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Abstract Reconstruction model is a powerful method for component condition monitoring and fault detection by considering the model prediction residuals. In this article, a new signal reconstruction modeling technique is proposed using support vector regression. Multiple indicators are calculated to recognize slight shift from normal condition, and detect the fault at an early stage. Input variables are selected based on correlation analysis and failure mode analysis. A sliding-time-window technique is employed to incorporate temporal information inherent in time-series data. Residuals between the observed signal and the reconstruction signal are utilized to indicate whether the desired quantity is different from its normal operation condition or not. Three statistical indicators (Deviation Index, Volatility Index and Significance Index) are defined to quantify the deviation level from normal condition to abnormal condition. Health index (HI) of a specific fault is derived from responsive statistical indicators, and the integral health index (integral-HI) of an entire component is composed of all individual health index. An experiment of real-life wind turbine high temperature fault detection scheme is studied. Results show that the proposed approach demonstrates improved performance in detecting wind turbine faults, and controlling false and missed alarms. Highlights • A new reconstruction modeling technique is developed combining support vector regression and sliding-time-window approach. • A framework of reconstruction model based on real-time fault detection method is proposed. • Three statistical indicators are defined to quantify the deviation level of abnormal condition. • Health index and integral health index is derived to characterize component's health condition. [ABSTRACT FROM AUTHOR]

Redox-active organometallic molecules offer a promising avenue for increasing the energy density and cycling stability of redox flow batteries. The molecular properties change dramatically as the ligands are functionalized and these variations allow for improving the solubility and controlling the redox potentials to optimize their performance when used as electrolytes. Unfortunately, it has been difficult to predict and design the stability of redoxactive molecules to enhance cyclability in a rational manner, in part because the relationship between electronic structure and redox behavior has been neither fully understood nor systematically explored. In this work, rational strategies for exploiting two common principles in organometallic chemistry for enhancing the robustness of pseudo-octahedral cobalt-polypyridyl complexes are developed. Namely, the spin-crossover between low and highspin states and the chelation effect emerging from replacing three bidentate ligands with two tridentate analogues. Quantum chemical models are used to conceptualize the approach and make predictions that are tested against experiments by preparing prototype Co-complexes and profiling them as catholytes and anolytes. In good agreement with the conceptual predictions, very stable cycling performance over 600 cycles is found. [ABSTRACT FROM AUTHOR]

Owing to the transient nature of the intermediates formed during the oxygen evolution reaction (OER) on the surface of transition metal oxides, their nature remains largely elusive by the means of simple techniques. The use of chemical probes is proposed, which, owing to their specific affinities towards different oxygen species, unravel the role played by these species on the OER mechanism. For that, tetraalkylammonium (TAA) cations, previously known for their surfactant properties, are introduced, which interact with the active oxygen sites and modify the hydrogen bond network on the surface of OER catalysts. Combining chemical probes with isotopic and pH-dependent measurements, it is further demonstrated that the introduction of iron into amorphous Ni oxyhydroxide films used as model catalysts deeply modifies the proton exchange properties, and therefore the OER mechanism and activity. [ABSTRACT FROM AUTHOR]

Owing to the transient nature of the intermediates formed during the oxygen evolution reaction (OER) on the surface of transition metal oxides, their nature remains largely elusive by the means of simple techniques. The use of chemical probes is proposed, which, owing to their specific affinities towards different oxygen species, unravel the role played by these species on the OER mechanism. For that, tetraalkylammonium (TAA) cations, previously known for their surfactant properties, are introduced, which interact with the active oxygen sites and modify the hydrogen bond network on the surface of OER catalysts. Combining chemical probes with isotopic and pH-dependent measurements, it is further demonstrated that the introduction of iron into amorphous Ni oxyhydroxide films used as model catalysts deeply modifies the proton exchange properties, and therefore the OER mechanism and activity. [ABSTRACT FROM AUTHOR]

The stability of carbon-supported Pt electrocatalysts is long regarded as a critical issue. In this study, we demonstrate that by physically mixing a commercial Pt/C catalyst with 20 wt% of 2-dimensional tungsten oxide (WO 3 ) nanoplates, the stability of the Pt/C-WO 3 composite is greatly improved as both ECSA and catalytic activity are maintained approximately twice higher than the commercial Pt/C after a long-time accelerated degradation test. Interestingly, Pt nanoparticles are observed to migrate or re-nucleate on the surface of WO 3 nanoplates from the carbon surface during degradation, which circumstantially triggers the ‘hydrogen spillover’ effect between Pt and WO 3 , and results in the CO stripping peaks being gradually shifted towards lower potentials. The outcome of this work provides crucial insight regarding the degradation behaviors of Pt nanoparticles in a heterogeneous catalyst system and can lead to the development and design of other stable Pt-based electrocatalysts. [ABSTRACT FROM AUTHOR]

Highly porous iron‐nitrogen‐doped hollow coremesoporous shell (Fe‐N‐HCMS) carbon is synthesized with regular mesopores, thus providing high surface area and large pore volume. Excellent mass transfer, durability, and methanol tolerance, in addition to high activity for the oxygen reduction reaction, are demonstrated. The limiting current density is the highest reported for non‐precious‐metal nitrogen‐doped carbons. [ABSTRACT FROM AUTHOR]

Abstract: A microwave-assisted microemulsion synthesis of carbon supported Pt-WO3 nanoparticles is presented. Amorphous WO3 nanoparticles of 1.0nm in size were first deposited onto carbon from an alkaline tungstate containing microemulsion via mixing with an acid containing microemulsion under controlled microwave exposure. Platinum was subsequently deposited onto the carbon supported WO3 nanoparticles by reducing H2PtCl6 in a microemulsion under controlled microwave exposure forming nanoparticles with an average size of 2.5nm. This method produced a homogeneous distribution of nanoparticles on the carbon support with a uniform Pt:W ratio. The Pt:W can be well controlled by varying the metal precursors’ Pt:W ratio. Hydrogen adsorption, CO-stripping and Cu-UPD stripping method were used to estimate the electrochemical surface area of Pt in the Pt-WO3 mixed catalyst system. Cyclic voltammetry and chronopotentiometry experiments demonstrate that a 1:1 ratio of Pt:W has the highest electrocatalytic activity based on Pt mass for methanol oxidation in sulfuric acid. The enhanced electrocatalytic activity is attributed to both physical and chemical influence of the WO3 component. [Copyright &y& Elsevier]

Abstract: The differential pressure fluctuation frequency characteristics were studied in a bench-scale dual-leg fluidized bed with dimensions of 0.24m width, 0.02m depth, 0.8m height and 0.16m height for the legs. The differential pressure monitoring system was established to measure pressure fluctuations in two half beds and processed by power spectrum density (PSD) to get the dominant frequency and its energy. In addition, the analysis of PSD was combined with digital images of solid distribution to study the bubbling actions and the behaviors of solid exchange between two half beds with fluidization velocities at 1.88, 2.71, 3.42, 4.16 and 5.06m/s for static bed material heights 40, 60, 80 and 100mm respectively. The PSD results show two dominant frequencies with less than 1Hz for the first dominant frequency and bigger than 3Hz for the second dominant frequency. Analytical results by combining with the digital images indicate that the first dominant frequency represents solid exchange between two half beds in the form of clusters and the second dominant frequency stands for both bubbling actions and solid exchange behaviors in the form of single particles. Furthermore, with the increase of fluidization velocity, the second dominant frequency and its energy both decrease representing that the difference of bubbling actions is weaker gradually, while the first dominant frequency and its energy vary complexly. Higher static bed material height contributes the second dominant frequency to decrease, and the effect of static bed material height on the first dominant frequency is complex at different fluidization velocities. Energy of the dominant frequency increases firstly and then levels off with increasing static bed material height. The dominant frequency can be used to describe the bubbling actions and solid exchange behaviors between two half beds. Power spectrum density analysis is verified a useful way to study the bed material overturn in the dual-leg fluidized bed. [Copyright &y& Elsevier]

Considering that CO2 reduction is mostly a multielectron reaction, it is necessary for the photocatalysts to integrate multiple catalytic sites and cooperate synergistically to achieve efficient photocatalytic CO2 reduction to various products, such as C2 hydrocarbons. Herein, through crystal engineering, we designed and constructed a metal–organic framework‐derived Zr/Ti bimetallic oxide solid solution support, which was confirmed by X‐ray diffraction, electron microscopy and X‐ray absorption spectroscopy. After anchoring Au nanoparticles, the composite photocatalyst exhibited excellent performances toward photocatalytic CO2 reduction to syngas (H2 and CO production rates of 271.6 and 260.6 μmol g−1 h−1) and even C2 hydrocarbons (C2H4 and C2H6 production rates of 6.80 and 4.05 μmol g−1 h−1). According to the control experiments and theoretical calculations, the strong interaction between bimetallic oxide solid solution support and Au nanoparticles was found to be beneficial for binding intermediates and reducing CO2 reduction, highlighting the synergy effect of the catalytic system with multiple active sites. [ABSTRACT FROM AUTHOR]

Considering that CO2 reduction is mostly a multielectron reaction, it is necessary for the photocatalysts to integrate multiple catalytic sites and cooperate synergistically to achieve efficient photocatalytic CO2 reduction to various products, such as C2 hydrocarbons. Herein, through crystal engineering, we designed and constructed a metal–organic framework‐derived Zr/Ti bimetallic oxide solid solution support, which was confirmed by X‐ray diffraction, electron microscopy and X‐ray absorption spectroscopy. After anchoring Au nanoparticles, the composite photocatalyst exhibited excellent performances toward photocatalytic CO2 reduction to syngas (H2 and CO production rates of 271.6 and 260.6 μmol g−1 h−1) and even C2 hydrocarbons (C2H4 and C2H6 production rates of 6.80 and 4.05 μmol g−1 h−1). According to the control experiments and theoretical calculations, the strong interaction between bimetallic oxide solid solution support and Au nanoparticles was found to be beneficial for binding intermediates and reducing CO2 reduction, highlighting the synergy effect of the catalytic system with multiple active sites. [ABSTRACT FROM AUTHOR]

A single–phase flow model was used to analyze the uniformity of the flow field in the desulfurization tower under different baffle combinations, and a multiphase flow model was used to explain the gas and solid two–phase flow characteristics and chemical reaction characteristics in the tower. The stability of the flow behavior of gas and solids in one furnace and two towers was discussed. The results show that the installation of shielding plates at appropriate positions in the tower for sulfur removal is beneficial to enhance the uniform distribution of flow in space, reduce the pulsation interference of bed pressure in the tower, keep the state of gas and solid flow unchanged, and maintain the efficiency of desulfurization at a high level. Reducing the instability of gas–solid two–phase flow is the basis of ensuring the stable switching between single and double towers. [ABSTRACT FROM AUTHOR]

[Display omitted] Urea oxidation reaction (UOR) has been widely considered as an alternative anodic reaction to water oxidation for the green production of hydrogen fuel. Due to the high catalytic activity of transition metal oxides towards UOR, various strategies have been developed to improve their syntheses and catalytic properties. However, little is known about the underlying mechanisms of UOR on catalyst surface. In this work, three transition metal oxides, including NiO, Co 3 O 4 , and Fe 2 O 3 are investigated as model catalysts. Through analyzing the electrochemical properties by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and operando Raman spectroscopy, it is revealed that NiO has a unique high catalytic activity towards UOR due to simultaneous formation of a thin layer of oxyhydroxide species above 1.40 V vs. RHE in alkaline media. In addition, density functional theory (DFT) calculations further suggest that the adsorption of urea molecules is largely affected by surface interactions resulting in different space configurations, which impose large influences on the consecutive deprotonation and N N formation processes. Overall, results of this work point to the subtle adsorption − kinetics relationship in UOR and highlight the importance of the interfacial electronic interactions on catalyst surface. [ABSTRACT FROM AUTHOR]

In a recent article published in Angewandte Chemie, researchers Lei Li, Qiang Xu, and their team discuss their findings on achieving efficient photocatalytic CO2 reduction. The researchers utilized crystal engineering and derivation techniques to create a metal-organic framework-derived Zr/Ti bimetallic oxide solid solution anchored with Au nanoparticles. This innovative approach resulted in the successful reduction of CO2 to syngas and C2 hydrocarbons under simulated solar light irradiation. The study highlights the importance of integrating multiple catalytic sites and cooperation between them for effective CO2 reduction. [Extracted from the article]

A Journal of the German Chemical Society AngewandteChemie www. angewandte. org International Edition 2024– 63/ 21 I. ntegrating multiple catalytic sites … … and cooperating synergistically are the keys to achieve efficient photocatalytic CO2 reduction. In their Research Article ( e202319177), Lei Li, Qiang Xu et al. report a metal- organic framework- derived Zr/ Ti bimetallic oxide solid solution anchored with Au nanoparticles through crystal engineering and derivation, achieving photocatalytic CO2 reduction to syngas and eventually C2 hydrocarbons under simulated solar light irradiation. [Extracted from the article]

[Display omitted] Solar-driven water splitting has been regarded as a promising strategy for renewable hydrogen production. Among many semiconductor photocatalysts, graphitic carbon nitride (g-C 3 N 4) has received tremendous attention due to its two-dimensional structure, appropriate band gap and decent photocatalytic activity. However, it suffers severe charge recombination problems, affecting its practical performance. In this work, we demonstrated that dual heteroatoms (C and O) doped g-C 3 N 4 can exhibit about 3 times higher catalytic performance for hydrogen evolution than that of the normal g-C 3 N 4 with a hydrogen evolution rate reaching 2595.4 umol g−1h−1 and an apparent quantum efficiency at 420 nm of 16.6%. The heteroatoms (C and O) doped g-C 3 N 4 photocatalyst also exhibited superior removal performance when removing Rhodamine B (RhB). X-ray photoelectron spectroscopy (XPS), solid-state nuclear magnetic resonance (ssNMR) and X-ray absorption near-edge structure (XANES) spectroscopy reveal that the carbon and oxygen dopants replace the sp2 nitrogen and bridging N atom, respectively. DFT calculations demonstrate the codoping of carbon and oxygen- induced the generation of mid-gap state, leading to the improvement of light harvesting and charge separation. [ABSTRACT FROM AUTHOR]

Synthetic hydrogels are unique tissue mimics but rarely reproduce the strain‐stiffening properties of native tissues. This mechanical mismatch impairs the performance of hydrogels in practical applications. Inspired by the crimped structure of collagenous tissues, a series of strain‐stiffening hydrogels composed of curved parallel fibers are developed. These fibers are constructed from a bundle of intertwisted nanofibrils composed of short alkyl side chain‐modified polymer chains. This hierarchical organization enables exquisitely cascaded deformation that facilitates soft‐to‐firm and resilience‐to‐viscoelasticity transitions, thus synergically mimicking the strain‐adaptive stiffening and damping behaviors of natural tissues. Together with structural evolution and a constitutive model, rationally tuning the tortuosity and flexibility of the curved fibers produces a diverse combination of strain‐stiffening properties and unprecedented penetration into the regions of several tissues. The crimped structure and the resultant stiffening properties constitute major improvements to nanofiber‐based scaffolds for use in collagenous tissue repair. [ABSTRACT FROM AUTHOR]

Metal-free graphitic carbon nitride (g-C3N4) is a promising semiconductor material that can utilize visible light for photocatalytic hydrogen production. The photocatalytic activity can be further enhanced by improving the kinetics of photocarrier transfer and absorption efficiency of visible light. Herein, we demonstrate a facile strategy for the synthesis of C-doped g-C3N4 with porous hierarchical structure by simple co-pyrolyzation of acrylamide and dicyandiamide together. The addition of trace amount of acrylamide not only endows g-C3N4 with high porosity and specific surface area, but also promotes electron–hole separation and charge transfer due to the introduction of carbon dopant into the g-C3N4 structure. With 2 wt% of acrylamide in the precursor, the resulted C-doped g-C3N4 can deliver 3.4 times higher photocatalytic activity for hydrogen evolution than that of the bulk g-C3N4. Our present work provides valuable information for the performance-based optimization of composition and structural properties, as well as large scale production of high performance g-C3N4 photocatalysts. [ABSTRACT FROM AUTHOR]

Nickel foam has been applying as the electrode support material for alkaline direct ethanol fuel cells, since its unique three-dimensional network structure helps efficiently use the catalyst to improve the cell performance. In this work, the effect of the thickness of nickel foam electrodes on cell performance is investigated. The experimental results show that the nickel foam thickness influences both the electron conduction and mass transfer, and the optimal thickness is a trade-off between them. Through XRD, SEM image, polarization curve test, EIS test and CV test, it is found that the nickel foam electrode with the thickness of 0.6 mm has better performance than that of 0.3 mm and 1.0 mm. The thinner the nickel foam, the better the conductivity. However, the corresponding three-dimensional space becomes narrower, which leads to partial agglomeration of the catalyst and hindrance of mass transfer. In addition, the influence of catalyst loading on the performance of 0.6 mm nickel foam electrode is explored. The maximum power density of 1.0 mg cm−2 Pd loading reaches 56.3 mW cm−2 at 60 °C, which is higher than that of 2.0 mg cm−2 loading, indicating that the three-dimensional network structure of nickel foam can efficiently utilize the catalyst, and fully exert the catalytic function of the catalyst even at a lower catalyst loading. Moreover, the effects of operating temperature and ethanol concentration on cell performance are also studied. The cell performance increases with the increase of temperature, and it reaches the highest with 3 M ethanol. The thickness of nickel foam influences both the electron conduction and mass transfer in 3D porous anode, and the optimal thickness is a trade-off between them. The 0.6 mm thickness nickel foam electrode with 1 mg cm−2 Pd loading reaches 56.3 mW cm−2 at 60 °C, which is higher than that of 2 mg cm−2 loading, proving the efficient utilization of catalyst. Image 1 • 3D porous structure of nickel foam enables efficient use of catalyst. • There is a trade-off in foam thickness between charge transfer and mass transfer. • 0.6 mm foam electrode with 1 mg cm−2 Pd loading exhibits the power of 56 mW cm−2. [ABSTRACT FROM AUTHOR]

The conventional electrodes of direct methanol fuel cells (DMFCs) usually encounter a problem that the catalysts sink into the diffusion layer after a period of operation, causing a lowered catalyst utilization and degraded cell performance. Aiming to alleviate this problem, in this work a novel anode electrode structure is proposed, in which a microporous layer containing Nafion polymer is added between the catalyst layer and the microporous layer with PTFE. The presence of the Nafion-contained layer can expand the three-phase interface region of the electrochemical reactions and improve the utilization of the catalyst. The single cell test showed that the peak power densities of the novel membrane electrode assembly (MEA) fed with 0.5 M and 2 M methanol solutions reached 38.35 mW cm−2 and 101.82 mW cm−2, which increased by 100.42% and 15.27% compared with those of conventional single microporous layer. Electrochemical impedance spectroscopy (EIS) measurements indicated the charge transfer resistance of the conventional MEA structure was increased by 303.78%, while the new one was decreased by 47.91% after continuously operating for 48 h. The anode electrochemical active surface area (ECSA) values of the novel MEA and the conventional MEA were 52.6 m2 g-1 and 44.3 m2 g-1. These experimental results showed that the performance of the double microporous layer MEA was higher than that of the conventional MEA. This new microporous layer structure is promising to be used in fuel cells to improve cell performance and alleviate performance degradation after long-term operating. An anode electrode structure with a microporous layer containing Nafion added between the catalyst layer and the microporous layer with PTFE can improve the performance of DMFC and alleviate performance degradation. Image 1 • A double microporous layer (MPL) structure is proposed for DMFCs. • The peak power density of the new MEA can increase as high as 100.42%. • The reduction of charge transfer resistance of DMFC could reach 89.26%. • The ECSA of the DMFC could increase by 18.7%. • The addition of the inner microporous layer increases the catalyst utilization. [ABSTRACT FROM AUTHOR]

The significant reduction in capacity and cyclability of lithium-ion batteries (LIBs) at low temperature is still limiting its application in cold climate. Limited literature has addressed the low temperature performance of LIB anodes, mostly restrict to low current performance showing low durability (<100 cycles). This is the first report of excellent durability in Li 4 Ti 5 O 12 -based composite cycling at a high current (10C) over 1000 cycles under sub-zero temperatures. We embed Li 4 Ti 5 O 12 nanoparticles in hierarchical macropore-mesoporous shell carbon network (HCMS carbon) to form Li 4 Ti 5 O 12 /HCMS carbon nanocomposite. The HCMS carbon is an ideal support for Li 4 Ti 5 O 12 to achieve excellent high rate sub-freezing LIB performance by providing short, intertwining Li-ion diffusion pathways between embedded Li 4 Ti 5 O 12 particles and Li-ion reservoirs, and ample routes for continuous, multi-directional electron flow to Li 4 Ti 5 O 12 particles. At −20 °C, the Li 4 Ti 5 O 12 /HCMS carbon composite delivers the highest literature-reported specific energy of 80 Wh/kg at a high specific power of 3000 W/kg. This work demonstrates our Li 4 Ti 5 O 12 /HCMS carbon composite can be a viable LIB anode material with fast and efficient Li-ion and electron transport active in sub-zero temperature operation. Image 1 [ABSTRACT FROM AUTHOR]

Fuel cells directly convert chemical energy stored in fuels into electrical energy through electrochemical reactions and have been identified as one of the most promising technologies for the clean energy industry of the future. In recent years, fuel cells have been applied in the medical field in both exploratory research and prospective products, as they offer multiple advantages over conventional batteries, including ease of recharging, environmentally friendly character and high security. In this paper, we summarize the up to date progress of this energy system in implantable medical devices which use microorganisms, enzymes and precious metals as catalysts, respectively. Safety is the most concerned issue in this application. In addition, we introduce a variety of applications of fuel cells on the vitro medical equipments (such as blood glucose meter, alcohol tester, wound treatment instrument). The introduction of fuel cells on implementable medical devices is in early stage of research, nonetheless the prospects/potential of this application are grant. Evidently, mankind could come across a new medical revolution upon the successful introduction of fuel cells to the human body. [ABSTRACT FROM AUTHOR]