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As promising energy-storage devices, zinc–air batteries (ZABs) exhibit slow reaction kinetics for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) occurring at their electrodes. High-performance bifunctional catalysts must thus be synthesized to accelerate the reversible conversion of oxygen and improve the rate and overall performance of ZABs. Herein, we reported the promising prospects of self-supported composite electrodes composed of wood-derived carbon (WDC) and bimetallic cobalt-iron alloys/oxides (CoFe-CoFe2O4@WDC) as efficient electrocatalysts for alkaline ORR/OER. WDC provided a favorable three-phase interface for heterogeneous reactions owing to its layered porous structure and genetic stability, thereby enabling mass diffusion and improving reaction kinetics. The CoFe2O4 spinel surface was reduced to bimetallic CoFe alloy to form abundant heterostructure interfaces that promote electron transfer. Under alkaline conditions, the optimized composite electrode exhibited a remarkable high half-wave potential of 0.85 V and an exceptionally low overpotential of 1.49 V. It also exhibited stable performance over an impressive 2340 cycles in a ZAB. Theoretical calculations also confirmed that the heterointerface addresses the issue of proton scarcity throughout the reaction and actively facilitates the creation of O–O bonds during the reversible transformation of oxygen. This study introduces a new concept for developing bifunctional and efficient electrocatalysts based on charcoal and encourages the sustainable and high-value use of forest biomass resources. Highlights: Water dissociation was regulated to provide proton for smooth response under alkaline conditions and accelerate the conversion of *O2 to *OOH. The alloy surface formed CoFe oxyhydroxide in the OER voltage range, and the adsorption capacity of intermediates was adjusted to facilitate O–O bond formation. The d-band center moved downward due to interface electron interaction, modifying the binding ability of intermediates. [ABSTRACT FROM AUTHOR]

The 2024-1.5 wt%CNTs@Ni (Nickel-coated carbon nanotubes) composite were subjected to equal channel angle pressing (ECAP) deformation treatment and the microstructure, hardness distribution and tensile properties were investigated and discussed. The quasi-in-situ corrosion observation and COMSOL corrosion simulation were used to analyze and reveal its corrosion behavior. The results showed that the stress and microstrain are mainly concentrated in the area near the inside corner, and the closer the inside corner, the finer the grain size and the more dispersed the second phase and CNTs@Ni. The average hardness of the ECAP-treated composite was about 136.54 HV, which was 44.41% higher than that of the as-cast composite (94.55 HV). The properties of the ECAP-treated composite were all higher than the as-cast composite, with the yield strength, tensile strength and elongation increasing to 283.49 MPa, 399.18 MPa and 11.69%, respectively, which were about 44.99%, 45.97% and 344.49% higher than the as-cast composite. The electrochemical properties of the ECAP-treated composite were better than the as-cast composite, with a corrosion current density of 88.319 μA∙cm2, which was 12.33% lower than that of the as-cast composite. The COMSOL simulation results indicated that the ECAP-treated composite required a longer time when the electrolyte was immersed to the same depth. [ABSTRACT FROM AUTHOR]

Expanding the application scenarios of wood-derived biochar guided by the conversion of traditional energy to new energy shows great promise as a field. As thrilling energy conversion apparatus, zinc-air batteries (ZABs) require cathode catalysts with high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities and stability. Herein, two-dimensional nickel-iron hydroxide nanosheets were creatively assembled in N-doped wood-derived biochar (NiFe-LDH@NC) by an in-situ growth method. The categorized porous organization in wood-derived biochar facilitates the rapid seepage of electrolytes and rapid diffusion of reaction gases. The unique interfacial structure of biochar and NiFe-LDH accelerates electron transfer during oxygen electrocatalysis, and endows NiFe-LDH@NC with first-class catalytic activity and durability for ORR and OER. The ZAB derived from NiFe-LDH@NC showed elevated discharge productivity and cycle endurance, making it promising for viable applications. This work provided a convenient way for the conversion of wood-derived biochar to high-value added electrocatalysts. Article Highlights: Heteroatom-doped wood-derived biochar was assisted in situ growth of NiFe-LDH. NiFe-LDH@NC exhibited excellent bifunctional activity and stability toward ORR/OER. The ZAB achieved a peak power density of 123 mW cm−2 and a cycling stability of 270 h. [ABSTRACT FROM AUTHOR]

Ferroelectric polymers have great potential applications in mechanical/thermal sensing, but their sensitivity and detection limit are still not outstanding. We propose interface engineering to improve the charge collection in a ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) copolymer (P(VDF-TrFE)) thin film via cross-linking with poly(3,4-ethylenedioxythiophene) doped with polystyrenesulfonate (PEDOT:PSS) layer. The as-fabricated P(VDF-TrFE)/PEDOT:PSS composite film exhibits an ultrasensitive and linear mechanical/thermal response, showing sensitivities of 2.2 V kPa−1 in the pressure range of 0.025–100 kPa and 6.4 V K−1 in the temperature change range of 0.05–10 K. A corresponding piezoelectric coefficient of −86 pC N−1 and a pyroelectric coefficient of 95 μC m−2 K−1 are achieved because more charge is collected by the network interconnection interface between PEDOT:PSS and P(VDF-TrFE), related to the increase in the dielectric properties. Our work shines a light on a device-level technique route for boosting the sensitivity of ferroelectric polymer sensors through electrode interface engineering. The piezoelectric and pyroelectric coefficients of ferroelectric materials are critical to improving the sensitivity and detection limit in sensing. Here, the authors report an interface engineering strategy using a PEDOT:PSS penetrating electrode, that realizes high pressure and temperature sensitivity. [ABSTRACT FROM AUTHOR]

Surface roughness is an important indicator for shaft grinding, and its prediction is always a core issue in practice. The surface roughness of each part for a large shaft would be different with same processing parameters, which leads to traditional processing parameter-based prediction being ineffective; thus, the surface roughness prediction of large shaft grinding is more difficult. This paper proposes a surface roughness prediction method for large shaft grinding based on deep learning, and three kinds of process signals are selected as the inputs, including spindle current, vibration, and acoustic emission. An experiment considering the contribution degree of each processing parameter is designed to generate the dataset on a large shaft grinding platform, and the appropriate surface roughness intervals are divided. The multiple process signals are fused through an attentional CNN-LSTM architecture, in which the CNN is used to extract the features of the process signals, the LSTM deals with the sequential output of CNN, and the self-attention mechanism is utilized to realize the automatic weight allocation. Moreover, the model degradation problem after long-term use of the grinding platform is solved by the parameters fine-tuning approach. The experimental results show that the proposed method achieves the best accuracy than all comparative items, and the model performance can be recovered through parameters fine-tuning; thus, the proposed method is effective. [ABSTRACT FROM AUTHOR]

The charge-to-spin conversion efficiency is a crucial parameter in determining the performance of many useful spintronic materials. Usually, this conversion efficiency is predetermined by the intrinsic nature of solid-state materials, which cannot be easily modified without invoking chemical or structural changes in the underlying system. Here we report on successful modulation of charge-spin conversion efficiency via the metal-insulator transition in a quintessential strongly correlated electron compound vanadium dioxide (VO2). By employing ferromagnetic resonance driven spin pumping and the inverse spin Hall effect measurement, we find a dramatic change in the spin pumping signal (decrease by > 80%) and charge-spin conversion efficiency (increase by five times) upon insulator to metal transition. The abrupt change in the structural and electrical properties of this material therefore provides useful insights on the spin related physics in a strongly correlated material undergoing a phase transition. The interconversion of spin and charge is fundamental to the operation of spintronic devices. Here the authors demonstrate spin-to-charge conversion in the correlated material vanadium dioxide, and show that the efficiency changes dramatically across the metal-insulator transition. [ABSTRACT FROM AUTHOR]

Manipulation of antiferromagnetic (AFM) spins by electrical means is on great demand to develop the AFM spintronics with low power consumption. Here we report a reversible electrical control of antiferromagnetic moments of FeMn up to 15 nm, using an ionic liquid to exert a substantial electric-field effect. The manipulation is demonstrated by the modulation of exchange spring in [Co/Pt]/FeMn system, where AFM moments in FeMn pin the magnetization rotation of Co/Pt. By carrier injection or extraction, the magnetic anisotropy of the top layer in FeMn is modulated to influence the whole exchange spring and then passes its influence to the [Co/Pt]/FeMn interface, through a distance up to the length of exchange spring that fully screens electric field. Comparing FeMn to IrMn, despite the opposite dependence of exchange bias on gate voltages, the same correlation between carrier density and exchange spring stiffness is demonstrated. Besides the fundamental significance of modulating the spin structures in metallic AFM via all-electrical fashion, the present finding would advance the development of low-power-consumption AFM spintronics. [ABSTRACT FROM AUTHOR]

The mechanism of the oxygen evolution reaction over NiFe-layered double hydroxides is investigated using first-principles DFT + U calculations. We consider three possible reaction pathways for O evolution. Our calculations show that O evolution from the OH*-OH* species has high energy barrier and from OOH* species have a little high energy barrier. Finally, we discover that O can easily release from OO* species. Graphical Abstract: The mechanism of oxygen evolution reaction (OER) over NiFe-layered double hydroxides was investigated using DFT + U method by First-principle. The present work considered two possible reaction pathways for O evolution. Our calculation suggested that O evolution from the OOH* species may be more favorable because of advantages in energy profile, oxygen adsorption, and overall energy barrier. In addition, density of states (DOS) and partial density of states (PDOSs) of NiFe-LDH and Ni(OH) showed that NiFe-LDH had a more stronger capability for electron transportation and higher activity than Ni(OH). Additionally, it was found that Bader charge of Ni had a large fluctuation in the former elementary steps, while in the later that of Fe had. The research suggested that the transitional metal Fe/Ni-based hydrotalcite was a suitable material for OER, for not only they had great activity and stability, but also they were widely used and comparatively cheap.[Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The first-principles calculations were used to investigate the oxygen evolution reaction (OER) on the (100) surface of the spinel CoO, a high-performance oxidation catalyst. We compared the OER activities by the free-energy changes on three different covered surfaces including (i) clean, (ii) 0.5 monolayer O covered, and (iii) 0.5 monolayer OH covered surfaces, and the computed overpotential ( η) for the three surfaces followed the order: O covered ( η = 0.45 V)

Calcium carbonate often precipitates in anaerobic reactors treating wastewater with high calcium content. The aim of this paper is to study the effect of wastewater composition on calcium carbonate precipitation in upflow anaerobic sludge blanket (UASB) reactors. Two laboratory-scale UASB reactors were operated with calcium-containing influents using acetate and carbohydrate as substrate, respectively. There was an obvious accumulation of inorganic precipitate observed in the biogranules. Observations via scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) showed that the acclimated biogranules in the two reactors differed in microstructure. Calcium carbonate was found to have precipitated on the surface of acetate-degrading biogranules, but precipitated at the core of the carbohydrate-degrading biogranules. The results indicated that substrates had significant influence on the location of calcium carbonate precipitation in anaerobic granular sludge, which was expected due to the different methanogens distribution and pH gradient within the granular sludge degrading various substrates. Moreover, the location of calcium carbonate precipitation substantially affected the specific methanogenic activity (SMA) of the granular sludge. The SMA of the acetate-degrading biogranules dropped from $$ 1.96 gCOD_{CH_4 } \cdot gVSS^{ - 1} \cdot d^{ - 1} $$ to $$ 0.61 gCOD_{CH_4 } \cdot gVSS^{ - 1} \cdot d^{ - 1} $$ after 180-d of operation in the reactor. However, the SMA of the carbohydrate-degrading biogranules was not adversely affected by calcium carbonate precipitation. [ABSTRACT FROM AUTHOR]

A series of CZ-xS catalysts for deNO(x) were prepared by sol–gel method. The effects of preparation methods and the amount of sulfuric acid in the sol–gel preparation process on the performance of catalyst were investigated by means of X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), N2 adsorption–desorption, NH3-temperature programmed desorption (NH3-TPD), H2-temperature-programmed (H2-TPR) and Scanning electron microscope/Energy Dispersive Spectrometer (SEM/EDS). The results showed that when the mass ratio of SO42−/ZrO2 (CZ-0.4S catalyst) was 0.4, the catalytic performance of the catalyst prepared by sol–gel method was greatly improved compared with the sample prepared by coprecipitation + impregnation method. When the space velocity was 220,000 h−1 and the reaction temperature was in range of 290–500 °C, the NO conversion was higher than 90% on CZ-0.4S catalyst. Its excellent denitrification performance was attributed to its larger acidity, higher Ce3+ content, more surface adsorbed oxygen and larger specific surface area.Graphical Abstract: A series of CZ-xS catalysts for deNO(x) were prepared by sol–gel method. The effects of preparation methods and the amount of sulfuric acid in the sol–gel preparation process on the performance of catalyst were investigated by means of X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), N2 adsorption–desorption, NH3-temperature programmed desorption (NH3-TPD), H2-temperature-programmed (H2-TPR) and Scanning electron microscope/Energy Dispersive Spectrometer (SEM/EDS). The results showed that when the mass ratio of SO42−/ZrO2 (CZ-0.4S catalyst) was 0.4, the catalytic performance of the catalyst prepared by sol–gel method was greatly improved compared with the sample prepared by coprecipitation + impregnation method. When the space velocity was 220,000 h−1 and the reaction temperature was in range of 290–500 °C, the NO conversion was higher than 90% on CZ-0.4S catalyst. Its excellent denitrification performance was attributed to its larger acidity, higher Ce3+ content, more surface adsorbed oxygen and larger specific surface area. [ABSTRACT FROM AUTHOR]