Centimeter-sized Cs_(3)Cu_(2)I_(5)single crystals grown by oleic acid assisted inverse temperature crystallization strategy and their films for high-quality X-ray imaging

Low-dimensional halide perovskites have become the most promising candidates for X-ray imaging,yet the issues of the poor chemical stability of hybrid halide perovskite,the high poisonousness of lead halides and the relatively low detectivity of the lead-free halide perovskites which seriously restrain its commercialization.Here,we developed a solution inverse temperature crystal growth(ITCG)method to bring-up high quality Cs_(3)Cu_(2)I_(5)crystals with large size of centimeter order,in which the oleic acid(OA)is introduced as an antioxidative ligand to inhibit the oxidation of cuprous ions effieiently,as well as to decelerate the crystallization rate remarkalby.Based on these fine crystals,the vapor deposition technique is empolyed to prepare high quality Cs_(3)Cu_(2)I_(5)films for efficient X-ray imaging.Smooth surface morphology,high light yields and short decay time endow the Cs_(3)Cu_(2)I_(5)films with strong radioluminescence,high resolution(12 lp/mm),low detection limits(53 nGyair/s)and desirable stability.Subsequently,the Cs_(3)Cu_(2)I_(5)films have been applied to the practical radiography which exhibit superior X-ray imaging performance.Our work provides a paradigm to fabricate nonpoisonous and chemically stable inorganic halide perovskite for X-ray imaging.

The hydrogen storage performance and catalytic mechanism of theMgH_(2)-MoS_(2)composite

In this work,we synthesized MoS_(2)catalyst via one-step hydrothermal method,and systematically investigated the catalytic effect of MoS_(2)on the hydrogen storage properties of MgH_(2).The MgH_(2)-5MoS_(2)composite milled for 5 h starts to release hydrogen at 259℃.Furthermore,it can desorb 4.0 wt.%hydrogen within 20 min at 280℃,and absorb 4.5 wt.%hydrogen within 5 min at 200℃.Mo and MoS_(2)coexistedin the ball milled sample,whereas only Mo was kept in the sample after dehydrogenation and rehydrogenation,which greatly weakens theMg-H bonds and facilitates the dissociation of MgH_(2)on the surface of Mo(110).The comparative study show that the formed MgS has nocatalytic effect for MgH_(2).We believed that the evolution and the catalytic mechanism of MoS_(2)will provide the theoretical guidance for theapplication of metal sulfide in hydrogen storage materials.

Zinc Anode for Mild Aqueous Zinc-Ion Batteries: Challenges, Strategies, and Perspectives

The rapid advance of mild aqueous zinc-ion batteries(ZIBs)is driving the development of the energy storage system market.But the thorny issues of Zn anodes,mainly including dendrite growth,hydrogen evolution,and corrosion,severely reduce the performance of ZIBs.To commercialize ZIBs,researchers must overcome formidable challenges.Research about mild aqueous ZIBs is still developing.Various technical and scientific obstacles to designing Zn anodes with high stripping efficiency and long cycling life have not been resolved.Moreover,the performance of Zn anodes is a complex scientific issue determined by various parameters,most of which are often ignored,failing to achieve the maximum performance of the cell.This review proposes a comprehensive overview of existing Zn anode issues and the corresponding strategies,frontiers,and development trends to deeply comprehend the essence and inner connection of degradation mechanism and performance.First,the formation mechanism of dendrite growth,hydrogen evolution,corrosion,and their influence on the anode are analyzed.Furthermore,various strategies for constructing stable Zn anodes are summarized and discussed in detail from multiple perspectives.These strategies are mainly divided into interface modification,structural anode,alloying anode,intercalation anode,liquid electrolyte,non-liquid electrolyte,separator design,and other strategies.Finally,research directions and prospects are put forward for Zn anodes.This contribution highlights the latest developments and provides new insights into the advanced Zn anode for future research.

Insights into the efficient charge separation over Nb_(2)O_(5)/2D-C_(3)N_(4) heterostructure for exceptional visible-light driven H_(2) evolution

Two-dimensional carbon nitride(2 D-C_(3) N_(4))nanosheets are promising materials in photocatalytic water splitting,but still suffer from easy agglomeration and fast photogene rated electron-hole pairs recombination.To tackle this issue,herein,a hierarchical Nb_(2) O_(5)/2 D-C_(3) N_(4) heterostructure is precisely constructed and the built-in electric field between Nb_(2)O_(5) and 2 D-C_(3) N_(4) can provide the driving force to separate/transfer the charge carriers efficiently.Moreover,the strongly Lewis acidic Nb_(2)O_(5) can adsorb TEOA molecules on its surface at locally high concentrations to facilitate the oxidation reaction kinetics under irradiation,resulting in efficient photogene rated electrons-holes separation and exceptional photocatalytic hydrogen evolution.As expected,the champion Nb_(2)O_(5)/2 D-C_(3)N_(4) heterostructure achieves an exceptional H2 evolution rate of 31.6 mmol g^(-1) h^(-1),which is 213.6 times and 4.3 times higher than that of pristine Nb_(2)O_(5) and2 D-C_(3)N_(4),respectively.Moreover,the champion heterostructure possesses a high apparent quantum efficiency(AQE)of 45.08%atλ=405 nm and superior cycling stability.Furthermore,a possible photocatalytic mechanism of the energy band alignment at the hetero-interface is proposed based on the systematical characterizations accompanied by density functional theory(DFT)calculations.This work paves the way for the precise construction of a high-quality heterostructured photocatalyst with efficient charge separation to boost hydrogen production.

Redox-etching induced porous carbon cloth with pseudocapacitive oxygenic groups for flexible symmetric supercapacitor

Constructing high-performance electrodes with both wide potential window(e.g.≥2 V in aqueous electrolyte)and excellent mechanical flexibility represents a great challenge for supercapacitors.Because of the outstanding conductivity and flexibility,carb on cloth(CC)has show n unlimited prospects for constructing flexible electrodes,but is rarely used directly as electrode material due to its electrochemical inertness and small specific surface area.To tackle these two critical limitations,we design a novel redox-etching strategy to synthesize CC-based electrode with 3D interconnecting pore structure.The sponge-like highly porous CC was further activated by strong oxidant to form abundant oxygenic groups,which occupy the interior and surface of current collector to render substantial pseudocapacitance.The as-synthesized CC electrode yielded an impressive capacitance of 4035 mF cm^(-2) at 3 mA cm^(-2) and satisfying cycling durability in a wide potential range of-1-1 V vs.SCE,which surpass the majority of reported CC-based electrodes.A symmetric supercapacitor with stable voltage of 2 V is assembled and delivers remarkable energy density of 6.57 mWh cm^(-3).Significantly,the device demonstrates an unparalleled flexibility with no capacitive decay after 100 bending cycles.This facile chemical etching and post-treatment processes are designed for large-scale manufacturing of the CC electrodes by providing high surface area and abundant electrochemically active sites,promising for industry application.The innovative synthetic strategy ope ns up new opportunities for high-performance flexible en ergy storage.

Main group metal elements for ambient-condition electrochemical nitrogen reduction

Electrocatalytic N_(2) reduction under ambient-condition is considered to be the most appealing strategy to the conventional Haber-Bosch process for synthetic ammonia to alleviate greenhouse emissions and reduce environmental pollution, mainly powered by renewable energy. Recent years, rapid advances have been gained in this attractive research field, and numerous electrocatalysts have been exploited. However, its conversion efficiency is still far behind the requirement of industrial applications owing to the breakage of the N≡N triple bond, which is an energetically challenging kinetically complex multistep reaction and the strong competing reaction of hydrogen evolution reaction. Recently, main group metal-based catalysts have been demonstrated promising application prospect for ammonia production, significantly boosting their further application in this field. However, a comprehensive review of main group metal-based catalysts towards electrochemical ammonia production applications is still lacking. In this review, the fundamentals of N_(2) reduction, such as the reaction pathways, the reaction potential and the challenges of N_(2) reduction have been comprehensively discussed. And then, the role, mechanism, and effect of each main group element-based catalysts used for N_(2) reduction (Li, K, Al, Ga, Sn, Sb, Bi, and their compounds) are systematically summarized. Finally, several state-of-the-art strategies to promote their NRR catalytic performance, as well as the existing problems and prospects are put forward. This review is expected to guide the design and establishment of more efficient electrocatalytic N_(2) reduction systems based on main group metal elements in the future.

Precisely decorating CdS on Zr-MOFs through pore functionalization strategy: A highly efficient photocatalyst for H2 production

Different materials,such as metal sulphides,are often combined with metal‐organic frameworks(MOFs)to develop multi‐functional composites and improve their photocatalytic properties.However,the high interfacial energy barrier limits the formation and nano‐assembly of the heterogeneous junctions between MOFs and metal sulphides.Herein,the heterostructured Zr‐MOF‐S@CdS are successfully constructed through a sequential synthesis method,in which the mesoporous Zr‐MOF are firstly decorated with thioglycolic acid through pore functionalization,and followed by the S^(2-)anion exchange process resulting in the surface close attached growth of CdS onto Zr‐MOF‐S materials.Due to the presence of molecules linkers,the CdS can be precisely decorated onto Zr‐MOF‐S without aggregation,which can provide more active sites.Moreover,the intimate connections and the suitable band structures between two materials can also facilitate the photogenerated electron‐hole pairs separation.Therefore,the resulting Zr‐MOF‐S@CdS with appropriate ratio exhibits high photocatalytic activity for water reduction,in which the H_(2) evolution rate can reach up to 1861.7μmol·g^(‒1)·h^(‒1),4.5 times higher than pure CdS and 2.3 times higher than of Zr‐MOF/CdS,respectively.Considering the promising future of MOF‐based photocatalysts,this work may provide an avenue for the further design and synthesis MOF‐based composite photocatalysts for efficient H_(2) evolution.

Binary ionic liquid electrolyte design for ultrahigh-energy density graphene-based supercapacitors

Although room temperature ionic liquids(ILs)have emerged as potential next-generation electrolytes for their wide electrochemical stability window(ESW),the trade-off between this window and viscosity has hindered their widespread use in energy storage devices.Here,we present for the first time that such a trade-off can be balanced by mixing two ILs with the common anion([NTf_(2)]^(-))but different cations([EMIM]^(+) and[N1114]^(+))together.The[EMIM]cation-based IL possesses low viscosity while the[N1114]cation-based IL exhibits wide ESW.Since the concentrations of each IL in the mixtures can result in different electrolyte properties,we demonstrate a systematic approach by exploring the properties of various concentration combinations.In addition,the corresponding cell voltage of their resulting graphene supercapacitors(SCs)accompanied based on the interaction between the binary ionic liquid and the electrodes,and the associated electrochemical performance were studied to determine the optimum electrolyte system for the highest SC energy density.The well-balanced viscosity/ESW trade-off is achieved in binary IL consisting 50 vol%[EMIM][NTf_(2)]and 50 vol%[N1114][NTf_(2)]as evident from the extraordinary electrode specific capacitance of 293.1 F g^(-1) and the ultrahigh SC energy density of 177 Wh kg^(-1),which approaches that of a lithium-ion battery.

Specializing liquid electrolytes and carbon-based materials in EDLCs for low-temperature applications

Electric double-layer capacitors(EDLCs) are emerging technologies to meet the ever-increasing demand for sustainable energy storage devices and systems in the 21 st Century owing to their advantages such as long lifetime, fast charging speed and environmentally-friendly nature, which play a critical part in satisfying the demand of electronic devices and systems. Although it is generally accepted that EDLCs are suitable for working at low temperatures down to-40℃, there is a lack of comprehensive review to summarize the quantified performance of EDLCs when they are subjected to low-temperature environments. The rapid and growing demand for high-performance EDLCs for auxiliary power systems in the aeronautic and aerospace industries has triggered the urge to extend their operating temperature range,especially at temperatures below-40℃. This article presents an overview of EDLC’s performance and their challenges at extremely low temperatures including the capability of storing a considerable amount of electrical energy and maintaining long-term stability. The selection of electrolytes and electrode materials is crucial to the performance of EDLCs operating at a desired low-temperature range. Strategies to improve EDLC’s performance at extremely low temperatures are discussed, followed by the future perspectives to motivate more future studies to be conducted in this area.

Gradient solid electrolyte interphase induced by bisfuoroacetamide for stable lithium metal batteries

With continuous development of portable electronics and electric vehicles,the conventional lithium-ion batteries(LIBs)could not meet the demand for higher energy density[1,2].Instead,the lithium metal batteries(LMBs)are regarded as the most promising candidate for next generation energy storage systems due to the highest specific capacity(3860 mAh g^(-1))and lowest redox potential(-3.04 V vs.standard hydrogen electrode)of Li metal[3,4].

First-row transition metal compounds for aqueous metal ion batteries

In recent years,a series of aqueous metal ion batteries(AMIBs)has been developed to improve the safety and cost-efficiency of portable electronics and electric vehicles.However,the significant gaps in energy density,power density,and cycle stability of AMIBs directly hinder them from replacing the currently widely used non-aqueous metal ion batteries,which stems from the lack of reasonable configuration and performance optimization of electrode materials.First-row transition metal compounds(FRTMCs),with the advantages of optional voltage ranges(from low to high),adjustable crystal structures(layered and tunnel types with large spacing),and designable morphology(multi-dimensional nanostructures),are widely used to construct high-performance AMIBs.However,no comprehensive review papers were generated to highlight their specific and significant roles in AMIBs.In this review,we first summarize the superiority and characteristics of FRTMCs in AMIBs.Then,we put forward control strategies of FRTMCs from subsurface engineering to inner construction to promote capacitance control and diffusion control energy storage.After that,the electrochemical performance of the FRTMCs regulation strategies in AMIBs is reviewed.Finally,we present potential directions and challenges for further enhancements of FRTMCs in AMIBs.The review aims to provide an in-depth understanding of regulation strategies for enhancing energy storage to build high-performance AMIBs that meet practical applications.

CNT@MnO_(2) composite ink toward a flexible 3D printed micro-zinc-ion battery

Flexible energy storage devices have played a significant role in multiscenario applications,while flexible zinc-ion batteries(ZIBs),as an essential branch,have developed rapidly in recent years.Three-dimensional(3D)printing is an extremely advanced technology to design and modify the structure of batteries and provides unlimited possibilities for the diversified development of energy storage equipment.Herein,by utilizing 3D printing technology,carbon nanotube(CNT)is coated by MnO_(2) to form a flexible CNT@MnO_(2) ink as a cathode for flexible aqueous micro-ZIBs for the first time and zinc powder ink is used as an anode due to its high flexibility and bendability.The Zn//CNT@MnO_(2) flexible battery shows a stable capacity of 63μAh cm^(−2) at 0.4mA cm^(−2).When the battery is bent in different states,the maximum capacity loss compared with the initial value is only 2.72%,indicating its stability.This study shows the potential of 3D printing technology in the development of flexible manganese-based ZIBs.

Generation of super-resolved optical needle and multifocal array using graphene oxide metalenses

Ultrathin flat metalenses have emerged as promising alternatives to conventional diffractive lenses,offering new possibilities for myriads of miniaturization and interfacial applications.Graphene-based materials can achieve both phase and amplitude modulations simultaneously at a single position due to the modification of the complex refractive index and thickness by laser conversion from graphene oxide into graphene like materials.In this work,we develop graphene oxide metalenses to precisely control phase and amplitude modulations and to achieve a holistic and systematic lens design based on a graphene-based material system.We experimentally validate our strategies via demonstrations of two graphene oxide metalenses:one with an ultra-long(~16λ)optical needle,and the other with axial multifocal spots,at the wavelength of 632.8 nm with a 200 nm thin film.Our proposed graphene oxide metalenses unfold unprecedented opportunities for accurately designing graphene-based ultrathin integratable devices for broad applications.

Giant and light modifiable third-order optical nonlinearity in a free-standing h-BN film

Recently,hexagonal boron nitride(h-BN)has become a promising nanophotonic platform for on-chip information devices due to the practicability in generating optically stable,ultra-bright quantum emitters.For an integrated information-processing chip,high optical nonlinearity is indispensable for various fundamental functionalities,such as all-optical modulation,high order harmonic generation,optical switching and so on.Here we study the third-order optical nonlinearity of free-standing h-BN thin films,which is an ideal platform for on-chip integration and device formation without the need of transfer.The films were synthesized by a solution-based method with abundant functional groups enabling high third-order optical nonlinearity.Unlike the highly inert pristine h-BN films synthesized by conventional methods,the free-standing h-BN films could be locally oxidized upon tailored femtosecond laser irradiation,which further enhances the third-order nonlinearity,especially the nonlinear refraction index,by more than 20 times.The combination of the free-standing h-BN films with laser activation and patterning capability establishes a new promising platform for high performance on-chip photonic devices with modifiable optical performance.

Improved nitrogen reduction electroactivity by unique MoS_(2)‐SnS_(2) heterogeneous nanoplates supported on poly(zwitterionic liquids)functionalized polypyrrole/graphene oxide

Unique MoS_(2)‐SnS_(2)heterogeneous nanoplates have successfully in‐situ grown on poly(3‐(1‐vinylimidazolium‐3‐yl)propane‐1‐sulfonate)functionalized polypyrrole/graphene oxide(PVIPS/PPy/GO).PVIPS can attract heptamolybdate ion(Mo7O246−)and Sn^(4+)as the precursors by the ion‐exchange,resulting in the simultaneous growth of 1T’‐MoS2 and the berndtite‐2T‐type hexagonal SnS_(2)by the interfacial induced effect of PVIPS.The obtained MoS_(2)‐SnS_(2)/PVIPS/PPy/GO can serve as electrocatalysts,exhibiting good NRR performance by the synergistic effect.The semi‐conducting SnS_(2)would limit the surface electron accessibility for suppressing HER process of 1T’‐MoS_(2),while metallic 1T’‐MoS_(2)might efficiently improve the NRR electroactivity of SnS_(2)by the creation of Mo‐Sn‐Sn trimer catalytic sites.Otherwise,the irreversible crystal phase transition has taken place during the NRR process.Partial 1T’‐MoS_(2)and SnS_(2)have electrochemically reacted with N_(2),and irreversibly converted into Mo^(2)N and SnxNz due to the formation of Mo−N and Sn−N bonding,meanwhile,partial SnS_(2) has been irreversibly evolved into SnS due to the reduction by the power source in the electrochemical system.It would put forward a new design idea for optimizing the preparation method and electrocatalytic activity of transition metal dichalcogenides.

Highly efficient flexible structured metasurface by roll-to-roll printing for diurnal radiative cooling

An ideal radiative cooler requires accurate spectral control capability to achieve efficient thermal emission in the atmospheric transparency window(8-13μm),low solar absorption,good stability,scalability,and a simple structure for effective diurnal radiative cooling.Flexible cooling films made from polymer relying on polymer intrinsic absorbance represent a cost-effective solution but lack accuracy in spectral control.Here,we propose and demonstrate a metasurface concept enabled by periodically arranged three-dimensional(3D)trench-like structures in a thin layer of polymer for high-performance radiative cooling.The structured polymer metasurface radiative cooler is manufactured by a roll-to-roll printing method.It exhibits superior spectral breadth and selectivity,which offers outstanding omnidirectional absorption/emission(96.1%)in the atmospheric transparency window,low solar absorption(4.8%),and high stability.Impressive cooling power of 129.8 W m^(-2) and temperature deduction of 7℃ on a clear sky midday have been achieved,promising broad practical applications in energy saving and passive heat dispersion fields.

Preface to special issue on catalysing production of renewable fuels

Development of renewable fuels,such as hydrogen,liquid ammonia,is of great significance for relieving the pressure of anthropogenic CO_(2)emissions and depletion of traditional fossil energy sources.For the past two decades,heterogeneous catalysis has received increased attention as an efficient route for the production of renewable fuels.Typical heterogeneous catalytic reactions include photocatalysis,electrocatalysis,photoelectrocatalysis,thermalcatalysis,photothermalcatalysis as well as some emerging catalytic pathways,e.g.piezocatalysis.Each catalytic reaction has its own advantages.For instance,electrocatalysis has the characteristic of high efficiency,photocatalysis is featured by the sustainability and low cost,thermalcatalysis generally shows a high practicability and scalability for industrialization,and coupled‐catalysis can integrate the merits of diversified catalytic reactions,achieving a more efficient catalytic performance for production of renewable fuels.Developing new catalytic reactions is anticipated to enrich the selection of possible catalytic system,and to advance the understanding of heterogeneous catalytic mechanism.

Diffraction-Limited Imaging with a Graphene Metalens

Planar graphene metalens has demonstrated advantages of ultrathin thickness(200 nm),high focusing resolution(343 nm)and efficiency(>32%)and robust mechanical strength and flexibility.However,diffraction-limited imaging with such a graphene metalens has not been realized,which holds the key to designing practical integrated imaging systems.In this work,the imaging rule for graphene metalenses is first derived and theoretically verified by using the Rayleigh-Sommerfeld diffraction theory to simulate the imaging performance of the 200 nm ultrathin graphene metalens.The imaging rule is applicable to graphene metalenses in different immersion media,including water or oil.Based on the theoretical prediction,high-resolution imaging using the graphene metalens with diffraction-limited resolution(500 nm)is demonstrated for the first time.This work opens the possibility for graphene metalenses to be applied in particle tracking,microfluidic chips and biomedical devices.

Exploration of single Fe atom supported on anatase TiO_(2)(001)for methane oxidation:A DFT study

Partial oxidation of methane is a promising alternative strategy for methanol production under mild reaction conditions;however,significant challenges hinder the development of appropriate catalysts.In this study,based on first-principles calculations,we demonstrate that a single Fe atom supported on anatase TiO_(2)(001)provides double active sites(Fe and Ti_(5C))to activate gas-phase O_(2)and form O-assisted intermediates.The triple state Fe-O/TiO_(2)(001)system exhibited better activity for methane activation(ΔG max=1.02 eV).Our findings offer new insights into the design of non-noble-3 d transition metal single-atom catalysts on TiO_(2)(001)for partial methane oxidation via an inexpensive O_(2)oxidant under mild reaction conditions.

Ultrafast direct laser writing of 2D materials for multifunctional photonics devices [Invited]

Recently,fundamental properties and practical applications of two-dimensional(2D)materials have attracted tremendous interest.Micro/nanostructures and functional devices in 2D materials have been fabricated by various methods.Ultrafast direct laser writing(DLW)with the advantages of rich light-matter interactions;unique three-dimensional processing capability;arbitrary-shape design flexibility;and minimized thermal effect,which enables high fabrication accuracy resolution,has been widely applied in the fabrication of 2D materials for multifunctional devices.This timely review summarizes the laser interactions with 2D materials and the advances in diverse functional photonics devices by DLW.The perspectives and challenges in designing and improving laser-fabricated 2D material photonic devices are also discussed.