Ligand-modified nanoparticle surfaces influence CO electroreduction selectivity

Improving the kinetics and selectivity of CO2/CO electroreduction to valuable multi-carbon products is a challenge for science and is a requirement for practical relevance. Here we develop a thiol-modified surface ligand strategy that promotes electrochemical CO-to-acetate. We explore a picture wherein nucleophilic interaction between the lone pairs of sulfur and the empty orbitals of reaction intermediates contributes to making the acetate pathway more energetically accessible. Density functional theory calculations and Raman spectroscopy suggest a mechanism where the nucleophilic interaction increases the sp2 hybridization of CO(ad), facilitating the rate-determining step, CO* to (CHO)*. We find that the ligands stabilize the (HOOC-CH2)* intermediate, a key intermediate in the acetate pathway. In-situ Raman spectroscopy shows shifts in C-O, Cu-C, and C-S vibrational frequencies that agree with a picture of surface ligand-intermediate interactions. A Faradaic efficiency of 70% is obtained on optimized thiol-capped Cu catalysts, with onset potentials 100 mV lower than in the case of reference Cu catalysts.

Selective Electrified Propylene-to-Propylene Glycol Oxidation on Activated Rh-Doped Pd

Renewable-energy-powered electrosynthesis has the potential to contribute to decarbonizing the production of propylene glycol, a chemical that is used currently in the manufacture of polyesters and antifreeze and has a high carbon intensity. Unfortunately, to date, the electrooxidation of propylene under ambient conditions has suffered from a wide product distribution, leading to a low faradic efficiency toward the desired propylene glycol. We undertook mechanistic investigations and found that the reconstruction of Pd to PdO occurs, followed by hydroxide formation under anodic bias. The formation of this metastable hydroxide layer arrests the progressive dissolution of Pd in a locally acidic environment, increases the activity, and steers the reaction pathway toward propylene glycol. Rh-doped Pd further improves propylene glycol selectivity. Density functional theory (DFT) suggests that the Rh dopant lowers the energy associated with the production of the final intermediate in propylene glycol formation and renders the desorption step spontaneous, a concept consistent with experimental studies. We report a 75% faradic efficiency toward propylene glycol maintained over 100 h of operation.

Efficient multicarbon formation in acidic CO2 reduction via tandem electrocatalysis

The electrochemical reduction of CO2 in acidic conditions enables high single-pass carbon efficiency. However, the competing hydrogen evolution reaction reduces selectivity in the electrochemical reduction of CO2, a reaction in which the formation of CO, and its ensuing coupling, are each essential to achieving multicarbon (C2+) product formation. These two reactions rely on distinct catalyst properties that are difficult to achieve in a single catalyst. Here we report decoupling the CO2-to-C2+ reaction into two steps, CO2-to-CO and CO-to-C2+, by deploying two distinct catalyst layers operating in tandem to achieve the desired transformation. The first catalyst, atomically dispersed cobalt phthalocyanine, reduces CO2 to CO with high selectivity. This process increases local CO availability to enhance the C-C coupling step implemented on the second catalyst layer, which is a Cu nanocatalyst with a Cu-ionomer interface. The optimized tandem electrodes achieve 61% C2H4 Faradaic efficiency and 82% C2+ Faradaic efficiency at 800 mA cm-2 at 25 °C. When optimized for single-pass utilization, the system reaches a single-pass carbon efficiency of 90 ± 3%, simultaneous with 55 ± 3% C2H4 Faradaic efficiency and a total C2+ Faradaic efficiency of 76 ± 2%, at 800 mA cm-2 with a CO2 flow rate of 2 ml min-1.

Reduction of 5-Hydroxymethylfurfural to 2,5-Bis(hydroxymethyl)Furan at High Current Density using a Ga-Doped AgCu:Cationomer Hybrid Electrocatalyst

Hydrogenation of biomass-derived chemicals is of interest for the production of biofuels and valorized chemicals. Thermochemical processes for biomass reduction typically employ hydrogen as the reductant at elevated temperatures and pressures. Here, the authors investigate the direct electrified reduction of 5-hydroxymethylfurfural (HMF) to a precursor to bio-polymers, 2,5-bis(hydroxymethyl)furan (BHMF). Noting a limited current density in prior reports of this transformation, a hybrid catalyst consisting of ternary metal nanodendrites mixed with a cationic ionomer, the latter purposed to increase local pH and facilitate surface proton diffusion, is investigated. This approach, when implemented using Ga-doped Ag-Cu electrocatalysts designed for p-d orbital hybridization, steered selectivity to BHMF, achieving a faradaic efficiency (FE) of 58% at 100 mA cm-2 and a production rate of 1 mmol cm-2 h-1, the latter a doubling in rate compared to the best prior reports.

Site-selective protonation enables efficient carbon monoxide electroreduction to acetate

Electrosynthesis of acetate from CO offers the prospect of a low-carbon-intensity route to this valuable chemical--but only once sufficient selectivity, reaction rate and stability are realized. It is a high priority to achieve the protonation of the relevant intermediates in a controlled fashion, and to achieve this while suppressing the competing hydrogen evolution reaction (HER) and while steering multicarbon (C2+) products to a single valuable product--an example of which is acetate. Here we report interface engineering to achieve solid/liquid/gas triple-phase interface regulation, and we find that it leads to site-selective protonation of intermediates and the preferential stabilization of the ketene intermediates: this, we find, leads to improved selectivity and energy efficiency toward acetate. Once we further tune the catalyst composition and also optimize for interfacial water management, we achieve a cadmium-copper catalyst that shows an acetate Faradaic efficiency (FE) of 75% with ultralow HER (<0.2% H2 FE) at 150 mA cm-2. We develop a high-pressure membrane electrode assembly system to increase CO coverage by controlling gas reactant distribution and achieve 86% acetate FE simultaneous with an acetate full-cell energy efficiency (EE) of 32%, the highest energy efficiency reported in direct acetate electrosynthesis.

Unusual Sabatier principle on high entropy alloy catalysts for hydrogen evolution reactions

The Sabatier principle is widely explored in heterogeneous catalysis, graphically depicted in volcano plots. The most desirable activity is located at the peak of the volcano, and further advances in activity past this optimum are possible by designing a catalyst that circumvents the limitation entailed by the Sabatier principle. Herein, by density functional theory calculations, we discovered an unusual Sabatier principle on high entropy alloy (HEA) surface, distinguishing the "just right" (ΔGH* = 0 eV) in the Sabatier principle of hydrogen evolution reaction (HER). A new descriptor was proposed to design HEA catalysts for HER. As a proof-of-concept, the synthesized PtFeCoNiCu HEA catalyst endows a high catalytic performance for HER with an overpotential of 10.8 mV at -10 mA cm-2 and 4.6 times higher intrinsic activity over the state-of-the-art Pt/C. Moreover, the unusual Sabatier principle on HEA catalysts can be extended to other catalytic reactions.

Two-dimensional III-nitride alloys: electronic and chemical properties of monolayer Ga(1-x)AlxN

Potential applications of III-nitrides have led to their monolayer allotropes, i.e., two-dimensional (2D) III-nitrides, having attracted much attention. Recently, alloying has been demonstrated as an effective method to control the properties of 2D materials. In this study, the stability, and the electronic and chemical properties of monolayer Ga(1-x)AlxN alloys were investigated employing density functional theory (DFT) calculations and the cluster expansion (CE) method. The results show that 2D Ga(1-x)AlxN alloys are thermodynamically stable and complete miscibility in the alloys can be achieved at ambient temperature (>85 K). By analyzing CE results, the atomic arrangement of 2D Ga(1-x)AlxN was revealed, showing that Ga/Al atoms tend to mix with the Al/Ga atoms in their next nearest site. The band gaps of Ga(1-x)AlxN random alloys can be tuned by varying the chemical composition, and the corresponding bowing parameter was calculated as -0.17 eV. Biaxial tensile strain was also found to change the band gap values of Ga(1-x)AlxN random alloys ascribed to its modifications to the CBM positions. The chemical properties of Ga(1-x)AlxN can also be significantly altered by strain, making them good candidates as photocatalysts for water splitting. The present study can play a crucial role in designing and optimizing 2D III-nitrides for next-generation electronics and photocatalysis.

[ANOCOR registry]

Anomalous aortic origin of the coronary arteries are congenital anomalies with many anatomical forms. Due to the varying risk of sudden death, these abnormalities must be classified accurately. There are still questions about the mechanism and individual risk of sudden death, the natural history of these abnormalities and the benefits of a surgical correction. Large-scale observational registries may provide more evidence-based data to practitioners caring for the patients concerned. The ANOCOR registry, the largest in size published to date, enrolled 472 patients (mean age 63 years) with 496 coronary abnormalities. The angiographic representation (with invasive coronary angiography or coronary CT angiography) according to the coronary artery and initial ectopic course could be specified with the identification of two main phenotypes: the circumflex artery (n = 235) with a retroaortic course in 97% of cases and the right coronary artery (n = 165) with an interarterial course in 89.7% of cases. Two left coronary anatomical forms have been confused by non-expert cardiologists: those with a retropulmonary or interarterial course. Sudden death related to coronary anomaly was a very rare mode of presentation (3 patients or 0.6% of the cohort) in this population with very few young patients < 35 years (11 cases or 2.3% of the cohort).

Epoxy-rich Fe Single Atom Sites Boost Oxygen Reduction Electrocatalysis

Electrocatalysts for highly efficient oxygen reduction reaction (ORR) are crucial for energy conversion and storage devices. Single-atom catalysts with maximized metal utilization and altered electronic structure are the most promising alternatives to replace current benchmark precious metals. However, the atomic level understanding of the functional role for each species at the anchoring sites is still unclear and poorly elucidated. Herein, we report Fe single atom catalysts with the sulfur and oxygen functional groups near the atomically dispersed metal centers (Fe1/NSOC) for highly efficient ORR. The Fe1/NSOC delivers a half-wave potential of 0.92 V vs. RHE, which is much better than those of commercial Pt/C (0.88 V), Fe single atoms on N-doped carbon (Fe1/NC, 0.89 V) and most reported nonprecious metal catalysts. The spectroscopic measurements reveal that the presence of sulfur group induces the formation of epoxy groups near the FeN4S2 centers, which not only modulate the electronic structure of Fe single atoms but also participate the catalytic process to improve the kinetics. The density functional theory calculations demonstrate the existence of sulfur and epoxy group engineer the charges of Fe reactive center and facilitate the reductive release of OH* (rate-limiting step), thus boosting the overall oxygen reduction efficiency.

Single-site decorated copper enables energy- and carbon-efficient CO2 methanation in acidic conditions

Renewable CH₄ produced from electrocatalytic CO₂ reduction is viewed as a sustainable and versatile energy carrier, compatible with existing infrastructure. However, conventional alkaline and neutral CO₂-to-CH₄ systems suffer CO₂ loss to carbonates, and recovering the lost CO₂ requires input energy exceeding the heating value of the produced CH₄. Here we pursue CH₄-selective electrocatalysis in acidic conditions via a coordination method, stabilizing free Cu ions by bonding Cu with multidentate donor sites. We find that hexadentate donor sites in ethylenediaminetetraacetic acid enable the chelation of Cu ions, regulating Cu cluster size and forming Cu-N/O single sites that achieve high CH₄ selectivity in acidic conditions. We report a CH₄ Faradaic efficiency of 71% (at 100 mA cm^-2) with <3% loss in total input CO₂ that results in an overall energy intensity (254 GJ/tonne CH₄), half that of existing electroproduction routes.

Pressure dependence in aqueous-based electrochemical CO2 reduction

Electrochemical CO₂ reduction (CO₂R) is an approach to closing the carbon cycle for chemical synthesis. To date, the field has focused on the electrolysis of ambient pressure CO₂. However, industrial CO₂ is pressurized-in capture, transport and storage-and is often in dissolved form. Here, we find that pressurization to 50 bar steers CO₂R pathways toward formate, something seen across widely-employed CO₂R catalysts. By developing operando methods compatible with high pressures, including quantitative operando Raman spectroscopy, we link the high formate selectivity to increased CO₂ coverage on the cathode surface. The interplay of theory and experiments validates the mechanism, and guides us to functionalize the surface of a Cu cathode with a proton-resistant layer to further the pressure-mediated selectivity effect. This work illustrates the value of industrial CO₂ sources as the starting feedstock for sustainable chemical synthesis.

Constrained C2 adsorbate orientation enables CO-to-acetate electroreduction

The carbon dioxide and carbon monoxide electroreduction reactions, when powered using low-carbon electricity, offer pathways to the decarbonization of chemical manufacture^1,2. Copper (Cu) is relied on today for carbon-carbon coupling, in which it produces mixtures of more than ten C₂₊ chemicals^3-6: a long-standing challenge lies in achieving selectivity to a single principal C₂₊ product^7-9. Acetate is one such C₂ compound on the path to the large but fossil-derived acetic acid market. Here we pursued dispersing a low concentration of Cu atoms in a host metal to favour the stabilization of ketenes¹⁰-chemical intermediates that are bound in monodentate fashion to the electrocatalyst. We synthesize Cu-in-Ag dilute (about 1 atomic per cent of Cu) alloy materials that we find to be highly selective for acetate electrosynthesis from CO at high *CO coverage, implemented at 10 atm pressure. Operando X-ray absorption spectroscopy indicates in situ-generated Cu clusters consisting of <4 atoms as active sites. We report a 12:1 ratio, an order of magnitude increase compared to the best previous reports, in the selectivity for acetate relative to all other products observed from the carbon monoxide electroreduction reaction. Combining catalyst design and reactor engineering, we achieve a CO-to-acetate Faradaic efficiency of 91% and report a Faradaic efficiency of 85% with an 820-h operating time. High selectivity benefits energy efficiency and downstream separation across all carbon-based electrochemical transformations, highlighting the importance of maximizing the Faradaic efficiency towards a single C₂₊ product¹¹.

An ultrasensitive FET biosensor based on vertically aligned MoS2 nanolayers with abundant surface active sites

Molybdenum disulfide (MoS₂) nanolayers are one of the most promising two-dimensional (2D) nanomaterials for constructing next-generation field-effect transistor (FET) biosensors. In this article, we report an ultrasensitive FET biosensor that integrates a novel format of 2D MoS₂, vertically-aligned MoS₂ nanolayers (VAMNs), as the channel material for label-free detection of the prostate-specific antigen (PSA). The developed VAMNs-based FET biosensor shows two distinctive advantages. First, the VAMNs can be facilely grown using the conventional chemical vapor deposition (CVD) method, permitting easy fabrication and potential mass device production. Second, the unique advantage of the VAMNs for biosensor development lies in its abundant surface-exposed active edge sites that possess a high binding affinity with thiol-based linkers, which overcomes the challenge of molecule functionalization on the conventional planar MoS₂ nanolayers. The high binding affinity between 11-mercaptoundecanoic acid and the VAMNs was demonstrated through experimental surface characterization and theoretical calculations via density functional theory. The FET biosensor allows rapid (within 20 min) and ultrasensitive PSA detection in human serum with simple operations (limit of detection: 800 fg mL^-1). This FET biosensor offers excellent features such as ultrahigh sensitivity, ease of fabrication, and short assay time, and thereby possesses significant potential for early-stage diagnosis of life-threatening diseases.

Surface hydroxide promotes CO2 electrolysis to ethylene in acidic conditions

Performing CO₂ reduction in acidic conditions enables high single-pass CO₂ conversion efficiency. However, a faster kinetics of the hydrogen evolution reaction compared to CO₂ reduction limits the selectivity toward multicarbon products. Prior studies have shown that adsorbed hydroxide on the Cu surface promotes CO₂ reduction in neutral and alkaline conditions. We posited that limited adsorbed hydroxide species in acidic CO₂ reduction could contribute to a low selectivity to multicarbon products. Here we report an electrodeposited Cu catalyst that suppresses hydrogen formation and promotes selective CO₂ reduction in acidic conditions. Using in situ time-resolved Raman spectroscopy, we show that a high concentration of CO and OH on the catalyst surface promotes C-C coupling, a finding that we correlate with evidence of increased CO residence time. The optimized electrodeposited Cu catalyst achieves a 60% faradaic efficiency for ethylene and 90% for multicarbon products. When deployed in a slim flow cell, the catalyst attains a 20% energy efficiency to ethylene, and 30% to multicarbon products.

Doping Shortens the Metal/Metal Distance and Promotes OH Coverage in Non-Noble Acidic Oxygen Evolution Reaction Catalysts

Acidic water electrolysis enables the production of hydrogen for use as a chemical and as a fuel. The acidic environment hinders water electrolysis on non-noble catalysts, a result of the sluggish kinetics associated with the adsorbate evolution mechanism, reliant as it is on four concerted proton-electron transfer steps. Enabling a faster mechanism with non-noble catalysts will help to further advance acidic water electrolysis. Here, we report evidence that doping Ba cations into a Co₃O₄ framework to form Co_3-xBa_xO₄ promotes the oxide path mechanism and simultaneously improves activity in acidic electrolytes. Co_3-xBa_xO₄ catalysts reported herein exhibit an overpotential of 278 mV at 10 mA/cm² in 0.5 M H₂SO₄ electrolyte and are stable over 110 h of continuous water oxidation operation. We find that the incorporation of Ba cations shortens the Co-Co distance and promotes OH adsorption, findings we link to improved water oxidation in acidic electrolyte.

Strong-Proton-Adsorption Co-Based Electrocatalysts Achieve Active and Stable Neutral Seawater Splitting

Direct electrolysis of pH-neutral seawater to generate hydrogen is an attractive approach for storing renewable energy. However, due to the anodic competition between the chlorine evolution and the oxygen evolution reaction (OER), direct seawater splitting suffers from a low current density and limited operating stability. Exploration of catalysts enabling an OER overpotential below the hypochlorite formation overpotential (≈490 mV) is critical to suppress the chloride evolution and facilitate seawater splitting. Here, a proton-adsorption-promoting strategy to increase the OER rate is reported, resulting in a promoted and more stable neutral seawater splitting. The best catalysts herein are strong-proton-adsorption (SPA) materials such as palladium-doped cobalt oxide (Co3- x Pdx O4 ) catalysts. These achieve an OER overpotential of 370 mV at 10 mA cm-2 in pH-neutral simulated seawater, outperforming Co3 O4 by a margin of 70 mV. Co3- x Pdx O4 catalysts provide stable catalytic performance for 450 h at 200 mA cm-2 and 20 h at 1 A cm-2 in neutral seawater. Experimental studies and theoretical calculations suggest that the incorporation of SPA cations accelerates the rate-determining water dissociation step in neutral OER pathway, and control studies rule out the provision of additional OER sites as a main factor herein.

Abundant (110) Facets on PdCu3 Alloy Promote Electrochemical Conversion of CO2 to CO

Electrochemical conversion of CO₂ to high-value chemical fuels offers a promising strategy for managing the global carbon balance but faces huge challenges due to the lack of effective electrocatalysts. Here, we reported PdCu₃ alloy nanoparticles with abundant exposed (110) facets supported on N-doped three-dimensional interconnected carbon frameworks (PdCu₃/NC) as an efficient and durable electrocatalyst for electrochemical CO₂ reduction to CO. The catalyst exhibits extremely high intrinsic CO₂ reduction selectivity for CO production with a Faraday efficiency of nearly 100% at a mild potential of -0.5 V. Moreover, a rechargeable high-performance Zn-CO₂ battery with PdCu₃/NC as a cathode is developed to deliver a record-high energy efficiency of 99.2% at 0.5 mA cm^-2 and rechargeable stability of up to 133 h. Theoretical calculations elucidate that the exposed (110) facet over PdCu₃/NC is the active center for CO₂ activation and rapid formation of the key *COOH intermediate.

Design of Ru-Ni diatomic sites for efficient alkaline hydrogen oxidation

Anion exchange membrane fuel cells are limited by the slow kinetics of alkaline hydrogen oxidation reaction (HOR). Here, we establish HOR catalytic activities of single-atom and diatomic sites as a function of *H and *OH binding energies to screen the optimal active sites for the HOR. As a result, the Ru-Ni diatomic one is identified as the best active center. Guided by the theoretical finding, we subsequently synthesize a catalyst with Ru-Ni diatomic sites supported on N-doped porous carbon, which exhibits excellent catalytic activity, CO tolerance, and stability for alkaline HOR and is also superior to single-site counterparts. In situ scanning electrochemical microscopy study validates the HOR activity resulting from the Ru-Ni diatomic sites. Furthermore, in situ x-ray absorption spectroscopy and computational studies unveil a synergistic interaction between Ru and Ni to promote the molecular H₂ dissociation and strengthen OH adsorption at the diatomic sites, and thus enhance the kinetics of HOR.

A single-atom library for guided monometallic and concentration-complex multimetallic designs

Atomically dispersed single-atom catalysts have the potential to bridge heterogeneous and homogeneous catalysis. Dozens of single-atom catalysts have been developed, and they exhibit notable catalytic activity and selectivity that are not achievable on metal surfaces. Although promising, there is limited knowledge about the boundaries for the monometallic single-atom phase space, not to mention multimetallic phase spaces. Here, single-atom catalysts based on 37 monometallic elements are synthesized using a dissolution-and-carbonization method, characterized and analysed to build the largest reported library of single-atom catalysts. In conjunction with in situ studies, we uncover unified principles on the oxidation state, coordination number, bond length, coordination element and metal loading of single atoms to guide the design of single-atom catalysts with atomically dispersed atoms anchored on N-doped carbon. We utilize the library to open up complex multimetallic phase spaces for single-atom catalysts and demonstrate that there is no fundamental limit on using single-atom anchor sites as structural units to assemble concentration-complex single-atom catalyst materials with up to 12 different elements. Our work offers a single-atom library spanning from monometallic to concentration-complex multimetallic materials for the rational design of single-atom catalysts.

Accelerating CO2 Electroreduction to Multicarbon Products via Synergistic Electric-Thermal Field on Copper Nanoneedles

Electrochemical CO₂ reduction is a promising way to mitigate CO₂ emissions and close the anthropogenic carbon cycle. Among products from CO₂RR, multicarbon chemicals, such as ethylene and ethanol with high energy density, are more valuable. However, the selectivity and reaction rate of C₂ production are unsatisfactory due to the sluggish thermodynamics and kinetics of C-C coupling. The electric field and thermal field have been studied and utilized to promote catalytic reactions, as they can regulate the thermodynamic and kinetic barriers of reactions. Either raising the potential or heating the electrolyte can enhance C-C coupling, but these come at the cost of increasing side reactions, such as the hydrogen evolution reaction. Here, we present a generic strategy to enhance the local electric field and temperature simultaneously and dramatically improve the electric-thermal synergy desired in electrocatalysis. A conformal coating of ∼5 nm of polytetrafluoroethylene significantly improves the catalytic ability of copper nanoneedles (∼7-fold electric field and ∼40 K temperature enhancement at the tips compared with bare copper nanoneedles experimentally), resulting in an improved C₂ Faradaic efficiency of over 86% at a partial current density of more than 250 mA cm^-2 and a record-high C₂ turnover frequency of 11.5 ± 0.3 s^-1 Cu site^-1. Combined with its low cost and scalability, the electric-thermal strategy for a state-of-the-art catalyst not only offers new insight into improving activity and selectivity of value-added C₂ products as we demonstrated but also inspires advances in efficiency and/or selectivity of other valuable electro-/photocatalysis such as hydrogen evolution, nitrogen reduction, and hydrogen peroxide electrosynthesis.

Boride-derived oxygen-evolution catalysts

Metal borides/borates have been considered promising as oxygen evolution reaction catalysts; however, to date, there is a dearth of evidence of long-term stability at practical current densities. Here we report a phase composition modulation approach to fabricate effective borides/borates-based catalysts. We find that metal borides in-situ formed metal borates are responsible for their high activity. This knowledge prompts us to synthesize NiFe-Boride, and to use it as a templating precursor to form an active NiFe-Borate catalyst. This boride-derived oxide catalyzes oxygen evolution with an overpotential of 167 mV at 10 mA/cm² in 1 M KOH electrolyte and requires a record-low overpotential of 460 mV to maintain water splitting performance for over 400 h at current density of 1 A/cm². We couple the catalyst with CO reduction in an alkaline membrane electrode assembly electrolyser, reporting stable C₂H₄ electrosynthesis at current density 200 mA/cm² for over 80 h.

Aortic tortuosity is related to aortic phenotype in patients with bicuspid aortic valve: a CT scan study of 83 cases

Background

Although the incidence of aortic dissection is higher in patients with bicuspid aortic valve (BAV) compared to tricuspid aortic valve (TAV), risk stratification remains unclear. Guidelines focus on ascending aorta diameters, regardless of the location, and do not take into account the morphology of the aorta. Aortic tortuosity (AT) is emerging as a novel biomarker associated with more severe aortopathy in patients with Marfan syndrome. AT has not been accuretely assessed in BAV.

Our aim is to describe the relationship between AT and ascending aortic phenotype in patients with BAV.

Methods

83 patients (43±16 years, 19 women) diagnosed with BAV and without significant aortic valve disease nor prior aortic intervention were included. CT scans were retrospectively analysed with measurements of aortic diameters and aortic tortuosity. For 61 patients with abdominal images available, descending and total aortic length and tortuosity were measured.

Results

In our cohort, 62 (75%) patients presented a typical BAV. Pathological aorta (Root and/or tubular Z-score &gt;2) was found in 80 patients (96%) and 67 (81%) presented a tubular dilatation. The aortic phenotype, the maximal aortic diameters and aortic tortuosity index were similar in typical and atypical BAV.

Total aortic tortuosity index was correlated to Z-score tubular diameter (r=0.31; p=0,014) but not with Z-score Valsalva diameter (p=0,55). In patients with tubular dilatation (Z score &gt;2), total aortic tortuosity index was higher than in patient without tubular dilatation (2.01 vs 1.85; p=0,015).

Conclusion

Total aortic tortuosity is associated with tubular dilatation but not with root dilatation in BAV patients suggesting that tubular phenotype may be at higher risk of complication in BAV. Further studies evaluating the association between aortic tortuosity and clinical outcomes in BAV are needed.

Funding Acknowledgement

Type of funding sources: None.

Gold-in-copper at low *CO coverage enables efficient electromethanation of CO2

The renewable-electricity-powered CO2 electroreduction reaction provides a promising means to store intermittent renewable energy in the form of valuable chemicals and dispatchable fuels. Renewable methane produced using CO2 electroreduction attracts interest due to the established global distribution network; however, present-day efficiencies and activities remain below those required for practical application. Here we exploit the fact that the suppression of *CO dimerization and hydrogen evolution promotes methane selectivity: we reason that the introduction of Au in Cu favors *CO protonation vs. C-C coupling under low *CO coverage and weakens the *H adsorption energy of the surface, leading to a reduction in hydrogen evolution. We construct experimentally a suite of Au-Cu catalysts and control *CO availability by regulating CO2 concentration and reaction rate. This strategy leads to a 1.6× improvement in the methane:H2 selectivity ratio compared to the best prior reports operating above 100 mA cm-2. We as a result achieve a CO2-to-methane Faradaic efficiency (FE) of (56 ± 2)% at a production rate of (112 ± 4) mA cm-2.

A microfluidic field-effect transistor biosensor with rolled-up indium nitride microtubes

Field-effect-transistor (FET) biosensors capable of rapidly detecting disease-relevant biomarkers have long been considered as a promising tool for point-of-care (POC) diagnosis. Rolled-up nanotechnology, as a batch fabrication strategy for generating three-dimensional (3D) microtubes, has been demonstrated to possess unique advantages for constructing FET biosensors. In this paper, we report a new approach combining the two fascinating technologies, the FET biosensor and the rolled-up microtube, to develop a microfluidic diagnostic biosensor. We integrated an excellent biosensing III-nitride material-indium nitride (InN)-into a rolled-up microtube and used it as the FET channel. The InN possesses strong, intrinsic, and stable electron accumulation (~10¹³ cm^-2) on its surface, thereby providing a high device sensitivity. Multiple rolled-up InN microtube FET biosensors fabricated on the same substrate were integrated with a microfluidic channel for convenient fluids handling, and shared the same external electrode (inserted into the microchannel outlet) for gating voltage modulation. Using human immunodeficiency virus (HIV) antibody as a model disease marker, we characterized the analytical performance of the developed biosensor and achieved a limit of detection (LOD) of 2.5 pM for serum samples spiked with HIV gp41 antibodies. The rolled-up InN microtube FET biosensor represents a new type of III-nitride-based FET biosensor and holds significant potential for practical POC diagnosis.

Mineralogical phase transformation of Fe containing sphalerite at acidic environments in the presence of Cu2

Dissolution of the exposed sphalerite (marmatite) in abandoned mining sites and tailings may exacerbate acid and metalliferous drainage (AMD) hazards. Cupric ions are inevitable ions in AMD systems but its action mechanism on the dissolution of sphalerite is still unclear. In this work, the possible phase transition from sphalerite to chalcopyrite is firstly discovered in acidic cupric ions solution according to the results of Raman and (synchrotron radiation-based) X-ray (micro-) diffractometer spectra, which should be an important reason that mediates the dissolution of sphalerite. Results of DFT calculations reveal the underlying mechanism that Cu²⁺ can selectively replace zinc in marmatite lattices and further diffuse into the matrix. Additionally, a strong correlation between the cupric ion consumption with the pH value variation is discussed and the effects of the formed new phase on the dissolution kinetics of marmatite were researched. According to this work, the action mechanism of cupric ions on sphalerite dissolution in acidic environments is furtherly clarified.

Aortic tortuosity index as a predictor of type A aortic dissection

Introduction

The risk ok type A aortic dissection (AAD) depends on the degree of aortic wall's alteration, which can result in dilatation or tortuosity. The estimate of this risk relies solely on the evaluation of the diameter of the ascending aorta.

Purpose

The purpose of this study is to evaluate the presence and importance of aortic tortuosity in patients with type A aortic dissection.

Method

Postoperative CT scans of patients with type A aortic dissection were compared with CT scans from controls matched for gender and age. After 3D reconstruction, total length (actual distance along aortic center line = Ltot) and geometric length (length of a straight line between start and end of the aortic segment = Lgeo) were measured to calculate the tortuosity index (TI = Ltot / Lgeo).

Results

Ltot, Lgeo and TI from different aortic segments of the AAD group were higher than in the control group. Ltot and TI of the whole aorta (from aortic valve to bifurcation) were greater in patients with type A aortic dissection (527.7±46.1 mm vs. 475.8±39.7, p&lt;0.0001; and 2.05±0.24 vs. 1.98±0.21, p=0.002 respectively). Total length and TI were greater after exclusion of the ascending part, and a value of this TI &gt;1.3 identifies AAD patients with an accuracy of 74.8% (AUC = 0.792, p&lt;0.0001). TI is altered by risk factors for aortic dissection: it increases with hypertension and age but not by tobacco use, and TI decreases in diabetes.

Conclusions

Type A aortic dissection is associated with longer aorta and increased aortic tortuosity. This index may help recognize patients at risk for type A aortic dissection.

Calculation of tortuosity indexes

Funding Acknowledgement

Type of funding source: None

Few-Atomic-Layers Iron for Hydrogen Evolution from Water by Photoelectrocatalysis

The carbon-free production of hydrogen from water splitting holds grand promise for the critical energy and environmental challenges. Herein, few-atomic-layers iron (Fe_FAL) anchored on GaN nanowire arrays (NWs) is demonstrated as a highly active hydrogen evolution reaction catalyst, attributing to the spatial confinement and the nitrogen-terminated surface of GaN NWs. Based on density functional theory calculations, the hydrogen adsorption on Fe_FAL:GaN NWs is found to exhibit a significantly low free energy of −0.13 eV, indicative of high activity. Meanwhile, its outstanding optoelectronic properties are realized by the strong electronic coupling between atomic iron layers and GaN(10ī0) together with the nearly defect-free GaN NWs. As a result, Fe_FAL:GaN NWs/n⁺-p Si exhibits a prominent current density of ∼ −30 mA cm⁻² at an overpotential of ∼0.2 V versus reversible hydrogen electrode with a decent onset potential of +0.35 V and 98% Faradaic efficiency in 0.5 mol/L KHCO₃ aqueous solution under standard one-sun illumination.

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Few-atomic-layers iron was anchored on GaN nanowires as an efficient HER catalyst

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The spatial-confinement and N-rich GaN is essential for forming atomic iron layers

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Low hydrogen absorption free energy is theoretically revealed over Fe_3L:GaN

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The device exhibits a prominent performance for PEC water splitting to H₂

Decoupling Strategy for Enhanced Syngas Generation from Photoelectrochemical CO2 Reduction

Photoelectrochemical CO₂ reduction into syngas (a mixture of CO and H₂) provides a promising route to mitigate greenhouse gas emissions and store intermittent solar energy into value-added chemicals. Design of photoelectrode with high energy conversion efficiency and controllable syngas composition is of central importance but remains challenging. Herein, we report a decoupling strategy using dual cocatalysts to tackle the challenge based on joint computational and experimental investigations. Density functional theory calculations indicate the optimization of syngas generation using a combination of fundamentally distinctive catalytic sites. Experimentally, by integrating spatially separated dual cocatalysts of a CO-generating catalyst and a H₂-generating catalyst with GaN nanowires on planar Si photocathode, we report a record high applied bias photon-to-current efficiency of 1.88% and controllable syngas products with tunable CO/H₂ ratios (0–10) under one-sun illumination. Moreover, unassisted solar CO₂ reduction with a solar-to-syngas efficiency of 0.63% is demonstrated in a tandem photoelectrochemical cell.

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Combined experimental and theoretical investigations were performed

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A record high applied bias photon-to-current efficiency of 1.88% was achieved

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The CO/H₂ ratio in the syngas product can be controllably tuned in a wide range

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Unassisted syngas generation was proved in a tandem photoelectrochemical cell

Simultaneous Enhancement of Near-Infrared Emission and Dye Photodegradation in a Racemic Aspartic Acid Compound via Metal-Ion Modification

Changing functionalities of materials using simple methods is an active area of research, as it is "green" and lowers the developing cost of new products for the enterprises. A new small molecule racemic N,N-dimethyl aspartic acid has been prepared. Its structure is determined by single-crystal X-ray diffraction. It is characterized by FTIR, XPS, ¹H NMR, and mass spectroscopy. Its near-infrared luminescence can be enhanced by the combination of metal ions, including Dy³⁺, Gd³⁺, Nd³⁺, Er³⁺, Sr³⁺, Y³⁺, Zn²⁺, Zr⁴⁺, Ho³⁺, Yb³⁺, La³⁺, Pr⁶⁺/Pr³⁺, and Sm³⁺ ions. An optical chemistry mechanism upon interaction between the sensitizer and activator is proposed. Furthermore, the association of Ca²⁺, Sr²⁺, or Zr⁴⁺ ions to the molecule enhanced its photodegradation for dyes under white-light irradiation. Specifically, rhodamine 6G can be degraded by the Ca²⁺-modified molecule; rhodamine B, rhodamine 6G, and fluorescein sodium salt can be degraded by the Sr²⁺- or Zr⁴⁺-modified molecule. This surprising development opens a way in simultaneously increasing NIR luminescence and the ability of dye photodegradation for the investigated molecule.

P1476Global longitudinal strain assessed by 2-D speckle tracking echocardiography identifies myocardial viability and predicts LV function and remodeling after acute MI with systolic dysfunction

Aims

To assess whether two-dimensional speckle-tracking echocardiography (2D-STE) could (1) identify myocardial viability in comparison with late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR); (2) predict global left ventricular (LV) functional recovery and remodeling and (3) assess prognosis after acute myocardial infarction (MI) with LV systolic dysfunction.

Methods

Seventy one first STEMI patients with LVEF ≤45%, treated with acute percutaneous coronary intervention, underwent 2D-echocardiography for 2D-STE analysis and LGE CMR between 2 and 45 days after STEMI. Segments were defined as viable when transmural LGE extension was <50% and non viable when transmural LGE extension was ≥50%. At 8-month follow-up, transthoracic echocardiography was repeated to determine global LV functional recovery (increase in LVEF ≥5%) and LV remodeling (increase in end-systolic volume >15%) (n=30) and clinical outcomes were obtained (n=46).

Results

Global longitudinal strain (GLS) was lower in non viable than in viable infarct segments (−6.6±6.1% vs −10.3±5.9%, p<0.0001) and in viable infarct segments than in normal segments (−10.3±5.9% vs −14.5±6.4%, p<0.0001). GLS >−12% had sensitivity of 78% and specificity of 69% to identify non viable segments (area under the curve (AUC), 0.79; 95% confidence interval (CI), 0.77–0.81, p<0.0001). GLS >−11.3% had sensitivity of 53% and specificity of 100% to predict the absence of global functional improvement (AUC=0.73 (CI: 0.55–0.87) p=0.01) at 8-month follow-up. GLS <−12.5% predicted the absence of adverse LV remodeling at 8-month follow-up with a sensitivity of 100% and a specificity of 54% (AUC=0.83 (CI: 0.66–0.94) p<0.0001). GLS >−11.5% was associated with a poor prognosis.

Conclusions

In patients with recent first acute MI with LV systolic dysfunction, GLS assessed by 2D-STE: (1) is able to identify non viable segments in comparison with LGE CMR, (2) allows prediction of LV global functional recovery and LV remodeling at 8-month follow-up and (3) provides strong prognostic information, independently of LVEF.

Effect of indium doping on motions of 〈a〉-prismatic edge dislocations in wurtzite gallium nitride

The influences of indium doping on dynamics of 〈a〉-prismatic edge dislocation along [Formula: see text] shuffle plane in wurtzite GaN have been investigated employing classical molecular dynamics (MD) simulations. The dependence of dislocation motion mode and dislocation velocity on indium doping concentration, temperature, and applied shear stress was clarified. Moreover, the simulation results were further analyzed using elastic theory of dislocation and thermal activation theory of dislocation motion, showing excellent agreement with the simulation. Our findings help gain deep insights into modifying dynamic behaviors of TDs through the alloying doping and offer generic tools to the study of other wurtzite materials of promising application prospects, such as AlGaN and ZnO.

Single molybdenum center supported on N-doped black phosphorus as an efficient electrocatalyst for nitrogen fixation

Ammonia (NH₃) is one of the most significant industrial chemical products due to its wide applications in various fields. However, the production of NH₃ from the electrochemical nitrogen (N₂) reduction reaction (NRR) under ambient conditions is one of the most important issues that remain challenging for chemists. Herein, the candidacy of a series of molybdenum (Mo)-based single-atom catalysts (SACs) supported on N-doped black phosphorus (BP) as the electrocatalyst for the NRR has been evaluated by means of density functional theory (DFT) calculations. In particular, Mo₁N₃ has been found to chemically adsorb N₂, and it exhibits the highest catalytic activity toward the NRR with an ultralow overpotential of 0.02 V via the associative distal mechanism, indicative of catalyzing the NRR under ambient conditions. Additionally, Mo₁N₃ shows the fast removal of the produced NH₃ with a free energy uphill of only 0.56 eV and good stability of NRR intermediates. Moreover, the Mo-based SACs were demonstrated to be more selective to the NRR over the competing hydrogen evolution reaction (HER) process. These excellent features render Mo₁N₃ on BP as a compelling highly efficient and durable catalyst for electrochemical N₂ fixation. Our results provide a rational paradigm for catalytic nitrogen fixation by SACs in two-dimensional (2D) materials under ambient conditions.

Reduction of Fermi level pinning at Cu-BP interfaces by atomic passivation

Black phosphorus (BP) is a semiconducting material with a direct finite band gap in its monolayer, attracting intense attention for its application in field-effect transistors. However, strong Fermi level pinning (FLP) has been observed for contacts between BP and high work function metals, e.g., Cu. Such FLP presents an undesirable hurdle preventing the achievement of high performance field-effect devices. In this regard, there is a crucial need to understand the FLP occurring at the metal-BP interfaces and explore the possibility to reduce it. The present work studied atomic passivation in reducing FLP for the Cu-BP system using density functional theory calculations. The passivation by H, N, F, S, and Cl atoms on the Cu(111) surface has been considered. The results showed that the passivated atoms can shield the direct contact between Cu(111) and BP, thus reducing FLP at Cu-BP interfaces. In particular, S and Cl atoms were found to be highly effective agents to achieve a significant reduction of FLP, leading to Cu-BP contacts with ultralow Schottky barrier height (SBH) and suggesting the possibility of ohmic contact formation. Our findings demonstrate surface passivation as an effective method towards depinning the Fermi level at the metal-BP interface and subsequently controlling the SBH for BP-based electronic devices.