Electrocatalysts with atomic-level site for nitrate reduction to ammonia

Ammonia(NH_(3))is an important raw material for modern agriculture and industry,being widely demanded to sustain the sustainable development of modern society.Currently,the industrial production methods of NH_(3),such as the traditional Haber-Bosch process,have drawbacks including high energy consumption and significant carbon dioxide emissions.In recent years,the electrocatalytic nitrate reduction reaction(NO_(3)RR)powered by intermittent renewable energy sources has gradually become a multidisciplinary research hotspot,as it allows for the efficient synthesis of NH_(3)under mild conditions.In this review,we focus on the research of electrocatalysts with atomic-level site,which have attracted attention due to their extremely high atomic utilization efficiency and unique structural characteristics in the field of NO_(3)RR.Firstly,we introduce the mechanism of nitrate reduction for ammonia synthesis and discuss the in-situ characterization techniques related to the mechanism study.Secondly,we review the progress of the electrocatalysts with atomic-level site for nitrate reduction and explore the structure-activity relationship to guide the rational design of efficient catalysts.Lastly,the conclusions of this review and the challenges and prospective of this promising field are presented.

Experimental study on the properties of CMTs-incorporated geopolymers prepared at low temperatures

Considering that copper mine tailings(CMTs)are commonly mixed with ordinary Portland cement,fly ash(FA),and kaolin to produce geopolymers,to make full use of CMTs,the properties of geopolymers manufactured under different material mass ratios and curing methods(standard curing,water bath curing,and 60℃curing)are evaluated with significantly increased dosage of CMTs.Porosity and unconfined compressive strength tests,X-ray diffraction,field emission scanning electron microscopy,and energy dispersive spectroscopy are used to determine the physical and mechanical properties,microstructure,and mineral composition of geopolymers.Finally,costs and CO 2 emissions of specimens with different material mass ratios during the preparation processes are compared.The results show that during the geopolymerization of low-calcium materials,various geopolymer gels,including calcium silicate,calcium silicoaluminate,and mainly sodium silicoaluminate gels,coexist.The solid waste,cost,and carbon dioxide emission reductions can reach 100%,166.3 yuan/t,and 73.3 kg/t,respectively.Under a curing condition of 60℃,the sample with a CMTs mass fraction of 70%and an FA mass fraction of 30%meets the requirements of porosity,compressive strength.The resource utilization of CMT and FA is realized in a more economical way.

In-situ/operando characterization techniques in lithium-ion batteries and beyond

Nowadays,in-situ/operando characterization becomes one of the most powerful as well as available means to monitor intricate reactions and investigate energy-storage mechanisms within advanced batteries.The new applications and novel devices constructed in recent years are necessary to be reviewed for inspiring subsequent studies.Hence,we summarize the progress of in-situ/operando techniques employed in rechargeable batteries.The members of this large family are divided into three sections for introduction,including bulk material,electrolyte/electrode interface and gas evolution.In each part,various energy-storage systems are mentioned and the related experimental details as well as data analysis are discussed.The simultaneous strategies of various in-situ methods are highlighted as well.Finally,current challenges and potential solutions are concluded towards the rising influence and enlarged appliance of in-situ/operando techniques in the battery research.

Decoding lithium batteries through advanced in situ characterization techniques

Given the energy demands of the electromobility market,the energy density and safety of lithium batteries(LBs)need to be improved,whereas its cost needs to be decreased.For the enhanced performance and decreased cost,more suitable electrode and electrolyte materials should be developed based on the improved understanding of the degradation mechanisms and structure–performance correlation in the LB system.Thus,various in situ characterization technologies have been developed during the past decades,providing abundant guidelines on the design of electrode and electrolyte materials.Here we first review the progress of in situ characterization of LBs and emphasize the feature of the multi-model coupling of different characterization techniques.Then,we systematically discuss how in situ characterization technologies reveal the electrochemical processes and fundamental mechanisms of different electrode systems based on representative electrode materials and electrolyte components.Finally,we discuss the current challenges,future opportunities,and possible directions to promote in situ characterization technologies for further improvement of the battery performance.

Neutron-based characterization techniques for lithium-ion battery research

During the past decades,Li-ion batteries have been one of the most important energy storage devices.Large-scale energy storage requires Li-ion batteries which possess high energy density,low cost,and high safety.Other than advanced battery materials,in-depth understanding of the intrinsic mechanism correlated with cell reaction is also essential for the development of high-performance Li-ion battery.Advanced characterization techniques,especially neutron-based techniques,have greatly promoted Li-ion battery researches.In this review,the characteristics or capabilities of various neutron-based characterization techniques,including elastic neutron scattering,quasi-elastic neutron scattering,neutron imaging,and inelastic neutron scattering,for the related Li-ion-battery researches are summarized.The design of in-situ/operando environment is also discussed.The comprehensive survey on neutron-based characterizations for mechanism understanding will provide guidance for the further study of high-performance Li-ion batteries.

Progress and perspective of high-voltage lithium cobalt oxide in lithium-ion batteries

Lithium cobalt oxide(LiCoO_(2),LCO)dominates in 3C(computer,communication,and consumer)electronics-based batteries with the merits of extraordinary volumetric and gravimetric energy density,high-voltage plateau,and facile synthesis.Currently,the demand for lightweight and longer standby smart portable electronic products drives the development of the upper cut-off voltage of LCO-based batteries to further improve the energy density.However,several challenges,including irreversible structural transformation,surface degradation,cobalt dissolution and oxygen evolution along with detrimental side reactions with the electrolyte remain with charging to a high cut-off voltage(>4.2 V vs.Li/Li+),resulting in rapid capacity decay and safety issues.Based on the degradation mechanisms and latest advances of the high-voltage LCO,this review summarizes modification strategies in view of the LCO structure,artificial interface design and electrolytes optimization.Meanwhile,many advanced characterization and monitoring techniques utilized to clarify the structural and interfacial evolution of LCO during charge/discharge process are critically emphasized.Moreover,the perspectives in terms of integrating multiple modification strategies,applying gel and solid-state electrolytes,optimizing the recovery process and scalable production are presented.

Research progress of precise structural regulation of single atom catalyst for accelerating electrocatalytic oxygen reduction reaction

The development and utilization of renewable clean energy can effectively solve the two major problems of energy and environment. As an efficient power generation device that converts hydrogen energy into electric energy, fuel cell has attracted more and more attention. For fuel cells, the oxygen reduction reaction(ORR) at the cathode is the core reaction, and the design and development of high-performance ORR catalysts remain quite challenging. Since the microenvironment of the active center of single atom catalysts(SACs) has an important influence on its catalytic performance, it has been a research focus to improve the ORR activity and stability of electrocatalysts by adjusting the structure of the active center through reasonable structural regulation methods. In this review, we reviewed the preparation and structure–activity relationship of SACs for ORR. Then, the structural precision regulation methods for improving the activity and stability of ORR electrocatalysts are discussed. And the advanced in-situ characterization techniques for revealing the changes of active sites in the electrocatalytic ORR process are summarized. Finally, the challenges and future design directions of SACs for ORR are discussed. This work will provide important reference value for the design and synthesis of SACs with high activity and stability for ORR.

Rational design of bismuth-based catalysts for electrochemical CO_(2) reduction

Sustainable conversion of carbon dioxide(CO_(2))to high value-added chemicals and fuels is a promising solution to solve the problem of excessive CO_(2) emissions and alleviate the shortage of fossil fuels,maintaining the balance of the carbon cycle in nature.The development of catalytic system is of great significance to improve the efficiency and selectivity for electrochemical CO_(2) conversion.In particular,bismuth(Bi)based catalysts are the most promising candidates,while confronting challenges.This review aims to elucidate the fundamental issues of efficient and stable Bi-based catalysts,constructing a bridge between the category,synthesis approach and electrochemical performance.In this review,the categories of Bi-based catalysts are firstly introduced,such as metals,alloys,single atoms,compounds and composites.Followed by the statement of the reliable and versatile synthetic approaches,the representative optimization strategies,such as morphology manipulation,defect engineering,component and heterostructure regulation,have been highlighted in the discussion,paving in-depth insight upon the design principles,reaction activity,selectivity and stability.Afterward,in situ characterization techniques will be discussed to illustrate the mechanisms of electrochemical CO_(2) conversion.In the end,the challenges and perspectives are also provided,promoting a systematic understanding in terms of the bottleneck and opportunities in the field of electrochemical CO_(2) conversion.

Synthesis and Characterization of La_(0.8)Sr_(0.2)MnO_(3−δ) Nanostructures for Solid Oxide Fuel Cells

La0.8Sr0.2MnO3-δ (LSM) perovskite was synthesized using different methods, such as solid state reaction, soft-chemical and sol-gel methods for solid oxide fuel cells (SOFCs) for use as a cathode material. The pristine material was characterized by X-ray diffraction, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). X-ray diffraction results show that the pure phase of La0.8Sr0.2MnO3-δ (LSM) perovskite was formed at 1250oC. Scanning electron microscopy characterization shows that a highly porous material can be obtained using a soft-chemical method with different 3,3’,3”-nitrilotripropionic acid ( NTP) to metal-ion ratio R.

Understanding and unveiling the electro-chemo-mechanical behavior in solid-state batteries

Solid-state batteries(SSBs)are attracting growing interest as long-lasting,thermally resilient,and high-safe energy storage systems.As an emerging area of battery chemistry,there are many issues with SSBs,including strongly reductive lithium anodes,oxidized cathodes(state of charge),the thermodynamic stability limits of solid-state electrolytes(SSEs),and the ubiquitous and critical interfaces.In this Review,we provided an overview of the main obstacles in the development of SSBs,such as the lithium anode|SSEs interface,the cathode|SSEs interface,lithium-ion transport in the SSEs,and the root origin of lithium intrusions,as well as the safety issues caused by the dendrites.Understanding and overcoming these obstacles are crucial but also extremely challenging as the localized and buried nature of the intimate contact between electrode and SSEs makes direct detection difficult.We reviewed advanced characterization techniques and discussed the complex ion/electron-transport mechanism that have been plaguing electrochemists.Finally,we focused on studying and revealing the coupled electro-chemo-mechanical behavior occurring in the lithium anode,cathode,SSEs,and beyond.

How to enable highly efficient and large‐area fabrication on specific textures for monolithic perovskite/silicon tandem solar cells?

Perovskite/silicon tandem solar cells(PVSK/Si TSCs)have emerged as a promising photovoltaic technology toward achieving a high power conversion efficiency(PCE)along with cost‐effective manufacturing.The PCE of PVSK/Si TSCs has skyrocketed to a certified 33.9%,surpassing the theoretical limit of any single‐junction solar cell.This achievement is partially attributed to ad-vancements in surface textures for Si bottom cells.In this regard,we present an overview of the recent developments concerning surface textures of Si in monolithic PVSK/Si TSCs,including planar,pyramid texture,and nanotexture.Following,the prevailing perovskite deposition methods on these textures are thoroughly discussed,and the corresponding challenges are evaluated.Addi-tionally,we provide a summary of the advanced morphological,structural,optical,and electrical characterization techniques being utilized for theses textures.Finally,the prospects for further development of PVSK/Si TSCs are outlined,including designing novel textures with industrial compatibility,developing perovskite deposition methods with scalability,and exploring more pertinent characterization techniques for textured PVSK/Si TSCs.

Advanced characterizations and measurements for sodium-ion batteries with NASICON-type cathode materials

NASICON (Na superionic conductor)-type cathode materials for sodium-ion batteries (SIBs) have attractedextensive attention due to their mechanically robust three-dimensional (3D) framework, which has sufficient openchannels for fast Na^(+) transportation. However, they usually suffer from inferior electronic conductivity and lowcapacity, which severely limit their practical applications. To solve these issues, we need to deeply understand thestructural evolution, redox mechanisms, and electrode/electrolyte interface reactions during cycling. Recently,rapid developments in synchrotron X-ray techniques, neutron-based resources, magnetic resonance, as well asoptical and electron microscopy have brought numerous opportunities to gain deep insights into the Na-storagebehaviors of NASICON cathodes. In this review, we summarize the detection principles of advanced characterization techniques used with typical NASICON-structured cathode materials for SIBs. The special focus is on bothoperando and ex situ techniques, which help to investigate the relationships among phase, composition, andvalence variations within electrochemical responses. Fresh electrochemical measurements and theoretical computations are also included to reveal the kinetics and energy-storage mechanisms of electrodes upon charge/discharge. Finally, we describe potential new developments in NASICON-cathodes with optimized SIB systems,foreseeing a bright future for them, achievable through the rational application of advanced diagnostic methods.

Advancements and Challenges in Organic–Inorganic Composite Solid Electrolytes for All‑Solid‑State Lithium Batteries

To address the limitations of contemporary lithium-ion batteries,particularly their low energy density and safety concerns,all-solid-state lithium batteries equipped with solid-state electrolytes have been identified as an up-and-coming alternative.Among the various SEs,organic–inorganic composite solid electrolytes(OICSEs)that combine the advantages of both polymer and inorganic materials demonstrate promising potential for large-scale applications.However,OICSEs still face many challenges in practical applications,such as low ionic conductivity and poor interfacial stability,which severely limit their applications.This review provides a comprehensive overview of recent research advancements in OICSEs.Specifically,the influence of inorganic fillers on the main functional parameters of OICSEs,including ionic conductivity,Li+transfer number,mechanical strength,electrochemical stability,electronic conductivity,and thermal stability are systematically discussed.The lithium-ion conduction mechanism of OICSE is thoroughly analyzed and concluded from the microscopic perspective.Besides,the classic inorganic filler types,including both inert and active fillers,are categorized with special emphasis on the relationship between inorganic filler structure design and the electrochemical performance of OICSEs.Finally,the advanced characterization techniques relevant to OICSEs are summarized,and the challenges and perspectives on the future development of OICSEs are also highlighted for constructing superior ASSLBs.

Characterization of planar photonic crystals using surface coupling techniques at large wavelengths

We report a non-destructive characterization of planar two-dimensional （2D） photonic crystals （PhCs） made in silicon on insulator （SOI） wafers using ellipsometric or Fourier transformed infrared （FTIR） spectroscope. At large wavelengths, devices behave as homogeneous isotropic materials defined by an effective filling factor. The experimental results related to the PhC limited dimensions confirm this characterization.

PMD and CD Characterization of Chirped FBG Using Microwave Photonic Technique

We present and demonstrate experimentally a new method for measuring the polarization-mode-dispersion(PMD) of a Chirped Fiber Bragg Grating. The technique has also been applied to accurate chromatic dispersion evaluation by removing the influence of PMD.

Recent progress of covalent organic frameworks membranes:Design,synthesis,and application in water treatment

To date,significant efforts have been devoted to eliminating hazardous components to purify wastewater through the development of various nanomaterials.Covalent organic frameworks(COFs),an important branch of the porous crystalline family,possess the peculiarity of ultrahigh surface area,adjustable pore size,and facile functionality.Exciting studies from design fabrication to potential applications in water treatment by COF-based membranes(COMs)have emerged.This review summarizes various preparation strategies and synthesis mechanisms for COMs,including layer-by-layer stacking,in situ growth,interfacial polymerization,and electrochemical synthesis,and briefly describes the advanced characterization techniques for COMs.Moreover,the application of COMs in heavy metal removal,dye separation,purification of radionuclides,pollutant detection,sea water desalination,and so on,is described and discussed.Finally,the perspectives on future opportunities for designing COMs in water purification have been proposed.

Doping Strategy in Nickel-Rich Layered Oxide Cathode for Lithium-Ion Battery

Ni-rich layered oxides have been regarded as the most promising cathode material for next-generation high energy density Li-ion batteries because of their advantages in capacity and cost.However,these cathodes suffer from irreversible structural degradation,fast capacity attenuation as well as seriously reduced safety in their practical applications.Doping strategies with different elements have been employed to address the above issues.In this review,we summarize the research advances of the elemental doping in a Ni-rich layered oxide cathode.The experimental methods and dopant selection rules are briefly introduced.Then we discuss here the effects of the elemental doping from the aspects of the crystal lattice,electronic structure,nanomorphology,and surface stability.In addition,this review surveys the first-principles calculation and advanced structural characterization techniques,which have played important roles in elucidating the structure-performance correlations.Finally,perspectives regarding the future of doping strategy are given.

Progress in niobium-based oxides as anode for fast-charging Li-ion batteries

With the increasing popularity of electric/hybrid vehicles and the rapid development of 3C electronics,there is a growing interest in high-rate energy storage systems.The rapid development and widespread adoption of lithiumion batteries(LIBs)can be attributed to their numerous advantages,including high energy density,high operating voltage,environmental friendliness,and lack of memory effect.However,the progress of LIBs is currently hindered by the limitations of energy storage materials,which serve as vital components.Therefore,there is an urgent need to address the development of a new generation of high-rate energy storage materials in order to overcome these limitations and further advance LIB technology.Niobium-based oxides have emerged as promising candidates for the fabrication of fast-charging Li-ion batteries due to their excellent rate capability and long lifespan.This review paper provides a comprehensive analysis of the fundamentals,methodologies,and electrochemistries of niobium-based oxides,with a specific focus on the evolution and creation of crystal phases of Nb_(2)O_(5),fundamental electrochemical behavior,and modification methods including morphology modulation,composite technology,and carbon coating.Furthermore,the review explores Nb_(2)O_(5)-derived compounds and related advanced characterization techniques.Finally,the challenges and issues in the development of niobiumbased oxides for high-rate energy storage batteries are discussed,along with future research perspectives.

Visualizing surface-enriched Li storage with a nanopore-array model battery

The coupling of model batteries and surface-sensitive techniques provides an indispensable platform for interrogating the vital surface/interface processes in battery systems.Here,we report a sandwich-format nanopore-array model battery using an ultrathin graphite electrode and an anodized aluminum oxide(AAO)film.The porous framework of AAO regulates the contact pattern of the electrolyte with the graphite electrode from the inner side,while minimizing contamination on the outer surface.This model battery facilitates repetitive charge-discharge processes,where the graphite electrode is reversibly intercalated and deintercalated,and also allows for the in-situ characterizations of ion intercalation in the graphite electrode.The ion distribution profiles indicate that the intercalating Li ions accumulate in both the inner and outer surface regions of graphite,generating a high capacity of~455 mAh·g^(-1)(theory:372 mAh·g^(-1)).The surface enrichment presented herein provides new insights towards the mechanistic understanding of batteries and the rational design strategies.

S-scheme heterojunction photocatalysts for CO_(2) conversion: Design, characterization and categories

Photocatalytic CO_(2) conversion into valuable hydrocarbon fuels via solar light is a promising strategy to simul-taneously address energy shortage and environmental pollution.However,the photocatalytic CO_(2) reduction performance is too poor to be practically utilized due to the rapid recombination of photogenerated charge carriers.Constructing step-scheme(S-scheme)heterojunction photocatalysts can facilitate the charge separation and maximize the redox ability,thus remarkably enhancing the photocatalytic CO_(2) reduction activity.This review summarizes the progress of S-scheme heterojunction photocatalysts applied in the photocatalytic CO_(2) reduction reactions.Firstly,we introduce the fundamental design principles and characterization methods.The direct and indirect techniques to confirm the S-scheme charge transfer mechanism are disclosed.Secondly,we divide S-scheme composite photocatalyst into the following categories depending on their compositions:g-C_(3)N_(4)-based,metal-chalcogenide-based,TiO_(2)-based,bismuth-based,other metal oxide-based and other semiconductor-based S-scheme photocatalysts.The synergistic effect of the S-scheme charge transfer pathway as well as the unique intrinsic properties of semiconductor materials on the photocatalytic CO_(2) reduction performance is discussed in detail.Finally,concluding perspectives on the challenges and opportunities for the further exploration of highly efficient S-scheme photocatalysts in photocatalytic CO_(2) conversion are presented.