Tailored deep-eutectic solvent method to enable 3D porous iron fluoride bricks for conversion-type lithium batteries

Conversion-type fluoride cathode can provide considerable energy density for Li batteries,however its scalable and facile synthesis strategies are still lacking.Here,a novel Fe-based deep eutectic solvent composed of nitrite and methylsulfonylmethane is proposed as both the reaction medium and precursor to synthesize O-doped FeF3porous bricks.This method is cheaper,safe,mildly operable,environmentally friendly and recyclable for non-fluorinated metal cations.The homogenization of charge and mass transport in cathode network effectively mitigates the volume extrusion and electrode coarsening even for the micro-sized monolithic particles.The Co-solvation modulated fluoride cathode delivers high reversible capacity in a wide temperature range(486 and 235 mA h g^(-1)at 25℃ and-20℃ respectively),excellent rate performance(312 mA h g^(-1)at 1000 mA g^(-1)),corresponding to an energy density as high as672.1 W h kg^(-1)under a power density of 2154.3 W kg^(-1).The successful operation of fluoride pouchcell with a capacity exceeding 450 mA h g^(-1)(even under thin Li foil and lean electrolyte conditions) indicates its potentiality of commercial application.

Highly efficient and selective photocatalytic dehydrogenation of benzyl alcohol for simultaneous hydrogen and benzaldehyde production over Ni-decorated Zn_(0.5)Cd_(0.5)S solid solution

Photocatalytic conversion of solar energy into hydrogen and high value-added fine chemicals has attracted increasing attention. Herein, we demonstrate an efficient photocatalytic system for simultaneous hydrogen evolution and benzaldehyde production by dehydrogenation of benzyl alcohol over Nidecorated Zn_(0.5)Cd_(0.5)S solid solution under visible light. The photocatalytic system shows an excellent hydrogen production rate of 666.3 μmol h^(-1) with high stability. The optimal apparent quantum yield of52.5% is obtained at 420 nm. This noble-metal-free photocatalytic system displays much higher activity than pure Zn_(0.5)Cd_(0.5)S and Pt-loaded Zn_(0.5)Cd_(0.5)S solid solution. Further studies reveal that the metallic Ni nanocrystals play an important role in accelerating the separation of photogenerated charge carriers and the subsequent cleavage of α-C–H bond during dehydrogenation of benzyl alcohol.

Preparation of dense Ta-LLZO/MgO composite Li-ion solid electrolyte:Sintering, microstructure, performance and the role of MgO

Cubic phase Li7La3Zr2O12(LLZO),a member of the Li–Garnet family,is a promising solid electrolyte and has been widely studied in recent years.However,LLZO samples prepared via conventional ambient air sintering reported in the published literature often contain large grains with lower than desired(<94%)relative density.In this study,a non-contact method of co-firing with mother powder method is proposed to prepare high-quality Ta-doped LLZO–MgO composite ceramics.By sintering at 1150℃for 5 h,the ceramics can reach relative density of 98.2%,conductivity of 5.17×10^-4 S cm^-1 at 25℃and fracture strength of 150 MPa.The sintered samples have uniform fine-grained microstructure and high critical current densities of 0.75–0.95 mA cm-2 at room temperature in Li–Li symmetry cell with Au modification.In addition,systematic sintering experiments and characterizations are conducted to explore the function of MgO in inhibiting the Ta-LLZO grain growth and its existing form inside the composite ceramics.

Carbon materials for stable Li metal anodes: Challenges, solutions, and outlook

Lithium(Li)metal is regarded as the ultimate anode for next-generation Li-ion batteries due to its highest specific capacity and lowest electrochemical potential.However,the Li metal anode has limitations,including virtually infinite volume change,nonuniform Li deposition,and an unstable electrode-electrolyte interface,which lead to rapid capacity degradation and poor cycling stability,significantly hindering its practical application.To address these issues,intensive efforts have been devoted toward accommodating and guiding Li deposition as well as stabilizing the interface using various carbon materials,which have demonstrated excellent effectiveness,benefiting from their vast variety and excellent tunability of the structure-property relationship.This review is intended as a guide through the fundamental challenges of Li metal anodes to the corresponding solutions utilizing carbon materials.The specific functionalities and mechanisms of carbon materials for stabilizing Li metal anodes in these solutions are discussed in detail.Apart from the stabilization of the Li metal anode in liquid electrolytes,attention has also been paid to the review of anode-free Li metal batteries and solid-state batteries enabled by strategies based on carbon materials.Furthermore,we have reviewed the unresolved challenges and presented our outlook on the implementation of carbon materials for stabilizing Li metal anodes in practical applications.

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.

Bifunctional TiO2 Catalysts for Efficient Cr（VI） Photoreduction Under Solar Light Irradiation Without Addition of Acids

Bifunctional TiO2 光催化剂与氮和硫共同做被铵 titanyl 硫酸盐的控制热分解准备先锋。他们举办 photocatalytic 活动和 Br ? nsted 酸味，并且没有酸的增加，因此在太阳的轻照耀下面在 Cr (VI ) 的光致还原是活跃的。这项活动比在在 H2SO4 调整的一样的 pH 的酸化的暂停的 Degussa P25 的优异。

Revisiting the Role of Physical Confinement and Chemical Regulation of 3D Hosts for Dendrite-Free Li Metal Anode

Lithium metal anode has been demonstrated as the most promising anode for lithium batteries because of its high theoretical capacity,but infinite volume change and dendritic growth during Li electrodeposition have prevented its practical applications.Both physical morphology confinement and chemical adsorption/diffusion regulation are two crucial approaches to designing lithiophilic materials to alleviate dendrite of Li metal anode.However,their roles in suppressing dendrite growth for long-life Li anode are not fully understood yet.Herein,three different Ni-based nanosheet arrays(NiO-NS,Ni_(3)N-NS,and Ni_(5)P_(4)-NS)on carbon cloth as proof-of-concept lithiophilic frame-works are proposed for Li metal anodes.The two-dimensional nanoarray is more promising to facilitate uniform Li^(+)flow and electric field.Compared with the NiO-NS and the Ni_(5)P_(4)-NS,the Ni_(3)N-NS on carbon cloth after reacting with molten Li(Li-Ni/Li_(3)N-NS@CC)can afford the strongest adsorption to Li+and the most rapid Li+diffusion path.Therefore,the Li-Ni/Li_(3)N-NS@CC electrode realizes the lowest overpotential and the most excellent electrochemical performance(60 mA cm^(−2)and 60 mAh cm^(−2)for 1000 h).Furthermore,a remarkable full battery(LiFePO_(4)||Li-Ni/Li_(3)N-NS@CC)reaches 300 cycles at 2C.This research provides valuable insight into designing dendrite-free alkali metal batteries.

NS codoped carbon nanorods as anode materials for high-performance lithium and sodium ion batteries

NS codoped carbon nanorods(NS-CNRs) were prepared using crab shell as template and polyphenylene sulfide(PPS) as both the C and S precursor, followed by carbonization in NH_3. The as-obtained NS-CNRs had a diameter of ~50 nm, length of several micrometers, and N and S contents of 12.5 at.% and 3.7 at.%,respectively, which can serve as anodes for both lithium-ion batteries(LIBs) and sodium ion batteries(SIBs). When serving as an anode of LIB, the NS-CNRs delivered gravimetric capacities of 2154 mAh g^(-1)at current densities of 0.1 A g^(-1)and 625 mAh g^(-1)at current densities of 5.0 A g^(-1)for 1000 cycles.When serving as an anode of SIB, the NS-CNRs delivered gravimetric capacities of 303 mAh g^(-1)at current densities of 0.1 A g^(-1)and 230 mAh g^(-1)at current densities of 1.0 A g^(-1)for 3000 cycles. The excellent electrochemical performance of NS-CNRs could be ascribed to the one-dimensional nanometer structure and high level of heteroatom doping. We expect that the obtained NS-CNRs would benefit for the future development of the doped carbon materials for lithium ion batteries and other extended applications such as supercapacitor, catalyst and hydrogen storage.

Morphology-dependent structures and catalytic performances of Au nanostructures on Cu_2O nanocrystals synthesized by galvanic replacement reaction

Au nanostructures were prepared on uniform Cu_2O octahedra and rhombic dodecahedra via the galvanic replacement reaction between HAu Cl4 and Cu2O. The compositions and structures were studied by Scanning Electron Microscope(SEM), Transmission Electron Microscope(TEM), High-Resolution Transmission Electron Microscope(HRTEM), X-Ray Diffraction(XRD), X-Ray Absorption Spectroscopy(XAS), X-ray Photoelectron Spectroscopy(XPS) and in-situ DRIFTS spectroscopy of CO adsorption. Different from the formation of Au–Cu alloys on Cu_2O cubes by the galvanic replacement reaction(Chem Nano Mat 2(2016)861-865), metallic Au particles and positively-charged Au clusters form on Cu_2O octahedra and rhombic dodecahedra at very small Au loadings and only metallic Au particles form at large Au loadings. Metallic Au particles on Cu_2O octahedra and rhombic dodecahedra are more active in catalyzing the liquid phase aerobic oxidation reaction of benzyl alcohol than positively-charged Au clusters. These results demonstrate an obvious morphology effect of Cu_2O nanocrystals on the liquid–solid interfacial reactions and prove oxide morphology as an effective strategy to tune the surface reactivity and catalytic performance.

Molecular Engineering Design for High-Performance Aqueous Zinc-Organic Battery

Novel small sulfur heterocyclic quinones(6a,16adihydrobenzo[b]naphtho[2′,3′:5,6][1,4]dithiino[2,3-i]thianthrene-5,7,9,14,16,18-hexaone(4S6Q)and benzo[b]naphtho[2′,3′:5,6][1,4]dithiino[2,3-i]thianthrene-5,9,14,18-tetraone(4S4Q))are developed by molecule structural design method and as cathode for aqueous zincorganic batteries.The conjugated thioether(–S–)bonds as connected units not only improve the conductivity of compounds but also inhibit their dissolution by both extendedπ-conjugated plane and constructed flexible molecular skeleton.Hence,the Zn//4S6Q and Zn//4S4Q batteries exhibit satisfactory electrochemical performance based on 3.5 mol L-1(M)Zn(ClO4)2electrolyte.For instance,the Zn//4S6Q battery obtains 240 and 208.6 mAh g^(-1)of discharge capacity at 150 mA g^(-1)and 30 A g^(-1),respectively.The excellent rate capability is ascribed to the fast reaction kinetics.This system displays a superlong life of 20,000 cycles with no capacity fading at 3 A g^(-1).Additionally,the H+-storage mechanism of the 4S6Q compound is demonstrated by ex situ analyses and density functional theory calculations.Impressively,the battery can normally work at-60℃benefiting from the anti-freezing electrolyte and maintain a high discharge capacity of 201.7 mAh g^(-1),which is 86.2%of discharge capacity at 25℃.The cutting-edge electrochemical performances of these novel compounds make them alternative electrode materials for Zn-organic batteries.

Facile deposition of cobalt oxide based electrocatalyst on low-cost and tin-free electrode for water splitting

Facile deposition of a water-splitting catalyst on low-cost electrode materials could be attractive for hydrogen production from water and solar energy conversion. Herein we describe fast electrodeposition of cobalt-based water oxidation catalyst(Co-WOC) on simple graphite electrode for water splitting. The deposition process is quite fast, which reaches a plateau in less than 75 min and the final current density is～1.8 mA/cm2under the applied potential of 1.31 V at pH = 7.0. The scanning electron microscopy(SEM) study shows the formation of nanometer-sized particles(10-100 nm) on the surface of the electrode after only 2 min and micrometer-sized particles(2-5 μm) after 90 min of electrolysis. X-ray photoelectron spectroscopy(XPS) data demonstrate the as-synthesized ex-situ catalyst mainly contains Co2+and Co3+species incorporating a substantial amount of phosphate anions. These experiments suggest that cost-efficient cobalt oxide materials on graphite exhibit alluring ability for water splitting, which might provide a novel method to fabricate low-cost devices for electrochemical energy storage.

High-Performance Chemical Information Database towards Accelerating Discovery of Metal-Organic Frameworks for Gas Adsorption with Machine Learning

Chemical structure searching based on databases and machine learning has at-tracted great attention recently for fast screening materials with target func-tionalities.To this end,we estab-lished a high-performance chemical struc-ture database based on MYSQL engines,named MYDB.More than 160000 metal-organic frameworks(MOFs)have been collected and stored by using new retrieval algorithms for effcient searching and recom-mendation.The evaluations results show that MYDB could realize fast and effcient key-word searching against millions of records and provide real-time recommendations for similar structures.Combining machine learning method and materials database,we developed an adsorption model to determine the adsorption capacitor of metal-organic frameworks to-ward argon and hydrogen under certain conditions.We expect that MYDB together with the developed machine learning techniques could support large-scale,low-cost,and highly convenient structural research towards accelerating discovery of materials with target func-tionalities in the eld of computational materials research.

A robust fluorine-containing ceramic cathode for direct CO_(2) electrolysis in solid oxide electrolysis cells

Stro ntium-doped lanthanum ferrite(LSF)is a potential ceramic cathode for direct CO_(2) electrolysis in solid oxide electrolysis cells(SOECs),but its application is limited by insufficient catalytic activity and stability in CO_(2)-containing atmospheres.Herein,a novel strategy is proposed to enhance the electrolytic performance as well as chemical stability,achieved by doping F into the O-site of the perovskite LSF.Doping F does not change the phase structure but reduces the cell volume and improves the chemical stability in a CO_(2)-rich atmosphere.Importantly,F doping favors oxygen vacancy formation,increases oxygen vacancy concentration,and enhances the CO_(2) adsorption capability.Meanwhile,doping with F greatly improves the kinetics of the CO_(2) reduction reaction.For example,kchem increases by 78%from3.49×10^(-4) cm s^(-1) to 6.24×10^(-4) cm s^(-1),and Dchem doubles from 4.68×10^(-5) cm^(2) s^(-1) to 9.45×10^(-5)cm^(2) s^(-1).Consequently,doping F significantly increases the electrochemical performance,such as reducing R_(p) by 52.2%from 0.226Ωcm^(2) to 0.108Ωcm^(2) at 800℃.As a result,the single cell with the Fcontaining cathode exhibits an extremely high current density of 2.58 A cm^(-2) at 800℃and 1.5 V,as well as excellent durability over 200 h for direct CO_(2) electrolysis in SOECs.

Unraveling abnormal buried interface anion defect passivation mechanisms depending on cation-induced steric hindrance for efficient and stable perovskite solar cells

Although ionic liquids(ILs)have been widely employed to heal the defects in perovskite solar cells(PSCs),the corresponding defect passivation mechanisms are not thoroughly understood up to now.Herein,we first reveal an abnormal buried interface anion defect passivation mechanism depending on cationinduced steric hindrance.The IL molecules containing the same anion([BF4]^(-))and different sizes of imidazolium cations induced by substituent size are used to manipulate buried interface.It was revealed what passivated interfacial defects is mainly anions instead of cations.Theoretical and experimental results demonstrate that the large-sized cations can weaken the ionic bond strength between anions and cations,and facilitate the interaction between anions and SnO2as well as perovskites,which is conducive to interfacial defect passivation and ameliorating interfacial contact.It can be concluded that interfacial chemical interaction strength and defect passivation effect are positively correlated with the size of cations.The discovery breaks conventional thinking that large-sized modification molecules would weaken their chemical interaction with perovskite.Compared with the control device(21.54%),the device based on 1,3-Bis(1-adamantyl)-imidazolium tetrafluoroborate(BAIMBF4)with maximum size cations achieves a significantly enhanced efficiency of 23.61%along with much increased moisture,thermal and light stabilities.

Filterless narrowband photodetectors enabled by controllable band modulation through ion migration: The case of halide perovskites

Narrowband photodetectors conventionally rely on optical structure design orbandpass filters to achieve the narrowband regime. Recently, a strategy forfilterless narrowband photoresponse based on the charge collection narrowing(CCN) mechanism was reported. However, the CCN strategy requires an electrically and optically “thick” photoactive layer, which poses challenges in controlling the narrowband photoresponse. Here we propose a novel strategy forconstructing narrowband photodetectors by leveraging the inherent ion migration in perovskites, which we term “band modulation narrowing” (BMN). Bymanipulating the ion migration with external stimuli such as illumination,temperature, and bias voltage, we can regulate in situ the energy-band structure of perovskite photodetectors (PPDs) and hence their spectral response.Combining the Fermi energy levels obtained by the Kelvin probe force microscopy, the internal potential profiles from solar cell capacitance simulator simulation, and the anion accumulation revealed by the transient ion-drifttechnique, we discover two critical mechanisms behind our BMN strategy: theextension of an optically active but electronically dead region proximal to the top electrode and the down-bending energy bands near the electron transportlayer. Our findings offer a case for harnessing the often-annoying ionmigration for developing advanced narrowband PPDs.

Oxygen vacancy stabilized Bi_(2)O_(2)CO_(3)nanosheet for CO_(2)electroreduction at low overpotential enables energy efficient CO-production of formate

Bismuth-based electrocatalysts are promising candidates for electrochemical CO_(2)reduction to formate attributing to the accelerated formation of*OCHO intermediate,while the high-energy consumption remains a major challenge for practicability.Herein,we present the ultrathin Bi_(2)O_(2)CO_(3)nanosheets with abundant oxygen vacancy(Vo-BOC-NS)reconstructed from S,N-co-doped bismuth oxides that can act as durable electrocatalyst for CO_(2)-to-formate conversion with faradic efficiency(FEformate)of>95%,partial current density of 286 mA cm^(-2) with energy efficiency of 73.8%at-0.62 V(vs.RHE)and low overpotential of 200 mV in a flow electrolyzer.The theoretical calculations decipher that the oxygen vacancy can optimize*OCOH adsorption/desorption for the accelerated conversion kinetics.The pair-electrosynthesis tactic of formate co-production can enable a superior FE_(formate) of>90%at wide cell voltage of 2–3.3 V and total yield rate of 3742μmol cm^(-2)h^(-1)at 3.3 V,suggesting great potential for future industrialization.

Nanosheet-structured K–Co–MoS_2 catalyst for the higher alcohol synthesis from syngas: Synthesis and activation

The nanosheets structured K–Co–MoS_2 catalyst was prepared through a one-step hydrothermal synthesis combined with the wetness impregnation. The fresh catalyst has a high dispersion of Co–Mo–S active phase and no Co_9S_8 is found. The pure H_2 activated catalyst shows a higher intrinsic activity, especially the C_(2+) OH selectivity for the higher alcohol synthesis compared to the one activated by 5% H_2/N_2 atmosphere. The reason is attributed to that the pure H_2 activation more effectively suppresses the formation of Co_9S_8 and stabilizes the Co–Mo–S active phase during the reaction due to the formation of SH species.

A multi-layered Ti3C2/Li2S composite as cathode material for advanced lithium-sulfur batteries

Lithium-sulfur(Li-S)batteries with lithium sulfide(Li2S)as cathode have attracted great attention recently,because of high specific capacity(1166 mA h g^-1)of Li2S and potential safety of using Li metal-free anode.Li2S cathode has lower volume expansion and higher thermal stability than the traditional sulfur cathode.However,the problems of"shuttle effect"and poor electrical conductivity of the cathode material still need to be overcome.In this work,multi-layered Ti3C2/Li2S(ML-Ti3C2/Li2S)composite has been prepared and applied as a cathode in advanced Li-S batteries.The unique multi-layer sheet structure of Ti3 C2 provides space for the storage of Li2S,and its good conductivity greatly enhances the usage ratio of Li2 S and improves the conductivity of the whole Li2S cathode.Compared with commonly used graphene,ML-Ti3C2 can trap polysulfides effectively by chemical adsorption and also activate the reaction of Li2S to polysulfides by forming Ti-S bond.As a result,during the cycling of the batteries with ML-Ti3C2/Li2S cathodes,the activation voltage barrier of the first cycle has decreased to 2.8 V,and the"shuttle effect"has been suppressed effectively.The cycling and rate performances of the ML-Ti3C2/Li2S cathodes have been significantly improved compared to that of graphene/Li2 S cathodes.They maintain a capacity of 450 mAh g^-1 at 0.2 C after 100 cycles,and deliver attractive rate performances of 750,630,540,470 and 360 mAh g^-1 at 0.1 C,0.2 C,0.5 C,1 C,and 2 C,respectively.

A molecular cobaloxime cocatalyst and ultrathin FeOOH nanolayers co-modifiedBiVO_(4) photoanode for efficient photoelectrochemical water oxidation

BiVO_(4) has been attracting a lot of interest in photoelectrochemical (PEC) water oxidation due to its efficient solar absorption and appropriate band positions.So far,sluggish water oxidation kinetics and fast photogenerated charge recombination still hinder the PEC performance ofBiVO_(4) .In this study,a novel PEC photoanode was designed by depositing ultrathin FeOOH nanolayers on the surface of nanoporousBiVO_(4) electrode,followed by modification with a cobaloxime (Co(dmgH)_(2)(4-COOH-py)Cl) molecular cocatalyst.Under irradiation of a 100 mW cm^(-2)(AM 1.5G) Xe lamp,the photocurrent density of the cobaloxime/FeOOH/BiVO_(4) composite photoanode reached 5.1 mA cm^(-2)at 1.23 V vs.RHE in 1.0 M potassium borate buffer solution (pH=9.0).The onset potential of the optimal cobaloxime/FeOOH/BiVO_(4) photoanode exhibited a 460 m V cathodic shift relative to bareBiVO_(4) .In addition,the surface charge injection efficiency of the composite photoanode reached~80%at 1.23 V vs.RHE and the incident photon-to-current efficiency (IPCE) reached~88%at 420 nm.