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Single-atom site catalysts (SACs) have made great achievements due to their nearly 100% atomic utilization and uniform active sites. Regulating the surrounding environment of active sites, including electron structure and coordination environment via atom-level interface regulation, to design and construct an advanced SACs is of great significance for boosting electrocatalytic reactions. In this review, we systemically summarized the fundamental understandings and intrinsic mechanisms of SACs for electrocatalytic applications based on the interface site regulations. We elaborated the several different regulation strategies of SACs to demonstrate their ascendancy in electrocatalytic applications. Firstly, the interfacial electronic interaction was presented to reveal the electron transfer behavior of active sites. Secondly, the different coordination structures of metal active center coordinated with two or three non-metal elements were also summarized. In addition, other atom-level interfaces of SACs, including metal atom–atom interface, metal atom-X-atom interface (X: non-metal element), metal atom-particle interface, were highlighted and the corresponding promoting effect towards electrocatalysis was disclosed. Finally, we outlooked the limitations, perspectives and challenges of SACs based on atomic interface regulation.

Single-atom catalysis is the new frontier of heterogeneous catalysis, and have attracted considerable attention for they exhibit great potential in hydrogen evolution to mitigate energy crisis and environmental issues. The support materials of single-atom catalysts (SACs) play a significant role in stabilizing the metal atoms, preventing their aggregation, and enhancing the catalytic activity. Two-dimensional sp2 hybridized PHE-graphene might be a real support for SACs due to the potential energy well induced by its enneagon, hexgon and pentagon carbon rings. In this study, eleven transitional metal (TM) atoms adsorbed on the PHE-graphene (TM@PHEs) are taken into account based on density functional theory (DFT) and the PHE-graphene is proved to be an ideal single-atom carrier for water splitting. In particular, the TM@PHEs (TM= Fe, Ni, Ru, and Pd) exhibit high catalytic activity toward hydrogen evolution reaction (HER). The reaction path of water splitting is also determined. Due to much lower energy barrier, both Fe@PHE and Ru@PHE are more promising SACs. In addition, the charge density difference, Bader charge analysis and spin projected density of states (PDOS) are investigated.

Single-atom site catalysts (SACs) and two-dimensional materials (2DM) have gradually become two hot topics in catalysis over the past decades. Their combination with each other can further endow the derived SACs with extraordinary properties such as high loading, identical active sites, uniform coordination environment, distinctive metal-support interaction, and enhanced catalytic activities. In this review, we highlight the recent development in this specific research topic according to the types of substrates and focus on their applications in energy conversion field. Additionally, we also make a brief introduction to the synthesis and characterization methods for SACs supported on 2DM (SACs/2DM). Finally, the challenges and perspectives are summarized based on the current development status. It is believed that this work will make contributions to the rational design and fabrication of novel SACs/2DM, promoting their practical energy applications in the future.

As one of the most promising fluorescent nanomaterials, carbon dots (CDs) have been extensively studied for their fluorescent properties in solution. However, research on the synthesis of multicolor solid-state fluorescence (SSF) CDs (from blue to red) is rarely reported. Herein, we used o-phenylenediamine, m-phenylenediamine and p-phenylenediamine with dithiosalicylic acid (DTSA) in the solvothermal reaction using acetic acid as a solvent to obtain aggregation-induced emissive (AIE) CDs of red (620 nm), green (520 nm), and blue (478 nm), respectively. XPS spectra and TEM image show that with the red-shift of luminescence, the particle size and content of C = O of the CDs gradually increases. Finally, based on the non-matrix solid-state multicolor luminescence characteristics of CDs, the application of white light LED devices is realized. Besides, based on the fat-soluble properties of CDs, fingerprint detection applications are realized.

Lithium-sulfur (Li-S) batteries suffer from multiple complex and often interwoven issues, such as the low electronic conductivity of sulfur and Li2S/Li2S2, shuttle effect, and sluggish electrochemical kinetics of lithium polysulfides (LiPSs). Guided by theoretical calculations, a multifunctional catalyst of isolated single-atom nickel in an optimal Ni-N5 active moiety incorporated in hollow nitrogen-doped porous carbon (Ni-N5/HNPC) is constructed and acts as an ideal host for a sulfur cathode. The host improved electrical conductivity, enhanced physical-chemical dual restricting capability toward LiPSs, and, more importantly, boosted the redox reaction kinetics by the Ni-N5 active moiety. Therefore, the Ni-N5/HNPC/S cathode exhibits superior rate performance, long-term cycling stability, and good areal capacity at high sulfur loading. This work highlights the important role of the coordination number of active centers in single-atom catalysts and provides a strategy to design a hollow nanoarchitecture with single-atom active sites for high-performance Li-S batteries.

Developing highly efficient oxygen evolution reaction (OER) catalyst for the acidic corrosive operating conditions is a challenging task. Herein, we report the synthesis of uniform RuO2 clusters with ∼ 2 nm in size via electrochemical leaching of Sr from SrRuO3 ceramic in acid. The RuO2 clusters exhibit ultrahigh OER activity with overpotential of ∼ 160 mV at 10 mA·cmgeo−2 in 1.0 M HClO4 solution for 30-h testing. The extended X-ray absorption fine structure measurement reveals enlarged Jahn-Teller distortion of RuO octahedra in the RuO2 clusters compared to its bulk counterpart. Density function theory calculations show that the enhanced Jahn-Teller distortion can improve the intrinsic OER activity of RuO2.

This paper presents a resonant differential-pressure (DP) microsensor with temperature (T) and static-pressure (SP) compensations. In this microsensor, three resonators were positioned on and beside the pressure-sensitive diaphragm and the corresponding intrinsic frequencies were translated into differential pressure under the interferences of temperature and static pressure. Finite element simulation was conducted for device modeling, locating the relationship between the intrinsic resonant frequencies of three resonators and values of differential pressure, temperature and static pressure. Microfabrication (e.g., photolithography, deep reactive-ion etching and anodic bonding) was employed to manufacture the microsensor with key fabrication results displayed in this study. Experimental characterizations were conducted, which indicated that the maximum fitting error of the fabricated microsensor was deceased from 2145.7 Pa (before compensation) to 98.2 Pa (after compensation) under a differential-pressure range from 0 kPa to 100 kPa, a temperature range from 10 °C to 60 °C and a static-pressure range from 110 kPa to 200 kPa.

The electron paramagnetic resonance (EPR) parameters of the impurity Ni3+ (and Cu2+) in MgNH4PO4·6H2O (MAPH) are theoretically studied from the perturbation formulas for 3d7 (and 3d9) ions under or...

It is still of great difficulty to develop the non-platinum catalyst with high catalytic efficiency towards hydrogen evolution reaction via the strategies till now. Therefore, it is necessary to develop the new methods of catalyst designing. Here, we put forward the catalyst designed by the electronic metal-support interaction (EMSI), which is demonstrated to be a reliable strategy to find out the high-efficiency catalyst. We carried out the density functional theory calculation first to design the proper EMSI of the catalyst. We applied the model of M1-M2-X (X=C, N, O) during the calculation. Among the catalysts we chose, the EMSI of Rh1TiC, with the active sites of Rh1-Ti2C2, is found to be the most proper one for HER. The electrochemical experiment further demonstrated the feasibility of the EMSI strategy. The single atomic site catalyst of Rh1-TiC exhibits higher catalytic efficiency than that of state-of-art Pt/C. It achieves a small overpotential of 22 mV and 86 mV at the at the current density of 10 mA cm-2 and 100 mA cm-2 in acid media, with a Tafel slope of 25 mV dec-1 and a mass activity of 54403.9 mA cm-2 mgRh -1 (vs. 192.2 mA cm-2 mgPt -1 of Pt/C). Besides, it also shows appealing advantage in energy saving compared with Pt/C (≈20 % electricity consuming decrease at 2 kA m-2 ) Therefore, we believe that the strategy of regulating EMSI can act as a possible way for achieving the high catalytic efficiency on the next step of SACs.

Surface characterization of metal nanoparticles is a critical need in nanocatalysis for in-depth understanding of the structure-function relationships. The surface structure of nanoparticles is often different from the subsurface, and it is challenging to separately characterize the surface and the subsurface. In this work, theoretical calculations and extended X-ray absorption fine structure (EXAFS) analysis illustrate that the surface atoms of noble metals (Pt and Pd) are oxidized in the air, while the subsurface atoms are not easily oxidized. Taking advantage of the oxidation properties, we suggest a stepwise reduction-oxidation approach to determine the surface atomic arrangement of noble metal nanoparticles, and confirm the rationality of this approach by identifying the surface structure of typical 2–3 nm Pt and Pd nanoparticles. The reduction-oxidation approach is applied to characterize the surface structure of model Pd-Sb bimetallic catalyst, which illustrates that the surface Pd is well isolated by Sb atoms with short bond distance at 2.70 A, while there are still Pd-Pd bonds in the subsurface. Density functional theory (DFT) calculations and Pd L edge X-ray absorption near edge structure (XANES) indicate that the isolation of surface Pd significantly decreases the adsorption energies of Pd-hydrocarbon, which leads to the high propylene selectivity and turnover frequency Pd-Sb bimetallic catalyst for propane dehydrogenation.

Effecting the synergistic function of single metal atom sites and their supports is of great importance to achieve high-performance catalysts. Herein, we successfully fabricate polyoxometalates (POMs)-stabilized atomically dispersed platinum sites by employing three-dimensional metal-organic frameworks (MOFs) as the finite spatial skeleton to govern the accessible quantity, spatial dispersion, and mobility of metal precursors around each POM unit. The isolated single platinum atoms (Pt1) are steadily anchored in the square-planar sites on the surface of monodispersed Keggin-type phosphomolybdic acid (PMo) in the cavities of various MOFs, including MIL-101, HKUST-1, and ZIF-67. In contrast, either the absence of POMs or MOFs yielded only platinum nanoparticles. Pt1-PMo@MIL-101 are seven times more active than the corresponding nanoparticles in the diboration of phenylacetylene, which can be attributed to the synergistic effect of the preconcentration of organic reaction substrates by porous MOFs skeleton and the decreased desorption energy of products on isolated Pt atom sites., It is of great significance to exert the synergistic effect between single atom and support. Here, the authors prepare polyoxometalates-stabilized single-atom site catalysts in confined space with enhanced activity for alkynes diboration.

We presented and demonstrated a new type of vertical nanowire (NW) and nanosheet (NS) field-effect transistors (FETs), named vertical sandwich gate-all-around FETs or VSAFETs, which were formed with the process compatible in the main stream industry. The VSAFETs with self-aligned high- ${k}$ metal gates (HKMGs) were fabricated with epitaxy of Si/SiGe/Si sandwich structure, an isotropic quasi-atomic-layer-etch (qALE) process, and gate replacement process. The gate-length of VSAFETs is mainly determined by the thickness of SiGe film grown by epitaxy. The NW diameter and NS thickness could be obtained by the isotropic qALE method, which can be used to the Si-selective etching of SiGe. As a result, p-type NS and NW VSAFETs with good device characteristics were fabricated. Device performance and the influence of silicide, Ge fraction, Si cap, and high thermal process were investigated; threshold voltage tuning and reliability were also discussed.

Metal-nitrogen-carbon (M-N-C) single-atom catalysts exhibit desirable electrochemical catalytic properties. However, the replacement of N atoms by heteroatoms (B, P, S, etc.) has been regarded as a useful method for regulating the coordination environment. The structure engineered M-N-C sites via doping heteroatoms play an important role to the adsorption and activation of the oxygen intermediate. Herein, we develop an efficient strategy to construct dual atomic site catalysts via the formation of a Co1-PN and Ni1-PN planar configuration. The developed Co1-PNC/Ni1-PNC catalyst exhibits excellent bifunctional electrocatalytic performance in alkaline solution. Both experimental and theoretical results demonstrated that the N/P coordinated Co/Ni sites moderately reduced the binding interaction of oxygen intermediates. The Co1-PNC/Ni1-PNC endows a rechargeable Zn-air battery with excellent power density and cycling stability as an air-cathode, which is superior to that of the benchmark Pt/C+IrO2. This work paves an avenue for design of dual single-atomic sites and regulation of the atomic configuration on carbon-based materials to achieve high-performance electrocatalysts.

Summary Atomically dispersed Fe–N–C catalyst has shown great performance in the CO2-to-CO conversion, yet the high CO selectivity is achieved only within a rather narrow potential range, which cannot well meet the requirements for the following CO dimerization or hydrogenation. Here, we developed a hydrogen-pyrolysis etching strategy to precisely manipulate the uncoordinated N dopants in the Fe–N–C catalyst. This strategy could preferentially eliminate pyridinic and pyrrolic N atoms while leaving graphitic N. The resulting catalyst gave a CO faradaic efficiency (FECO) above 90% over a broad window from −0.3 to −0.8 V (versus RHE) (in particular, FECO > 97% at −0.6 V). In situ ATR-SEIRAS and first-principle calculations further revealed that this strategy can not only suppress the parasitic H2 generation but also promote CO2 activation and protonation with the assistance of co-adsorbed H2O on the “atomic interface” of “FeN4/graphitic N.”

Epoxidation is an efficient chemical process for manufacturing styrene oxide; however, it remains a huge challenge to develop cost-effective and environment-friendly catalysts for facilitating this...

This paper presents a high-sensitivity micromachined resonant differential pressure sensor based on bulk silicon. The sensor includes a sensing unit made of a SOI wafer, which is vacuum packaged by a glass-on-silicon (GOS) wafer. More specifically, two resonators located in the SOI device layer were coupled to the GOS glass layer and deployed on the central and side areas of the pressure-sensitive diaphragm respectively, enabling differential outputs. According to the relevant theory of elasticity, the differential pressure sensitivity is high, where the conversion efficiency of the differential pressure to resonators stress is improved by the special cap design, large pressure-sensitive diaphragm and narrow resonators. The developed differential pressure microsensors were manufactured leveraging well-established microfabrication steps including lithography, etching and boning. Characterization of the micromachined sensors was conducted, reporting averaged differential pressure sensitivities of 1) −143.17 Hz/kPa (~2051 ppm/kPa) and a linear correlation coefficient of 0.999992 under a static pressure of 110 kPa and a temperature range from −°C to 40°C; 2) −143.36 Hz/kPa (~2051 ppm/kPa) and a linear correlation coefficient of 0.999997 under a static pressure range from 110 kPa to 250 kPa and a temperature of 25°C. Compared to previous study, the high differential pressure sensitivity of the sensor can pave ways for the subsequent high-precision measurement of differential pressures, which can be used to measure micro differential pressure in the field of nuclear power.

Today, Pt/C catalysts are widely used in proton exchange membrane fuel cells (PEMFCs). The practical applications of PEMFCs still face many limitations in the preparation of advanced Pt‐based catalysts, including high cost, limited life‐time, and insufficient power density. A kinetically sluggish oxygen reduction reaction (ORR) is primarily responsible for these issues. The development of advanced Pt‐based catalysts is crucial for solving these problems when the large‐scale application of PEMFCs is to be realized. Herein, we demonstrate the design principle of advanced Pt‐based catalysts with an emphasis on theoretical understandings to practical applications. Generally, three main strategies (including strain effect, electronic effect, and ensemble effect) that governing the initial activity of Pt‐based electrocatalysts are elaborated in detail in this review. Recent advanced Pt‐based ORR catalysts are summarized and we present representative achievements to further reveal the relationship of excellent ORR performance based on theoretical mechanisms. Then we focus on the preparation standards of membrane electrode assembles and testing protocols in practice. Finally, we predict the remaining challenges and present our perspectives with regards to design strategies for improving ORR performance of Pt‐based catalysts in the future.

The development of the synthesis methods of single-atom catalysts (SACs) is of great significance for the study of the specificity of SACs. Herein, we report a strategy to immobilize Ru atom using ...

Regulating the selectivity of catalysts in selective hydrogenation reactions at the atomic level is highly desirable but remains a grand challenge. Here we report a simple and practical strategy to synthesize a monolithic single-atom catalyst (SAC) with isolated Pd atoms supported on bulk nitrogen-doped carbon foams (Pd-SAs/CNF). Moreover, we demonstrate that the single-atom Pd sites with unique electronic structure endow Pd-SAs/CNF with an isolated site effect, leading to excellent activity and selectivity in 4-nitrophenylacetylene semi-hydrogenation reaction. In addition, benefiting from the great integrity and excellent mechanical strength, monolithic Pd-SAs/CNF catalyst is easy to separate from the reaction system for conducting the subsequent recycling. The cyclic test demonstrates the excellent reusability and stability of monolithic Pd-SAs/CNF catalyst. The discovery of isolated site effect provides a new approach to design highly selective catalysts. And the development of monolithic SACs provides new opportunities to advance the practical applications of single-atom catalysts.

We report an Ag1 single-atom catalyst (Ag1 /MnO2 ), which was synthesized from thermal transformation of Ag nanoparticles (NPs) and surface reconstruction of MnO2 . The evolution process of Ag NPs to single atoms is firstly revealed by various techniques, including in situ ETEM, in situ XRD and DFT calculations. The temperature-induced surface reconstruction process from the MnO2 (211) to (310) lattice plane is critical to firmly confine the existing surface of Ag single atoms; that is, the thermal treatment and surface reconstruction of MnO2 is the driving force for the formation of single Ag atoms. The as-obtained Ag1 /MnO2 achieved 95.7 % Faradic efficiency at -0.85 V vs. RHE, and coupled with long-term stability for electrochemical CO2 reduction reaction (CO2 RR). DFT calculations indicated single Ag sites possessed high electronic density close to Fermi Level and could act exclusively as the active sites in the CO2 RR. As a result, the Ag1 /MnO2 catalyst demonstrated remarkable performance for the CO2 RR, far surpassing the conventional Ag nanosized catalyst (AgNP /MnO2 ) and other reported Ag-based catalysts.

Fischer–Tropsch synthesis (FTS) is a significant catalytic process for the production of liquid fuel and fine chemicals from natural gas-, coal-, and biomass-derived syngas. However, exploring high...

The Rayleigh wave propagation in the irregular bottom of the ocean, which is the interface of a homogeneous non-viscous liquid layer overlaying a porous half-space, under the influence of different...

Complexity in strongly correlated oxides such as perovskite strictly dominates their performance for oxygen reduction reaction (ORR). Precise control of the physical correlations among spin, charge, orbital, and lattice degrees of freedom in these oxides can exercise considerable enhancement of ORR activity, but has until now remained elusive. Here, we show that nonmagnetic hexavalent molybdenum (Mo6+) atomically dispersed within oxide lattice steers the intrinsic activity of catalytically active sites by entrapping extrinsic electrons at their 3d orbitals, without the occurrence of lattice symmetry breaking and magnetic perturbation. With double perovskite La2Co2+Mn4+O6 as a model catalyst, the atomic-scale electron trap generates additional high-spin, catalytically active Mn3+(t32ge1g) sites and highly conductive Co2+(e2g)–O–Mn3+(e1g) double exchange channels, leading to five-fold improvement in ORR activity. First-principles calculations reveal a substantial increase of the spin density on Mn sites caused by electron trapping, and unambiguously confirm a more exothermic reaction pathway as well as a lower barrier of the rate-limiting surface hydroxide regeneration on Mo1/La2CoMnO6. We can also extend this strategy with atomic precision easily to other four oxide catalysts and achieve large enhancement in their ORR activities as anticipated, indicating its broad utility. This work embodies the theories of condensed matter physics in rational design of ORR catalysts, and may inspire further development of the control of electron correlation in strongly correlated electron systems.

On the path to deploying the electrochemical CO2 reduction reaction (CO2RR) to CO, the narrow potential range under the high Faraday efficiency of CO (FECO) still blocks its ultimate practical viability. Engineering the electronic structure via heteroatom doping is supposed to be efficient. However, a feasible synthesis and precise control are still challenging. Here, we propose a fast-pyrolyzing and controllable-activation strategy to construct an O-rich carbonaceous support and atomically dispersed FeN4 site with axial O coordination (Fe1N4–O1), which was confirmed by aberration-corrected electron microscopy and X-ray absorption spectroscopy. A wide potential range of 310 mV (−0.56 V to −0.87 V vs. RHE) could be achieved when FECO was continuously maintained at nearly 100%, which exceeded the existing results to the best of our knowledge. DFT calculations revealed that the superior performance originated from the axial O-coordination induced electronic localization enhancement, which could facilitate the desorption of CO and increase the energy barrier for the competitive hydrogen evolution reaction.

Electrocatalysis is viewed as one of the most effective ways to mitigate the energy problems and produce fuels or value‐added chemicals in a gentle manner. However, duo to the limited electrochemical properties of various systems, there is an intensive search for highly efficient electrocatalysts by more rational control over the topographic structure, chemical structure, and electronic structure. At present, the development of electrocatalysts mainly includes two directions: (1) nanoparticle electrocatalysts, and (2) single atom site electrocatalysts (SACs). Nanoparticle and SACs display their own advantages, and have been widely studied in the field of electrocatalysis. Considering the state‐of‐the‐art progress for nanoparticles or SACs, the selection of effective electrocatalysts has been a topic of great research value. Therefore, this paper summarizes the advantages, commonalities, and problems of nanoparticle and SACs, as well as their developing methods and experiences. In addition, the selection of nanoparticle and SACs in electrocatalytic reactions was discussed from the aspects of their respective influencing factors, active sites and synergistic effect. Finally, the research of nanoparticle and single atom sites electrocatalysts were prospected, providing a general guidance for the selection of efficient electrocatalysts.

Atomic-scale structures and energetics of the Co3O4 (001) surface are studied combining high-resolution transmission electron microscopy observations and density functional theory calculations. The...

Decorating semi-conducting metal oxide with noble metal has been recognized as a viable approach to improve the sensitivity of gas sensor. However, conventional method which relys on noble metal nanoparticles is confronted with drawback of significantly increased cost. To maximize the atom efficiency and reduce the cost for practical industrial application, designing sensor material with noble metal isolated single atom sites (ISAS) doping is a desired option. Here, we report an atomically dispersed platinum on one-dimensional arranged porous γ-Fe2O3 nanoparticle composites as highly efficient ethanol gas sensor. The optimized sample (Pt1-Fe2O3-ox) exhibited a high response (Ra/Rg = 102.4) and good selectivity to ethanol gas. It is demonstrated only the Pt single atom sites with high valance can effectively promote the adsorption capacity to ethanol and consequently enhance the sensitivity of sensing process by changing the electrical structure of Fe2O3 support. This work indicates the single atom sites could play a vital role in improving the performance of conventional metal oxides gas sensors and pave way for the exploration of ISAS-enhanced gas sensor for other volatile organic compounds (VOCs).

Supported atomic clusters with uniform metal sites and definite low-nuclearity are intermediate states between single-atom catalysts (SACs) and nanoparticles in size. Benefiting from the presence of metal–metal bonds, supported atomic clusters can trigger synergistic effects among every metal atom, which contributes to achieving unique catalytic properties different from SACs and nanoparticles. However, the scalable and precise synthesis and atomic-level insights into the structure–properties relationship of supported atomic clusters is a great challenge. This perspective presents the latest progress of the synthesis of supported atomic clusters, highlights how the structure affects catalytic properties, and discusses the limitations as well as prospects., Supported atomic clusters with precise nuclearity are intermediate states between single-atom catalysts and nanoparticles in size. Here the authors summarize and discuss synthetic strategies of supported atomic clusters with unique catalytic properties for heterogeneous reactions.

The demand for high-performance non-precious-metal electrocatalysts to replace the noble metal-based catalysts for oxygen reduction reaction (ORR) is intensively increasing. Herein, single-atomic copper sites supported on N-doped three-dimensional hierarchically porous carbon catalyst (Cu1/NC) was prepared by coordination pyrolysis strategy. Remarkably, the Cu1/NC-900 catalyst not only exhibits excellent ORR performance with a half-wave potential of 0.894 V (vs. RHE) in alkaline media, outperforming those of commercial Pt/C (0.851 V) and Cu nanoparticles anchored on N-doped porous carbon (CuNPs/NC-900), but also demonstrates high stability and methanol tolerance. Moreover, the Cu1/NC-900 based Zn-air battery exhibits higher power density, rechargeability and cyclic stability than the one based on Pt/C. Both experimental and theoretical investigations demonstrated that the excellent performance of the as-obtained Cui/NC-900 could be attributed to the synergistic effect between copper coordinated by three N atoms active sites and the neighbouring carbon defect, resulting in elevated Cu d-band centers of Cu atoms and facilitating intermediate desorption for ORR process. This study may lead towards the development of highly efficient non-noble metal catalysts for applications in electrochemical energy conversion.

The design of non-noble metal heterogeneous catalyst with superior performance for selective hydrogenation or transfer hydrogenation of nitroarenes to amines is significant but challenging. Herein, a single-atom Fe supported by nitrogen-doped carbon (Fe1/N-C) catalyst is reported. The Fe1/N-C sample shows superior performances for the selective hydrogenation and transfer hydrogenation of nitrobenzene to aniline at different temperatures. Density functional theory (DFT) calculations show that the superior catalytic activity for the selective hydrogenation at lower temperatures could be attributed to the effective activation of the reactant and intermediates by the Fe1/N-C. Moreover, the excellent performance of Fe1/N-C for the selective transfer hydrogenation could be attributed to that the reaction energy barrier for dehydrogenation of isopropanol can be overcome by elevated temperatures.

Main-group element indium (In) is a promising electrocatalyst which triggers CO2 reduction to formate, while the high overpotential and low Faradaic efficiency (FE) hinder its practical application. Herein, we rationally design a new In single-atom catalyst containing exclusive isolated Inδ+ -N4 atomic interface sites for CO2 electroreduction to formate with high efficiency. This catalyst exhibits an extremely large turnover frequency (TOF) up to 12500 h-1 at -0.95 V versus the reversible hydrogen electrode (RHE), with a FE for formate of 96 % and current density of 8.87 mA cm-2 at low potential of -0.65 V versus RHE. Our findings present a feasible strategy for the accurate regulation of main-group indium catalysts for CO2 reduction at atomic scale.

This paper presents a wireless passive pressure sensor based on a pressure-sensitive capacitor specifically designed to monitor intracranial pressure (ICP) in patients with traumatic brain injuries. It is crucial that temperature will affect the accuracy of pressure detection. To improve temperature stability, the capacitor is composed of an SOI wafer as the sensing element and a glass cap for vacuum packaging. To realize reliable vacuum packaging, it is vital to transfer the electrical signal out of the vacuum cavity. The experimental results show that the proposed sensor demonstrated averaged pressure sensitivity and averaged temperature sensitivity of 0.5803 Hz/kPa and 0.024 Hz/°C. Additionally, the in-vivo test in the animal show that the proposed sensor has the similar detection effect with the commercial wired sensor, and naturally has the advantage of reducing the risk of infection, which further validated the feasibility and effectiveness of the wireless passive ICP monitoring system.

Tin phosphide (Sn4P3) that identified as a potential anode for sodium ion batteries (SIBs) based on its high theoretical specific capacity mostly confronts with the huge challenges in rapid capacity decay, severe volume evolution and weak diffusion kinetics upon cycling. It is of great theoretical and practical significance to develop the multilevel structured metal phosphide anode in high performance SIBs systems. Herein, we construct a nanochain-like architecture built from hollow yolk-shell Sn4P3@C nanospheres (Sn4P3@CNF) by electrospinning method and phosphorization treatment, in which all hollow Sn4P3 nanospheres are uniformly chained to one dimensional (1D) carbon nanofibers, forming a necklace-like hybrid conductive construction. The synergistic effect between hollow Sn4P3 nanospheres and nanochain architecture not only offers unblocked transfer channels for Na+ and accelerates the long-distance electronic transmission, but also guarantees excellent electrode kinetics and accommodates volume expansion. The Sn4P3@CNF electrode delivers a highly reversible discharge capacity of 297.6 mAh g−1 at 1 A g−1 after 1750 cycles, 250.6 mAh g−1 at 2 A g−1 after 4700 cycles, as well as ultrastable cycling durability up to 14000 cycles with a capacity of 157.8 mAh g−1 even at a high rate of 5 A g−1. These results demonstrate the greatest cyclability reported so far on Sn4P3-based anodes for SIBs. Meanwhile, the consecutive CV measurement further confirms a capacitive electrochemical redox behavior of Sn4P3@CNF upon cycling. More interestingly, the Sn4P3@CNF electrode displays the superior cycling stability and rate capability in sodium ion full cells as combined with a high-voltage Na3V2(PO4)3 cathode, where the full cell delivers an initial discharge capacity of 286.4 mAh g−1 and maintains a 67.2% capacity retention after 160 cycles at 1 A g−1, making it a great potential for practical application in SIBs systems.

The evolution of hydrogen from water using renewable electrical energy is a topic of current interest. Pt/C exhibits the highest catalytic activity for the H2 evolution reaction (HER), but scarce supplies and high cost limit its large-scale application. Atomic active centers in single-atom catalysts, single-atom alloys, and catalysts with two atom sorts exhibit maximum atomic efficiency, unique structure, and exceptional activity for the HER. Interactions between well-defined active sites and supports are known to affect electron transfer and dramatically accelerate the reaction. This Review first highlights methods for studying atomic active centers for the HER. Then, active sites with different coordination configurations are described. Active centers with one metal atom, two different metal atoms as well as nonmetal atoms are analyzed at the atomic scale. Finally, future research perspectives are proposed.

Atomic non-noble metal materials show the potential to substitute noble metals in catalysis. Herein, melamine formaldehyde resin is developed to synthesize atomic iron on mesoporous nitrogen-doped carbon. The triazine units with abundant nitrogen content and cavity can realize effectively anchoring of single metal atoms. The atomic iron with unique charge and coordination characteristics shows superior catalytic performance in dehydrogenation reaction. Various N-heterocycles compounds and amines can be efficiently dehydrogenated into the corresponding products at room temperature, which is the mildest of all reported reaction conditions even when noble metal catalysts are considered. Therefore, development of atomic non-noble metal catalysts with mesoporous structure may provide an effective way to realize the substitution for noble metals in heterogeneous catalysis.

Mesocrystals, the non-classical crystals with highly ordered nanoparticle superstructures, have shown great potential in many applications because of their newly collective properties. However, there is still a lack of a facile and general synthesis strategy to organize and integrate distinct components into complex mesocrystals, and of reported application for them in industrial catalytic reactions. Herein we report a general bottom-up synthesis of CuO-based trimetallic oxide mesocrystals (denoted as CuO-M1Ox-M2Oy, where M1 and M2 = Zn, In, Fe, Ni, Mn, and Co) using a simple precipitation method followed by a hydrothermal treatment and a topotactic transformation via calcination. When these mesocrystals were used as the catalyst to produce trichlorosilane (TCS) via Si hydrochlorination reaction, they exhibited excellent catalytic performance with much increased Si conversion and TCS selectivity. In particular, the TCS yield was increased 19-fold than that of the catalyst-free process. The latter is the current industrial process. The efficiently catalytic property of these mesocrystals is attributed to the formation of well-defined nanoscale heterointerfaces that can effectively facilitate the charge transfer, and the generation of the compressive and tensile strain on CuO near the interfaces among different metal oxides. The synthetic approach developed here could be applicable to fabricate versatile complicated metal oxide mesocrystals as novel catalysts for various industrial chemical reactions.

The electronic paramagnetic resonance (EPR) parameters (g factor gi , and hyperfine structure constants Ai , with i = || and ⊥) and tetragonal distortion of the Cu2+ center in Al2O3 are unified int...

Herein, we report efficient single copper atom catalysts that consist of dense atomic Cu sites dispersed on a three-dimensional carbon matrix with highly enhanced mesoporous structures and improved active site accessibility (Cu-SA/NC(meso)). The ratio of +1 to +2 oxidation state of the Cu sites in the Cu-SA/NC(meso) catalysts can be controlled by varying the urea content in the adsorption precursor, and the activity for ORR increases with the addition of Cu

Abiotic stress severely threatens agriculture. Herein, we studied the effect of heteroatom-free carbon dots (CDs) on the alleviation of abiotic stresses in rice for the first time. During in vitro coincubation, suspended rice cells were exposed to 2,4-dichlorophenoxyacetate sodium (2,4-D-Na, 30 μg mL-1), 2,4-dichlorophenoxyacetic acid (2,4-D, 5 μg mL-1), NaCl (0.15 mol·L-1), and high light (2000 Lux), both with and without CDs (100 μg mL-1). After a week, CDs significantly reduced the inhibition rate of 2,4-D-Na on the rice cell biomass from 48.16 to 27.44% and increased the biomass of rice cells exposed to 2,4-D, NaCl, and high light, by 4.12, 1.10, and 4.01 times that of the control (pure nutrient medium), respectively. Furthermore, the growth of CD-germinated rice seedlings was not obviously affected by 2,4-D-Na, 2,4-D, and NaCl. Further results showed that the CDs demonstrated an intrinsic free-radical scavenging property and could increase the peroxidase activity and the contents of phenolics and flavonoids in rice by 125.81, 39.60, and 47.63%, respectively. Furthermore, CDs improved the nutrient assimilation of rice cells under 2,4-D stress by 14.69%. With higher antioxidant capacity and sufficient nutrients, the CD-treated rice showed excellent resistance to abiotic stresses. This study suggested the great potential of CDs in protecting crops against abiotic stress.

The rational design of efficient single-atomic (SA) catalysts is essential and highly desirable but impeded by the lack of sufficient acknowledge between structure and property. To this end, it is critical to clarify the effect of the coordination structure of active metal centers on the catalytic activities for the design of such catalysts. Here, we report that different coordination structures of SA Pt catalysts can dramatically influence their activities for anti-Markovnikov hydroboration of alkenes. Compared with the other two coordination structures (Pt-N4 and Pt-O2), the SA Pt species coordinated with three O atoms (Pt-O3) display the highest turnover number value of 3288 for the hydroboration reaction to access the important alkylboronic esters. Density functional theory calculations reveal that a superior catalytic activity can be expected for alkene hydroboration over the three O coordinated Pt species due to the lowest reaction energy (Δ G ) limiting step from the reaction phase diagram.

Atomic regulation of metal catalysts has emerged as an intriguing yet challenging strategy to boost product selectivity. Here, we report a density functional theory-guided atomic design strategy for the fabrication of a NiGa intermetallic catalyst with completely isolated Ni sites to optimize acetylene semi-hydrogenation processes. Such Ni sites show not only preferential acetylene π-adsorption, but also enhanced ethylene desorption. The characteristics of the Ni sites are confirmed by multiple characterization techniques, including aberration-corrected high-resolution scanning transmission electron microscopy and X-ray absorption spectrometry measurements. The superior performance is also confirmed experimentally against a Ni5 Ga3 intermetallic catalyst with partially isolated Ni sites and against a Ni catalyst with multi-atomic ensemble Ni sites. Accordingly, the NiGa intermetallic catalyst with the completely isolated Ni sites shows significantly enhanced selectivity to ethylene and suppressed coke formation.

Designing low-cost, high-efficiency, platinum-free electrocatalysts for the hydrogen oxidation reaction (HOR) in an alkaline electrolyte is of great importance for the development of anion exchange membrane fuel cells. Herein, we report a novel HOR catalyst, RuNi1, in which Ni is atomically dispersed on the Ru nanocrystals. To note, the as-prepared RuNi1 catalyst exhibits excellent catalytic activity and stability for HOR in alkaline media, which is superior to those of Ru-Ni bimetallic nanocrystals, pristine Ru, and commercial Pt/C catalysts. Density functional theory (DFT) calculations suggest that isolation of Ni atoms on Ru nanocrystals not only optimizes the hydrogen-binding energy but also decreases the free energy of water formation, thus leading to excellent electrocatalytic activity of RuNi1 catalyst. The results show that engineering a catalyst at an atomic level is highly effective for rational design of electrocatalysts with high performance.

The solar-driven photocatalytic reduction of CO2 (CO2 RR) into chemical fuels is a promising route to enrich energy supplies and mitigate CO2 emissions. However, low catalytic efficiency and poor selectivity, especially in a pure-water system, hinder the development of photocatalytic CO2 RR owing to the lack of effective catalysts. Herein, we report a novel atom-confinement and coordination (ACC) strategy to achieve the synthesis of rare-earth single erbium (Er) atoms supported on carbon nitride nanotubes (Er1 /CN-NT) with a tunable dispersion density of single atoms. Er1 /CN-NT is a highly efficient and robust photocatalyst that exhibits outstanding CO2 RR performance in a pure-water system. Experimental results and density functional theory calculations reveal the crucial role of single Er atoms in promoting photocatalytic CO2 RR.

The power extraction performance of a fully-active flapping foil with synthetic jet is numerically investigated in this work. An elliptic airfoil with ratio of 8, which is placed in a two-dimensional laminar flow, is adopted to extract power from the flow. The foil implements the imposed translational and rotational motions synchronously. A pair of synthetic jets with the same frequency and strength is integrated into the upper and lower surfaces of flapping foil. As a result, the flow field around the foil could be affected by the synthetic jets greatly. At the Reynolds number of 1000 and the pitching axis location of half chord, the effects of the jet strength, the inclined angle between the jet direction and the chord line, as well as the phase angle between the synthetic jets and the flapping motion on the power extraction performance are systematically investigated. Compared with the traditional flapping foil, it is demonstrated that the enhancement of power extraction efficiency can be achieved with the help of synthetic jets. Based on the numerical analysis, it is indicated that the jet flow on the foil surfaces alters the vortex-shedding process and modifies the pressure distribution on the foil surface. As a result, the overall power extraction of the flapping foil can be benefitted.

The local coordination environment of catalysts has been investigated for an extended period to obtain enhanced catalytic performance. Especially with the advancement of single-atom catalysts (SACs), research on the coordination environment has been advanced to the atomic level. The surrounding coordination atoms of central metal atoms play important roles in their catalytic activity, selectivity and stability. In recent years, remarkable improvements of the catalytic performance of SACs have been achieved by the tailoring of coordination atoms, coordination numbers and second- or higher-coordination shells, which provided new opportunities for the further development of SACs. In this review, the characterization of coordination environment, tailoring of the local coordination environment, and their related adjustable catalytic performance will be discussed. We hope this review will provide new insights on further research of SACs.