Constructing high coordination number of Ir-O-Ru bonds in IrRuO_(x)nanomeshes for highly stable acidic oxygen evolution reaction

IrRu bimetallic oxides are recognized as the promising acidic oxygen evolution reaction(OER)catalysts,but breaking the trade-off between their activity and stability is an unresolved question.Meanwhile,addressing the issues of mass transport obstruction of IrRu bimetallic oxides under high current remains a challenge for the development of proton exchange membrane water electrolysis(PEM-WE).Herein,we prepared an IrRuO_(x)nanomeshes(IrRuO_(x)NMs)with high coordination number(CN)of Ir-O-Ru bonds in a mixed molten salt with high solubility of the Ir/Ru precursor.X-ray absorption spectroscopy analysis revealed that the IrRuO_(x)NMs possess high coordination number of Ir-O-Ru bonds(CNIr-O-Ru=5.6)with a distance of 3.18Å.Moreover,the nanomesh structures of IrRuO_(x)NMs provided hierarchical channels to accelerate the transport of oxygen and water,thus further improving the electrochemical activity.Consequently,the IrRuO_(x)NMs as OER catalysts can simultaneously achieve high activity and stability with low overpotential of 196 mV to reach 10 mA·cm^(−2)and slightly increase by 70 mV over 650 h test.Differential electrochemical mass spectrometry tests suggest that the preferred OER mechanism for IrRuO_(x)NMs is the adsorbent evolution mechanism,which is beneficial for the robust structural stability.

Large-scale manufacturing of functional single-atom ink for convenient glucose sensing

Printing techniques hold great potential in the manufacture of electronics such as sensors,micro-supercapacitors,and flexible electronics.However,developing large-scale functional conductive inks with appropriate rheological properties and active components still remains a challenge.Herein,through optimizing the formulations of ink,iron single sites supported N-doped carbon black(Fe_(1)-NC)inks can serve as both conductive electrodes and high-reactive catalysts to realize convenient glucose detection,which pronouncedly reduces the dosage of enzyme and simplifies the sensors preparation.In detail,utilizing in-situ pyrolysis method,Fe_(1)-NC single-atom catalysts(SACs)are prepared in bulk(dekagram-level).The batched Fe_(1)-NC SACs materials can be uniformly mixed with modulated ink to realize the screen printing with high resolution and uniformity.Also,the whole scalable preparation and ink-functional process can be extended to various metals(including Co,Ni,Cu,and Mn).The introduction of highly active Fe_(1)-NC sites reduces the amount of enzyme used in glucose detection by at least 50%,contributing to the cost reduction of sensors.The strategy in harnessing the SACs onto the carbon inks thus provides a broad prospect for the low-cost and large-scale printing of sensitive sensing devices.

二维材料最新研究进展

Research on two-dimensional(2D) materials has been explosively increasing in last seventeen years in varying subjects including condensed matter physics, electronic engineering, materials science, and chemistry since the mechanical exfoliation of graphene in 2004. Starting from graphene, 2D materials now have become a big family with numerous members and diverse categories. The unique structural features and physicochemical properties of 2D materials make them one class of the most appealing candidates for a wide range of potential applications. In particular, we have seen some major breakthroughs made in the field of 2D materials in last five years not only in developing novel synthetic methods and exploring new structures/properties but also in identifying innovative applications and pushing forward commercialisation. In this review, we provide a critical summary on the recent progress made in the field of 2D materials with a particular focus on last five years. After a brief backgroundintroduction, we first discuss the major synthetic methods for 2D materials, including the mechanical exfoliation, liquid exfoliation, vapor phase deposition, and wet-chemical synthesis as well as phase engineering of 2D materials belonging to the field of phase engineering of nanomaterials(PEN). We then introduce the superconducting/optical/magnetic properties and chirality of 2D materials along with newly emerging magic angle 2D superlattices. Following that, the promising applications of 2D materials in electronics, optoelectronics, catalysis, energy storage, solar cells, biomedicine, sensors, environments, etc. are described sequentially. Thereafter, we present the theoretic calculations and simulations of 2D materials. Finally, after concluding the current progress, we provide some personal discussions on the existing challenges and future outlooks in this rapidly developing field.

Cu_(2+1)O/CuO_(x)heterostructures promote the electrosynthesis of C^(2+)products from CO_(2)

Manipulating the oxidation state of Cu catalysts can significantly affect the selectivity and activity of electrocatalytic carbon dioxide reduction(CO_(2)RR).However,the thermodynamically favorable cathodic reduction to metallic states typically leads to catalytic deactivation.Herein,a defect construction strategy is employed to prepare crystalline/amorphous Cu_(2+1)O/CuO_(x)heterostructures(c/a-CuO_(x))with abundant Cu0 and Cuδ+(0<δ<1)sites for CO_(2)RR.The C^(2+)Faradaic efficiency of the heterostructured Cu catalyst is up to 81.3%,with partial current densities of 406.7 mA·cm−2.Significantly,real-time monitoring of the Cu oxidation state evolution by in-situ Raman spectroscopy confirms the stability of Cuδ+species under long-term high current density operation.Density functional theory(DFT)calculations further reveal that the adjacent Cu0 and Cuδ+sites in heterostructured c/a-CuO_(x)can efficiently reduce the energy barrier of CO coupling for C^(2+)products.

The promoting effect of interstitial hydrogen on the oxygen reduction performance of PtPd alloy nanotubes for fuel cells

Highly efficient and stable oxygen reduction reaction(ORR)electrocatalysts are remarkably important but challenging for advancing the large-scale commercialization of practical proton exchange membrane fuel cells(PEMFCs).In this work,we report that the introduction of interstitial hydrogen atoms into PtPd nanotubes can significantly promote ORR performance without scarifying the durability.The enhanced mass activity was 8.8 times higher than that of commercial Pt/C.The accelerated durability test showed negligible activity attenuation after 30,000 cycles.Additionally,H2/O2 fuel cell tests further verified the excellent activity of PtPd-H nanotubes with a maximum power density of 1.32 W·cm^(−2),superior to that of commercial Pt/C(1.16 W·cm^(−2)).Density functional theory calculations demonstrated the incorporation of hydrogen atoms gives rise to the broadening of Pt d-band and the downshift of d-band center,which consequently leads to the weaker intermediates binding and enhanced ORR activity.

Supporting IrO_(x) nanosheets on hollow TiO_(2) for highly efficient acidic water splitting

The efficiency of proton exchange membrane water electrolysis(PEM-WE)for hydrogen production is heavily dependent on the noble metal iridium-based catalysts.However,the scarcity of iridium limits the large-scale application of PEM-WE.To address this issue,it is promising to select an appropriate support because it not only enhances the utilization efficiency of noble metals but also improves mass transport under high current.Herein,we supported amorphous IrO_(x) nanosheets onto the hollow TiO_(2) sphere(denoted as IrO_(x)),which demonstrated excellent performance in acidic electrolytic water splitting.Specifically,the annealed IrO_(x)catalyst at 150℃in air exhibited a mass activity of 1347.5 A·gIr^(−1),which is much higher than that of commercial IrO_(2) of 12.33 A·gIr^(−1) at the overpotential of 300 mV for oxygen evolution reaction(OER).Meanwhile,the annealed IrO_(x) exhibited good stability for 600 h operating at 10 mA·cm^(−2).Moreover,when using IrO_(x) and annealed IrO_(x) catalysts for water splitting,a cell voltage as low as 1.485 V can be achieved at 10 mA·cm^(−2).The cell can continuously operate for 200 h with negligible degradation of performance.

Interstitial carbon induces enriched Cu^(δ+) sites in Cu_(2)O nanoparticles to facilitate CO_(2) electroreduction to C_(2+) products

The electrochemical CO_(2) reduction reaction(CO_(2)RR)holds significant promise in advancing carbon neutrality.Developing catalysts for the electrochemical CO_(2)RR to multi-carbon(C_(2+))products(e.g.,C_(2)H_(4))under industrial-level current density is urgently needed and pivotal.Herein,we report the Cu_(2)O nanoparticles doped with interstitial carbon atoms(denoted as C-Cu_(2)O NPs)for the conversion of CO_(2) to C_(2+)products.The interstitial carbon promotes the C-Cu_(2)O NPs to possess abundant unsaturated Cu–O bonds,leading to a high-density Cu^(δ+)(0<δ<1)species.The obtained C-Cu_(2)O NPs exhibited significant Faradic efficiency(FE)of C_(2+) products approaching 76.9%and a partial current density reaching 615.2 mA·cm^(–2)under an industrial-level current density of 800 mA·cm^(–2).Furthermore,the efficient electrosynthesis of C_(2)H_(4) achieved an FE of 57.4%with a partial current density of 459.2 mA·cm^(–2).In situ electrochemical attenuated total reflection Fourier transform infrared spectroscopy and in situ Raman spectroscopy analyses revealed that C-Cu_(2)O NPs stabilized the intermediate*CO and facilitated C–C coupling,leading to increased selectivity towards C_(2+) products.

Single-element amorphous metals

To unveil the nature of amorphous states,single-element amorphous metals have been the perfect research subject due to the simplest composition.However,the extreme crystal nucleation and growth rate in single-element metal make the synthesis of single-element amorphous metals seemingly impossible in the past.Fortunately,benefited by several delicate synthetic strategies developed recently,the single-element amorphous metals have been successfully demonstrated.This review aims to provide a systematic overview of the synthesis of single-element amorphous metals covering the challenges in physics and recent achieve-ments.In addition,current understanding of the atomic and electronic structures of single-element amorphous metal has also been included.Finally,the challenges that worth further investigation are discussed.By identifying the potential avenues for further exploration,this review aims to contribute valuable insights that will propel the cognition of single-element amorphous metals.

Porous bimetallic Pt-Fe nanocatalysts for highly efficient hydrogenation of acetone

Porous Pt-Fe bimetallic nanocrystals have been synthesized via self-assembly and can effectively facilitate the synthesis of 2-propanol from acetone. The bimetallic catalyst has three--dimensional channels and shows turnover frequencies （TOFs） of up to 972 h^-1 for a continuous process more than 50 h. Preliminary mechanistic studies suggest that the high reactivity is related to the interface consisting of a bimetallic Pt-Fe alloy and Fe2O3-x. An understanding of real catalytic behavior and the catalytic mechanism based on model systems has been shown to help fabricate an improved Pt/Fe3O4 catalyst with increased activity and lifetime which has great potential for large-scale industrial applications.

Understanding of the major reactions in solution synthesis of functional nanomaterials

This review covers the major reactions involved in the solution synthesis of nanomaterials.It was designed to classify the traditional strategies such as precipitation,reduction,seed growth,etching,and so on into two basic processes which are termed as bottom-up and top-down routines.The discussion is focused on the basic mechanism and principles during the nudeation and growth of nanocrystals,especially in the solution system.This review also presents a prediction for how to utilize these intrinsic processes to artificially construct the desired specific and functional nanostructures.We try to describe the most directive and effective way to control the structures of nanocrystals for researchers who can master the major reaction mechanism and grasp the basic technologies in synthetic nanoscience.

Interface-induced formation of onion-like alloy nanocrystals by defects engineering

The ability to controlled introduction of defects, particularly twin defects in Pt-based nanocrystals （NCs） provides a possibility to regulate the performance of Pt-based nanocatalyst. However, because of the high internal strain energy existed in twinned structures, the fabrication of defects in Pt-based NCs is sufficiently challenging. Here we demonstrate a ＂low-temperature interface-induced assembly＂ approach that provides precise control over Pt-Cu nanoparticles assembled at the hexadecylamine/water interface, yielding onion-like Pt-Cu NCs exposed a high density of twin defects. Moreover, a bending mechanism is proposed to elucidate the appearance of twin defects and lattice expanding （contraction） based on aberration corrected scanning transmission electron microscopy analysis. This work opens new routes to engineer defects in metal- based alloy NCs, enabling more opportunities in catalysis.

Controlling the lateral and vertical dimensions of Bi2Se3 nanoplates via seeded growth

Modulation of the morphology of nanostructures is often a rewarding but challenging task. We have employed the seeded growth method and induced kinetic control to synthesize Bi2Se3 nanoplates with modifiable morphology. By manipulating the rate at which precursor solutions were injected into seeds solution with syringe pumps, two distinctive growth modes could be realized. With a fast injection, the thickness of Bi2Se3 nanoplates slightly increased from N7.5 nm （seeds） to -9.5 nm while the edge length grew up from ~160 nm （seeds） to N12 ~tm, after 6 successive rounds of seeded growth. With a slow injection, the thickness and edge length increased simultaneously to -35 nm and -6 b^m after 6 rounds of growth, respectively. These two modes could be viewed as a competition between atomic deposition and surface migration. The products showed interesting, thickness-dependent Raman properties. In addition, NIR transparent, highly conductive and flexible Bi2Se3 thin films with different thicknesses were constructed by the assembly of the as-synthesized Bi2Se3 nanoplates. This approach based on seeded growth and kinetic control can significantly promote the development of versatile nanostructures with diverse morphology.

New understanding of phase segregation of bimetallic nanoalloys

In a recent online publication of Science,Professor Peter Strasser of the Technical University of Berlin,Germany,and his collaborators reported element-specific anisotropic growth of Pt and Ni in shaped Pt alloy synthesis[1].They showed that the surface steps in the Pt3Ni concave hexapod alloy formed in the initial stage of the synthesis were crucial in the segregation of an M-rich(M=Ni,Co,

One-pot synthesis of Bi2Se3 nanostructures with rationally tunable morphologies

Shape control has proven to be a powerful and versatile means of tailoring the properties of Bi2Se3 nanostructures for a wide variety of applications. Here, three different Bi2Se3 nanostructures, i.e., spiral-type nanoplates, smooth nanoplates, and dendritic nanostructures, were prepared by manipulating the supersaturation level in the synthetic system. This mechanism study indicated that, at low supersaturation, defects in the crystal growth could cause a step edge upon which Bi2Se3 particles were added continuously, leading to the formation of spiral-type nanoplates. At intermediate supersaturation, the aggregation of amorphous Bi2Se3 particles and subsequent recrystallization resulted in the formation of smooth nanoplates. Furthermore, at high supersaturation, polycrystalline Bi2Se3 cores formed initially, on which anisotropic growth of Bi2Se3 occurred. This work not only advances our understanding of the growth mechanism but also offers a new approach to control the morphology of Bi2Se3 nanostructures.

用于高活性和选择性加氢反应的氧化镍纳米片的非晶态策略

过渡金属氧化物(TMOs)作为低成本的加氢催化剂,具有良好的选择性和耐久性.然而,由于缺乏氢气解离所需的金属活化位点,通常需要在高压(1-5 Mpa H_(2))和高温(100-250℃)等苛刻条件下才能实现氢的活化.在此,我们开发了一种具有极低的Ni-Ni配位数的非晶态氧化镍纳米片,这种独特的特征不仅有利于H_(2)的活化,而且在室温(25℃)和室压(100 kPa H_(2))下,乙烯基的加氢过程具有显著的活性与高选择性(~99%).

Exposing Cu-rich {110} active facets in PtCu nanostars for boosting electrochemical performance toward multiple liquid fuels electrooxidation

In catalysis,tuning the structural composition of the metal alloy is known as an efficient way to optimize the catalytic activity.This work presents the synthesis of compositional segregated six-armed PtCu nanostars via a facile solvothermal method and their distinct composition-structure-dependent performances in electrooxidation processes.The alloy is shown to have a unique six arms with a Cu-rich dodecahedral core,mainly composed of {110} facets and exhibit superior catalytic activity toward alcohols electrooxidation compared to the hollow counterpart where Cu was selectively etched.Density functional theory (DFT) calculations suggest that the formation of hydroxyl intermediate (OH^*) is crucial to detoxify CO poisoning during the electrooxidation processes.The addition of Cu is found to effectively adjust the d band location of the alloy catalyst and thus enhance the formation of ^*OH intermediate from water splitting,which decreases the coverage of ^*CO intermediate.Our work demonstrates that the unique compositional anisotropy in alloy catalyst may boost their applications in electrocatalysis and provides a methodology for the design of this type catalyst.

Concave Cu-Pd bimetallic nanocrystals： Ligand-based Co-reduction and mechanistic study

The synthesis of highly uniform alloy nanocrystals with a concave feature is desirable for applications in catalysis but is an arduous task. This article proposes an initiative protocol for the fabrication of novel Cu-Pd alloy nanocrystals, wherein the volume of decylamine （DA） in the reaction system was found to greatly influence the formation of different morphologies, including the tetrahedron （TH）, concave tetrahedron （CTH）, rhombohedral-tetrapod （RTP）, and tetrapod （TP）. The alloy structure of the products arises from the coordination interaction between the DA and metal ions, which affects the reduction potential of Cu and Pd species, and thus yields co-reduction. Other reaction parameters, such as the type of ligand, amount of reductant, and temperature, were also altered to study the growth mechanism, yielding consistent conclusions in the diffusion-controlled regime. As a catalyst, 48-nm Cu-Pd concave tetrahedral nanocrystals were highly active for the hydrogenation of 3-nitrostyrene and exhibited 〉99.9% chemoselectivity to C=C instead of-NO2.

Two-dimensional Noble Metal Nanomaterials for Electrocatalysis

Two-dimensional noble metal nanomaterials(2D NMNs)are widely used as electrocatalyst.In recent years the researchers have focused on the svnthesis of 2D NMNs at the atomic scale,and realize the improvement of electrocatalytic performance through further structural modification to reduce the usage of noble metals.Herein,we systematically introduce the synthesis methods of 2D NMNs categorized by element type.Subsequently,the catalytic applications toward a variety of electrocatalytic reactions are described in detail including the hydrogen evolution reaction(HER),oxygen reduction reaction(ORR),oxygen evolution reaction(OER)and COz reduction reaction(CO,RR).Finally,the potential opportunities and remaining challenges in this emerging research area are proposed.

Anisotropic Cu@Cu-BTC core-shell nanostructure for memory device

The activity and stability of Cu nanostructures strongly depend on their sizes,morphology and structures.Here we report the preparation of two-dimensional(2 D)Cu@Cu-BTC core-shell nanosheets(NSs).The thickness of the Cu NSs could be tuned to sub-10 nm through a mild etching process,in which the Cu-BTC in situ grow along with the oxidation on the surface of the Cu NSs.This unique strategy can also be extended to synthesize one-dimensional(1 D)Cu@Cu-BTC nanowires(NWs).Furthermore,the obtained Cu@Cu-BTC NSs could be applied as an effective material to the memory device with the write-onceread-many times(WORM)behavior and the high ION/I(OFF)ratio(>2.7×103).