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/cm
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/cm
. We couple the catalyst with CO reduction in an alkaline membrane electrode assembly electrolyser, reporting stable C
H
electrosynthesis at current density 200 mA/cm
for over 80 h.
Electrochemical reduction of CO2 (CO2 RR) has great potential to transform the petrochemical sector toward sustainability and to mitigate greenhouse gas emissions. However, direct CO2 RR suffers from ...carbonate formation, which brings a dramatic rise in the energy consumption. By quantitative energy analysis, the idea of using CO2‐CO‐C2+ tandems can avoid the energy penalty caused by carbonate formation and improve total energy efficiency. Thus, proposed carbonate‐free system is of great importance for commercial CO2 RR economic viability
Tin halide perovskites are promising lead-free candidates for light-emitting diodes (LEDs), but their performance is hindered by the poor crystallinity quality and the oxidation of tin. It is ...necessary but challenging to simultaneously realize modulating crystallization, suppressing oxidation, and passivating defects to boost the device’s performance. Here, naphthol sulfonic salt is demonstrated as an effective multifunctional additive. The sulfonic group can retard crystallization by forming intermediate complexes with perovskite to form a pinhole-free film. The reducing hydroxyl group can prevent Sn2+ from oxidation and hinder the migration of I– ions. The high electron density of the naphthol ring can enhance the electrostatic attraction toward undercoordinated Sn2+ to passivate the defects. The synergistic effect of the multifunctional additive contributes to a boosted efficiency of 0.72% and a brightness of 132 cd m–2 for quantum-well structure phenethylammonium tin iodide ((PEA)2SnI4) LEDs, which represents the most effective lead-free perovskite LEDs in pure-red regions as far as we know.
Abstract The copper (Cu)-catalyzed electrochemical CO 2 reduction provides a route for the synthesis of multicarbon (C 2+ ) products. However, the thermodynamically favorable Cu surface (i.e. ...Cu(111)) energetically favors single-carbon production, leading to low energy efficiency and low production rates for C 2+ products. Here we introduce in situ copper faceting from electrochemical reduction to enable preferential exposure of Cu(100) facets. During the precatalyst evolution, a phosphate ligand slows the reduction of Cu and assists the generation and co-adsorption of CO and hydroxide ions, steering the surface reconstruction to Cu (100). The resulting Cu catalyst enables current densities of > 500 mA cm −2 and Faradaic efficiencies of >83% towards C 2+ products from both CO 2 reduction and CO reduction. When run at 500 mA cm −2 for 150 hours, the catalyst maintains a 37% full-cell energy efficiency and a 95% single-pass carbon efficiency throughout.
Energy‐absorbing materials are widely used under certain high‐frequency scenarios, such as cargo packaging or sport protection. Though negative stiffness mechanical metamaterials have many ...distinctive advantages, fairly low strength and poor specific energy absorption unfortunately limit their present industrial applications. Inspired by the excellent cushioning performance of the paw pads of mammals, a novel flexible energy‐absorbing negative stiffness mechanical metamaterial is proposed herein. Results show that the presented metamaterial outperforms traditional packaging materials with respect to cushion performance. Moreover, a performance programming strategy is proposed to achieve multistage tuning between large energy absorption and high rebound properties.
A novel flexible energy‐absorbing negative stiffness mechanical metamaterial, inspired by dog's paw pads, is proposed. The presented metamaterial outperforms traditional packaging materials with respect to cushion performance, and can be programming between large energy absorption and high rebound properties. The research paves the way for the large‐scale application of negative stiffness mechanical metamaterial.
Boron doped diamond (BDD) electrode is a promising electrochemical material for detecting dopamine level in the human’s body. In this work, we developed a new doping source - graphite and solid boron ...oxide powders to synthesize BDD film with microwave plasma chemical vapor deposition, so as to avoid using toxic or corrosive dopants, such as boroethane and trimethylborate. The synthesized BDD film is pinhole free and with high doping density of 8.44 × 1020 cm−3 calculated from the Raman spectroscopy. Subsequently, Au nanospheres were decorated on the surface of BDD film to improve electrochemical performance of the BDD film. The Au nanoparticles modified BDD electrode demonstrates an excellent electrochemical response, a high sensitivity (in the range of 5 μM-1 mM), and a low detection limit (∼ 0.8 μM) for detecting dopamine.
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In this study, a polyaniline-modified 3D-spongy SnS photocatalyst (PANI/SnS) has been prepared using an in-situ oxidative polymerization technique for the enhanced photocatalytic ...degradation of methyl orange. PANI/SnS reached to a rate constant of 4.040 × 10−2 min-1 > 2 times of that pure SnS and maintained a good stability after four cycling runs for methyl orange degradation. The better photocatalytic activity and stability of PANI/SnS catalyst were ascribed to the π-conjugated structure characteristic of PANI and the interaction between PANI and SnS. On the one hand, induced π-conjugated electrons transferred from PANI to SnS could effectually inhibite the electrons and holes recombination. On the other hand, the presence of C–S and Sn-N bonds between PANI and SnS could protect the S and/or Sn element from direct exposure to the corrosive environment, then restraining photocorrosion behavior. This study implies that conductive conjugated polymer (PANI) modified tin sulfide will be a potential reusable and stable photocatalyst for methyl orange removal from waste-water by photocatalysis.
Polyurea is a block copolymer with excellent shock absorption. It has a unique phase separation structure, yet there are few reports on how the mesoscale structure affects the dynamic mechanical ...properties. In this paper, the effect of two-phase structure on the dynamic modulus and shock-wave dissipation of polyurea is investigated by coarse-grained molecular dynamics. Shear relaxation modulus is calculated by the Green-Kubo method. Pulse load is applied by non-equilibrium molecular dynamics. The two-phase structure improves the dynamic modulus by restricting the segment movement. Shock-wave energy is dissipated by heat dissipation, viscous retardation, and plastic dissipation. The two-phase structure must obey deformation coordination, which results in more strain energy and internal friction. Hydrogen bond dissociation and structure destruction occur during the impact. Furthermore, the simulations results are verified by AFM, X-ray diffraction, and DMA experiments.
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•Mesoscale structure of polyurea limits segment movement to improve dynamic modulus.•Deformation coordination causes more strain energy and internal friction under shock.•Hydrogen bond dissociation and hard phase destruction dissipate the extra energy.
This paper presents a novel tri-directional negative stiffness (NS) mechanical metamaterial, consisting of disk structure elements arranged in three-dimensions. The NS behavior was achieved through ...the elastic instability of the disk structure. Through the combination of numerical simulations and experiments, the NS property, the deformation mechanisms, and the basic mechanical performance of the disk structure and the novel NS mechanical metamaterial were systematically investigated. The influence of the geometric parameters on the snap-through behaviors of the NS metamaterial was investigated through the experimentally verified numerical method, and further designs were conducted on the disk structure to tailor its mechanical responses. Also based on the instability of the disk structure, several novel multidirectional NS structures, which can achieve NS behavior along five and seven loading directions, were firstly proposed. This innovation improves the homogeneity of the NS metamaterials, and is expected to expand the application scope of such metamaterial, considering that the previous reported NS metamaterial can exhibit NS behavior along three-dimensions at most. Moreover, the mechanical performance of the proposed NS metamaterial is tunable, benefited from the special structure form of itself. To our knowledge, this work is first to design NS metamaterial using the disk structures, and report the multidirectional (more than tri-directions) NS metamaterials.
•Negative stiffness (NS) metamaterial is potential in the application of energy absorption due to its repeatable property and snap-through behavior.•Plastic deformation rather than energy trapping or ...damping dissipation of NS metamaterial is introduced to dissipate energy.•Results of cyclic compression tests show that the proposed NS metamaterial is highly repeatable, although plastic deformation occurs.•Research results show that the proposed metamaterial has higher specific energy absorption than previous traditional NS metamaterial.
This study investigated negative stiffness (NS) structures, which are promising metamaterials that can potentially be useful in the energy absorption field. However, low specific energy absorption restricts their implementation in engineering applications. In this paper, a reusable metal structure is proposed. This structure can dissipate energy through plastic deformation and exhibits NS behavior through inelastic instability. Its mechanical properties were investigated by conducting compression tests and simulations. The influence of the geometric parameters on energy absorption was revealed using an experimentally verified numerical model. The repeatability of the structure was investigated through cyclic compression, and the impact of the structural dimensions on repeatability was preliminarily investigated. Moreover, annealing treatment was conducted to improve repeatability. Based on the interlocking assembly method, a 3D NS structure is proposed and fabricated. The results obtained by this study reveal that the specific energy absorption of the proposed structure is larger than that of most traditional NS structures, and its energy absorption efficiency is high. Additionally, the structure is highly repeatable but its repeatability declines as its dimensions increase. Although repeatability can be substantially improved with annealing treatment, the mechanical performance deteriorates.
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