Dilute Aqueous-Aprotic Electrolyte Towards Robust Zn-Ion Hybrid Supercapacitor with High Operation Voltage and Long Lifespan

With the merits of the high energy density of batteries and power density of supercapacitors,the aqueous Zn-ion hybrid supercapacitors emerge as a promising candidate for applications where both rapid energy delivery and moderate energy storage are required.However,the narrow electrochemical window of aqueous electrolytes induces severe side reactions on the Zn metal anode and shortens its lifespan.It also limits the operation voltage and energy density of the Zn-ion hybrid supercapacitors.Using'water in salt'electrolytes can effectively broaden their electrochemical windows,but this is at the expense of high cost,low ionic conductivity,and narrow temperature compatibility,compromising the electrochemical performance of the Zn-ion hybrid supercapacitors.Thus,designing a new electrolyte to balance these factors towards high-performance Zn-ion hybrid supercapacitors is urgent and necessary.We developed a dilute water/acetonitrile electrolyte(0.5 m Zn(CF_(3)SO_(3))_(2)+1 m LiTFSI-H_(2)O/AN)for Zn-ion hybrid supercapacitors,which simultaneously exhibited expanded electrochemical window,decent ionic conductivity,and broad temperature compatibility.In this electrolyte,the hydration shells and hydrogen bonds are significantly modulated by the acetonitrile and TFSI-anions.As a result,a Zn-ion hybrid supercapacitor with such an electrolyte demonstrates a high operating voltage up to 2.2 V and long lifespan beyond 120,000 cycles.

MOF-Transformed In_(2)O_(3-x)@C Nanocorn Electrocatalyst for Efficient CO_(2)Reduction to HCOOH

For electrochemical CO_(2) reduction to HCOOH,an ongoing challenge is to design energy efficient electrocatalysts that can deliver a high HCOOH current density(JHCOOH)at a low overpotential.Indium oxide is good HCOOH production catalyst but with low con-ductivity.In this work,we report a unique corn design of In_(2)O_(3-x)@C nanocatalyst,wherein In_(2)O_(3-x)nanocube as the fine grains dispersed uniformly on the carbon nanorod cob,resulting in the enhanced conductivity.Excellent performance is achieved with 84%Faradaic efficiency(FE)and 11 mA cm^(−2)JHCOOH at a low potential of−0.4 V versus RHE.At the current density of 100 mA cm^(−2),the applied potential remained stable for more than 120 h with the FE above 90%.Density functional theory calculations reveal that the abundant oxygen vacancy in In_(2)O_(3-x) has exposed more In^(3+) sites with activated electroactivity,which facilitates the formation of HCOO*intermediate.Operando X-ray absorp-tion spectroscopy also confirms In^(3+) as the active site and the key intermediate of HCOO*during the process of CO_(2) reduction to HCOOH.

Atomscopic of ripple origins for two-dimensional monolayer transition metal dichalcogenides

During the development of ultrathin two-dimensional(2D)materials,the appearance of ripples has been widely observed.However,the formation mechanisms and their influences are still rarely investigated,especially their contributions to the electronic structures and optical properties.To compensate for the knowledge gap,we have carried out comprehensive theoretical studies on the monolayer WSe_(2) with a series of ripple structures from 0 to 12Åin different lattice sizes.The sensitivity of the formation energy,band structures,electronic structures,and optical properties to the ripple structures have been performed systematically for the first time.The formation of ripples in Armchair and zigzag simultaneously are more energetically favorable,leading to more flexible optimizations of the optoelectronic properties.The improved charge-locking effect and extension of absorption ranges indicate the significant role of ripple structures.The spontaneous formation of ripples is associated with orbital rearrangements and structural distortions.This leads to the unique charge carrier correlate inversion between W-5d and Se-4p orbitals,resulting in the pinning of the Fermi level.This work has supplied significant references to understand ultrathin 2D structures and benefit their future developments and applications in high-performance optoelectronic devices.

Non-bonding modulations between single atomic cerium and monodispersed selenium sites towards efficient oxygen reduction

Currently,dual atomic catalysts(DACs)with neighboring active sites for oxygen reduction reaction(ORR)still meet lots of challenges in the synthesis,especially the construction of atomic pairs of elements from different blocks of the periodic table.Herein,a“rare earth(Ce)-metalloid(Se)”non-bonding heteronuclear diatomic electrocatalyst has been constructed for ORR by rational coordination and carbon support defect engineering.Encouraging,the optimized Ce-Se diatomic catalysts(Ce-Se DAs/NC)displayed a half-wave potential of 0.886 V vs.reversible hydrogen electrode(RHE)and excellent stability,which surpass those of separate Ce or Se single atoms and most single/dual atomic catalysts ever reported.In addition,a primary zinc-air battery constructed using Ce-Se DAs/NC delivers a higher peak power density(209.2 mW·cm^(−2))and specific capacity(786.4 mAh·gZn^(−1))than state-of-the-art noble metal catalysts Pt/C.Theoretical calculations reveal that the Ce-Se DAs/NC has improved the electroactivity of the Ce-N_(4)region due to the electron transfer towards the nearby Se specific activity(SA)sites.Meanwhile,the more electron-rich Se sites promote the adsorptions of key intermediates,which results in the optimal performances of ORR on Ce-Se DAs/NC.This work provides new perspectives on electronic structure modulations via non-bonded long-range coordination micro-environment engineering in DACs for efficient electrocatalysis.

Neighboring effect in single-atom catalysts for the electrochemical carbon dioxide reduction reaction

Although single-atom catalysts(SACs)have attracted enormous attention for their applications in the electrochemical reduction of CO_(2)(CO_(2)RR)due to their extraordinary catalytic activity and well-defined active centers,neighboring effects and their influence on the electrochemical performance of SACs have not been well investigated.In this review,we present a summary of the neighboring effects on SACs for the CO_(2)RR process,where the surrounding atoms not only induce electronic modulation of the metal atom but also participate in the CO_(2)RR.Both theoretical and experimental studies have pointed out that the neighboring sites of the anchored metal center can provide second active/adsorption locations during the catalytic process,enhancing CO_(2)RR performance tremendously.This review supplies advanced insights into the significant roles and impacts of neighboring effects on the catalytic process,which also benefit the development of advanced SACs to achieve efficient electrocatalysis.

High-Performance H_(2) Photosynthesis from Pure Water over Ru−S Charge Transfer Channels

As a versatile energy carrier,H_(2) is considered as one of the most promising sources of clean energy to tackle the current energy crisis and environmental concerns,which can be produced from photocatalytic water splitting.However,solar-driven photocatalytic H_(2) production from pure water in the absence of sacrificial reagents remains a great challenge.Herein,we demonstrate that the incorporation of Ru single atoms(SAs)into ZnIn_(2)S_(4)(Ru-ZIS)can enhance the light absorption,reduce the energy barriers for water dissociation,and construct a channel(Ru-S)for separating photogenerated electron−hole pairs,as a result of a significantly enhanced photocatalytic water splitting process.Impressively,the productivity of H_(2) reaches 735.2μmol g^(-1) h^(-1) under visible light irradiation in the absence of sacrificial agents.The apparent quantum efficiency(AQE)for H_(2) evolution reaches 7.5% at 420 nm,with a solarto-hydrogen(STH)efficiency of 0.58%,which is much higher than the value of natural synthetic plants(~0.10%).Moreover,Ru-ZIS exhibits steady productivity of H_(2) even after exposure to ambient conditions for 330 days.This work provides a unique strategy for constructing charge transfer channels to promote the separation of photogenerated electron−hole pairs,which may motivate the fundamental researches on catalyst design for photocatalysis and beyond.

Atomically dispersed indium and cerium sites for selectively electroreduction of CO_(2)to formate

Currently,single-atom combo catalysts(SACCs)for carbon dioxide reduction reaction(CO_(2)RR)to the formation of HCOOH are still very limited,especially the lanthanide-based SACCs.In this work,the novel SACCs with atomically dispersed In and Ce active sites were successfully prepared on the nitrogen-doped carbon matrix(InCe/CN).Both aberration-corrected high-angle annular dark-field scanning transmission electron microscopy(AC-HAADF-STEM)images and the extended X-ray absorption fine structure(EXAFS)spectra proved the well-isolated In and Ce atoms.The as-prepared InCe/CN shows a high Faradaic efficiency(FE)(77%)and current density of HCOOH formation(j_(HCOOH))at-1.35 V vs.reversible hydrogen electrode(RHE),much higher than the single atom catalysts.Theoretical calculations have indicated that the introduced Ce single atom sites not only significantly promote electron transfer but also optimize the In-5p orbitals towards higher selectivity towards the HCOOH formation.This work innovatively extends the design of SACCs towards the main group and Ln metals for more applications.

Strain modulation of phase transformation of noble metal nanomaterials

Noble metals have been extensively studied owing to their high chemical stability and outstanding catalytic properties in various important reactions.However,their large-scale application of noble metals is still challenged by their high expense and scarcity on the earth,as well as the yet insufficient activity to give a satisfying performance.For decades,enormous research efforts have been devoted to the nanoengineering of noble metal nanocrystals,such as the size-,composition-,shape-,and/or morphology-controlled syntheses,and impressive advances have been achieved.Meanwhile,the discovery that the crystal structure of noble metal nanocrystals also has a significant impact on their properties opened a new pathway that modulates the crystal phases of noble metals to achieve better properties.Among the feasible methods for crystal phase transformation,the presence of strain is not negligible.Strain generally has two roles:the driving force of the phase transformation and/or the origin of the distinct properties of the new crystal structure.Strain effect on noble metals has also been extensively studied due to its capability of fine-tuning the surface catalytic activity.Therefore,combining the two hot research trends together,a possible research pathway is emerging.That is,utilizing the potential synergistic effect between novel crystal phases and the subsequent lattice strain to boost the performance of noble metal nanocrystal even further.Herein,a brief summary of the currently discovered noble metal phases and strain effect and the introduction of strain related phase modulation techniques along with the catalytic applications will be presented.Finally,a brief conclusion and future perspective is given.

Stable all-solid-state Li-Te battery with Li_(3)TbBr_(6) superionic conductor

Rare-earth(RE)halide solid electrolytes(HSEs)have been an emerging research area due to their good electrochemical and mechanical properties for all-solid-state lithium batteries(ASSBs).However,only very limited types of HSEs have been reported with high performance.In this work,tens of grams of RE-HSE Li_(3)TbBr_(6)(LTbB)was synthesized by a vacuum evaporationassisted method.The as-prepared LTbB displays a high ionic conductivity of 1.7 mS·cm^(-1),a wide electrochemical window,and good formability.Accordingly,the assembled solid lithium-tellurium(Li-Te)battery based on the LTbB HSE exhibits excellent cycling stability up to 600 cycles,which is superior to most previous reports.The processes and the chemicals during the discharge/charge of Li-Te batteries have been studied by various in situ and ex situ characterizations.Theoretical calculations have demonstrated the dominant conductivity contributions of the direct[octahedral]-[octahedral]([Oct]-[Oct])pathway for Li ion migrations in the electrolyte.The Tb sites guarantee efficient electron transfer while the Li 2s orbitals are not affected during migration,leading to a low activation barrier.Therefore,this successful fabrication and application of LTbB have offered a highly competitive solution for solid electrolytes in ASSBs,indicating the great potential of RE-based HSEs in energy devices.

Ultrastable bimetallic Fe_(2)Mo for efficient oxygen reduction reaction in pH-universal applications

Iron-based nanostructures represent an emerging class of catalysts with high electroactivity for oxygen reduction reaction(ORR)in energy storage and conversion technologies.However,current practical applications have been limited by insufficient durability in both alkaline and acidic environments.In particular,limited attention has been paid to stabilizing iron-based catalysts by introducing additional metal by the alloying effect.Herein,we report bimetallic Fe_(2)Mo nanoparticles on N-doped carbon(Fe_(2)Mo/NC)as an efficient and ultra-stable ORR electrocatalyst for the first time.The Fe_(2)Mo/NC catalyst shows high selectivity for a four-electron pathway of ORR and remarkable electrocatalytic activity with high kinetics current density and half-wave potential as well as low Tafel slope in both acidic and alkaline medias.It demonstrates excellent long-term durability with no activity loss even after 10,000 potential cycles.Density functional theory(DFT)calculations have confirmed the modulated electronic structure of formed Fe_(2)Mo,which supports the electron-rich structure for the ORR process.Meanwhile,the mutual protection between Fe and Mo sites guarantees efficient electron transfer and long-term stability,especially under the alkaline environment.This work has supplied an effective strategy to solve the dilemma between high electroactivity and long-term durability for the Fe-based electrocatalysts,which opens a new direction of developing novel electrocatalyst systems for future research.

Interface synergistic effects induced multi-mode luminescence

Mechanoluminescence(ML)has become the most promising material for broad applications in display and sensing devices,in which ZnS is the most commonly studied one due to its stable and highly repetitive ML performances.In this work,we have successfully prepared the biphase ZnS on a large scale through the facile in-air molten salt protection strategy.The obtained biphase has the best ML properties,which is mainly attributed to the synergistic effects of piezo-photonic,defect,and interface dislocations.DFT calculations have confirmed that the defects activate the local S and Zn sites and reduce the energy barrier for electron transfer.The much stronger X-ray induced luminescence than the commercial scintillator is also reached.The application of ZnS particles in both papers and inks delivers superior performance.Meanwhile,ZnS particles based screen printing ink is able to directly print on paper,plastic and other carriers to form clear marks.These proposed paper and ink hold great potentials in applications of information security and anti-counterfeiting based on the multi-mode luminescence properties.This work provides a new avenue to understand and realize the high-performance multi-mode luminescence,inspiring more future works to extend on other ML materials and boosting their practical applications.

Engineering the synergistic effect of carbon dots-stabilized atomic and subnanometric ruthenium as highly efficient electrocatalysts for robust hydrogen evolution

Currently,the most efficient electrocatalyst for the hydrogen evolution reaction(HER)in water dissociation is Pt-based catalyst.Unfortunately,the high cost and less than perfect efficiency hinder wide-range industrial/technological applications.Here,by controlling the treatment temperature of tris(2,2-bipyridine)ruthenium dichloride hexahydrate,synthesis of compounds with novel ruthenium single/dual atoms(Ru S/DAs)mixed with Ru nanoclusters(Ru S/DAs+Ru NCs)and supported by carbon dots is demonstrated.These compounds are shown to be highly efficient and competitive catalysts for hydrogen evolution.Ru S/DAs+Ru NCs exhibit very high activity,with overpotentials of 15 and 40mV at a current density of 10mA/cm2 in 1.0mol/L KOH and 0.5mol/L H2SO4,respectively.Furthermore,the composites are found to possess outstanding stability and rapid HER kinetics.X ray absorption fine structure analysis,supported by density functional theory calculations,shows charge rearrangement in single-atomic Ru,and the Ru dual sites promote active hydrogen adsorption and recombination.Ru S/DAs and Ru NCs demonstrate high electroactivity due to the electroactive Ru 4d orbitals.The introduction of Ru NCs activates the carbon support,providing a high electronic conductivity to transfer electrons from Ru NCs to Ru S/DAs,and facilitates water dissociation for the HER process.

Segmented Au/PtCo heterojunction nanowires for efficient formic acid oxidation catalysis

Exploring a new strategy for the removal of adsorbed CO (CO^(*)) on a Pt surface at a low potential is the key to achieving enhanced catalysis for the formic acid oxidation reaction (FAOR);however, the development of such a strategy remains a significant challenge. Herein, we report a class of Au/PtCo heterojunction nanowires (HNWs) as efficient electrocatalysts for accelerating the FAOR. This heterojunction structure and the induced Co alloying effects can facilitate formic acid adsorption/activation on Pt with high CO tolerance, generating the FAOR pathway from dehydration to dehydrogenation. The optimized Au_(23)/Pt_(63)Co_(14) HNWs showed the highest specific and mass activities of 11.7 mA cm^(−2)Pt and 6.42 A mg^(−1)Pt reported to date, respectively, which are considerably higher than those of commercial Pt/C. DFT calculations confirmed that the electron-rich Au segment enhances the electronic activity of the PtCo NWs, which not only allows the construction of a highly efficient electron transfer channel for the FAOR but also suppresses CO formation.

Chiral self-assembly of terminal alkyne and selenium clusters organic–inorganic hybrid

The on-surface self-assembly of inorganic atomic clusters and organic molecules offers significant opportunities to design novel hybrid materials with tailored functionalities.By adopting the advantages from both inorganic and organic components,the hybrid self-assembly molecules have shown great potential in future optoelectrical devices.Herein,we report the co-deposition of 4,8-diethynylbenzo[1,2-d-4,5-d0]bisoxazole(DEBBA)and Se atoms to produce a motif-adjustable organic–inorganic hybrid self-assembly system via the non-covalent interactions.By controlling the coverage of Se atoms,various chiral molecular networks containing Se,Se_(6),Se_(8),and terminal alkynes evolved on the Ag(111)surface.In particular,with the highest coverage of Se atoms,phase segregation into alternating one-dimensional chains of non-covalently bonded Se_(8) clusters and organic ligands has been noticed.The atom-coverage dependent evolution of self-assembly structures reflects the remarkable structural adaptability of Se clusters as building blocks based on the spontaneous resize to reach the maximum non-covalent interactions.This work has significantly extended the possibilities of flexible control in self-assembly nanostructures to enable more potential functions for broad applications.

Carboxylated carbon nanotubes with high electrocatalytic activity for oxygen evolution in acidic conditions

Since most electrocatalysts for oxygen evolution reaction(OER),except for precious metal oxides RuO_(2) and IrO_(2),are unstable in harsh acidic solutions,it is highly desirable to develop high-performance OER electrocatalysts for acidic media,though it is still a big challenge.Herein,we report a simple strategy to produce carboxyl-enriched multiwalled carbon nanotubes(COOH-MWNTs)that exhibit stable and high electrocatalytic activities for OER in acidic solutions,showing an overpotential at a current density of 10 mA cm^(–2) and a Tafel slope as low as of 265 mV and 82 mV dec^(–1),respectively.As far as we are aware,these results represent the best OER performance for metal-free electrocatalysts,even comparable to those of RuO_(2) and IrO_(2).We have further revealed the catalytic mechanism,which involves one electron lose from the COOH-MWNTs catalyst at the beginning of the OER process to trigger H_(2)O molecule oxidation by forming peralcohol,followed by the recapture of one electron from water molecule to oxidize water and to recover the initial state for the COOH-MWNTs catalyst.The unravel of this new OER mechanism is important as it provides new insights into the crucial role of organic functional groups in electrocatalytic processes.Also,the mechanistic understanding can be used to guide the design and development of novel metalfree catalysts for acidic OER electrocatalysis and beyond.

Machine learning driven rational design of dual atom catalysts on graphene for carbon dioxide electroreduction

The development of high-performance atomiccatalysts for the carbon dioxide reduction reaction(CO_(2)RR)is atime-consuming process due to the complexity of the reactionmechanism and the uncertainty of the active site.Herein,wehave proposed combining density functional theory(DFT)andmachine learning(ML)to investigate the potential of topologicalgraphene-based dual-atom catalysts(DACs)as CO_(2)RRelectrocatalysts.By analyzing the ML results,we identify thenumber of d-orbital electrons in the active site as a key factorinfluencing the CO_(2)RR catalytic activity.Additionally,wepropose a simple descriptor to measure the CO_(2)RR activity ofthese DACs.Our findings provide plausible explanations for thesynergistic interactions between bimetallic atoms in CO_(2)RR andallow us to screen the homogeneous Ni-Ni pair as the mostpromising dual-atom catalysts.This work offers a fast MLapproach based on limited DFT calculations to predict the mostelectroactive and stable DACs on carbon support for CO_(2)RR,facilitating rapid screening of high-performance dual-atomcatalysts.