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.

Role of Catalytic Materials on Conversion of Sulfur Species for Room Temperature Sodium–Sulfur Battery

Room temperature sodium–sulfur(RT Na-S)battery with high theoretical energy density and low cost has spurred tremendous interest,which is recognized as an ideal candidate for large-scale energy storage applications.However,serious sodium polysulfide shutting and sluggish reaction kinetics lead to rapid capacity decay and poor Coulombic efficiency.Recently,catalytic materials capable of adsorbing and catalyzing the conversion of polysulfides are profiled as a promising method to improve electrochemical performance.In this review,the research progress is summarized that the application of catalytic materials in RT Na-S battery.For the role of catalyst on the conversion of sulfur species,specific attention is focused on the influence factors of reaction rate during different redox processes.Various catalytic materials based on lightweight and high conductive carbon materials,including heteroatom-doped carbon,metals and metal compounds,single-atom and heterostructure,promote the reaction kinetic via lowered energy barrier and accelerated charge transfer.Additionally,the adsorption capacity of the catalytic materials is the key to the catalytic effect.Particular attention to the interaction between polysulfides and sulfur host materials is necessary for the exploration of catalytic mechanism.Lastly,the challenges and outlooks toward the desired design of efficient catalytic materials for RT Na-S battery are discussed.

Electrochemical synthesis of catalytic materials for energy catalysis

Electrocatalysis is a process dealing with electrochemical reactions in the interconversion of chemical energy and electrical energy.Precise synthesis of catalytically active nanostructures is one of the key challenges that hinder the practical application of many important energy‐related electrocatalytic reactions.Compared with conventional wet‐chemical,solid‐state and vapor deposition synthesis,electrochemical synthesis is a simple,fast,cost‐effective and precisely controllable method for the preparation of highly efficient catalytic materials.In this review,we summarize recent progress in the electrochemical synthesis of catalytic materials such as single atoms,spherical and shaped nanoparticles,nanosheets,nanowires,core‐shell nanostructures,layered nanomaterials,dendritic nanostructures,hierarchically porous nanostructures as well as composite nanostructures.Fundamental aspects of electrochemical synthesis and several main electrochemical synthesis methods are discussed.Structure‐performance correlations between electrochemically synthesized catalysts and their unique electrocatalytic properties are exemplified using selected examples.We offer the reader with a basic guide to the synthesis of highly efficient catalysts using electrochemical methods,and we propose some research challenges and future opportunities in this field.

Performance optimization of chalcogenide catalytic materials in lithium-sulfur batteries:Structural and electronic engineering

Lithium-sulfur batteries(LSBs)boasting remarkable energy density have garnered significant attention within academic and industrial spheres.Nevertheless,the progression of LSBs remains constrained by the languid redox kinetics intrinsic to sulfur and the pronounced shuttle effect induced by lithium polysulfides(Li PSs),which seriously affecting the energy density,cycling life and rate capacity.The conceptualization and implementation of catalytic materials stand acknowledged as a propitious stratagem for orchestrating kinetic modulation,particularly in excavating the conversion of LiPSs and has evolved into a focal point for disposing.Among them,chalcogenide catalytic materials(CCMs)have shown satisfactory catalytic effects ascribe to the unique physicochemical properties,and have been extensively developed in recent years.Considering the lack of systematic summary regarding the development of CCMs and corresponding performance optimization strategies,herein,we initiate a comprehensive review regarding the recent progress of CCMs for effective collaborative immobilization and accelerated transformation kinetics of Li PSs.Following that,the modulation strategies to improve the catalytic activity of CCMs are summarized,including structural engineering(morphology engineering,surface/interface engineering,crystal engineering)and electronic engineering(doping and vacancy,etc.).Finally,the application prospect of CCMs in LSBs is clarified,and some enlightenment is provided for the reasonable design of CCMs serving practical LSBs.

Deformable Catalytic Material Derived from Mechanical Flexibility for Hydrogen Evolution Reaction

Deformable catalytic material with excellent flexible structure is a new type of catalyst that has been applied in various chemical reactions,especially electrocatalytic hydrogen evolution reaction(HER).In recent years,deformable catalysts for HER have made great progress and would become a research hotspot.The catalytic activities of deformable catalysts could be adjustable by the strain engineering and surface reconfiguration.The surface curvature of flexible catalytic materials is closely related to the electrocatalytic HER properties.Here,firstly,we systematically summarized self-adaptive catalytic performance of deformable catalysts and various micro–nanostructures evolution in catalytic HER process.Secondly,a series of strategies to design highly active catalysts based on the mechanical flexibility of lowdimensional nanomaterials were summarized.Last but not least,we presented the challenges and prospects of the study of flexible and deformable micro–nanostructures of electrocatalysts,which would further deepen the understanding of catalytic mechanisms of deformable HER catalyst.

Surface reconstruction,modification and functionalization of natural diatomites for miniaturization of shaped heterogeneous catalysts

Since the discovery of mesoporous silica in 1990s,there have been numerous mesoporous silica-based nanomaterials developed for catalytic applications,aiming at enhanced catalytic activity and stability.Recently,there have also been considerable interests in endowing them with hierarchical porosities to overcome the diffusional limitation for those with long unimodal channels.Present processes of making mesoporous silica largely rely on chemical sources which are relatively expensive and impose environmental concerns on their processes.In this regard,it is desirable to develop hierarchical silica supports from natural minerals.Herein,we present a series of work on surface reconstruction,modification,and functionalization to produce diatomite-based catalysts with original morphology and macro-meso-micro porosities and to test their suitability as catalyst supports for both liquid-and gas-phase reactions.Two wet-chemical routes were developed to introduce mesoporosity to both amorphous and crystalline diatomites.Importantly,we have used computational modeling to affirm that the diatomite morphology can improve catalytic performance based on fluid dynamics simulations.Thus,one could obtain this type of catalysts from numerous natural diatoms that have inherently intricate morphologies and shapes in micrometer scale.In principle,such catalytic nanocomposites acting as miniaturized industrial catalysts could be employed in microfluidic reactors for process intensification.

Toward effective electrocatalytic C–N coupling for the synthesis of organic nitrogenous compounds using CO_(2)and biomass as carbon sources

Thermochemical conversion of fossil resources into fuels,chemicals,andmaterials has rapidly increased atmospheric CO_(2)levels,hindering global efforts toward achieving carbon neutrality.With the increasing push for sustainability,utilizing electrochemical technology to transform CO_(2)or biomass into value-added chemicals and to close the carbon cycle with sustainable energy sources represents a promising strategy.Expanding the scope of electrosynthesis technology is a prerequisite for the electrification of chemical manufacturing.To this end,constructing the C─N bond is considered a priority.However,a systematic review of electrocatalytic processes toward building C─N bonds using CO_(2)and biomass as carbon sources is not available.Accordingly,this review highlights the research progress in the electrosynthesis of organic nitrogen compounds from CO_(2)and biomass by C─N coupling reactions in view of catalytic materials,focusing on the enlightenment of traditional catalysis on C─N coupling and the understanding of the basis of electrochemical C─N coupling.The possibility of C─N bond in electrocatalysis is also examined from the standpoints of activation of substrates,coupling site,mechanism,and inhibition of hydrogen evolution reaction(HER).Finally,the challenges and prospects of electrocatalytic C─N coupling reactions with improved efficiency and selectivity for future development are discussed.

Plasma-assisted Co/Zr-metal organic framework catalysis of CO_(2)hydrogenation:influence of Co precursors

In this study,Co/Zr-metal organic framework(MOF)precursors were obtained by a roomtemperature liquid-phase precipitation method and the equivalent-volume impregnation method,respectively,using a Zr-MOF as the support,and Co/Zr-MOF-M and Co/Zr-MOF-N catalysts were prepared after calcination in a hydrogen-argon mixture gases(VAr:V_(H_(2))=9:1)at 350℃for 2 h.The catalytic activities of the prepared samples for CO_(2)methanation under atmosphericpressure cold plasma were studied.The results showed that Co/Zr-MOF-M had a good synergistic effect with cold plasma.At a discharge power of 13.0 W,V_(H_(2)):VCO_(2)=4:1 and a gas flow rate of 30 ml·min^(-1),the CO_(2)conversion was 58.9%and the CH4 selectivity reached 94.7%,which was higher than for Co/Zr-MOF-N under plasma(CO_(2)conversion 24.8%,CH4 selectivity 9.8%).X-ray diffraction,scanning electron microscopy,transmission electron microscopy,N_(2)adsorption and desorption(Brunauer-Emmett-Teller)and x-ray photoelectron spectroscopy analysis results showed that Co/Zr-MOF-M and Co/Zr-MOF-N retained a good Zr-MOF framework structure,and the Co oxide was uniformly dispersed on the surface of the Zr-MOF.Compared with Co/Zr-MOF-N,the Co/Zr-MOF-M catalyst has a larger specific surface area and higher Co^(2+)/Cototaland Co/Zr ratios.Additionally,the Co oxide in Co/ZrMOF-M is distributed on the surface of the Zr-MOF in the form of porous particles,which may be the main reason why the catalytic activity of Co/Zr-MOF-M is higher than that of Co/ZrMOF-N.

Synthesis and Application of a Zeolite-containing Composite Material Made from Spent FCC Catalyst

Novel composite material with a wide pore distribution was synthesized by an in situ technique using spent FCC catalyst as raw material. The characterization results indicated that the composite material contained 56.7% of zeolite Y and exhibited a much larger specific surface area and pore volume as well as strong hydrothermal stability. Fluid catalytic cracking(FCC) catalyst was prepared based on the composite material. The results indicated that the as-prepared catalyst possessed a unique pore structure that was advantageous to the diffusion-controlled reactions. In addition, the attrition resistance, activity and hydrothermal stability of the studied catalyst were superior to those of the reference catalyst. The catalyst also exhibited excellent nickel and vanadium passivation performance, strong bottoms upgrading selectivity, and better gasoline and coke selectivity. In comparison to the reference catalyst, the yields of the gasoline and light oil increased by 1.61 and 1.31 percentage points, respectively, and the coke yield decreased by 0.22 percentage points, and the olefin content in the produced gasoline reduced by 2.51 percentage points, with the research octane number increased by 0.7 unit.

Preparation of 3,4-Dihydro-2H-pyran Catalyzed by Modified Gamma Alumina

A promising catalytic material, modified ga mma alumina with high surface area (300m2/g) and higher c ontents of strong acid sites was developed. It was prepared by a special precip itation method with aluminum nitrate solution containing a certain amounts of or thosilicic acid and ammonia aqueous solution. Compared with commercial gamma alu mina, the modified gamma alumina is an effective catalyst for dehydration of tet rahydrofurfuryl alcohol to 3,4-Dihydro-2H-pyran.Under the optimized reaction conditions, an improved yield of 3,4-Dihydro-2H-pyran of 93.4% was achieved. The profiles of pyridine TPD show that the modified gamma alumina exhibits more strong acid sites than that in the commercial gamma alumina, indicating the stro ng acid sites on the surface of the catalyst may play a crucial role in this rea ction.

Phosphorus modulated porous CeO_(2)nanocrystallines for accelerated polysulfide catalysis in advanced Li-S batteries

The insulating nature of sulfur species,sluggish reaction kinetics,and uncontrolled dissolution of lithium polysulfide(LiPS)intermediates during the complex and multiphase sulfur redox process,have severely inhibited the applications of Li-S batteries.In this study,we report a rational strategy to accelerate the polysulfide catalysis via constructing phosphorus modulated porous CeO_(2)(P-CeO_(2))for advanced Li-S batteries.The morphology and surface analysis demonstrate that the P-CeO_(2)consists of abundant Pmodulated porous CeO_(2)nanocrystallines.The battery performance reveals that the introduction of P will lead to an improved initial capacity of 1027 mA hg^(-1)than that of bare CeO_(2)(895.7 mA hg^(-1))at 0.2 C.In addition,the P-CeO_(2)cathode can maintain a low capacity decay ratio of 0.10%per cycle after 500 cycles at 1.0 C.The coin battery tests suggest that the P-CeO_(2)cathode presents faster oxidation-reduction kinetics of LiPS and quick diffusion of Li^+ions.Meanwhile,the studies of redox processes and chemical interactions of LiPS have demonstrated the P-CeO_(2)cathode displays stronger adsorption of Li_(2)S_(6),higher redox peak current,and earlier precipitation of Li_(2)S than the bare CeO_(2).This study demonstrates for the first time that the P-modulation of metal oxide surface can simultaneously promote the catalytic reaction kinetics and chemical interaction of LiPS.We anticipate that this P-modulation method can be extended to many other nanostructured metal catalytic sites for developing affordable advanced Li-S batteries.