular catalysts for the electrochemical conversion of CO_(2) to value-added C_(2) products.

Catalyst Enhanced Chemical Vapor Depositionof Nickel on Polymer Surface

Catalyst enhanced chemical vapor deposition of nickel film on high Tg polymers such as teflon(PTFE), polyimide(PI), and polysulfone(PS) was investigated by hot wall and cold wall CVD, in which Ni(dmg)_2, Ni(acac)_2, Ni(hfac)_2, Ni(TMHD)_2, and Ni(cp)_2 are used as precursors, and palladium complexes are used as catalysts. The films obtained were shiny with silvery color. The Ni was metallic and the purity of Ni was about 92%-95% from XPS analysis. SEM micrographs show that the film had good morphology. The conductivity of the film was about 0.5-4 W·cm^(-1). Ni films had good adhesion with polyimide and polysulfone.

Recycling and Upgrading Utilization of Polymer Plastics

Due to the current situation of massive waste consumption and accumulation,the recycling and upgrading utilization of polymer materials is an effective technology to solve environmental pollution.In this work,the recycling and upgrading methods of polymers are summarized,and the latest progress in polymer upcycling is discussed from the perspective of upgrading materials.The common polymer recovery methods,including mechanical recovery,chemical recovery,biocatalysis,and photocatalytic recovery,are discussed based on their mechanism and industrialized application.The upgrading products of polymers are divided into monomers,fuels and fine chemicals.The challenges and prospects of polymer degradation technology are discussed.

Continuous nitrogen-doped carbon nanotube matrix for boosting oxygen electrocatalysis in rechargeable Zn-air batteries

Developing robust oxygen electrocatalyst with high-performance is very significant for practical rechargeable Zn-air battery.We report herein the preparation of three-dimensional continuous nanocarbon network composed of interconnected nitrogen-doped carbon nanotubes and its application as oxygen electrocatalysis in rechargeable Zn-air battery.Except the excellent electrochemical bifunctionality,this carbon nanotube matrix also delivers an impressive battery performance.Specifically,an opencircuit voltage of 1.50 V as well as a high power density of 220 m W cm^(-2) with remarkable cycling stability for 1600 h is achieved in the rechargeable Zn-air battery.The study not only provides an efficient bifunctional oxygen electrocatalyst but more importantly may pave significant concepts in designing robust electrode for long-life rechargeable Zn-air battery and other energy technologies.

Research advances in unsupported Pt-based catalysts for electrochemical methanol oxidation

Direct methanol fuel cells are one of the most promising alternative energy technologies in the foreseeable future, but its successful commercialization in large scale is still heavily hindered by several technical shortfalls, especially the undesirable activity and durability issues of electrocatalysts toward methanol oxidation reaction. In light of these challenges, the inherent advantages of unsupported Pt based nanostructures demonstrate their great potentials as durable and efficient electrocatalysts for direct methanol fuel cells. This review will summarize recent achievements of unsupported Pt-based electrocatalysts toward methanol oxidation, with highlighting the interactions between the performance and structure tailoring and composition modulating. At last, a perspective is proposed for the upcoming challenges and possible opportunities to further prompt the practical application of unsupported Pt-based electrocatalysts for direct methanol fuel cells.

Corrosion formation and phase transformation of nickel-iron hydroxide nanosheets array for efficient water oxidation

Designing earth-abundant electrocatalysts with high performance towards water oxidation is highly decisive for the sustainable energy technologies. This study develops a facile natural corrosion approach to fabricate nickel-iron hydroxides for water oxidation. The resulted electrode demonstrates an outstanding activity and stability with an overpotential of 275 mV to deliver 10 mA·cm^(−2). Experimental and theoretical results suggest the corrosion-induced formation of hydroxides and their transformation to oxyhydroxides would account for this excellent performance. This work not only provides an interesting corrosion approach for the fabrication of excellent water oxidation electrode, but also bridges traditional corrosion engineering and novel materials fabrication, which would offer some insights in the innovative principles for nanomaterials and energy technologies.

Bio-inspired design of hierarchical FeP nanostructure arrays for the hydrogen evolution reaction

Hierarchical FeP nanoarray films composed of FeP nanopetals were successfully synthesized via a bio-inspired hydrothermal route followed by phosphorization. Glycerol as a crystal growth modifier, plays a significant role in controlling the morphology and structure of the FeO（OH） precursor during the biomineralization process, while the following transfer and pseudomorphic transformation of the FeO（OH） film successfully give rise to the FeP array film. The as-prepared FeP film electrodes exhibit excellent hydrogen evolution reaction （HER） performance over a wide pH range. Theoretical calculations reveal that the mixed P/Fe termination in the FeP film is responsible for the high catalytic activity of the nanostructured electrodes. This new insight will promote further explorations of efficient metal phosphoride-based catalysts for the HER. More importantly, this study bridges the gap between biological and inorganic self-assembling nanosystems and may open up a new avenue for the preparation of functional nanostructures with application in energy devices.

Defect-rich bismuth metallene for efficient CO_(2) electroconversion

1.Introduction Carbon dioxide reduction(CO_(2)RR)technology has attracted much attention in recent years and can effectively decrease the greenhouse effect and simultaneously achieve chemical energy storage[1].In the electrochemical process,a large overpotential is generally required to activate inert CO_(2)molecules,resulting in the inevitable competition reaction from the hydrogen evolution reaction(HER)and consequently decreasing the faradaic efficiency of CO_(2)RR[2,3].Among various reduction products of CO_(2)RR,formate is the most prevalent product with important applications in the energy conversion and chemical industries.Among a host of catalysts that can convert CO_(2)to formate,bismuth(Bi)-based nanomaterials are highly promising electrocatalysts for the conversion of CO_(2)to formate due to their high faradaic efficiency and good stability.However,the preparation method and catalytic activity of Bi-based nanomaterials still need to be further improved for industrial conversion of the CO_(2)RR.

Progress in MXene-based catalysts for oxygen evolution reaction

Electrochemical water splitting for hydrogen generation is considered one of the most promising strategies for reducing the use of fossil fuels and storing renewable electricity in hydrogen fuel.However,the anodic oxygen evolution process remains a bottleneck due to the remarkably high overpotential of about 300 mV to achieve a current density of 10 mA cm^(−2).The key to solving this dilemma is the development of highly efficient catalysts with minimized overpotential,long-term stability,and low cost.As a new 2D material,MXene has emerged as an intriguing material for future energy conversion technology due to its benefits,including superior conductivity,excellent hydrophilic properties,high surface area,versatile chemical composition,and ease of processing,which make it a potential constituent of the oxygen evolution catalyst layer.This review aims to summarize and discuss the recent development of oxygen evolution catalysts using MXene as a component,emphasizing the synthesis and synergistic effect of MXene-based composite catalysts.Based on the discussions summarized in this review,we also provide future research directions regarding electronic interaction,stability,and structural evolution of MXene-based oxygen evolution catalysts.We believe that a broader and deeper research in this area could accelerate the discovery of efficient catalysts for electrochemical oxygen evolution.

Enhanced photocatalytic activity by the construction of a TiO2/carbon nitride nanosheets heterostructure with high surface area via direct interracial assembly

A TiO2 heterostructure modified with carbon nitride nanosheets （CN-NSs） has been synthesized via a direct interfacial assembly strategy. The CN-NSs, which have a unique two-dimensional structure, were favorable for supporting TiOa nanoparticles （NPs）. The uniform dispersion of TiO2 NPs on the surface of the CN-NSs creates sufficient interfacial contact at their nanojunctions, as was confirmed by electron microscopy analyses. In comparison with other reported metal oxide/CN composites, the strong interactions of the ultrathin CN-NSs layers with the TiO2 nanoparticles restrain their re-stacking, which results in a large specific surface area of 234.0 m2.g-1. The results indicate that the optimized TiOJCN-NSs hybrid exhibits remarkably enhanced photocatalytic efficiency for dye degradation （with k of 0.167 min-1 under full spectrum） and Ha production （with apparent quantum yield -- 38.4% for A = 400 ＋ 15 nm monochromatic light）. This can be ascribed to the improved surface area and quantum efficiency of the hybrid, with a controlled ratio that reaches the appropriate balance between producing sufficient nanojunctions and absorbing enough photons. Furthermore, based on the identification of the main active species for photodegradation, and the confirmation of active sites for H2 evolution, the charge transfer pathway across the TiO2/CN-NSs interface under simulated solar light is proposed.

Customizing the microenvironment of CO_(2) electrocatalysis via three‐phase interface engineering

Converting CO_(2) into high‐value fuels and chemicals by renewable‐electricitypowered electrochemical CO_(2) reduction reaction(CRR)is a viable approach toward carbon‐emissions‐neutral processes.Unlike the thermocatalytic hydrogenation of CO_(2) at the solid‐gas interface,the CRR takes place at the three‐phase gas/solid/liquid interface near the electrode surface in aqueous solution,which leads to major challenges including the limited mass diffusion of CO_(2) reactant,competitive hydrogen evolution reaction,and poor product selectivity.Here we critically examine the various methods of surface and interface engineering of the electrocatalysts to optimize the microenvironment for CRR,which can address the above issues.The effective modification strategies for the gas transport,electrolyte composition,controlling intermediate states,and catalyst engineering are discussed.The key emphasis is made on the diverse atomic‐precision modifications to increase the local CO_(2) concentration,lower the energy barriers for CO_(2) activation,decrease the H2O coverage,and stabilize intermediates to effectively control the catalytic activity and selectivity.The perspectives on the challenges and outlook for the future applications of three‐phase interface engineering for CRR and other gasinvolving electrocatalytic reactions conclude the article.

Opportunities for ionic liquid-based electrolytes in rechargeable lithium batteries

Ionic liquids(ILs)have been deemed as promising electrolyte materials for building safer and highly-performing rechargeable lithium batteries,owing to their negligible volatility,low-flammability,and high thermal stability,etc.The profound structural designability of IL cations and anions allows relatively facile regulations of their key physical(e.g.,viscosities,and ionic conductivities)and electrochemical(e.g.,anodic,and cathodic stabilities)properties,and therefore fulfills the critical requirements stipulated by various battery configurations.In this review,a historical overview on the development of ILs for nonaqueous electrolytes is provided,and the correlations between chemical structures and the basic properties of ILs are discussed.Furthermore,the key achievements in the field of IL-based electrolytes are scrutinized,including liquid electrolytes,polymer electrolytes,and composite polymer electrolytes.Based on literature reports and our previous work in this field,possible strategies to improve the performance of IL-based electrolytes and their rechargeable batteries are discussed.The present work not only provides the status quo in the development of IL-based electrolytes but also inspires the structural design of ILs for other kinds of rechargeable batteries(e.g.,sodium,potassium,zinc batteries).

Solid-state electrolytes for safe rechargeable lithium metal batteries:a strategic view

Despite the efforts devoted to the identification of new electrode materials with higher specific capacities and electrolyte additives to mitigate the well-known limitations of current lithium-ion batteries,this technology is believed to have almost reached its energy density limit.It suffers also of a severe safety concern ascribed to the use of flammable liquid-based electrolytes.In this regard,solid-state electrolytes(SSEs)enabling the use of lithium metal as anode in the so-called solid-state lithium metal batteries(SSLMBs)are considered as the most desirable solution to tackle the aforementioned limitations.This emerging technology has rapidly evolved in recent years thanks to the striking advances gained in the domain of electrolyte materials,where SSEs can be classified according to their core chemistry as organic,inorganic,and hybrid/composite electrolytes.This strategic review presents a critical analysis of the design strategies reported in the field of SSEs,summarizing their main advantages and disadvantages,and providing a future perspective toward the rapid development of SSLMB technology.

Preventing surface passivation of transition metal nanoparticles in oxygen electrocatalyst to extend the lifespan of Zn-air battery

Prolonging the lifespan of oxygen catalysts in Zn-air batteries was urgently required for the potential commercialization.Herein,two interactional active species were integrated into porous N-doped carbon microspheres(Co-Fe-Ru/PNCS)to act as bifunctional oxygen electrocatalysts.Due to the electron transfer from Ru to Co/Fe element,the high value state of Ru could promote OER performance and reduce the charge voltage of the battery.An extended cycle stability of 200 h was achieved in Co-Fe-Ru/PNCS-based battery.Moreover,the quasi in-situ potentiodynamic sweep of air-electrode in battery cell confirmed it was the incorporation of Ru that avoided the passivation of Co/Fe-based nanoparticles.Accordingly,this novel electrocatalyst may provide a new strategy of designing durable bifunctional oxygen electrocatalyst for Zn-air batteries.

Lithium(fluorosulfonyl)(n-nonafluorobutanesulfonyl)imide for stabilizing cathode-electrolyte interface in sulfonamide electrolytes

Rechargeable lithium metal batteries(RLMBs)have been regarded as promising successors for contemporary lithium-ion batteries,in view of their high gravimetric and volumetric energy densities.Conventional non-aqueous liquid electrolytes containing organic carbonate solvents possess high chemical reactivities with metallic lithium anode and high flammability,which induces considerable safety threats under extreme conditions(e.g.,overcharging and thermal runaway).Herein,we propose the utilization of fluorinated sulfonamide(i.e.,N,N-dimethyl fluorosulfonamide(DMFSA))as solvent,together with lithium(fluorosulfonyl)(n-nonafluorobutanesulfonyl)imide(LiFNFSI)as co-salt and/or electrolyte additive for accessing safer and highperforming RLMBs.Comprehensive physical(e.g.,thermal transition,viscosity,and ionic conductivity)and electrochemical(e.g.,anodic stability on different electrodes)characterizations have been performed,aiming to reveal the inherent characteristics of the sulfonamide-based electrolytes and the particular role of LiFNFSI on the stabilization of LiCoO_(2) cathode.It has been demonstrated that the sulfonamide-based electrolytes exhibit superior flame-retardant abilities and decent ionic conductivities(>1 mS·cm^(-1)at room temperature).The incorporation of LiFNFSI as co-salt and/or electrolyte additive could significantly suppress the side reactions occurring at the cathode compartment,through the preferential decompositions of the FNFSI-anion.This work is anticipated to give an in-depth understanding on the working mechanism of LiFNFSI in the sulfonamide-based electrolytes,and also spurs the development of high-energy and safer RLMBs.

N,N-Dimethyl fluorosulfonamide for suppressed aluminum corrosion in lithium bis(trifluoromethanesulfonyl)imide-based electrolytes

Effective passivation of aluminum(Al)current collector at high potentials(>4.0 V vs.Li/Li^(+))is of essence for the long-term operation of lithium-based batteries.Unfortunately,the non-aqueous liquid electrolytes comprising lithium bis(trifluoromethanesulfonyl)imide(LiTFSI)and organic carbonates are corrosive toward Al current collector at high potentials(>4.0 V vs.Li/Li^(+)),despite their intriguing features(e.g.,good chemical stability and high ionic conductivity).Herein,we propose the utilization of N,N-dimethyl fluorosulfonamide(DMFSA)as electrolyte solvent for suppressing Al corrosion in the LiTFSI-based electrolytes.It has been demonstrated that the electrolyte of 1.0 M LiTFSI-DMFSA shows decent ionic conductivities(1.76 mS·cm^(−1)at 25℃)with good fluidities(2.44 cP at 25℃).In particular,the replacement of organic carbonates(e.g.,ethylene carbonate and ethyl methyl carbonate)with DMFSA leads to significant suppressed Al corrosion.Morphological and compositional characterizations utilizing scanning electron microscopy(SEM)and X-ray photoelectron spectroscopy(XPS)reveal that DMFSA favors the formation of insoluble species(i.e.,aluminum fluoride(AlF_(3)))on the surface of Al electrode,which effectively inhibits continuous exposure of fresh Al surface to electrolyte during cycling.This work provides not only a deeper understanding on the Al corrosion in LiTFSI-based electrolyte but also an elegant path to stabilize the Al current collector at high potentials(>4.0 V vs.Li/Li^(+)),which may give an impetus into the development of lithium-based batteries.

调节铜催化剂表面分子亲电性以调控电催化二氧化碳还原选择性

Cu是唯一能选择性将二氧化碳电还原(CRR)为多碳产物的过渡金属.然而,调控Cu的CRR选择性获得多种产物仍非常具有挑战性.本文选择了一系列具有不同亲电性的分子来修饰Cu催化剂以调控其CRR选择性,从而产生CH_(4)或C_(2)H_(4).理论计算表明,分子的亲电性决定催化反应中的质子活度,进而能促进或抑制CRR中的质子耦合电子转移(PCET)过程.实验发现,低亲电性分子(如1,2-双(4-吡啶基)乙烷)可以促进质子转移,加快^(*)CO中间体氢化过程而生成CH_(4),实现58.2%的法拉第效率;而高亲电性分子(如顺-1,2-双(4-吡啶基)乙烯)能构建强的氢键以稳定^(*)CO中间体,促进其偶联生成C_(2)H_(4),实现65.9%的法拉第效率.理论计算结合原位光谱表征揭示,分子亲电性可调节催化剂质子活度,影响CRR反应中^(*)CO氢化或偶联,进而调控CRR选择性.不同于常规的催化剂结构工程,本策略通过调节CRR中的PCET过程来调控选择性,为CRR的发展提供了新的认识.