查看更多>>摘要：? 2022 Elsevier B.V.An effective ZnIn2S4 nanosheets/SnO2 quantum dots/TiO2 nanotubes (ZST NTs) composite was successfully synthesized by anodic oxidation, in-situ dipping, and hydrothermal methods. The photocurrent densities of the ZST NTs composites under visible light were as high as 715 μA cm?2, which was 25 times that of pure TiO2 NTs. The ZST NTs showed the largest open circuit potential drop (859.0 mV vs. SCE) when coupled with 316 stainless steel under illumination. These indicated that ZST NTs composites showed highly effective photocathodic protection on 316 stainless steel under visible light. This enhancement was mainly due to that ZnIn2S4 sensitization extended the light absorption into the visible region and heterostructure construction was beneficial for the separation of photogenerated charges. Interestingly, the composites could provide delayed protection of the protected metal for up to 10 h under dark conditions because the SnO2 quantum dots acted as energy storage layer, which was rather important for practical application.
查看更多>>摘要：? 2022 Elsevier B.V.Hydrogen is among the most promising episodic energy carriers. Consequently, sodium borohydride has attracted attention owing to its high H content and good stability. However, its applications are limited by slow reaction kinetics, and it is necessary to identify new high-performance catalysts with good durability. Nickel foam (NF) is a stable, hollow, and porous carrier material that is inexpensive and widely available. In this study, an NF framework was coated with Co–Ni layered double hydroxide (LDH) using a one-step hydrothermal method. Thereafter, a Ru@CoNi-LDH/NF composite catalyst was prepared by etching Ru on the CoNi-LDH surface via an impregnation method and reducing it in situ with a NaBH4 solution. Inductively coupled plasma mass spectrometry was used to analyze the Ru content of the sample, which was found to be 1.27 wt%. X-ray photoelectron spectroscopy was employed to confirm the existence of elemental Ru. Catalysts prepared using precursors with different ratios of Co and Ni were investigated. The catalytic performance of the catalyst prepared with a Co to Ni ratio of 1:2 was 38 L·min?1·gRu?1 at 30 °C, demonstrating the beneficial effect of the NF on performance. The catalyst maintained 79.3 % of its initial activity after ten cycles, owing to the framework and high-activity catalyst loading.
查看更多>>摘要：? 2022 Elsevier B.V.MXenes are 2D materials dominated by carbides and nitrides, whose properties can be tailored for a wide range of applications. Here, generic method was adopted to etch MAX phases through direct redox coupling strategy between the A element and the cation of Lewis acid molten salt, allowing us to anticipate the MAX phase reactivity in molten salt. Fluorine free Ti3C2 MXenes with halogen terminals, such as -Cl, -Br and -I, were synthesized using the molten salts synthesis method. Ti3C2Cl2, Ti3C2Br2 and Ti3C2I2 exhibit distinct charge-discharge rates and pseudocapacitive like behaviors in 3 M H2SO4 electrolyte, with significant specific capacity of 92 C g?1, 29 C g?1 and 63 C g?1, respectively, corresponding to retention rates of 32%, 85.22% and 49.1%, respectively, after 10,000 cycles. The exceptional supercapacitive performances of the Ti3C2 MXenes as electrodes with aqueous electrolytes are attributed to the high electrochemical activity of Cl, Br or I. This study demonstrates the efficacy of the Lewis-acidic-melt etching technique for fine tuning the surface chemistry and hence extending the applications of MXene family.
查看更多>>摘要：? 2022 Elsevier B.V.In the present work, the degradation of methyl orange (MO) by visible-light-driven photocatalytic activation of persulfate (PDS) was studied. Macro-aerogel g-C3N4-doped graphene aerogel (GA) composite with stratified structure was fabricated by a simple hydrothermal method and applied as a recoverable heterogeneous catalyst along with visible light (VL) irradiation for activation of PDS. The microstructure, physical-chemical and photoelectrochemical properties of composite catalysts were characterized and various reaction parameters including the reaction systems, catalyst activator dose, PDS concentration, g-C3N4 doping amount and the initial pH of the solution were evaluated on the MO removal efficiency. Photocatalytic activation of GA for MO degradation was enhanced significantly after modified by g-C3N4. Under optimum conditions (15 mg/L MO, 75 mg/L PDS and 0.012 g/L GCN-3), the catalytic efficiency of g-C3N4 doped GA with the mass ratio of 3:7 (GCN-3) was 2.96 times than that of GA. The strengthening effect of GCN-3 benefited from the synergistic effect of the photogenerated hole (h+), the C[dbnd]O functional groups and rapid electron transfer in GCN-3/VL/PDS system. Given the flexibility and recyclability of GCN-3, the GCN-3/VL/PDS system is a promising technique for practical wastewater purification.
查看更多>>摘要：? 2022 Elsevier B.V.High alloying elements effectively strengthen zinc alloys, but these elements also usually decrease the ductility and corrosion resistance of such alloys. In the present study, energy-saving and efficient rotary-die equal-channel angular pressing (ECAP) was successfully applied to a zinc alloy with a low Mg content (0.1 wt%) at room temperature (RT), which facilitated the formation of a microstructure with a fine grain size (1.14 ± 0.22 μm), weak texture, and dynamically precipitated nano-sized Mg-Zn precipitates at the grain interior. The Zn-0.1Mg alloy formed via RT-ECAP exhibited an outstanding performance, with a high ultimate tensile strength of 383 MPa, excellent ductility of 45.6 %, and a suitable biodegradation rate of 0.014 mm/y in Hank's solution. This alloy is thus a promising candidate for various biodegradable medical applications.
查看更多>>摘要：? 2022 Elsevier B.V.A highly efficient photocatalytic system was rationally designed and prepared for hydrogen production under visible light. Through a two-step cation exchange reaction with Cd2+ ions under alkaline environment, the metal hydroxide shells were assembled on the surface of MIL-88A. Then the shells were integrated into a heterogeneous metal sulfide shell layer via a thermal vulcanization reaction, which also achieved the doping of transition metals simultaneously. The formed hybrid structure can reduce the volume-surface diffusion length and recombine photogenerated electrons. Moreover, using the molecular cocatalyst (Ni-Salens) in the photocatalytic system can efficiently induce the transfer of photogenerated electrons, thereby improving the catalytic efficiency and stability of this catalytic system. The maximum amount of hydrogen production reached 7956 μmolg-1h-1, significantly higher than that of CdS-based catalysts reported recently. The current work provides an effective and feasible strategy to improve the efficiency of photocatalytic H2 production.
查看更多>>摘要：? 2022 Elsevier B.V.The development of a facile strategy to fabricate inexpensive and efficient nonnoble metal-based alloys to replace their traditionally costly noble-metal counterparts for electrocatalytic water splitting holds great appeal. Here, we report novel FeNi-FeCo-C composite nanofibers (FeNi-FeCo-C CNFs), which was prepared simply by electrospinning a precursor solution containing Fe, Ni and Co nitrates together with polyacrylonitrile powders and subsequent thermal treatment. The optimal FeNi-FeCo-C CNFs prepared with 10 wt% polyacrylonitrile at a thermal treatment temperature of 800 °C show excellent electrocatalytic performance for oxygen evolution in a 1 mol·L?1 KOH aqueous solution with a relatively small overpotential of 262 mV at 10 mA cm?2, a low Tafel slope of 47.2 mV dec?1, and excellent cycling stability. The present strategy will provide new insight for the design and fabrication of electrocatalysts for water splitting.
查看更多>>摘要：? 2022 Elsevier B.V.The rotating backward extrusion (RBE), as a novel severe plastic deformation process, has prosperous industrial application prospect. However, the capability and potential of the RBE process to prepare samples with different heterogeneous microstructures has not attracted attention. In order to explore the relationship between different microstructural compositions and mechanical properties of tubular component prepared by RBE process, the grain size distribution, grain orientation and mechanical properties of a ZK61 Mg alloy tubular component prepared by the RBE process in different regions (along the wall thickness and height directions) were investigated. The results show that the microstructure evolution in different regions is closely related to the equivalent strain distribution. The grain refinement effect is positively correlated with the equivalent strain, but a higher applied strain also leads to a strong basal orientation and high residual stress. Furthermore, the tensile deformation behavior of different samples revealed that samples with preferentially microstructural compositions (volume fraction of fine grains: 40～60%) have better work hardening capability and strong-toughness synergy. This is mainly attributed to more effective coordinated deformation between different regions (fine grain region and coarse grain region), which can relieve local stress concentration and accommodate more dislocations. In contrast, an excessively high volume fraction of fine grains in samples limits their ability to store dislocations that saturate rapidly with increasing strain, while an excessively low volume fraction of fine grains in samples has difficulty accommodating the high density dislocations transferred from the coarse grain region, resulting in accumulation of high local stress at the interfaces of different regions (fine grain region and coarse grain region). Both of the above can deteriorate the work hardening ability and comprehensive performance, causing the sample to fail before sufficient work hardening occurs.
查看更多>>摘要：? 2022 Elsevier B.V.Using biomass as raw material to prepare porous carbon (BPC) through a simple heat treatment process is an environmentally friendly and economically feasible method to deal with electromagnetic pollution. In this work, a porous Ni@BPC-based composite material is synthesized using laver as raw materials, where the Ni nanometer microspheres are evenly distributed in BPC. Herein, the electromagnetic parameters of the composites are effectively tuned by the combination of magnetic Ni with dielectric BPC. The synthesized composite with 3D porous structure exhibit remarkable enhancement of microwave absorption. Results showed that when the mass ratio of Ni to BPC is 1:3, the minimum reflection loss (RL) of porous Ni@BPC composite reaches ? 35.73 dB at 3.0 mm with the effective absorption bandwidth (RL<?10 dB) of 6.37 GHz (from 10.35 to 16.72 GHz) at 2.5 mm. It is believed that the excellent microwave absorption properties are attributed to the enhanced synergistic effect of the losses, such as conductive loss, interfacial polarization, natural resonance, exchange resonance and multiple scattering. It is proved that the porous Ni@BPC composite exhibits potential applications in microwave absorption.
查看更多>>摘要：? 2022 Elsevier B.V.In this research, the effect of doping Cu and Fe on the properties of La0.7Sr1.3CoO4 as cathode for using in intermediate solid oxide fuel cells were studied. The x-ray diffraction patterns indicated that La0.7Sr1.3Co (1?x) (Fe/Cu)x O4 (x = 0, 0.1, 0.2 and 0.3) synthesized powders are tetragonal with I4/mmm space group. Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) revealed that oxygen vacancies were created easily in La0.7Sr1.3Co1?xCuxO4 synthesized powders while oxygen over-stoichiometry was observed in La0.7Sr1.3Co1?xFexO4 compounds. The temperature dependence of electrical conductivity showed the semiconducting behavior in all samples at the temperature range of 30–800 °C. Among the synthesized specimens, the maximum electrical conductivity was found in Cu doped samples. In order to study the electrochemical properties of the synthesized powders, electrochemical impedance spectroscopy (EIS) was used in which the cathodic processes were determined using distribution of the relaxation time (DRT) analysis. The results showed that, the polarization area-specific resistance (ASRp) decreased from 1.2 Ωcm2 for La0.7Sr1.3CoO4 to 0.56 Ωcm2 for La0.7Sr1.3Co0.8Fe0.2O4 sample and 0.38 Ωcm2 for La0.7Sr1.3Co0.8Cu0.2O4. The results revealed that Cu doping La0.7Sr1.3CoO4 improves the cathodic performance of La0.7Sr1.3CoO4, significantly. So we can conclude that Cu doped La0.7Sr1.3CoO4 can be a good cathode candidate to be used in intermediate solid oxide fuel cells.
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