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Nitrogen oxide (NO x ) pollution presents a severe threat to the environment and human health. Catalytic reduction of NO x with H 2 using single-atom catalysts poses considerable potential in the remediation of air pollution; however, the unfavorable process of H 2 dissociation limits its practical application. Herein, we report that the in situ formation of Pt Ti cocatalytic sites (which are stabilized by Pt–Ti bonds) over Pt 1 /TiO 2 significantly increases NO x conversion by reducing the energy barrier of H 2 activation. We demonstrate that two H atoms of H 2 molecule are absorbed by adjacent Pt atoms in Pt–O and Pt–Ti, respectively, which can promote the cleave of H–H bonds. Besides, Pt Ti sites facilitate the adsorption of NO molecules and further lower the activation barrier of the whole de-NO x reaction. Extending the concept to Pt 1 /Nb 2 O 5 and Pd 1 /TiO 2 systems also sees enhanced catalytic activities, demonstrating that engineering the cocatalytic sites can be a general strategy for the design of high-efficiency catalysts that can benefit environmental sustainability.

At the end of 2019, the sudden attack of the COVID-19 brought huge challenges to the management, operation and development of listed companies. In view of the suddenness of the epidemic, the internal governance of listed companies is even more important! The index system, governance structure and performance, structure and behavior, structure and performance of the proposed hypotheses affected by the behavior of the index system, the 2019-2020 China GEM listed companies as a sample of equity concentration, and the human capital board of directors as the sample explanatory variable , Business performance, innovation performance are dependent variables, supervision and behavior, as an intermediary to encourage behavior, related test hypotheses, verify the path that Chinese companies listed in the GEM governance structure affect governance performance through behavior.

An Fe-N-C catalyst with an FeN

Oxygen vacancy (Ov) as well as Ov migration in metal oxide are of great importance in structural evolution of active center in single-atom catalysts (SACs). Here, the interplay between invasive single Pt atom and native Ov in SA-Pt/rutile TiO2(110) surface, as well as their synergetic effect on water dissociation are investigated by density functional theory (DFT) calculations. We show that importing Pt atom as Pt-ads, Pt2c, Pt5c and Pt6c modes could decelerate the Ov migration effectively, especially in Pt6c mode. Under oxygen-rich conditions, Pt6c substitution could make oxygen Ov formation easier, but migration harder. On Pt6c/Ti1−yO2−x1(110) surface, as a bimetal center, Pt4c-Ti5c concave could not make water dissociation process easier; however, the O2c closed to Pt become a good proton acceptor to make water dissociation on Ti5c-O2c more convenient with the aid of topmost Ti5c.

Oxygen evolution reaction (OER) still suffers from the bottleneck in electrocatalytic water splitting. Herein, in virtue of volcano plots drawn by theoretical calculation, the (001) facet was screened as the superb facet of orthorhombic CoSe2 for OER. Afterwards, CoSe2(001) nanosheets were synthesized and the exposure ratio of (001) facet is controllable with thermodynamics methods effectively. The single-facet CoSe2(001) delivered an overpotential as low as 240 mV at 10 mA·cm−2 in 1 M KOH, which outperformed the bulk (380 mV) as well as other CoSe2-base OER catalysts reported before. Especially, a shorter Co-Co path was observed in CoSe2(001) by X-ray absorption spectroscopy. Further density functional theory (DFT) studies revealed that the reversible compression on the shorter Co-Co path could regulate the electronic structure of active sites during the OER process, and thus the energy barrier of the rate-determining step was reduced by 0.15 eV. This work could inspire more insights on the modification of electronic structure for OER electrocatalysts.

In this manuscript, ruthenium (Ru) nanoparticles functionalized with nitrene ligands through the ruthenium-nitrene (Ru N) π bonds are explored. By synthesizing the nitrene ligands with and without 15N-labelling, Ru N π bonds on Ru nanoparticles are evidenced by experimental and theoretically calculated FTIR spectra. The coordination of nitrene ligands on Ru nanoparticles surface, the interfacial charge delocalization and the impact of nitrene ligands on the catalytic performance of Ru nanoparticles are further characterized by magic-angle spinning solid-state carbon nuclear magnetic resonance spectroscopy (13C NMR) of 13CO-adsorbed Ru nanoparticles, photoluminescence and the hydrogenation of styrene.

The mechanical and electornic properties of AgTi, AgTi2 and AgTi3 intermetallic phases at zero pressure have been systemically investigated by first-principles calculations using ultrasoft pseudopo...

The oxidation of hydrocarbons to produce high value-added compounds (ketones or alcohols) using oxygen in air as the only oxidant is an efficient synthetic strategy from both environmental and economic views. Herein, we successfully synthesized cobalt single atom site catalysts (Co SACs) with high metal loading of 23.58 wt.% supported on carbon nitride (CN), which showed excellent catalytic properties for oxidation of ethylbenzene in air. Moreover, Co SACs show a much higher turn-over frequency (19.6 h−1) than other reported non-noble catalysts under the same condition. Comparatively, the as-obtained nanosized or homogenous Co catalysts are inert to this reaction. Co SACs also exhibit high selectivity (97%) and stability (unchanged after five runs) in this reaction. DFT calculations reveal that Co SACs show a low energy barrier in the first elementary step and a high resistance to water, which result in the robust catalytic performance for this reaction.

Developing cost-effective and highly efficient electrocatalysts is urgent for a sustainable hydrogen economy. In this work, a versatile electrocatalyst was developed by growing P-doped CoCO3 nanosheets on Co foam (P–CoCO3/CF). Benefiting from the well-designed nanostructure, good electrical conductivity and high intrinsic activity, the P–CoCO3/CF exhibits excellent multifunctional electrocatalytic performance towards the hydrogen evolution reaction (HER), the oxygen evolution reaction (OER), and the hydrazine oxidation reaction (HzOR), respectively. According to the results, only low cell voltages (at j = 10/100 mA cm−2) of 1.55/1.77 V are required for the P–CoCO3/CF(+)‖P–CoCO3/CF(−) two-electrode couples in 1 M KOH, which are both better than those of RuO2(+)‖Pt/C(−) couples. Surprisingly, for using the HzOR as a substitute for the OER, only a voltage (at j = 100 mA cm−2) of 0.13 V is needed, which is the smallest potential for hydrogen production reported so far. Theoretical calculations demonstrate that P doping tunes the electronic properties of catalytic center-Co, leading to the desired decrease of the free energy of the rate-determining-step (rds) and efficiency amelioration of HER and HzOR processes.

Electrocatalytic oxidation of organics using water as the oxygen source is a prospective but challenging method to produce high-value-added chemicals; especially, the competitive oxygen evolution reaction (OER) limits its efficiency. Herein, a tandem catalysis strategy based on a single-atom catalyst with Cr atoms atomically dispersed at a CoSe

Oxygen-involved electrochemical reactions are crucial for plenty of energy conversion techniques. Herein, we rationally designed a carbon-based Mn-N2C2 bifunctional electrocatalyst. It exhibits a half-wave potential of 0.915 V versus reversible hydrogen electrode for oxygen reduction reaction (ORR), and the overpotential is 350 mV at 10 mA cm-2 during oxygen evolution reaction (OER) in alkaline condition. Furthermore, by means of operando X-ray absorption fine structure measurements, we reveal that the bond-length-extended Mn2+-N2C2 atomic interface sites act as active centers during the ORR process, while the bond-length-shortened high-valence Mn4+-N2C2 moieties serve as the catalytic sites for OER, which is consistent with the density functional theory results. The atomic and electronic synergistic effects for the isolated Mn sites and the carbon support play a critical role to promote the oxygen-involved catalytic performance, by regulating the reaction free energy of intermediate adsorption. Our results give an atomic interface strategy for nonprecious bifunctional single-atom electrocatalysts.

The development of high-efficiency, low-cost, and earth-abundant electrocatalysts for overall water splitting remains a challenge. In this work, Ni-modified MoS2 hybrid catalysts are grown on carbon cloth (Ni-Mo-S@CC) through a one-step hydrothermal treatment. The optimized Ni-Mo-S@CC catalyst shows excellent hydrogen evolution reaction (HER) activity with a low overpotential of 168 mV at a current density of 10 mA cm-2 in 1.0 m KOH, which is lower than those of Ni-Mo-S@CC (1:1), Ni-Mo-S@CC (3:1), and pure MoS2 . Significantly, the Ni-Mo-S@CC hybrid catalyst also displays outstanding oxygen evolution reaction (OER) activity with a low overpotential of 320 mV at a current density of 10 mA cm-2 , and remarkable long-term stability for 30 h at a constant current density of 10 mA cm-2 . Experimental results and theoretical analysis based on density functional theory demonstrate that the excellent electrocatalytic performance can be attributed mainly to the remarkable conductivity, abundant active sites, and synergistic effect of the Ni-doped MoS2 . This work sheds light on a unique strategy for the design of high-performance and stable electrocatalysts for water-splitting electrolyzers.

It is highly desirable but challenging to optimize the structure of photocatalysts at the atomic scale to facilitate the separation of electron-hole pairs for enhanced performance. Now, a highly efficient photocatalyst is formed by assembling single Pt atoms on a defective TiO2 support (Pt1 /def-TiO2 ). Apart from being proton reduction sites, single Pt atoms promote the neighboring TiO2 units to generate surface oxygen vacancies and form a Pt-O-Ti3+ atomic interface. Experimental results and density functional theory calculations demonstrate that the Pt-O-Ti3+ atomic interface effectively facilitates photogenerated electrons to transfer from Ti3+ defective sites to single Pt atoms, thereby enhancing the separation of electron-hole pairs. This unique structure makes Pt1 /def-TiO2 exhibit a record-level photocatalytic hydrogen production performance with an unexpectedly high turnover frequency of 51423 h-1 , exceeding the Pt nanoparticle supported TiO2 catalyst by a factor of 591.

Efficient nonprecious multifunctional catalysts are indispensable to enable the widespread applications of several important electrochemical energy technologies. Herein, catalytically active metast...

The regulation of catalytic activity in the oxygen reduction reaction (ORR) is significant to the development of metal–air batteries and other oxygen involving energy conversion devices. Herein, we propose an atomic interface strategy to construct a single atom copper catalyst (denoted as Cu-SA/SNC) which exhibits enhanced ORR activity with a half-wave potential of 0.893 V vs. RHE in alkaline media. Moreover, synchrotron-radiation-based X-ray absorption fine structure (XAFS) investigations together with density functional theory (DFT) calculations reveal that the isolated bond-shrinking low-valence Cu (+1)–N4–C8S2 atomic interface moiety serves as an active site during the ORR process, and the synergistic mechanism between the Cu species and the carbon matrix at the atomic interface plays a critical role in boosting the ORR efficiency, by adjusting the reaction free energy of intermediate adsorption. This atomic interface concept may provide an alternative methodology for the rational design of advanced oxygen electrode materials and new probability to improve their catalytic performance.

Recently, a few in situ observations showed that reactant molecules can induce the hyper-fine surface change of catalyst under realistic conditions. However, hardly any report further illustrated that whether and how could this phenomenon affect the catalytic performance. Herein, using in situ TEM, we visually captured the reversible lattice expansion of Pt-WO3-x catalyst induced by NO in exemplified reduction of NO with H2. Results showed that the NO could adsorb on the oxygen vacancy sites and energetic favorably induced the reversible stretching of W-O-W bonds. 20% enhancement of catalytic activity was then correlated with this lattice expansion. Moreover, DFT calculations showed that the lattice expansion can reduce the adsorption energy of NO on Pt4 centers and also the energy barrier of the rate-determining step.

For single-atom (SA)-based catalysis, it is urgent to understand the nature and dynamic evolution of SA active sites during the reactions. In this work, an example of Pt SA-Zn

Atomic-level insight into the unique catalytic capability of single-atom catalysts that distinguished from nanometer-sized counterparts is highly desirable for catalyst design and catalysis research. By synthesizing single Pd atoms supported on TiO2 as a catalyst, here we demonstrate a steric hindrance effect of single atoms induced by the unique isolation of single-atom active sites to achieve a remarkable enhancement on catalytic performance in the synthesis of dimethyl carbonate. Experimental results and density functional theory calculations reveal that such steric hindrance effect of single atoms favors the yield of the desired product dimethyl carbonate against further reacting with intermediates to form byproduct, because no extra Pd species around single Pd atoms provide active sites to further adsorb and activate substrates directly. The discovery of such steric hindrance effect is a valuable supplement to single-atom catalysis, and may promote single-atom catalysts to be widely applied in selective catalytic reactions.

Oxygen-involved electrochemical reactions are crucial for plenty of energy conversion techniques. Herein, we rationally designed a carbon-based Mn-N

Single-atomic-site (SAS) catalysts, a new frontier of catalysts, always show extremely high atom efficiency and unexpected catalytic properties. Herein, a pyrolyzing coordinated polymer (PCP) strategy is developed, which is facile and widely applicable in the synthesis of a series of SAS catalysts including SAS-Fe, SAS-Ni, SAS-Cu, SAS-Zn, SAS-Ru, SAS-Rh, SAS-Pd, SAS-Pt, and SAS-Ir. The as-obtained SAS catalysts can be easily synthesized at gram scale and the metal loading of SAS-Fe catalysts achieves a record value of 30 wt%, which meets the requirement of practical applications. Moreover, it is discovered that SAS-Fe catalysts show unprecedented catalytic performance for epoxidation of styrene using O2 as the only oxidant (yield: 64%; selectivity: 89%), while Fe nanoparticles and ironporphyrin are inactive. This discovery is believed to pave the way for exploiting the unparalleled properties of SAS catalysts and promoting their industrial applications.

Recently, ambient electrochemical N2 fixation has gained great attention. However, the commercial Pt-based electrocatalyst hardly shows its potential in this field. Herein, it is found that the isolated Pt sites anchored on WO3 nanoplates exhibit the optimum electrochemical NH3 yield rate (342.4 µg h-1 mg-1 Pt ) and Faradaic efficiency (31.1%) in 0.1 m K2 SO4 at -0.2 V versus RHE, which are about 11 and 15 times higher than their nanoparticle counterparts, respectively. The mechanistic analysis indicates that N2 conversion to NH3 follows an alternating hydrogenation pathway, and positively charged isolated Pt sites with special Pt-3O structure can favorably chemisorb and activate the N2 . Furthermore, the hydrogen evolution reaction can be greatly suppressed on isolated Pt sites decorated WO3 nanoplates, which guarantees the efficient going-on of nitrogen reduction reaction.

In the present study, ruthenium nanoparticles functionalized with terminal and internal alkynes were prepared, and it was found that internal alkynes formed a η2 side-on configuration on the surfac...

Development of single-site catalysts supported by ultrathin two-dimensional (2D) porous matrix with ultrahigh surface area is highly desired but also challenging. Here we report a cocoon silk chemistry strategy to synthesize isolated metal single-site catalysts embedded in ultrathin 2D porous N-doped carbon nanosheets (M-ISA/CNS, M = Fe, Co, Ni). X-ray absorption fine structure analysis and spherical aberration correction electron microscopy demonstrate an atomic dispersion of metal atoms on N-doped carbon matrix. In particular, the Co-ISA/CNS exhibit ultrahigh specific surface area (2105 m2 g−1) and high activity for C–H bond activation in the direct catalytic oxidation of benzene to phenol with hydrogen peroxide at room temperature, while the Co species in the form of phthalocyanine and metal nanoparticle show a negligible activity. Density functional theory calculations discover that the generated O = Co = O center intermediates on the single Co sites are responsible for the high activity of benzene oxidation to phenol.

The enhanced works of separation for the low adhesive (0 0 0 1)ZnO|(1 1 1)ZrO2 interfacess via Y-doping in ZnO slab were systematically studied using data-mining technique and density functional theory (DFT) study. The lattice constants in 31 types of doped wurtzite Zn0.9375X0.0625O were evaluated from DFT calculations. No linear correlation is found between the lattice constants and atomic radii. A support vector regression (SVR) for the lattice constants of 32 Zn0.9375X0.0625O has been performed. SVR method with leave-one-out cross-validation is used for evaluating the regression models. The correlation coefficient obtained by the models was 0.905. The accuracy of SVR model was higher than those of artificial neural network (ANN) and partial least square (PLS) methods. Zn0.9375Y0.0625O has the largest lattice constants among the investigated systems. In Y-ZnO(0 0 0 1) surface, a significant segregation phenomena occurs. Hence, dopant Y expands the lateral lattice and leaves the Zn-terminal surface intact. For coherent (0 0 0 1)Y-ZnO|(1 1 1)ZrO2 interfaces, Y-doping can enhance the work of separation significantly (∼82%) compared with the undoped (0 0 0 1)ZnO|(1 1 1)ZrO2 interfaces.

In-depth understanding of interfacial adhesive properties is required to access the long-term performance of substrate-film structures. The ZnO|ZrO 2 (or ZnO|YSZ) interfaces are of widely interests in experiments, however, the study on their adhesive strength is rare. Works of separation for (0 0 0 1)ZnO|(1 1 1)ZrO 2 interfaces have been investigated by using density functional calculations. Four coherent interface configurations were calculated to clarify the influence of atom termination and stacking sequence on the interfacial strength. The coherent interface model indicates that the small values for the work of separation are attributed to the large lattice mismatch between two slabs. Among the four configurations, interface model with Zr ZrO2 -O ZrO2 ⋯O ZnO B -Zn ZnO β stacking sequence has the largest work of separation, followed by the model with Zr ZrO2 -O ZrO2 ⋯Zn ZnO β -O ZnO B stacking sequence. We also construct “semicoherent interface” models to investigate the effect of strain. The Zr ZrO2 -O ZrO2 ⋯O ZnO B -Zn ZnO β sequence brings in some direct electrostatically repulsive anion-anion interactions across the interface, which causes significant distortion for the interface, especially on ZnO slab. Based on the “semicoherent interface” model with Zr ZrO2 -O ZrO2 ⋯Zn ZnO β -O ZnO B sequence, we elucidate that the interfacial adhesive strength for (0 0 0 1)ZnO|(1 1 1)ZrO 2 interface is very low.

For guidance for developing Fe/Co-Sn-based anode materials for lithium-ion batteries, the mechanical, thermodynamic and electronic properties of FeSn5 and CoSn5 intermetallic phases under pressures ranging from 0 to 30 GPa have been investigated systematically using first-principles total-energy calculations within the framework of the generalized gradient approximation. The pressure was found to have significant effects on the mechanical, thermodynamic and electronic properties of these compounds. In the selected pressure range, CoSn5 has a more negative formation enthalpy than FeSn5. Based on the calculated elastic constants, the bulk modulus, shear modulus, and Young’s modulus were determined via the Viogt-Reuss-Hill averaging scheme. The variations of specific heats at constant volume for FeSn5 and CoSn5 in a wide pressure (0 - 30 GPa) and temperature (0 - 1000 K) range are also predicted from phonon density of states calculation. The calculated results suggested that both FeSn5 and CoSn5 are mechanically stable at pressure from 0 to 30 GPa. FeSn5 is dynamically stable at pressure up to, 30 GPa, at least, however, CoSn5 is dynamically stable no higher than 15 GPa.

The development of high-efficiency, low-cost, and earth-abundant electrocatalysts for overall water splitting remains a challenge. In this work, Ni-modified MoS

Purpose We evaluate the power of a next-generation sequencing-based ophthalmic targeted sequencing panel (NGS-based OTSP) as a genetics-testing tool for patients suspected of a wide range of hereditary eye diseases. Methods NGS-based OTSP encompasses 126 genes with identified mutations that account for the majority of Chinese families with hereditary eye diseases. A total of 568 probands suspected of having hereditary eye diseases underwent genetic testing by OTSP with targeted phenotype-driven analysis. Results NGS-based OTSP detected 329 potential pathogenic variants in 62 genes. These mutations might represent the genetic cause in 52% (293/568) of probands suspected of having hereditary eye diseases. Within the disease subgroups, the detection rates were 61% (124/202) for retinal degeneration disease, 53% (35/66) for eye tumors, 49% (53/108) for retinal vessel disease, 46% (13/28) for retinal detachment, 33% (19/58) for significant refractive error, 35% (16/46) for optic atrophy, 48% (11/23) for anterior segment dysgenesis, and 59% (22/37) for other hereditary eye diseases. These detection rates are comparable to those obtained in our previous study performed with whole exome sequencing. Mutations in the same gene were detected in different forms of hereditary eye diseases. The average turnaround time for OTSP is 30 days, and the average cost is 139 USD per patient. Conclusions NGS-based OTSP is a powerful tool for routine clinical genetic diagnostic testing in patients suspected of having hereditary eye diseases. Translational relevance NGS-based OTSP can be used as a routine clinical test to improve the genetic counseling and medical care of patients suspected of having hereditary eye diseases.

Photoanode material with high efficiency and stability is extensively desirable in photoelectrochemical (PEC) water splitting for green/renewable energy source. Herein, novel heterostructures is constructed via coating rutile TiO2 nanorods with metal organic framework (MOF) materials UiO-66 or UiO-67 (UiO-66@TiO2 and UiO-67@TiO2 ), respectively. The π electrons in the MOF linkers could increase the local electronegativity near the heterojunction interface due to the conjugation effect, thereby enhancing the internal electric field (IEF) at the heterojunction interface. The IEF could drive charge transfer following Z-scheme mechanism in the prepared heterostructures, inducing photogenerated charge separation efficiency increasing as 156% and 253% for the UiO-66@TiO2 and UiO-67@TiO2 , respectively. Correspondingly, the UiO-66@TiO2 and UiO-67@TiO2 enhanced the photocurrent density as approximate two- and threefolds compared with that of pristine TiO2 for PEC water oxidation in universal pH electrolytes. This work demonstrates an effective method of regulating the IEF of heterojunction toward further improved charge separation.

Strain engineering has been a powerful strategy to manipulate the catalytic reaction activity. Here, CO oxidation reaction on Cu2O(1 1 1) surface without and with biaxial strain was investigated with density functional theory. The barriers heights of rate-determining steps (rds) in Mars-van-Krevelen, Langmuir-Hinshelwood and Eley-Rideal mechanism are strain sensitive. Applying strain could tune the performance of CO oxidation on Cu2O(1 1 1) by varying rds barriers heights, while the preferred reaction mechanism would swing between Langmuir-Hinshelwood and Eley-Rideal under particular strain. Furthermore, it is suggested that proper interfacial construction is an effective strategy to introduce suitable strain amplitude to achieve the desired reaction activity.

The effects of invasive single atom Pt on native oxygen vacancy migration in anatase TiO2(1 0 1) surface, as well as their coupling effect on water dissociation are investigated by means of the first-principles calculations based on density functional theory (DFT). Our results show that introducing Pt atom as Pt-ads and Pt5c modes could accelerate the Ov migration effectively. However, the roles of Pt2c and Pt6c are to decelerate the Ov migration. Oxygen-poor condition is beneficial for forming Pt-ads/TiO2-x1(1 0 1) and Pt2c/TiO2-x2(1 0 1), whereas oxygen-rich condition is beneficial for forming Pt5c/Ti1-yO2-x1(1 0 1) and Pt6c/Ti1-yO2-x1(1 0 1). Under their optimal conditions, Pt5c and Pt6c substitutions could make oxygen Ov formation easier, while Pt-adsorption and Pt2c substitution show no effect on Ov formation. The effect of imported Pt atoms mainly applies to the paths where they are involved directly. When Pt substituted either Ti5c or Ti6c, Ov tends to distribute around it and decreases its coordination number to 4 for maintaining a planar coordinated configuration of Pt-O. The adjacent bimetal Pt4c-Ti4c site in Pt6c/TiO2-x(1 0 1) can serve as the active center for water dissociation reaction. These findings can provide a “quasi-dynamic” perspective to understand the catalytic process of single atom supported on metal oxide surfaces.