Defect and interface engineering for electrochemical nitrogen reduction reaction under ambient conditions

Electrochemical nitrogen reduction reaction(e-NRR)under ambient conditions is an emerging strategy to tackle the hydrogen-and energy-intensive operations for traditional Haber-Bosch process in industrial ammonia(NH_(3))synthesis.However,the e-NRR performance is currently impeded by the inherent inertness of N_(2) molecules,the extremely slow kinetics and the overwhelming competition from the hydrogen evolution reaction(HER),all of which cause unsatisfied yield and ammonia selectivity(Faradaic efficiency,FE).Defect and interface engineering are capable of achieving novel physical and chemical properties as well as superior synergistic effects for various electrocatalysts.In this review,we first provide a general introduction to the NRR mechanism.We then focus on the recent progress in defect and interface engineering and summarize how defect and interface can be rationally designed and functioned in NRR catalysts.Particularly,the origin of superior NRR catalytic activity by applying these approaches was discussed from both theoretical and experimental perspectives.Finally,the remaining challenges and future perspectives in this emerging area are highlighted.It is expected that this review will shed some light on designing NRR electrocatalysts with excellent activity,selectivity and stability.

Rare-earth-incorporated low-dimensional chalcogenides: Dry-method syntheses and applications

Chalcogenide thin films incorporating rare-earth (RE) elements with applicationsin optics, electronics, and magnetics have received considerable attention.Aiming at growing pure chalcogenides, dry-method syntheses have beendeveloped. In this review, we summarize the progress thus far on lowdimensionalRE-based chalcogenides (RECs), covering fabrication methods,structures, and applications. This review also provides the summary and perspectivesof the challenges of fabrication and opportunities on the applicationof RECs in the future.

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.

Temperature-driven reversible structural transformation and conductivity switching in ultrathin Cu_(9)S_(5)crystals

Two-dimensional(2D)materials with reversible phase transformation are appealing for their rich physics and potential applications in information storage.However,up to now,reversible phase transitions in 2D materials that can be driven by facile nondestructive methods,such as temperature,are still rare.Here,we introduce ultrathin Cu_(9)S_(5)crystals grown by chemical vapor deposition(CVD)as an exemplary case.For the first time,their basic electrical properties were investigated based on Hall measurements,showing a record high hole carrier density of~1022 cm^(-3) among 2D semiconductors.Besides,an unusual and repeatable conductivity switching behavior at~250 K were readily observed in a wide thickness range of CVD-grown Cu_(9)S_(5)(down to 2 unit-cells).Confirmed by in-situ selected area electron diffraction,this unusual behavior can be ascribed to the reversible structural phase transition between the room-temperature hexagonalβphase and low-temperatureβ’phase with a superstructure.Our work provides new insights to understand the physical properties of ultrathin Cu_(9)S_(5)crystals,and brings new blood to the 2D materials family with reversible phase transitions.

Improving the activity of electrochemical reduction of CO_(2) to C_(1) products by oxidation derived copper catalyst

Cu-based electrocatalysts have become the focus in the field of electrochemical CO_(2) reduction reaction(ECO_(2) RR)due to their ability to produce multicarbon products.However,the research on generating single carbon products with higher economic feasibility via ECO_(2) RR based on Cu-based electrocatalysts is rather rare,and the roles of the surface architecture and oxides of the electrocatalysts have not been explained exactly.In this work,a two-step method including thermal oxidation and electroreduction is proposed to introduce Cuþinto pure Cu foil to form Cu_(2)O/Cu electrocatalyst.By regulating the surface composition and morphology of the electrocatalyst in this way,the activity of ECO 2 RR to C_(1) products has been greatly improved.The Faradaic efficiency of carbon products of the Cu_(2)O/Cu electrode reaches 84%at?0.7 V vs.RHE with good selectivity for HCOOH and CO.The current density of Cu_(2)O/Cu electrode reaches-12.21 mA cm^(2) at-0.8 V vs.RHE,which is much higher than that of the Cu foil electrode(?0.09 mA cm?2).In-situ Raman characterization shows that Cuþin Cu_(2)O/Cu electrode could inhibit hydrogen generation and promote ECO_(2) RR by stabilizing the adsorption of CO_(2).

Synthesis,Structure and Chemical Bonding of Polyantimony Clusters Containing Coinage Metals[M_(2)Sb_(14)]^(4-)(M=Cu,Ag)

Binary polyantimony clusters,namely[Cu_(2)Sb_(14)]^(4–) and [Ag_(2)Sb_(14)]^(4–),containing coinage metals,were successfully synthesized and characterized,in which two homoatomic Sb73–subunits are bridged by two coinage metals in η^(4):η^(1) and η^(1):η^(1) coordination modes,respectively.In[M_(2)Sb_(14)]^(4-),two bridging Cu ions and two Sb atoms form a planar rhombic unit,which was revealed to have antiaromatic properties by theoretical calculations.Further electron structure and bonding analysis confirmed the presence of delocalized bonds in the rhombic unit and the metallophilic interaction between two formal M^(+) ions.

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.

Recent advances on rare earths in solid lithium ion conductors

Solid lithium-ion-conducting material is the key component in the fabrication of next-gene ration all solid state lithium ion batteries(LIBs)which would exhibit superior safety and performance compared with the currently widely used ones that resort to essentially inflammable and volatile organic solvents.To date,great efforts have been made in developing solid conductors with high lithium ion conductivity,such as polymers and inorganic materials.Rare earths play a very important role in this area and have attracted extensive interest since the recent decades for their unique properties in the realm of solidstate inorganic lithium-ion-conducting electrolyte materials.In this introduction,we focus on the role of rare earths in solid conductors for lithium ion,especially in a few most studied systems such as perovskites,garnets,silicates,borohydride and the recently reported halides in which rare earths act as a key framing component.Besides,the effect of rare earths as dopants is also discussed in some recently studied systems.Valence,coordination,and size are the most important factors that influence the crystal structure and property of these lithium ion conductors.The aim of this review is to highlight the great potentials of these unique elements of rare earths,and to help improve the performance of existing materials and explore new applications in the development of new LIBs with high performances.

Highly Stretchable Shape Memory Self-Soldering Conductive Tape with Reversible Adhesion Switched by Temperature

With practical interest in the future applications of next-generation electronic devices,it is imperative to develop new conductive interconnecting materials appropriate for modern electronic devices to replace traditional rigid solder tin and silver paste of high melting temperature or corrosive solvent requirements.Herein,we design highly stretchable shape memory self-soldering conductive(SMSC)tape with reversible adhesion switched by temperature,which is composed of silver particles encapsulated by shape memory polymer.SMSC tape has perfect shape and conductivity memory property and anti-fatigue ability even under the strain of 90%.It also exhibits an initial conductivity of 2772 S cm^(−1) and a maximum tensile strain of~100%.The maximum conductivity could be increased to 5446 S cm^(−1) by decreasing the strain to 17%.Meanwhile,SMSC tape can easily realize a heating induced reversible strong-to-weak adhe-sion transition for self-soldering circuit.The combination of stable conductivity,excellent shape memory performance,and temperature-switching reversible adhesion enables SMSC tape to serve two functions of electrode and solder simultaneously.This provides a new way for conductive interconnecting materials to meet requirements of modern electronic devices in the future.

Exploring the intercalation chemistry of layered yttrium hydroxides by 13C solid-state NMR spectroscopy

Layered rare earth hydroxides(LREHs)are a novel class of two-dimensional materials with potential applications in various fields.The exchange reactions with organic anions are typically the first step for the functionalization of LREHs.Although the laminar structures seem to be clear for anion-exchanged compounds,the state of intercalated organic anions and their interactions with cationic rare earth hydroxide layers remain unclear.Herein,we demonstrate that the use of 13C solid-state nuclear magnetic resonance(ssNMR)spectroscopy enables to extract key information on the state of intercalated organic anions such as their local chemical environment,stacking,and dynamics,which are often difficult or impossible to obtain previously.In combination with powder X-ray diffraction and ab initio density functional theory calculations,the intercalation chemistry of two representative layered yttrium hydroxides with selected monovalent organic anions was studied in detail.The products can undergo secondary exchange with a divalent organic anion,depending on the match between the basal spacing of two phases,i.e.,the replacement of benzenesulfonate(BS^(-)
),2,4-dimethylbenzene sulfonate(DMBS^(-)
),and 4-ethylbenzene sulfonate(EBS
)with 2,6-naphthalene disulfonate(NDS^(2-)
)is allowed due to the insignificant change in basal spacing after exchange,while the replacement of very long dodecyl benzene sulfonate(DBS^(-)
)and dodecyl sulfate(DS
)with NDS^(2-)is forbidden.The results therefore provide valuable insights into the structure-property relationships of LREH-based functional materials.

Hybrid Bioelastomer Reinforced by Ultrathin Nanowires of Lanthanide Hydroxycarbonates for Promising Biomedical Applications

Hybrids composed of biocompatible polymers reinforced with inorganic nanomaterials are useful for many biomedical applications including implantation and tissue regeneration and engineering.In this work,we report a new type of hybrid prepared by doping ultrathin nanowires of lanthanide hydroxycarbonates into classical biocompatible poly(citrates-siloxane).The doping of the inorganic nanowires imparts the hybrids with excellent miscibility with the polymeric matrix,producing hybrids with high elasticity and high tensile strength.The hybrids containing Eu(III)and Gd(III)display their respective luminescence and magnetic properties and thus,offer opportunities to monitor the fate of such hybrids when used in vivo.Insignificant degradation and excellent biocompatibility of these hybrids have also been demonstrated.Together,these favorable traits portend useful applications of the newly developed hybrid elastomers.

Light-, Middle- and Heavy-Lanthanide Ate-Complexes Bearing Ln(Ⅲ)-Si bonds: Structural, Spectroscopic, and Bonding Analysis

Recent decades have witnessed a rapid development of the lanthanide silicon chemistry.In this research,by reacting[(THF)_(3)LisiPh_(3)]with Cp_(3)Ln(Ⅰ)(THF)(Ln(I)=Sm(Ⅰ),Tb(Ⅱ),Dy(Ⅰ),Yb(Ⅰ)or Cp_(2)Lu(Ⅱ)CI(THF),a series of middle-and heavy-lanthanocene monosilyl/disilyl ate-complexes([(DME)_(3)Lil[Cp_(3)Ln(Ⅱ)SiPh_(3)]and[(DME)_(3)Li[Cp_(2)Lu(Ⅱ)(SiPh_(3))_(2)])were synthesized.The structures of the obtained lanthanocene monosilyl/disilyl ate-complexes were determined by single crystal X-ray diffraction.Together with the previously reported[(DME)_(3)Li[Cp_(3)La(Ⅱ)SiPh_(3)]and[(DME);Lil[Cp_(3)Ce(Ⅱ)SiPha],a complex group comprising silyl light-,middle-and heavy-lanthanocene with identical core coordination pattern are presented.

Pitch-derived 3D amorphous carbon encapsulated sulfur-rich cathode for aqueous Zn-S batteries

Rechargeable aqueous zinc batteries have attracted much attention due to their high security, plentiful zinc resources, and environmental friendliness. However, it can only offer limited specific capacity and energy density based on ion insertion chemistry cathode. Herein, we design a low-cost and high-energy density aqueous Zn-S battery where the conversion cathode was fabricated by pitch-derived three-dimensional(3D) amorphous carbon encapsulated industrial-grade sulfur powder. The cost of the chemical substances for this aqueous Zn-S battery might be reduced to $9.38 per kW h based on the affordable cost of the raw ingredients. It is found that the PAC/S-60.33% cathode reveals excellent electrochemical performance, including a high reversible capacity(633.5 mAh g^(-1)at 0.5 A g^(-1)), high energy density(297.5 Wh kg^(-1)), an excellent rate capability(204.5 mAh g^(-1) at 5.5 A g^(-1)), as well as good cycling stability(180 mAh g^(-1)after 400 cycles at 5.0 A g^(-1)). Besides, the reaction mechanism of the cathode was investigated using ex-situ X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS), and transmission electron microscope(TEM). It was demonstrated that the cathode undergoes a conversion reaction between S and Zn S. Furthermore, the discoveries also offer prospective possibilities to fabricate more secure and inexpensive battery systems.

探索Bi_(2)SeO_(5)的高介电性能:从块体到双层和单层

Bi_(2)SeO_(5)是一种具有优异电绝缘性能的范德华(vdW)层状介电材料,引起了极大关注.然而,目前关于Bi_(2)SeO_(5)的研究主要停留在实验层面,仍然缺乏对其原子级薄膜的介电性能的相关理论认识.本文通过第一性原理计算确定了Bi_(2)SeO_(5)的介电性能,发现其块体、双层和单层均具有超高平均介电常数(εr>20).研究表明,单层Bi_(2)SeO_(5)与双层Bi_(2)O_(2)Se之间的导带和价带能量偏移量均大于1 eV,表明单层Bi_(2)SeO_(5)依然可作为原子薄Bi_(2)O_(2)Se的良好介电层.此外,不同于h-BN或其他2D vdW绝缘体,Bi_(2)SeO_(5)的εr由其离子部分主导,且随着厚度的减小几乎保持不变.计算发现,单层Bi_(2)SeO_(5)的等效氧化层厚度可薄至0.3 n m,且单层Bi_(2)SeO_(5)在拉伸或压缩应变达到6%时均能保持高介电常数,这极大地促进了它与各种二维半导体的集成.本工作证明单层Bi_(2)SeO_(5)可以作为高性能二维电子器件良好的封装和介电层.

The first chiral cerium halide towards circularly-polarized luminescence in the UV region

Chiral organic-inorganic hybrid metal halides(OIHMHs)have attracted broader scientific community recently in spin lightemitting diodes,and circularly polarized light-emitting diodes.However,the emission peaks of the reported chiral OIHMHs mainly locate in the visible region,and chiral OIHMH with ultraviolet(UV)circularly polarized luminescence(CPL)has been rarely reported.To fill this gap,cerium,a unique rare-earth(RE)element with tunable luminescence from UV to the visible region owing to the 4 f-related electronic transition,was introduced to construct the first RE-based chiral OIHMHs,R/S-MCC.The chirality is successfully transferred from the chiral organic cations to the inorganic cerium chloride framework in R/S-MCC,as confirmed by the single crystal structures,circular dichroism,and CPL.The emission spectra of R/S-MCC are in the UV region,originating from the characteristic d-f transition of Ce^(3+),which making the Ce-based metal halides are ideal candidates towards CPL light sources in the UV region.Notably,R-and S-MCC are the first RE-based OIHMHs,also the first chiral metalhalides with UV CPL.Our work opens a new avenue for the development of the chiral OIHMH family towards RE-based chiral OIHMH.The RE-based chiral metal halides couple the unique and superior optical,electrical,magnetic,and spintronic properties of RE elements with chirality could accelerate the development of chiral optoelectronics and spintronics toward real applications.

CeO_(2)with diverse morphologies-supported IrOx nanocatalysts for efficient oxygen evolution reaction—Commemorating the 100th anniversary of the birth of Academician Guangxian Xu

IrOx-based catalysts are considered the most promising candidates for oxygen evolution reaction(OER)due to their high efficiency.However,improving their intrinsic catalytic activity is essential for practical application.In this work,CeO_(2)with three different morphologies(rod,cube,octahedron)and supported IrOx nanoparticles were fabricated,and they display morphology-dependent OER activity.The IrOx/CeO_(2)-rod shows the highest activity;the catalysts have a catalytic activity sequence of rod>cube>octahedron.A plausible mechanism was proposed:the CeO_(2)support with different morphologies modulates the electronic structure of IrOx by the synergistic interaction promoted by oxygen vacancies between the active component and the support,thereby altering the catalytic activity of the IrOx/CeO_(2)catalyst.

Synthesis and Structure of Binary Copper/Silver-Arsenic Clusters Derived from Zintl Ion As_(7)^(3-)

Polyarsenides containing coinage metals,[As_(7)Cu(PPh_(3))]^(2-)(1)and[M_(2)As_(14)]^(4-)(M=Cu,2;Ag,3),were synthesized by reactions of the nominal composition K_(3)As_(7) with Group 11 metal complexes.The possible intermediate,cluster 1,was isolated from the solution phase through subtle changes in reaction conditions in the formation process of complex 2.Hence,we establish the pathway of the bimetallic bridged clusters[Cu_(2)As_(14)]^(4-)by the oxidation of the[As_(7)Cu(PPh_(3))]^(2-).Quantum chemical calculations reveal the presence of metallophilic interaction in clusters 2 and 3.

Dancing on Ropes-Enantioselective Functionalization of Preformed Four-Membered Carbocycles

Cyclobutane derivatives have been recognized as useful structural motifs in organic synthesis and drug design.With the revival of photochemistry,the enantioselective synthesis of cyclobutane derivatives using[2+2]-cycloadditions has garnered numerous attentions.On the other hand,enantioselec-tive functionalization of preformed four-membered carbocycles is emerging as an important complementary approach to access chiral cyclobutane de-rivatives with versatile structural patterns.Herein,we summarize recent advances in this field from 2012.To avoid undesired C—C bond cleavage driv-en by strain-releasing,it is crucial to choose compatible methods for enantioselective functionalization and meanwhile preserving intact four-membered ring skeleton.Guided by calculated hydrogenation enthalpies,which are used to evaluate the strain energy of indicated C—C bond,a clear picture of the developed methodologies on functionalization of four-membered carbocycles combining the strain energy and enhanced reactivity is presented.

Efficient removal for multiple pollutants via Ag_(2)O/BiOBr heterojunction:A promoted photocatalytic process by valid electron transfer pathway

Multiple pollutants including pathogenic microorganism contaminations and emerging organic contaminations(EOCs)have shown a growing threat to the environment,especially the natural waters.However,the control and removal of pathogenic microorganism contaminations and EOCs have been greatly limited since limited knowledge of their environmental behaviors.Thus,a novel and efficient photocatalyst Ag_(2)O/BiOBr heterojunction was synthesized and used for removal of multiple pollutants including Escherichia coli(E.coli),Staphylococcus aureus(S.aureus),tetracycline and acetaminophen under visible light.The results showed that there were valid electron transfer pathways between BiOBr and Ag_(2)O,the main electron transfer direction was the BiOBr to Ag_(2)O.Photo-generated electrons were stored in Ag_(2)O and thus separation efficiency between holes and photo-generated electrons was obviously enhanced.Active oxygen species were highly produced and eventually end up with the high efficiency of removal of multiple pollutants.For Ag_(2)O/BiOBr with Ag_(2)O content at 3%(the best performance)under visible light,log decrease of E.coli was 7.16(removal efficiency was 100%)in 120 min,log decrease of S.aureus was 7.23(removal efficiency was 100%)in 160 min,C/C0 of tetracycline was 0.06 in 180 min,C/C0 of acetaminophen was 0.17 in 180 min.This work could provide a promising candidate in the actual contaminated natural waters for cleaning multiple pollutants.

Cerium ions crosslinked sodium alginate-carboxymethyl chitosan spheres with antibacterial activity for wound healing

For wound healing,wound infection caused by bacteria is one of the important reasons that delay wound healing process.Therefore,it is very meaningful to develop a multifunctional wound dressing with antibacterial capability to accelerate wound healing.Sodium alginate(SA)and carboxymethyl chitosan(CMCS)are the most commonly used compositions in wound dressing,but their poor stability inhibits the further applications.Introducing CMCS and using cerium ions(Ce^(3+))to crosslink CMCS and SA to form SA-CMCS hybrid spheres by electrostatic spray method,can not only improve the stability of SA hydrogels,but also endow the spheres with excelle nt antibacterial properties due to the characteristics of Ce^(3+).The gradual release of Ce^(3+)from the SA-CMCS spheres can effectively inhibit the growth of Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli).Combining the wound healing promotion ability of SA and CMCS,this kind of wound dressing can not only avoid wound infection caused by bacteria effectively,but also accelerate wound healing,thus it is an easily prepared material with potential applications in skin defect repair.