Phase-engineering modulation of Mn-based oxide cathode for constructing super-stable sodium storage

The Mn-based oxide cathode with enriched crystal phase structure and component diversity can provide the excellent chemistry structure for Na-ion batteries.Nevertheless,the broad application prospect is obstructed by the sluggish Na^(+)kinetics and the phase transitions upon cycling.Herein,we establish the thermodynamically stable phase diagram of various Mn-based oxide composites precisely controlled by sodium content tailoring strategy coupling with co-doping and solid-state reaction.The chemical environment of the P2/P'3 and P2/P3 biphasic composites indicate that the charge compensation mechanism stems from the cooperative contribution of anions and cations.Benefiting from the no phase transition to scavenge the structure strain,P2/P'3 electrode can deliver long cycling stability(capacity retention of 73.8%after 1000 cycles at 10 C)and outstanding rate properties(the discharge capacity of 84.08 mA h g^(-1)at 20 C)than P2/P3 electrode.Furthermore,the DFT calculation demonstrates that the introducing novel P'3 phase can significantly regulate the Na^(+)reaction dynamics and modify the local electron configuration of Mn.The effective phase engineering can provide a reference for designing other high-performance electrode materials for Na-ion batteries.

危中见机:全球系统性风险给中国人力资源管理研究带来的机遇和挑战

在环境和政治等多重不确定风险的威胁下,全球系统性风险问题频繁出现,引起了学术界的广泛重视。Tung(2023)从人力资源管理视角出发,将中国面临的多重挑战总结为人口老龄化、中美关系、全球人才战、中国与世界的联系四个方面。受该文启发,本文立足于微观企业视角,旨在发展Tung(2023)的观点,探讨全球性系统风险给中国企业的人力资源管理以及人力资源管理研究带来的机遇和挑战,具体总结为四个方面:①面向年长员工的人力资源管理;②融合AI技术的人力资源管理;③企业创新与人力资源管理;④企业的人才管理。针对这四个方面,本文提出了一些未来人力资源管理研究需要解决的问题和探索的方向,希望能够和Tung(2023)一起为中国人力资源管理研究进步提供支持。

Promoting surface reconstruction of NiFe layered double hydroxides via intercalating[Cr(C_(2)O_(4))_(3)]^(3-)for enhanced oxygen evolution

Rationally manipulating surface reconstruction of catalysts for water oxidation,inducing formation and dynamic accumulation of catalytically active centers still face numerous challenges.Herein,the introduction of[Cr(C_(2)O_(4))_(3)]^(3-)into NiFe LDHs by intercalation engineering to promote surface reconstruction achieves an advanced oxygen evolution reaction(OER)activity.In view of the weak electronegativity of Cr^(3+) in[Cr(C_(2)O_(4))_(3)]^(3-),the intercalation of[Cr(C_(2)O_(4))_(3)]^(3-)is expected to result in an electron-rich structure of Fe sites in NiFe LDHs,and higher valence state of Ni can be formed with the charge transfer between Fe and Ni.The optimized electronic structure of NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs with more active Ni^(3+) species and the expedited dynamic generation of Ni^(3+) (Fe)OOH phase during the OER process contributed to its excellent catalytic property,revealed by in situ X-ray absorption spectroscopy,Raman spectroscopy,and quasi-in situ X-ray photoelectron spectroscopy.With the modulated electronic structure of metal sites,NiFe-[Cr(C_(2)O_(4))_(3)]^(3-)-LDHs exhibited promoted OER property with a lower overpotential of 236 mV at the current density of 10 mA cm^(-2).This work illustrates the intercalation of conjugated anion to dynamically construct desired Ni^(3+) sites with the optimal electronic environment for improved OER electrocatalysis.

Activation of iridium site by anchoring ruthenium atoms on defects for efficient anodic catalyst in polymer electrolyte membrane water electrolyzers

1.Introduction Hydrogen is an ideal energy carrier to tackle the energy crisis and greenhouse effect,because of its high energy density and low emission.The production,storage and transportation of hydrogen are key factors to the practical application of hydrogen energy.As the scientific and technological understanding of the electrochemical devices was advancing in the past few decades,water electrolyzers based on the proton exchange membrane (PEM) have attracted much focus for its huge potential on the production of hydrogen via water splitting.PEM electrolyzers use perfluorinated sulfonic acid (PFSA) based membranes as the electrolyte.

Interfacial engineering of the layered oxide cathode materials for sodium-ion battery

The layered metal oxides are reviewed as the hopeful cathode materials for high-performance sodium-ion batteries(SIBs)due to their large theoretical capacity,favorable two-dimensional(2D)ion diffusion channel,and simple manipuility.However,their cycling stability,rate capability,and thermal stability are still significantly concerned and highlighted before further practical application.The chemical,mechanical and electrochemical stability of the cathode–electrolyte interfaces upon cycling is of great significance.Herein,the unique structural and electrochemical properties of the layered oxide cathode materials for SIB are reviewed.The mechanism of bulk/surface degradation induced by oxygen evolution,phase transition,microcrack,and electrolyte decomposition is thoroughly understood.Furthermore,the interfacial engineering to construct stable interface through various effective methods is fully discussed.The future outlook and challenges for interfacial engineering in this filed are also summarized.This review should shed light on the rational design and construct of robust interface for applications of superior layered oxide cathodes in SIB and may suggest future research directions.

Selective oxygen electroreduction to hydrogen peroxide in acidic media:The superiority of single-atom catalysts

Two-electron oxygen reduction reaction(2e-ORR)provides an environmentally friendly direction for the on-site production of hydrogen peroxide(H_(2)O_(2)).Central to this technology is the exploitation of efficient,economical,and safe 2e-ORR electrocatalysts.This overview starts with the fundamental chemistry of ORR to highlight the decisive role of adsorbing intermediates on the reaction pathway and activity,followed by a comprehensive survey of the tuning strategies to favor 2e-ORR on traditional precious metals.The latest achievements in designing efficient and selective precious-metal-based single-atom catalysts(SACs)and metal-nitrogen-carbon(M-Nx/C)catalysts,from the aspects of material synthesis,theoretical calculations,and mass transport promotion,are systematically summarized.Brief introductions on the evaluation metrics for 2e-ORR catalysts and the primary reactor designs for cathodic H_(2)O_(2)synthesis are also included.We conclude this review with an outlook on the challenges and direction of efforts to advance electrocatalytic 2e-ORR into realistic H_(2)O_(2)production.

Cobalt-iron oxide/black phosphorus nanosheet heterostructure:Electrosynthesis and performance of(photo-)electrocatalytic oxygen evolution

Highly active,stable,and cut-price(photo-)electrocatalysts are desired to overwhelm high energy barriers for anodic oxygen evolution reaction processes.Herein,a heterostructure of cobalt-iron oxide/black phosphorus nanosheets is in-situ synthesized via a facile and novel three-electrode electrolysis method.Bulky black phosphorus is exfoliated into its nanosheets at the cathode while the CoFe oxide is derived directly from the metal wire anode during the electrolysis process.This heterostructure exhibits excellent electrocatalytic oxygen evolution reaction(OER)performance,and the overpotential at 10 mA·cm^(−2)is 51 mV lower than that of the commercial RuO_(2)catalyst.Its superior OER performance stems from the favorable adsorption behavior and an enlarged electrochemical active surface area of the catalyst.To reveal the origin of excellent OER performance from the point of adsorption strength of OH*,methanol oxidation reaction(MOR)test is applied under the identified OER operating conditions.Further introduction of light illumination enhances the OER activity of this heterostructure.The overpotential drops down to 280 mV,benefiting from pronounced photochemical response of black phosphorus nanosheets and iron oxide inside the heterostructure.This work develops a new electrochemical method to construct high performance and light-sensitive heterostructures from black phosphorus nanosheets for the OER.

Activating surface atoms of high entropy oxides for enhancing oxygen evolution reaction

High entropy oxides(HEOs) have attracted extensive attention of researchers due to their remarkable properties. The electrocatalytic activity of electrocatalysts is closely related to the reactivity of their surface atoms which usually shows a positive correlation. Excellenet stability of HEOs leads to their surface atoms with relative poor reactivity, limiting the applications for electrocatalysis. Therefore, it is significant to activate surface atoms of HEOs. Constructing amorphous structure, introducing oxygen defects and leaching are very effective strategies to improve the reactivity of surface atoms. Herein, to remove chemical inert, low-crystallinity(Fe, Co, Ni, Mn, Zn)_(3)O_(4) (HEO-Origin) nanosheets with abundant oxygen vacancies was synthesized, showing an excellent catalytic activity with an overpotential of 265 mV at 10 mA/cm^(2), which outperforms as-synthesized HEO-500℃-air(335 mV). The excellent catalytic performance of HEO-Origin can be attributed to high activity surface atoms, the introduction of oxygen defects efficiently altered electron distribution on the surface of HEO-Origin. Apart from, HEO-Origin also exhibits an outstanding electrochemical stability for oxygen evolution reaction(OER).

Anti‑polyelectrolyte Zwitterionic Block Copolymers as Adaptable Uranium Harvester in High‑Salinity Environments:Catalyst‑Free Light‑Driven Polymerization and Conformational Dynamics Study

Developing polymeric adsorbents for uranium harvesting from high-salinity environments remains a daunting challenge due to the‘polyelectrolyte effect’-induced conformational collapse compromising the ligand availability.A catalyst-free,visible light-controlled radical polymerization has been presented here for the tailor-made synthesis of zwitterionic block copolymers(BCPs)bearing uranophilic ligands.The novel anti-polyelectrolyte uranium harvesters exhibited significant salinity resistance.The facile and robust photosynthetic strategy offers a significantly high monomer conversion(α>95%)that facilitates“one-pot”chain extension to develop the BCPs.Metal catalyst residues,as found in conventional controlled radical polymerizations,are avoided and promoted to synthesize fascinating polymeric materials.We also highlight the first study,by integrating computational modeling with QCM-D analysis,on the interplay between polymer conformational dynamics and chemical adsorption behaviors.With zwitterionic polymer segments as conformational regulators,the BCPs exhibit remarkable‘anti-polyelectrolyte effect’by maintaining stretched conformations in saline solutions.Improved ligand accessibility and promotion of diffusional mass transfer are achieved,enabling a high adsorption capacity toward uranium with remarkably fast kinetics in spiked natural seawater and salt lake brines.

Revealing component synergy of Ni‒Fe/black phosphorous composites synthesized by self-designed electrochemical method for enhancing photoelectrocatalytic oxygen evolution reaction

Developing high-activity and low-cost catalysts is the key to eliminate the limitation of sluggish anodic oxygen evolution reaction(OER)during electrocatalytic overall water splitting.Herein,Ni‒Fe/black phosphorous(BP)composites are synthesized using a simple three-electrode system,where exfoliation of bulky BP and synthesis of NiFe composites are simultaneously achieved.Under light illumination,the optimized Ni‒Fe/BP composite exhibits excellent photoelectrocatalytic OER performance(e.g.,the overpotential is 58 mV lower than a commercial RuO_(2) electrocatalyst at a current density of 10 mA·cm^(-2)).The electron transfer on this composite is proved to follow a Ni‒BP‒Fe pathway.The electronic structure of this Ni‒Fe/BP composite is effectively regulated,leading to optimized adsorption strength of the intermediate OH*and improved intrinsic activity for the OER.Together with active sites on the support,this Ni‒Fe/BP composite possesses abundant electrochemical active sites and a bug surface area for the OER.The introduction of light further accelerates the electrocatalytic OER.This work provides a novel and facile method to synthesize high-performance metal/BP composites as well as the approaches to reveal their OER mechanisms.

Bifunctional functionalized two-dimensional transition metal borides for fast reaction redox kinetics in lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries are regarded as one of the most promising next-generation energy storage systems due to their high theoretical specific energy density and low cost.However,serious shuttle effect and sluggish lithium polysulfides(LiPSs)redox kinetics severely impede the practical application of Li-S batteries.Employing polar sulfur hosts is an effective strategy to alleviate the above problems.Herein,the potential of two-dimensional(2D)Ti_(2)B-based sulfur hosts for Li-S batteries was comprehensively explored using first-principles calculations.The results show that functional groups of Ti_(2)B can significantly modulate its structural properties,thus affecting its interaction with sulfurcontaining species.Among S,Se,F,Cl,and Br elements,Ti_(2)B terminated with S and Se atoms possess stronger adsorption capability towards soluble Li_(2)S_(8),Li_(2)S_(6),and Li_(2)S_(4),obviously stronger than organic electrolytes,which indicates that they can completely suppress the shuttle effect.Besides,Ti_(2)BS_(2)and Ti_(2)BSe_(2)can powerfully expedite the electrochemical conversion of LiPSs.Moreover,the decomposition energy barrier of Li_(2)S and diffusion energy barrier of single Li ion on them are also fairly low,manifesting their excellent catalytic performance towards the oxidation of Li_(2)S.Finally,Ti_(2)BS_(2)and Ti_(2)BSe_(2)always keep metallic conductivity during the whole charge/discharge process.Taking all this into account,Ti_(2)BS_(2)and Ti_(2)BSe_(2)are proposed as promising bifunctional sulfur hosts for Li-S batteries.Our results suggest that increasing the proportion of S and Se groups during the synthesis of Ti_(2)B monolayers is greatly helpful for obtaining high-performance Li-S batteries.Besides,our work not only reveals the huge potential of 2D transition metal borides in Li-S batteries,but also provides insightful guidance for the design and screening of new efficient sulfur cathodes.

基于铜金属有机配合物的热活化延迟荧光材料

具有热活化延迟荧光(thermally activated delayed fluorescence,TADF)特性的配合物可以同时利用单重态和三重态激子,因此发光量子效率较高,近年来受到广大科研工作者的关注。特别是铜金属有机配合物,最低单重态和最低三重态的能量差较小,又可以通过不同配体或取代基进行调节,所以具有较好TADF性能。本文根据配位原子的类型,汇总和分析了近5年具有TADF性质的铜配合物的结构特点和发光性能,并简要讨论了其在有机发光二极管(organic light-emitting diodes,OLEDs)中的潜在应用。

Ni2P Nanosheets:A High Catalytic Activity Platform for Electrochemical Detection of Acetaminophen

Main observation and conclusion Accurate determination of acetaminophen concentration is essential for studying the metabolic status of acetaminophen in clinical practice.In this study,nickel phosphide was used for electrochemical detection of acetaminophen for the first time.