Synergetic bimetallic catalysts:A remarkable platform for efficient conversion of CO_(2) to high value-added chemicals

Carbon dioxide reduction reaction(CO_(2)RR) represents an efficient approach to achieving carbon neutrality and simultaneously generating clean energy.However,the strong stability of CO_(2) molecules and the diversity of products pose significant challenges.As an emerging material,bimetallic catalysts have been widely reported for their unique advantages,such as tunable electronic structures,suitable adsorption/desorption of CO_(2) and intermediates,and optimizable d-band centers of active sites through bimetallic synergy.These catalysts provide a remarkable platform for converting CO_(2) into high value-added chemicals.This review comprehensively summarizes recent research advances in bimetallic catalysts for CO_(2)RR.Firstly,the challenges associated with CO_(2)RR,including activity and selectivity are analyzed,followed by a discussion on the unique advantages of bimetallic catalysts.Next,their synthesis strategies are categorized into dual-atom site catalysts(DACs),bimetallic nanoparticles and nanoclusters,binary metal semiconductors,and layered double hydroxides(LDHs).Additionally,advanced characterization techniques of bimetallic catalysts and their applications in CO_(2)RR are thoroughly introduced.Finally,the prospects and challenges for the application of bimetallic materials are highlighted.This review aims to provide inspiration for CO_(2)RR into high-value chemicals and shed light on the research of bimetallic materials.

Single‑Atom Cobalt‑Based Electrochemical Biomimetic Uric Acid Sensor with Wide Linear Range and Ultralow Detection Limit

Uric acid(UA)detection is essential in diagnosis of arthritis,preeclampsia,renal disorder,and cardiovascular diseases,but it is very challenging to realize the required wide detection range and low detection limit.We present here a single-atom catalyst consisting of Co(Ⅱ)atoms coordinated by an average of 3.4 N atoms on an N-doped graphene matrix(A-Co-NG)to build an electrochemical biomimetic sensor for UA detection.The A-Co-NG sensor achieves a wide detection range over 0.4-41,950μM and an extremely low detection limit of 33.3±0.024 nM,which are much better than previously reported sensors based on various nanostructured materials.Besides,the A-Co-NG sensor also demonstrates its accurate serum diagnosis for UA for its practical application.Combination of experimental and theoretical calculation discovers that the catalytic process of the A-Co-NG toward UA starts from the oxidation of Co species to form a Co^3+-OH-UA*,followed by the generation of Co^3+-OH+^*UA_H,eventually leading to N-H bond dissociation for the formation of oxidized UA molecule and reduction of oxidized Co^3+to Co^2+for the regenerated A-Co-NG.This work provides a promising material to realize UA detection with wide detection range and low detection limit to meet the practical diagnosis requirements,and the proposed sensing mechanism sheds light on fundamental insights for guiding exploration of other biosensing processes.

Curtailing Carbon Usage with Addition of Functionalized NiFe2O4 Quantum Dots:Toward More Practical S Cathodes for Li-S Cells

Smartcombination of manifold carbonaceous materials with admirable functionalities(like full of pores/functional groups,high specific surface area) is still a mainstream/preferential way to address knotty issues of polysulfides dissolution/shuttling and poor electrical conductivity for S-based cathodes.However,extensive use of conductive carbon fillers in cell designs/technology would induce electrolytic overconsumption and thereby shelve high-energy-density promise of Li-S cells.To cut down carbon usage,we propose the incorporation of multi-functionalized NiFe2O4 quantum dots(QDs) as affordable additive substitutes.The total carbon content can be greatly curtailed from 26%(in traditional S/C cathodes) to a low/commercial mass ratio(~5%).Particularly,note that NiFe2O4 QDs additives own superb chemisorption interactions with soluble Li2Sn molecules and proper catalytic features facilitating polysulfide phase conversions and can also strengthen charge-transfer capability/redox kinetics of overall cathode systems.Benefiting from these intrinsic properties,such hybrid cathodes demonstrate prominent rate behaviors(decent capacity retention with ~526 mAh g^-1 even at 5 A g^-1) and stable cyclic performance in LiNO3-free electrolytes(only ~0.08% capacity decay per cycle in 500 cycles at 0.2 A g^-1).This work may arouse tremendous research interest in seeking other alternative QDs and offer an economical/more applicable methodology to construct low-carbon-content electrodes for practical usage.

Labyrinth maze-like long travel-reduction of sulfur and polysulfides in micropores of a spherical honeycomb carbon to greatly confine shuttle effects in lithium-sulfur batteries

Polysulfide absorption in a micropore-rich structure has been reported to be capable of efficiently confining the shuttle effect for high-performance lithium-sulfur(Li–S)batteries.Here,a labyrinth maze-like spherical honeycomb-like carbon with micropore-rich structure was synthesized,which is employed as a template host material of sulfur to study the shuttle effects.The results strongly confirm that a diffusion controlled process rather than an absorption resulted surface-controlled process occurs in an even micropore-rich cathode but still greatly inhibits the shuttle effect.Thus,the battery achieves a high initial discharge specific capacity of 1120 mAh g1 at 0.25 C and super cycling stability for 1635 cycles with only 0.035%capacity decay per cycle with 100%Coulombic efficiency.We would like to propose a new mechanism for shuttle effect inhibition in micropores.In terms of the diffusion control process in microporous paths of a labyrinth maze structure,polysulfides experience a long travel to realize continuous reductions of sulfur and polysulfides until formation of the final solid product.This efficiently prevents the polysulfides escaping to electrolyte.The labyrinth maze-like honeycomb structure also offers fast electron transfer and enhanced mass transport as well as robust mechanical strength retaining intact structure for long cycle life.This work sheds lights on new fundamental insights behind the shuttle effects with universal significance while demonstrating prominent merits of a robust labyrinth maze-like structure in high performance cathode for high-performance Li–S batteries.

Create Rich Oxygen Defects of Unique Tubular Hierarchical Molybdenum Dioxide to Modulate Electron Transfer Rate for Superior High-Energy Metal-Ion Hybrid Capacitor

Metal-ion capacitors could merit advantages from both batteries and capacitors,but they need to overcome the severe restrictions from their sluggish reaction kinetics of the battery type electrode and low specific capacitance of capacitor type electrode for both high energy and power density.Herein,we use the Kirkendall effect for the first time to synthesize unique tubular hierarchical molybdenum dioxide with encapsulated nitrogen-doped carbon sheets while in situ realizing phosphorus-doping to create rich oxygen vacancies(P-MoO_(2-x)@NP-C)as a sodium-ion electrode.Experimental and theoretical analysis confirm that the P-doping introduced oxygen defects can partially convert the high-bond-energy Mo–O to low-bond-energy Mo–P,resulting in a low oxidation state of molybdenum for enhanced surface reactivity and rapid reaction kinetics.The as-prepared P-MoO_(2-x)@NP-C as an ion-battery electrode is further used to pair active N-doped carbon nanosheet(N-C-A)electrode for Na-ion hybrid capacitor,delivering excellent performance with an energy density of 140.3 Wh kg^(−1),a power density of 188.5 W kg^(−1)and long stable life in non-aqueous solution,which ranks the best among all reported MoO x-based hybrid capacitors.P-MoO_(2-x)@NP-C is also used to fabricate a zinc-ion hybrid capacitor,also accomplishing a remarkable energy density of 43.8 Wh kg^(−1),a power density of 93.9 W kg^(−1),and a long stable life@2A g^(−1)of 32000 cycles in aqueous solutions,solidly verifying its universal significance.This work not only demonstrates an innovative approach to synthesize high-performance metal ion hybrid capacitor materials but also reveals certain scientific insights into electron transfer enhancement mechanisms.

Mesoporous molybdenum carbide for greatly enhanced hydrogen evolution at high current density and its mechanism studies

Currently the catalysis of hydrogen evolution reaction(HER)is mainly focused on the inherent electrocatalytic activity at relatively lower current densities while scarce at high current densities.Nevertheless,the latter is highly demanding in efficient mass-production of hydrogen.A SiO_(2) nanospheres template-synthesis is used to prepare mesoporous molybdenum carbide nanocrystals-embedded nitrogen-doped carbon foams(mp-Mo_(2)C/NC).The material shows much more excellent catalytic activity than the non-etched Mo_(2)C/NC toward hydrogen evolution reaction(HER)in acidic medium.More interestingly mp-Mo_(2)C/NC still has larger overpotential than Pt/C at lower current densities,but possess remarkably smaller overpotential than the latter at higher current densities for much better electrocatalytic performance.An approach is developed to investigate the electrode kinetics by Tafel plots,especially with eliminating the diffusion effect,indicating that Pt/C and mp-Mo_(2)C/NC display different reaction mechanisms.At low current densities the former presents reversible reaction,while the latter shows mixed electrochemical polarization/reversible electrode process.In the region of higher current densities,the former becomes totally gas-diffusion controlled with large overpotential,while the latter can still retain an electrode polarization process for much lower overpotential at the same current density.Result endorses that the meso-porously structured mp-Mo_(2)C/NC plays a critical role in avoiding gas diffusion control-resulting large overpotential at high current densities.This work holds great potential for an inexpensive catalyst better than Pt/C in practical applications of mass-production hydrogen at high current densities,while clearly shedding fundamental lights on designs of rational HER catalysts for the uses at high current densities.

Recent progress in electrochemical synthesis of carbon-free hydrogen carrier ammonia and ammonia fuel cells:A review

Ammonia(NH3)is a cornerstone widely used in the modern agriculture and industry,the annual global production gradually increases to almost 200 million tons.Nearly 80%of the produced NH3 is used in the fertilizer industry and is essential for the development of global agriculture and consequently for maintaining population growth.Furthermore,NH3 can power hydrogen(H2)fueled devices,such as H2 fuel cells(FC),to use the interconversion between chemical energy and electric energy of nitrogen(N2)cycle,which can effectively alleviate the intermittent problems of renewable energy.However,the problems faced by NH3 in storage and release still restrict its development.Herein,this review introduces the latest research and development of electrochemical NH3 synthesis and direct NH3 FC,as well as outlines the technical challenges,possible improvement measures and development perspectives.N2 reduction reaction(NRR)and nitrate reduction reaction(NO3RR)are two potential approaches for electrochemical NH3 synthesis.However,the existing research foundation still faces challenges in achieving high selectivity and efficiency.Direct NH3 FC are easy to transport and are expected to be widely used in mobile energy consuming equipment,but also limited by the lack of highly active and stable NH3 oxidation electrocatalysts.The perspectives of ammonia fuel cells as an alternative green energy are discussed.

Versatile and Low-cost Microfluidic Complement Fixation Combining with Luminol Chemiluminescence for rapid and sensitive Diseases Biomarker Detection

The complement fixation test(CFT)is a serological test that can be used to detect the presence of either specific antibody or antigen to diagnose infections,particularly with microbes that are not easily detected by culture methods.In the study,a polydimethylsiloxane(PDMS)/glass slide hybrid microfluidic device was firstly developed to manipu-

2-D/2-D heterostructured biomimetic enzyme by interfacial assembling Mn_(3)(PO_(4))_(2) and MXene as a flexible platform for realtime sensitive sensing cell superoxide

It is critical for fabricating flexible biosensors with both high sensitivity and good selectivity to realize real-time monitoring superoxide anion(O_(2)^(·−)),a specific reactive oxygen species that plays critical roles in various biological processes.This work delicately designs a Mn_(3)(PO_(4))_(2)/MXene heterostructured biomimetic enzyme by assembling two-dimensional(2-D)Mn_(3)(PO_(4))_(2) nanosheets with biomimetic activity and 2-D MXene nanosheets with high conductivity and abundant functional groups.The 2-D nature of the two components with strong interfacial interaction synergistically enables the heterostructure an excellent flexibility with retained 100%of the response when to reach a bending angle up to 180°,and 96%of the response after 100 bending/relaxing cycles.It is found that the surface charge state of the heterostructure promotes the adsorption of O_(2)^(·−),while the high-energy active site improves electrochemical oxidation of O_(2)^(·−).The Mn_(3)(PO_(4))_(2)/MXene as a sensing platform towards O2•−achieves a high sensitivity of 64.93µA·µM^(−1)·cm^(−2),a wide detection range of 5.75 nM to 25.93µM,and a low detection limit of 1.63 nM.Finally,the flexible heterostructured sensing platform realizes real-time monitoring of O_(2)^(·−)in live cell assays,offering a promising flexible biosensor towards exploring various biological processes.

Elevating kinetics of passivated Fe anodes with NH_(4)Cl regulator:Toward low-cost,long-cyclic and green cathode-free Fe-ion aqueous batteries

The environment benignity and battery cost are major concerns for grid-scale energy storage applications.The emerging dendrite-free Fe-ion aqueous batteries are promising due to the rich natural abundance,low cost and non-toxicity for Fe resources.However,serious passivation reactions on Fe anodes and poor long-term cyclability for matched cathodes still stand in the way for their practical usage.To settle above constraints,we herein use NH_(4)Cl as the electrolyte regulator to elevate the reaction kinetics of passivated Fe anodes,and also propose a special cathode-free design to prolong the cells lifetime over 1,000 cycles.The added NH_(4)Cl can erode/break inert passivation layers and strengthen the ion conductivity of electrolytes,facilitating the reversible Fe plating/stripping and Fe^(2+)shuttling.The highly puffed nano carbon foams function as current collectors and actives anchoring hosts,enabling expedite Fe^(2+)adsorption/desorption,FeII/FeIII redox conversions and FeIII deposition.The configured rocking-chair Fe-ion cells have good environmental benignity and decent energy-storage behaviors,including high reactivity/reversibility,outstanding cyclic stability and far enhanced operation longevity.Such economical,long-cyclic and green cathode-free Fe-ion batteries may hold great potential in near-future energy-storage power stations.

Recent advances of high performance SiOx(0

SiOx is attractive as an anode material for lithium-ion batteries(LIBs)due to its high capacity,low cost,and relatively higher cyclic stability than Si anode.However,the intrinsic low electronic conductivity,low initial coulombic efficiency(ICE),and volume expansion during cycles hinder its applications.In this review,we summarize advances in high performance SiOx anodes,mainly from two aspects:active material and binders.The future perspective is investigated at the end of this review.Our review provides strategical guidance for developing high performance SiOx anodes.

应用微束质子激发X荧光分析研究Ca和S在头发中的分布模式

应用微束质子激发X荧光分析研究了20余根来自几个成年中国人头发中的Ca和S的分布模式.成年女性头发S含量沿生长方向呈月周期的变化,而Ca含量在男女性生长期头发的中间层均明显偏高且呈现出昼夜周期.Ca的含量在脱落头发中从末梢到根部是逐渐降低的,而且黑头发中的Ca含量显著高于白头发中.

Mechanisms of water oxidation on heterogeneous catalyst surfaces

Water oxidation,an essential step in photosynthesis,has attracted intense research attention.Understanding the reaction pathways at the electrocatalyst/water interface is of great importance for the development of water oxidation catalysts.How the water is oxidized on the electrocatalyst surface by the positive charges is still an open question.This review summarizes current advances in studies on surface chemistry within the context of water oxidation,including the intermediates,reaction mechanisms,and their influences on the reaction kinetics.The Tafel analyses of some electrocatalysts and the rate-laws relative to charge consumption rates are also presented.Moreover,how the multiple charge transfer relies on the intermediate coverage and the accumulated charge numbers is outlined.Lastly,the intermediates and rate-determining steps on some water oxidation catalysts are discussed based on density functional theories.