Experimental Demonstration of Topological Catalysis for CO2 Electroreduction.

The past decade has witnessed substantial progress in understanding nontrivial band topology and discovering exotic topological materials in condensed-matter physics. Recently, topological physics has been further extended to the chemistry discipline, leading to the emergence of topological catalysis. In principle, the topological effect is detectable in catalytic reactions, but no conclusive evidence has been reported yet. Herein, by precisely manipulating the topological surface state (TSS) of Bi2Se3 nanosheets through thickness control and the application of a magnetic field, we provide direct experimental evidence to illustrate topological catalysis for CO2 electroreduction. With and without the cooperation of TSS, CO2 is mainly reduced into liquid fuels (HCOOH and H2C2O4) and CO, exhibiting high (up to 90% at -1.1 V versus reversible hydrogen electrode) and low Faradaic efficiency (FE), respectively. Theoretically, the product and FE difference can be attributed to the TSS-regulated adsorption of key intermediates and the reduced barrier of the potential-determining step. Our work demonstrates the inherent correlation between band topology and electrocatalysis, paving a new avenue for designing high-performance catalysts.

Giant Magnon-Polaron Anomalies in Spin Seebeck Effect in Double Umbrella-Structured Tb_{3}Fe_{5}O_{12} Films.

We report a giant hysteretic spin Seebeck effect (SSE) anomaly with a sign reversal at magnetic fields much stronger than the coercive field in a (001)-oriented Tb_{3}Fe_{5}O_{12} film. The high-field SSE enhancement reaches 4200% at approximately 105 K over its weak-field value and presents a nonmonotonic dependence on temperature. The unexpected high-field hysteresis of SSE is found to be associated with a magnetic transition of double-umbrella spin texture in TbIG. Nearly parallel dispersion curves of magnons and acoustic phonons around this neoteric transition are supported by theoretical calculations, leading to a high density of field-tuned magnon polarons and consequently an extraordinarily large SSE. Our study provides insight into the evolution of magnon dispersions of double-umbrella TbIG and could potentially boost the efficiency of magnon-polarons SSE devices.

Remote Synergy between Heterogeneous Single Atoms and Clusters for Enhanced Oxygen Evolution.

Integrating single atoms and clusters into one system is a novel strategy to achieve desired catalytic performances. Compared with homogeneous single-atom cluster catalysts, heterogeneous ones combine the merits of different species and therefore show greater potential. However, it is still challenging to construct single-atom cluster systems of heterogeneous species, and the underlying mechanism for activity improvement remains unclear. In this work, we developed a heterogeneous single-atom cluster catalyst (ConIr1/N-C) for efficient oxygen evolution. The Ir single atoms worked in synergy with the Co clusters at a distance of about 8 Å, which optimized the configuration of the key intermediates. Consequently, the oxygen evolution activity was significantly improved on ConIr1/N-C relative to the Co cluster catalyst (Con/N-C), exhibiting an overpotential lower by 107 mV than that of Con/N-C at 10 mA cm-2 and a turnover frequency 50.9 times as much as that of Con/N-C at an overpotential of 300 mV.

Regulating Spin States in Oxygen Electrocatalysis.

Developing efficient and stable transition metal oxides catalysts for energy conversion processes such as oxygen evolution reaction and oxygen reduction reaction is one of the key measures to solve the problem of energy shortage. The spin state of transition metal oxides is strongly correlated with their catalytic activities. In an octahedral structure of transition metal oxides, the spin state of active centers could be regulated by adjusting the splitting energy and the electron pairing energy. Regulating spin state of active centers could directly modulate the d orbitals occupancy, which influence the strength of metal-ligand bonds and the adsorption behavior of the intermediates. In this review, we clarified the significance of regulating spin state of the active centers. Subsequently, we discussed several characterization technologies for spin state and some recent strategies to regulate the spin state of the active centers. Finally, we put forward some views on the future research direction of this vital field.

Tuning the Electronic and Steric Interaction at the Atomic Interface for Enhanced Oxygen Evolution.

The two-dimensional surface or one-dimensional interface of heterogeneous catalysts is essential to determine the adsorption strengths and configurations of the reaction intermediates for desired activities. Recently, the development of single-atom catalysts has enabled an atomic-level understanding of catalytic processes. However, it remains obscure whether the conventional concept and mechanism of one-dimensional interface are applicable to zero-dimensional single atoms. In this work, we arranged the locations of single atoms to explore their interfacial interactions for improved oxygen evolution. When iridium single atoms were confined into the lattice of CoOOH, efficient electron transfer between Ir and Co tuned the adsorption strength of oxygenated intermediates. In contrast, atomic iridium species anchored on the surface of CoOOH induced inappreciable modification in electronic structures, whereas steric interactions with key intermediates at its Ir-OH-Co interface played a primary role in reducing its energy barrier toward oxygen evolution.

Pt Atom on the Wall of Atomic Layer Deposition (ALD)-Made MoS2 Nanotubes for Efficient Hydrogen Evolution.

Single-atom catalysts (SACs) can achieve excellent catalytic efficiency at ultralow catalyst consumptions. Herein, platinum (Pt) atoms are fixed on the wall of atomic layer deposition (ALD)-made molybdenum disulfide nanotube arrays (MoS2 -NTA) for efficient hydrogen evolution reaction (HER). More concretely, MoS2 -NTA with different nanotube diameters and wall thicknesses are fabricated by a sacrificial strategy of anodic aluminum oxide (AAO) template via ALD; then Pt atoms are fixed on the wall of Ti3 C2 -supported MoS2 -NTA as a catalytic system. The MoS2 -NTA/Ti3 C2 decorated with 0.13 wt.% of Pt results in a low overpotential of 32 mV to deliver a current density of 10 mA cm-2 , which is superior to 20 wt.% commercial Pt/C (41 mV). Ordered MoS2 -NTA instead of 2D MoS2 prevents Pt atoms from aggregating and then exerts catalytic activities. The density functional theory calculations suggest that the Pt atoms are more likely to occupy the sites on the tubular MoS2 than the planar MoS2 , and the Pt atoms accumulated at the Mo site of MoS2 -NT have a moderate Gibbs free energy (close to zero).

In-Situ Generated High-Valent Iron Single-Atom Catalyst for Efficient Oxygen Evolution.

Oxygen evolution reaction (OER) plays an important role in renewable energy supplies as the anodic reaction for electrochemical transformation of various chemicals. Iron-based OER catalysts are potential candidates due to their abundance but suffer from poor activity. Here we demonstrate that a single-atom iron catalyst with in-situ generated Fe4+ centers is highly active toward OER. Only an overpotential of 320 mV was needed to reach 10 mA cm-2. The catalyst exhibited an ultrahigh turnover frequency of 0.62 s-1 at an overpotential of 0.35 V, which is comparable to currently reported transitional-metal based OER catalysts. Experimental and theoretical studies revealed that the valence state of the metal center transferred from Fe3+ to highly active Fe4+ prior to the OER process. This transformation was originated from the strong interaction between atomic Fe and carbon support via C-O-Fe bonding, leading to a lower energy barrier of the rate-limiting *OOH formation.

Role of Magnon-Magnon Scattering in Magnon Polaron Spin Seebeck Effect.

The spin Seebeck effect (SSE) signal of magnon polarons in bulk-Y_{3}Fe_{5}O_{12} (YIG)/Pt heterostructures is found to drastically change as a function of temperature. It appears as a dip in the total SSE signal at low temperatures, but as the temperature increases, the dip gradually decreases before turning to a peak. We attribute the observed dip-to-peak transition to the rapid rise of the four-magnon scattering rate. Our analysis provides important insights into the microscopic origin of the hybridized excitations and the overall temperature dependence of the SSE anomalies.

Dimensionality Control of Electrocatalytic Activity in Perovskite Nickelates.

The dimensionality of the crystal structure plays an important role in the electronic structures of materials. Ruddlesden-Popper perovskite oxides offer an attractive platform for studying this role due to dimensional flexibility. The effects of dimensionality on physical properties in those oxides have been widely reported. However, the study of dimensional dependence on the chemical properties is still lacking. Here, we synthesized a series of Ruddlesden-Popper perovskite nickelates LanSrNinO3n+1 (n = 1, 2, 3, and ∞) to explore the role of dimensionality on oxygen-evolution reaction (OER) performance. As the dimensionality increased with n, the nickelates exhibited an enhanced OER activity. We found that the weakening of electron correlations among Ni 3d electrons by increasing the dimensionality induced an insulator-to-metal transition and a strengthened Ni-O hybridization, both of which accelerated the OER kinetics. This work sets up a bridge between the dimensionality and electrocatalysis, which provides guidance for designing highly efficient oxygen-evolving catalysts.

Breaking the Local Symmetry of LiCoO2 via Atomic Doping for Efficient Oxygen Evolution.

The obstacle for efficient electrochemical water splitting lies in the kinetically sluggish oxygen evolution reaction. Despite the various efforts that have been made to understand and tune the active sites for oxygen evolution reaction, an insight into the configurations of active sites from the electronic perspective is still lacking. Here, we report an atomic doping strategy to break the Oh symmetry of the CoO6 octahedron in LiCoO2. The specific activity of the La-doped LiCoO2 was 3.14 mA cm-2 at the overpotential of 0.35 V, which was 8.3 times higher than that of pristine LiCoO2. The overpotential with a value of 330 mV at 10 mA cm-2 was the lowest among the LiCoO2-based OER electrocatalysts ever reported. Mechanistic studies revealed that the superior activity originated from the asymmetric octahedral coordination of Co, resulting in the enhanced electronic conductivity and Co-O hybridization for the accelerated oxygen evolution kinetics. This work opens a door to enhance the catalytic performance through the manipulation of local symmetry.

Intercalated Iridium Diselenide Electrocatalysts for Efficient pH-Universal Water Splitting.

Developing bifunctional catalysts for both hydrogen and oxygen evolution reactions is a promising approach to the practical implementation of electrocatalytic water splitting. However, most of the reported bifunctional catalysts are only applicable to alkaline electrolyzer, although a few are effective in acidic or neutral media that appeals more to industrial applications. Here, a lithium-intercalated iridium diselenide (Li-IrSe2 ) is developed that outperformed other reported catalysts toward overall water splitting in both acidic and neutral environments. Li intercalation activated the inert pristine IrSe2 via bringing high porosities and abundant Se vacancies for efficient hydrogen and oxygen evolution reactions. When Li-IrSe2 was assembled into two-electrode electrolyzers for overall water splitting, the cell voltages at 10 mA cm-2 were 1.44 and 1.50 V under pH 0 and 7, respectively, being record-low values in both conditions.

Conductive Tungsten Oxide Nanosheets for Highly Efficient Hydrogen Evolution.

Exploring efficient and economical electrocatalysts for hydrogen evolution reaction is of great significance for water splitting on an industrial scale. Tungsten oxide, WO3, has been long expected to be a promising non-precious-metal electrocatalyst for hydrogen production. However, the poor intrinsic activity of this material hampers its development. Herein, we design a highly efficient hydrogen evolution electrocatalyst via introducing oxygen vacancies into WO3 nanosheets. Our first-principles calculations demonstrate that the gap states introduced by O vacancies make WO3 act as a degenerate semiconductor with high conductivity and desirable hydrogen adsorption free energy. Experimentally, we prepared WO3 nanosheets rich in oxygen vacancies via a liquid exfoliation, which indeed exhibits the typical character of a degenerate semiconductor. When evaluated by hydrogen evolution, the nanosheets display superior performance with a small overpotential of 38 mV at 10 mA cm-2 and a low Tafel slope of 38 mV dec-1. This work opens an effective route to develop conductive tungsten oxide as a potential alternative to the state-of-the-art platinum for hydrogen evolution.

A Silver Nanocluster Containing Interstitial Sulfur and Unprecedented Chemical Bonds.

The emergence of thiolated metal nanoclusters provides opportunities to identify significant and unprecedented phenomena because they are at quantum sizes and can be characterized with X-ray crystallography. Recently silver nanoclusters have received extensive interest owing to their merits, such as low-cost and rich properties. Herein, a thiolated silver nanocluster [Ag46 S7 (SPhMe2 )24 ]NO3 (Ag46 for short) with a face-centered cubic (fcc) structure was successfully synthesized and structurally resolved by X-ray analysis. Most importantly, interstitial sulfur was found in the lattice void of Ag46 without lattice distortion or expansion, indicating that the classic theory of interstitial metal solid solutions might be not applicable at quantum size. Furthermore, unprecedented chemical bonds and unique structural features (such as asymmetrically coordinated µ4 -S) were found in Ag46 and might be related to the interstitial sulfur, which is supported by natural population analyses.

MicroRNA-588 is upregulated in human prostate cancer with prognostic and functional implications.

BACKGROUND: Epigenetic factors of microRNAs (miRNAs) are important biomarkers and modulators in human prostate cancer (PCa). In this work, we characterized the expression, biomarker-potential and functional regulation of miR-588 in PCa. METHODS: Endogenous miR-588 levels were quantified by qRT-PCR in both prostate-specific antigen (PSA)-negative and PSA-positive PCa cell lines, as well as human PCa tumors. The associations between endogenous miR-588 and PCa patients' clinical outcomes and postoperative overall survival were statistically examined. Moreover, in both PSA-negative DU145 and PSA-positive LNCaP, downregulation of miR-588 was achived by transduction of miR-588 inhibitor lentivirus. The subsequent effects of miR-588 downregulation on PCa cell developments were investigated both in vitro and in vivo. RESULTS: MiR-588 was profoundly upregulated in both PSA-negative and PSA-positive PCa cells, as well as in PCa tumors. Significant miR-588 upregulation was found to be closely associated with PCa patients' poor clinical outcomes and shorter postoperative overall survivals. In DU145 and LNCaP cell lines, lentiviral transduction markedly downregulated endogenous miR-588 levels. MiR-588 downregulation was shown to profoundly inhibit PCa proliferation in vitro and xenograft in vivo. CONCLUSION: Aberrant upregulation of endogenous miR-588 in PCa patients may be a prognostic biomarker, indicative of their poor clinical outcomes. Inhibiting endogenous miR-588 may also serve as a therapeutic target for PCa treatment. This article is protected by copyright. All rights reserved.

Gold-Doping of Double-Crown Pd Nanoclusters.

Double-crown Ni, Pd, or Pt nanoclusters have attracted extensive interests due to their aesthetic structure and intriguing properties. However, their doping by other metals remains unknown until now. Herein, Pd4 (PET)8 and Pd5 (PET)10 (PET: SCH2 CH2 Ph) were successfully doped with gold and the doped nanoclusters were characterized by using multiple techniques such as mass spectrometry and X-ray crystallography. It is revealed that in the doping not one but two gold atoms replace one Pd with the other double-crown structure essentially unchanged, and the gold-doping results in the blue-shift of the maximum visible absorption, the increase of optical energy gap and the reduction of anti-aromaticity of monometal Pd nanoclusters. Importantly, it is found that Au4 Pd2 (PET)8 nanocluster bears chirality originating from not only the helixed Au4 Pd2 S8 framework, but also unanimous R or S configuration of sulfur atoms in the enantiomer. For the latter chirality origin, it was not previously reported or proposed. Au4 Pd2 (PET)8 reported here also represents the smallest chiral bimetal nanocluster so far to the best of our knowledge. This work advances one step toward both the tailoring of group 10 metal nanoclusters by doping and the understanding of chirality origin for metal nanoclusters.

Association of ADIPOQ single nucleotide polymorphisms with the risk of intracranial atherosclerosis.

BACKGROUND: The genetic mechanism of the racial distribution difference of intracranial atherosclerosis (ICAS) is unclear. The single nucleotide polymorphisms (SNPs) may be associated with different genetic susceptibility to ICAS. At present, the correlation between ADIPOQ gene SNPs and the risk of ICAS remains unknown. METHODS: Continuous inpatients were selected and divided into ICAS group and control group. Computed tomography angiography was performed to observe intracranial arteries. ADIPOQ SNPs were detected using the ligase detection reaction-PCR. The correlation between the identified SNPs and ICAS was determined using the binary logistic regression analysis. RESULTS: This study contained 602 patients in total, including 199 ICAS and 403 control cases. The binary logistic regression analysis showed that the AG/AA genotype of the rs2241767 (OR = 2.242, 95% CI: 1.037-4.878, P = 0.040) and the AG/GG genotype of the rs182052 (OR = 1.822, 95% CI: 1.111-2.987, P = 0.017) were closely related to the risk of ICAS after adjusting for conventional cardiovascular risk factors. The haploid analysis results indicated that the incidence of the A-G haplotype of the rs2241767 and rs182052 was higher in the ICAS group than in the control group (P = 0.026). CONCLUSIONS: The SNPs of the ADIPOQ gene are closely related to increased risk of ICAS in Chinese Han population.

Engineering the Electrical Conductivity of Lamellar Silver-Doped Cobalt(II) Selenide Nanobelts for Enhanced Oxygen Evolution.

Precisely engineering the electrical conductivity represents a promising strategy to design efficient catalysts towards oxygen evolution reaction (OER). Here, we demonstrate a versatile partial cation exchange method to fabricate lamellar Ag-CoSe2 nanobelts with controllable conductivity. The electrical conductivity of the materials was significantly enhanced by the addition of Ag+ cations of less than 1.0 %. Moreover, such a trace amount of Ag induced a negligible loss of active sites which was compensated through the effective generation of active sites as shown by the excellent conductivity. Both the enhanced conductivity and the retained active sites contributed to the remarkable electrocatalytic performance of the Ag-CoSe2 nanobelts. Relative to the CoSe2 nanobelts, the as-prepared Ag-CoSe2 nanobelts exhibited a higher current density and a lower Tafel slope towards OER. This strategy represents a rational design of efficient electrocatalysts through finely tuning their electrical conductivities.

Mono-Mercury Doping of Au25 and the HOMO/LUMO Energies Evaluation Employing Differential Pulse Voltammetry.

Controlling the bimetal nanoparticle with atomic monodispersity is still challenging. Herein, a monodisperse bimetal nanoparticle is synthesized in 25% yield (on gold atom basis) by an unusual replacement method. The formula of the nanoparticle is determined to be Au24Hg1(PET)18 (PET: phenylethanethiolate) by high-resolution ESI-MS spectrometry in conjunction with multiple analyses including X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). X-ray single-crystal diffraction reveals that the structure of Au24Hg1(PET)18 remains the structural framework of Au25(PET)18 with one of the outer-shell gold atoms replaced by one Hg atom, which is further supported by theoretical calculations and experimental results as well. Importantly, differential pulse voltammetry (DPV) is first employed to estimate the highest occupied molecular orbit (HOMO) and the lowest unoccupied molecular orbit (LUMO) energies of Au24Hg1(PET)18 based on previous calculations.

Correlation of single nucleotide polymorphisms in the pregnancy-associated plasma protein-A gene with carotid plaques.

BACKGROUND: Pregnancy-associated plasma protein A (PAPP-A) is abundantly expressed in carotid plaques. This study investigated the association between single nucleotide polymorphisms (SNPs) of PAPP-A and the presence of carotid plaques. METHODS: A total of 408 patients with carotid plaques and 493 controls were included in the study. All subjects were Southern Chinese Han. Carotid plaques were analyzed by computer tomography angiography. PAPP-A SNPs were identified by ligase detection reaction-polymerase chain reaction analysis. The PAPP-A genotypes rs3747823, rs7020782, and rs13290387 were analyzed. RESULTS: The rs7020782 C allele genotype correlated with an increased risk of developing carotid plaques under the dominant, recessive, and additive models (adjusted odds ratios: 2.60, 2.36, and 3.48, respectively; P ≤ 0.001). Only C allele-carrying genotypes correlated with a significantly increased risk of carotid plaque based on studies stratified by age and sex under the dominant model. rs7020782 remained significantly associated with the risk of carotid plaque calcification after adjusting for age and potential confounders (adjusted odds ratio, 1.89; 95 % confidence interval, 1.17-3.08; P = 0.010). CONCLUSIONS: This study found, for the first time, that the A˃C variation of rs7020782 might be an independent risk factor for carotid plaque development and calcification. The determination of such genotypes could provide a new tool for identifying individuals at high risk for carotid atherosclerosis.

Promotion of Acid-Water Oxidation by Lattice Distortion and Orbital Hybridization Induced by Ionic Dopant in Pyrochlore Y2Ru2O7.

For acid-water oxidation, pyrochloric ruthenates are thought to be extremely effective electrocatalysts. In this work, through partial B-site replacement with larger M2+ cations, the electronic states of Y2Ru2O7 with strong electron correlations are reasonably managed, by which the inherent performance is tremendously promoted. Based on this, the improved Y2Ru1.9Sr0.1O7 electrocatalyst exhibits an outstanding durability and presents a highly inherent mass activity of 1915.1 A gRu-1 (at 1.53 V vs RHE). The enhanced oxygen-evolving reaction (OER) activity by ionic dopant in YRO pyrochlore can be attributed to two aspects, i.e., the lattice distortion induced inhibition of the grain coarsening, which results in a large surface area for YRO-M and increases the OER active sites, and the weakening of electron correlation via broadening of the Ru 4d bandwidths due to the increase of the average radius of B-site ions, which gives rise to an enhancement of conductivity and a strengthened hybridization between Ru 4d and O 2p orbitals and improves the reaction kinetics. The synergistic effects of lattice distortion and orbital hybridization promote the enhanced OER activity. The results would provide fresh concepts for the design of improved electrocatalysts and underscore the significance of managing the intrinsic performance through the dual modification of microstructure morphology and electronic structure.