Highly stable preferential carbon monoxide oxidation by dinuclear heterogeneous catalysts.

Atomically dispersed catalysts have been shown highly active for preferential oxidation of carbon monoxide in the presence of excess hydrogen (PROX). However, their stability has been less than ideal. We show here that the introduction of a structural component to minimize diffusion of the active metal center can greatly improve the stability without compromising the activity. Using an Ir dinuclear heterogeneous catalyst (DHC) as a study platform, we identify two types of oxygen species, interfacial and bridge, that work in concert to enable both activity and stability. The work sheds important light on the synergistic effect between the active metal center and the supporting substrate and may find broad applications for the use of atomically dispersed catalysts.

A family of dual-anion-based sodium superionic conductors for all-solid-state sodium-ion batteries.

The sodium (Na) superionic conductor is a key component that could revolutionize the energy density and safety of conventional Na-ion batteries. However, existing Na superionic conductors are primarily based on a single-anion framework, each presenting inherent advantages and disadvantages. Here we introduce a family of amorphous Na-ion conductors (Na2O2-MCly, M = Hf, Zr and Ta) based on the dual-anion framework of oxychloride. Benefiting from a dual-anion chemistry and with the resulting distinctive structures, Na2O2-MCly electrolytes exhibit room-temperature ionic conductivities up to 2.0 mS cm-1, wide electrochemical stability windows and desirable mechanical properties. All-solid-state Na-ion batteries incorporating amorphous Na2O2-HfCl4 electrolyte and a Na0.85Mn0.5Ni0.4Fe0.1O2 cathode exhibit a superior rate capability and long-term cycle stability, with 78% capacity retention after 700 cycles under 0.2 C (1C = 120 mA g-1) at room temperature. The discoveries in this work could trigger a new wave of enthusiasm for exploring new superionic conductors beyond those based on a single-anion framework.

Layer-Polarized Anomalous Hall Effects from Inversion-Symmetric Single-Layer Lattices.

In the field of physics and materials science, the discovery of the layer-polarized anomalous Hall effect (LP-AHE) stands as a crucial development. The current research paradigm is rooted in topological or inversion-asymmetric valleytronic systems, making such a phenomenon rather rare. In this work, a universal design principle for achieving the LP-AHE from inversion-symmetric single-layer lattices is proposed. Through tight-binding model analysis, we demonstrate that by stacking into antiferromagnetic van der Waals bilayer lattices, the coupling physics between PT symmetry and vertical external bias can be realized. This coupling reveals the previously neutralized layer-locked Berry curvature, compelling the carriers to move in a specific direction within a given layer, thereby realizing the LP-AHE. Intriguingly, the chirality of the LP-AHE can be effectively switched by modulating the direction of vertical external bias. First-principles calculations validate this mechanism in bilayer T-FeCl2 and MnPSe3. Our results pave the way for new explorations of the LP-AHE.

Decoupling the roles of Ni and Co in anionic redox activity of Li-rich NMC cathodes.

Li[LixNiyMnzCo1-x-y-z]O2 (lithium-rich NMCs) are benchmark cathode materials receiving considerable attention due to the abnormally high capacities resulting from their anionic redox chemistry. Although their anionic redox mechanisms have been much investigated, the roles of cationic redox processes remain underexplored, hindering further performance improvement. Here we decoupled the effects of nickel and cobalt in lithium-rich NMCs via a comprehensive study of two typical compounds, Li1.2Ni0.2Mn0.6O2 and Li1.2Co0.4Mn0.4O2. We discovered that both Ni3+/4+ and Co4+, generated during cationic redox processes, are actually intermediate species for triggering oxygen redox through a ligand-to-metal charge-transfer process. However, cobalt is better than nickel in mediating the kinetics of ligand-to-metal charge transfer by favouring more transition metal migration, leading to less cationic redox but more oxygen redox, more O2 release, poorer cycling performance and more severe voltage decay. Our work highlights a compositional optimization pathway for lithium-rich NMCs by deviating from using cobalt to using nickel, providing valuable guidelines for future high-capacity cathode design.

Reversible Mn2+/Mn4+ double redox in lithium-excess cathode materials.

There is an urgent need for low-cost, resource-friendly, high-energy-density cathode materials for lithium-ion batteries to satisfy the rapidly increasing need for electrical energy storage. To replace the nickel and cobalt, which are limited resources and are associated with safety problems, in current lithium-ion batteries, high-capacity cathodes based on manganese would be particularly desirable owing to the low cost and high abundance of the metal, and the intrinsic stability of the Mn4+ oxidation state. Here we present a strategy of combining high-valent cations and the partial substitution of fluorine for oxygen in a disordered-rocksalt structure to incorporate the reversible Mn2+/Mn4+ double redox couple into lithium-excess cathode materials. The lithium-rich cathodes thus produced have high capacity and energy density. The use of the Mn2+/Mn4+ redox reduces oxygen redox activity, thereby stabilizing the materials, and opens up new opportunities for the design of high-performance manganese-rich cathodes for advanced lithium-ion batteries.

An Eco-Driving Strategy at Multiple Fixed-Time Signalized Intersections Considering Traffic Flow Effects.

To encourage energy saving and emission reduction and improve traffic efficiency in the multiple signalized intersections area, an eco-driving strategy for connected and automated vehicles (CAVs) considering the effects of traffic flow is proposed for the mixed traffic environment. Firstly, the formation and dissipation process of signalized intersection queues are analyzed based on traffic wave theory, and a traffic flow situation estimation model is constructed, which can estimate intersection queue length and rear obstructed fleet length. Secondly, a feasible speed set calculation method for multiple signalized intersections is proposed to enable vehicles to pass through intersections without stopping and obstructing the following vehicles, adopting a trigonometric profile to generate smooth speed trajectory to ensure good riding comfort, and the speed trajectory is optimized with comprehensive consideration of fuel consumption, emissions, and traffic efficiency costs. Finally, the effectiveness of the strategy is verified. The results show that traffic performance and fuel consumption benefits increase as the penetration rate of CAVs increases. When all vehicles on the road are CAVs, the proposed strategy can increase the average speed by 9.5%, reduce the number of stops by 78.2%, reduce the stopped delay by 82.0%, and reduce the fuel consumption, NOx, and HC emissions by 20.4%, 39.4%, and 46.6%, respectively.

OsMBF1a Facilitates Seed Germination by Regulating Biosynthesis of Gibberellic Acid and Abscisic Acid in Rice.

Seed germination is a pivotal stage in the plant life cycle, orchestrated by a myriad of internal and external factors, notably plant hormones. The underlying molecular mechanisms governing rice seed germination remain largely unelucidated. Herein, we uncover OsMBF1a as a crucial regulatory factor that employs a dual strategy to promote seed germination: positively activating genes involved in gibberellin (GA) biosynthesis pathways, while negatively regulating key genes responsible for abscisic acid (ABA) synthesis. Furthermore, OsMBF1a modulates the endogenous levels of ABA and GA in rice seeds, reinforcing its central role in the germination process. The expression of ZmMBF1a and ZmMBF1b, the homologous genes in maize, in rice seeds similarly affects germination, indicating the conserved functionality of MBF1 family genes in regulating seed germination. This study provides novel insights into the molecular mechanisms underlying rice seed germination and underscores the significance of MBF1 family genes in plant growth and development.

A Dual Anion Chemistry-Based Superionic Glass Enabling Long-Cycling All-Solid-State Sodium-Ion Batteries.

Glassy Na-ion solid-state electrolytes (GNSSEs) are an important group of amorphous SSEs. However, the insufficient ionic conductivity of state-of-the-art GNSSEs at room temperature lessens their promise in the development of all-solid-state Na-ion batteries (ASSNIBs) with high energy density and improved safety. Here we report the discovery of a new sodium superionic glass, 0.5Na2 O2 -TaCl5 (NTOC), based on dual-anion sublattice of oxychlorides. The unique local structures with abundant bridging and non-bridging oxygen atoms contributes to a highly disordered Na-ion distribution as well as low Na+ migration barrier within NTOC, enabling an ultrahigh ionic conductivity of 4.62 mS cm-1 at 25 °C (more than 20 times higher than those of previously reported GNSSEs). Moreover, the excellent formability of glassy NTOC electrolyte and its high electrochemical oxidative stability ensure a favourable electrolyte-electrode interface, contributing to superior cycling stability of ASSNIBs for over 500 cycles at room temperature. The discovery of glassy NTOC electrolyte would reignite research enthusiasm in superionic glassy SSEs based on multi-anion chemistry.

Unveiling Highly Sensitive Active Site in Atomically Dispersed Gold Catalysts for Enhanced Ethanol Dehydrogenation.

Developing a desirable ethanol dehydrogenation process necessitates a highly efficient and selective catalyst with low cost. Herein, we show that the "complex active site" consisting of atomically dispersed Au atoms with the neighboring oxygen vacancies (Vo) and undercoordinated cation on oxide supports can be prepared and display unique catalytic properties for ethanol dehydrogenation. The "complex active site" Au-Vo-Zr3+ on Au1/ZrO2 exhibits the highest H2 production rate, with above 37,964 mol H2 per mol Au per hour (385 g H2 g Au - 1 ${{\rm{g}}_{{\rm{Au}}}^{ - 1} }$ h-1) at 350 °C, which is 3.32, 2.94 and 15.0 times higher than Au1/CeO2, Au1/TiO2, and Au1/Al2O3, respectively. Combining experimental and theoretical studies, we demonstrate the structural sensitivity of these complex sites by assessing their selectivity and activity in ethanol dehydrogenation. Our study sheds new light on the design and development of cost-effective and highly efficient catalysts for ethanol dehydrogenation. Fundamentally, atomic-level catalyst design by colocalizing catalytically active metal atoms forming a structure-sensitive "complex site", is a crucial way to advance from heterogeneous catalysis to molecular catalysis. Our study advanced the understanding of the structure sensitivity of the active site in atomically dispersed catalysts.

Hydrogen Storage in Partially Exfoliated Magnesium Diboride Multilayers.

Metal boride nanostructures have shown significant promise for hydrogen storage applications. However, the synthesis of nanoscale metal boride particles is challenging because of their high surface energy, strong inter- and intraplanar bonding, and difficult-to-control surface termination. Here, it is demonstrated that mechanochemical exfoliation of magnesium diboride in zirconia produces 3-4 nm ultrathin MgB2 nanosheets (multilayers) in high yield. High-pressure hydrogenation of these multilayers at 70 MPa and 330 °C followed by dehydrogenation at 390 °C reveals a hydrogen capacity of 5.1 wt%, which is ≈50 times larger than the capacity of bulk MgB2 under the same conditions. This enhancement is attributed to the creation of defective sites by ball-milling and incomplete Mg surface coverage in MgB2 multilayers, which disrupts the stable boron-boron ring structure. The density functional theory calculations indicate that the balance of Mg on the MgB2 nanosheet surface changes as the material hydrogenates, as it is energetically favorable to trade a small number of Mg vacancies in Mg(BH4 )2 for greater Mg coverage on the MgB2 surface. The exfoliation and creation of ultrathin layers is a promising new direction for 2D metal boride/borohydride research with the potential to achieve high-capacity reversible hydrogen storage at more moderate pressures and temperatures.

Surface basicity controls C-C coupling rates during carbon dioxide-assisted methane coupling over bifunctional Ca/ZnO catalysts.

Carbon dioxide-assisted coupling of methane offers an approach to chemically upgrade two greenhouse gases and components of natural gas to produce ethylene and syngas. Prior research on this reaction has concentrated efforts on catalyst discovery, which has indicated that composites comprised of both reducible and basic oxides are especially promising. There is a need for detailed characterization of these bifunctional oxide systems to provide a more fundamental understanding of the active sites and their roles in the reaction. We studied the dependence of physical and electronic properties of Ca-modified ZnO materials on Ca content via X-ray photoelectron and absorption spectroscopies, electron microscopy, and infrared spectroscopic temperature-programmed desorption (IR-TPD). It was found that introduction of only 0.6 mol% Ca onto a ZnO surface is necessary to induce significant improvement in the catalytic production of C2 species: C2 selectivity increases from 5% on un-modified ZnO to 58%, at similar conversions. Evidence presented shows that this selectivity increase results from the formation of an interface between the basic CaO and reducible ZnO phases. The basicity of these interface sites correlates directly with catalytic activity over a wide composition range, and this relationship indicates that moderate CO2 adsorption strength is optimal for CH4 coupling. These results demonstrate, for the first time to our knowledge, a volcano-type relationship between CO2-assisted CH4 coupling activity and catalyst surface basicity, which can inform further catalyst development.

Exploration of spatial confinement and ligand effects for the oxygen reduction reaction on Fe-Nx embedded hole-graphene.

In this work, we constructed theoretical models by embedding Fe-TCPP and Fe-(mIM)n (n = 2,3,4) active sites into hole-graphene, and the structural stability was evaluated using molecular dynamics simulations. Based on the theoretical models, we systematically studied the oxygen reduction reaction (ORR) mechanism and the effect of spatial confinement and ligands with DFT calculations. The analysis of the ORR reaction pathway shows that Fe-TCPP and Fe-(mIM)4 have good catalytic activity. Subsequently, the confinement effect (5-14 Å) was introduced to investigate its influence on the catalytic activity. The Fe-TCPP and Fe-(mIM)4 active sites have the lowest overpotential at an axial space of 8 Å and 9 Å, respectively. We select four ligands (bpy, pya, CH3, and bIm) to explore their effect on the catalytic activity of the Fe-TCPP active site. With the modification of bpy, pya, and bIm_N (Fe-N4 sites become Fe-N5 active sites), the overpotential decreases by 26-31%. In the present work, the best catalytic system is Fe-TCPP_pya, which is on the top of the volcano plot.

Enhanced and stabilized hydrogen production from methanol by ultrasmall Ni nanoclusters immobilized on defect-rich h-BN nanosheets.

Employing liquid organic hydrogen carriers (LOHCs) to transport hydrogen to where it can be utilized relies on methods of efficient chemical dehydrogenation to access this fuel. Therefore, developing effective strategies to optimize the catalytic performance of cheap transition metal-based catalysts in terms of activity and stability for dehydrogenation of LOHCs is a critical challenge. Here, we report the design and synthesis of ultrasmall nickel nanoclusters (∼1.5 nm) deposited on defect-rich boron nitride (BN) nanosheet (Ni/BN) catalysts with higher methanol dehydrogenation activity and selectivity, and greater stability than that of some other transition-metal based catalysts. The interface of the two-dimensional (2D) BN with the metal nanoparticles plays a strong role both in guiding the nucleation and growth of the catalytically active ultrasmall Ni nanoclusters, and further in stabilizing these nanoscale Ni catalysts against poisoning by interactions with the BN substrate. We provide detailed spectroscopy characterizations and density functional theory (DFT) calculations to reveal the origin of the high productivity, high selectivity, and high durability exhibited with the Ni/BN nanocatalyst and elucidate its correlation with nanocluster size and support-nanocluster interactions. This study provides insight into the role that the support material can have both regarding the size control of nanoclusters through immobilization during the nanocluster formation and also during the active catalytic process; this twofold set of insights is significant in advancing the understanding the bottom-up design of high-performance, durable catalytic systems for various catalysis needs.

Resilient Consensus Control for Multi-Agent Systems: A Comparative Survey.

Due to the openness of communication network and the complexity of system structures, multi-agent systems are vulnerable to malicious network attacks, which can cause intense instability to these systems. This article provides a survey of state-of-the-art results of network attacks on multi-agent systems. Recent advances on three types of attacks, i.e., those on DoS attacks, spoofing attacks and Byzantine attacks, the three main network attacks, are reviewed. Their attack mechanisms are introduced, and the attack model and the resilient consensus control structure are discussed, respectively, in detail, in terms of the theoretical innovation, the critical limitations and the change of the application. Moreover, some of the existing results along this line are given in a tutorial-like fashion. In the end, some challenges and open issues are indicated to guide future development directions of the resilient consensus of multi-agent system under network attacks.

Research on Road Scene Understanding of Autonomous Vehicles Based on Multi-Task Learning.

Road scene understanding is crucial to the safe driving of autonomous vehicles. Comprehensive road scene understanding requires a visual perception system to deal with a large number of tasks at the same time, which needs a perception model with a small size, fast speed, and high accuracy. As multi-task learning has evident advantages in performance and computational resources, in this paper, a multi-task model YOLO-Object, Drivable Area, and Lane Line Detection (YOLO-ODL) based on hard parameter sharing is proposed to realize joint and efficient detection of traffic objects, drivable areas, and lane lines. In order to balance tasks of YOLO-ODL, a weight balancing strategy is introduced so that the weight parameters of the model can be automatically adjusted during training, and a Mosaic migration optimization scheme is adopted to improve the evaluation indicators of the model. Our YOLO-ODL model performs well on the challenging BDD100K dataset, achieving the state of the art in terms of accuracy and computational efficiency.

Highly Selective Photoelectroreduction of Carbon Dioxide to Ethanol over Graphene/Silicon Carbide Composites.

Using sunlight to produce valuable chemicals and fuels from carbon dioxide (CO2 ), i.e., artificial photosynthesis (AP) is a promising strategy to achieve solar energy storage and a negative carbon cycle. However, selective synthesis of C2 compounds with a high CO2 conversion rate remains challenging for current AP technologies. We performed CO2 photoelectroreduction over a graphene/silicon carbide (SiC) catalyst under simulated solar irradiation with ethanol (C2 H5 OH) selectivity of>99 % and a CO2 conversion rate of up to 17.1 mmol gcat -1 h-1 with sustained performance. Experimental and theoretical investigations indicated an optimal interfacial layer to facilitate the transfer of photogenerated electrons from the SiC substrate to the few-layer graphene overlayer, which also favored an efficient CO2 to C2 H5 OH conversion pathway.

Source of Rate Acceleration for Carbocation Cyclization in Biomimetic Supramolecular Cages.

The results of quantum chemical and molecular dynamics calculations reveal that polyanionic gallium-based cages accelerate cyclization reactions of pentadienyl alcohols as a result of substrate cage interactions, preferential binding of reactive conformations of substrate/H3O+ pairs, and increased substrate basicity. However, the increase in basicity dominates. Experimental structure-activity relationship studies in which the metal vertices and overall charge of the cage are varied confirm the model derived via calculations.

Ionic Conductive and Highly-Stable Interface for Alkali Metal Anodes.

Alkali metals are regarded as the most promising candidates for advanced anode for the next-generation batteries due to their high specific capacity, low electrochemical potential, and lightweight. However, critical problems of the alkali metal anodes, especially dendrite formation and interface stabilization, remain challenging to overcome. The solid electrolyte interphase (SEI) is a key factor affecting Li and Na deposition behavior and electrochemical performances. Herein, a facile and universal approach is successfully developed to fabricate ionic conductive interfaces for Li and Na metal anodes by modified atomic layer deposition (ALD). In this process, the Li metal (or Na metal) plays the role of Li (or Na) source without any additional Li (or Na) precursor during ALD. Moreover, the key questions about the influence of ALD deposition temperature on the compositions and structure of the coatings are addressed. The optimized ionic conductive coatings have significantly improved the electrochemical performances. In addition, the electrochemical phase-field model is performed to prove that the ionic conductive coating is very effective in promoting uniform electrodeposition. This approach is universal and can be potentially applied to other different metal anodes. At the same time, it can be extended to other types of coatings or other deposition techniques.

Detection and evaluation of myocardial fibrosis in Eisenmenger syndrome using cardiovascular magnetic resonance late gadolinium enhancement and T1 mapping.

BACKGROUND: Myocardial fibrosis is a common pathophysiological process involved in many cardiovascular diseases. However, limited prior studies suggested no association between focal myocardial fibrosis detected by cardiovascular magnetic resonance (CMR) late gadolinium enhancement (LGE) and disease severity in Eisenmenger syndrome (ES). This study aimed to explore potential associations between myocardial fibrosis evaluated by the CMR LGE and T1 mapping and risk stratification profiles including exercise tolerance, serum biomarkers, hemodynamics, and right ventricular (RV) function in these patients. METHODS: Forty-five adults with ES and 30 healthy subjects were included. All subjects underwent a contrast-enhanced 3T CMR. Focal replacement fibrosis was visualized on LGE images. The locations of LGE were recorded. After excluding LGE in ventricular insertion point (VIP), ES patients were divided into myocardial LGE-positive (LGE+) and LGE-negative (LGE-) subgroups. Regions of interest in the septal myocardium were manually contoured in the T1 mapping images to determine the diffuse myocardial fibrosis. The relationships between myocardial fibrosis and 6-min walk test (6MWT), N-terminal pro-brain natriuretic peptide (NT-pro BNP), hematocrit, mean pulmonary arterial pressure (mPAP), pulmonary vascular resistance index (PVRI), RV/left ventricular end-systolic volume (RV/LV ESV), RV ejection fraction (RVEF), and risk stratification were analyzed. RESULTS: Myocardial LGE (excluding VIP) was common in ES (16/45, 35.6%), and often located in the septum (12/45, 26.7%). The clinical characteristics, hemodynamics, CMR morphology and function, and extracellular volume fraction (ECV) were similar in the LGE+ and LGE- groups (all P > 0.05). ECV was significantly higher in ES patients (28.6 ± 5.9% vs. 25.6 ± 2.2%, P < 0.05) and those with LGE- ES (28.3 ± 5.9% vs. 25.6 ± 2.2%, P < 0.05) than healthy controls. We found significant correlations between ECV and log NT-pro BNP, hematocrit, mPAP, PVRI, RV/LV ESV, and RVEF (all P < 0.05), and correlations trends between ECV and 6MWT (P = 0.06) in ES patients. An ECV threshold of 29.0% performed well in differentiating patients with high-risk ES from those with intermediate or low risk (area under curve 0.857, P < 0.001). CONCLUSIONS: Myocardial fibrosis is a common feature of ES. ECV may serve as an important imaging marker for ES disease severity.

From inert gas to fertilizer, fuel and fine chemicals: N2 reduction and fixation.

The 100th anniversary of a leading nitrogen fixation technology developer like CASALE SA is a reason to reflect over the 20th century successful solution of the problem of world food supply, and to look out for solutions for sustainable developments with respect to ammonia production. We review the role of nitrogen as essential chemical constituent in photosynthesis and biology, and component of ammonia as it is used as fertilizer for primary production by photosynthesis for farming and food supply and its future role as energy carrier. While novel synthesis methods and very advanced synchrotron based x-ray analytical techniques are being developed, we feel it is important to refer to the historical and economical context of nitrogen. The breaking of the N≡N triple bond remains a fundamental chemical and energetic problem in this context. We review the electrochemical ammonia synthesis as an energetically and environmentally benign method. Two relatively novel X-ray spectroscopy methods, which are relevant for the molecular understanding of the catalysts and biocatalysts, i.e. soft X-ray absorption spectroscopy and nuclear resonant vibration spectroscopy are presented. We illustrate the perceived reality in fertilizer usage on the field, and fertilizer production in the factory complex with photos and thus provide a contrast to the academic view of the molecular process of ammonia function and production.