查看更多>>摘要：? 2022 Elsevier B.V.We carried out a comprehensive study of the electronic, magnetic, and thermodynamic properties of Ni-doped ZrTe2. High quality Ni0.04ZrTe1.89 single crystals show a possible coexistence of charge density waves (CDW, TCDW ≈ 287 K) with superconductivity (Tc ≈ 4.1 K), which we report here for the first time. The temperature dependence of the lower (Hc1) and upper (Hc2) critical magnetic fields both deviate significantly from the behaviors expected in conventional single-gap s-wave superconductors. However, the behaviors of the normalized superfluid density ρs(T) and Hc2(T) can be described well using a two-gap model for the Fermi surface, in a manner consistent with conventional multiband superconductivity. Electrical resistivity and specific heat measurements show clear anomalies centered near 287 K consistent with a CDW phase transition. Additionally, electronic-structure calculations support the coexistence of electron-phonon multiband superconductivity and CDW order due to the compensated disconnected nature of the electron- and hole-pockets at the Fermi surface. Our electronic structure calculations also suggest that ZrTe2 could reach a non-trivial topological type-II Dirac semimetallic state. These findings highlight that Ni-doped ZrTe2 can be uniquely important for probing the coexistence of superconducting and CDW ground states in an electronic system with non-trivial topology.
查看更多>>摘要：? 2022 Elsevier B.V.High-performance bifunctional electrocatalysts for both HER (hydrogen evolution reaction) and OER (oxygen evolution reaction) are very pivotal for large-scale production of H2 by water splitting. Herein, a series of novel hierarchical Co2P-x/Ni2P-y @ NF samples have been fabricated via a simple synthesizing method and employed as bifunctional catalytic electrodes for overall water splitting. Owing to the hierarchical heterostructure and interaction between the Co2P nanowires and Ni2P nanosheets, the optimal Co2P-1/Ni2P-1 @NF sample exhibited remarkable catalytic ability for both HER and OER in alkaline solution (79 mV and 310 mV at 10 mA cm-2, respectively.). As a result, the water electrolysis device based on Co2P-1/Ni2P-1 @NF || Co2P-1/Ni2P-1 @NF system only needs 1.63 V to offer 10 mA cm-2 and keeps excellent durability for 40 h, demonstrating its great practical application value for overall water splitting.
查看更多>>摘要：? 2022 Elsevier B.V.F, Mg and Ga co-doped ZnO (FMGZO) films are deposited on glass substrates at room temperature by magnetron sputtering using MgF2 and ZnO:Ga targets. The effects of RF sputtering power applied to the MgF2 target on structure, morphology, composition, electrical and optical properties of the films are investigated in detail. The experimental results show that all samples are polycrystalline films with hexagonal wurtzite structure and low surface roughness. The FMGZO film deposited at RF sputtering power of 15 W exhibits the highest figure of merit of 5.66 × 10?2 Ω?1 with the resistivity of 6.5 × 10?4 Ω cm, the carrier concentration of 4.12 × 1020 cm?3 and the Hall mobility of 23.38 cm2/V s, while the average optical transmittance is as high as 95.23% in the visible range. The photoelectric performance of the FMGZO film is significantly higher than that of previously reported co-doped ZnO films, which makes it suitable for various high-efficiency optoelectronic devices.
查看更多>>摘要：? 2022 Elsevier B.V.The urgent demand for high-performance energy storage components has been driving the exploration for superior battery-type electrode materials for hybrid supercapacitors, which is challenging but of considerable significance. In this paper, a one-step pyrolysis route was elaborated to prepare oxygen-enriched hierarchical porous carbon supported Co-Ni nanoparticles Co-Ni/OHPCs) by facile self-crosslinking assisted high internal phase emulsion (HIPE) templating. The oxygen-enriched porous carbon framework provides large specific surface area and structural stability, meanwhile Co doping can significantly reinforce the electrochemical performance of the Co-Ni/OHPCs battery-type electrodes. By optimizing the ratio of Ni2+ to Co2+ ions, the obtained Co-Ni/OHPC electrodes exhibited excellent electrochemical performance of 817.3 F g?1 at a scan rate of 5 mV s?1. Furthermore, coupling with an activated porous carbon anode, the assembled hybrid supercapacitor (HSC) possessed an appreciable energy density of 66.94 Wh kg?1 at 409.9 W kg?1 and a capacitance retention ratio of 73.89% after 5000 cycles, showing considerable application prospects. This structural design strategy provides new inspiration for the reasonable optimization of new electrode materials for promising hybrid supercapacitors.
查看更多>>摘要：? 2022 Elsevier B.V.Cobalt sulfides (CoSx) have been paid lots of attention as promising anode candidates for sodium-ion batteries owing to their merits of high theoretical capacity, good electrochemical reversibility and superior thermal stability. However, the preparation of cobalt sulfide with the excellent rate capability and long-term cyclic stability is still a great challenge. Herein, we have prepared cobalt sulfides by one-step solvothermal method using four sulfur sources including sodium thiosulfate, thioacetamide, thiourea and L-Cysteine, respectively. And the mechanism of the bond energies and groups of sulfur source molecules influence the crystal growth process are studied. Moreover, the four cobalt sulfides with different components, morphologies and structures are tested and analyzed as the anode materials for sodium-ion batteries (SIBs). The CoSx using sodium thiosulfate as the sulfur source achieves an excellent cycling performance, which still has a capacity of 690.0 mAh g?1 after 1000 cycles at 2 A g?1 with the retention of 98.1% and an outstanding rate capability of 626.6 mAh g?1 at 5 A g?1. This superiority may be attributed to its pure component cobalt disulfide (CoS2) with abundant active sites and the unique morphology leading to the high material utilization. Our studies give a clear evidence that sulfur sources play an important role in the crystal growth and constructing high-performance sulfide-based anode materials.
查看更多>>摘要：? 2022 Elsevier B.V.In this work, a composite of cobalt metal nanoparticles/three-dimensional carbon/reduced graphene oxide (Co-3DC-rGO) was synthesized using corn husk, ZIF-67, and graphene oxide as precursors. The Co-3DC-rGO was used to modify commercial PP to prepare the Co-3DC-rGO/PP separator. The performance of Co-3DC-rGO/PP separator was evaluated in lithium-sulfur batteries (LSBs). SEM images exhibited that a three-dimensional carbon (3DC) skeleton was obtained by corn husk transformation, and the ZIF-67-derived cobalt-decorated carbon dodecahedrons were homogeneously filled into the hierarchical pores of the 3DC structure. TEM images displayed that Co metal nanoparticles can escape from ZIF-67 and scatter on the rGO nano-sheets and 3DC skeleton. Benefitting from the synergy effects of the 3D carbon skeleton, rGO, and Co metal nanoparticles, the electrochemical performance of LSBs with Co-3DC-rGO/PP separator is better than LSBs with commercial PP separator. When tested at 1C, the LSB with Co-3DC-rGO/PP separator presents a high stable reversible capacity of 516.3 mA h g?1 after 500 cycles. This research provides new ideas for the preparation of LSBs separator.
查看更多>>摘要：? 2022 Elsevier B.V.Novel Dy3+:Zn2Ti3O8 (Dy3+:ZTO) nano-photocatalysts with different Dy3+ concentrations were applied to enhance the photocatalytic hydrogen generation activity from sodium borohydride hydrolysis reaction. XRD and Raman measurements confirm the formation of cubic Zn2Ti3O8 phase as a major phase in addition to minor TiO2 phase. The analysis of XPS spectra shows the existence of lattice oxygen (LO) and non-lattice oxygen (NLO) where 0.07 mol Dy3+:ZTO has the highest percentage of NLO compared to the undoped photocatalyst. The energy gap value decreases with increasing doping concentrations (3.137 eV for 0.07 mol Dy3+:ZTO). The degree of disorder, represented by Urbach energy, has an optimum high value (0.169 eV) for 0.07 mol Dy3+:ZTO. The photoluminescence studies revealed that Dy3+ dopant can effectively separate the photogenerated electron/hole pairs in the ZTO. These photocatalysts have strong photocatalytic hydrogen generation. The most active nano-photocatalyst towards hydrogen generation was 0.07 mol Dy3+: ZTO (5.6 mmol/g). The highest photocatalytic activity for 0.07 mol Dy3+: ZTO are attributed to the lower recombination rate associated with the higher disorder and oxygen vacancies relative to the undoped photocatalyst. The stability and reusability of the most active photocatalyst were investigated. The results confirm that the developed photocatalyst has good durability in hydrogen generation reaction. The results, moreover, revealed that Dy3+: ZTO nano-photocatalyst is a promising nanomaterial in the field of energy production.
查看更多>>摘要：? 2022The sluggish ionic transport and interface stability for single-crystal nickel-rich materials are the main challenge hindering its large-scale applications. Herein, the single-crystal LiNi0.7Co0.2Mn0.1O2 (NCM) cathode is treated with H3BO3 through a simple wet chemical process. Surprisingly, H3BO3 shows multifunctional effect on the electrochemical performance of NCM, both through a generation of B2O3/Li3BO3 coating layers and B3+ incorporation into the bulk phase, and the fundamental understanding of multifunctional effect are investigated through crystal structure and chemical states. The B2O3/Li3BO3 coating layers act as artificial barriers and Li+-conductor on the surface, which inhibit Ni dissolution and accelerate lithium ions migration. Additionally, B3+ doping can strengthen Li+ diffusion rate in the layered structure. As a result, the electrochemical performance of the modified NCM material is enhanced. The 87.4% capacity retention of the initial capacity after 150 cycles at 1 C with a high work voltage of 4.5 V and high reversible capacity of 162.7 mAh g?1 at 10 C rate can be obtained through H3BO3 modification. The multifunctional effect of H3BO3 provides a reference for the development and modification of lithium ions cathode materials in the future.
查看更多>>摘要：? 2022 Elsevier B.V.Asymmetric supercapacitors (ASCs) have been designed due to their lower cost effectiveness, better safety, long cycle life, and high energy/power density. Herein, the ASC of double “ion-buffering reservoirs” NiCo2O4-CNT-c-PEGm//rGO-PANI (NiCo//G-PANI) with high capacity and ultralong lifetime were fabricated and evaluated. The three-dimensional hierarchical flower-like NiCo2O4-CNT-c-PEGm microspheres were prepared via solvothermal method. In these composites, the incorporated CNTs were modified with methoxypolyethylene glycol (mPEG) polymer by Cu(I)-catalyzed click chemistry. The NiCo2O4-CNT-c-PEGm composites with typical honeycomb-like “ion-buffering reservoir” structures exhibited the specific capacity of 191.3 mAh g?1 at 0.5 A g?1. Moreover, the rGO-PANI composites with hierarchical interconnected porous network structures as “ion-buffering reservoir” were prepared via in situ polymerization and chemical reduction. Further, the rGO-PANI electrode materials could achieve the specific capacity of 81.5 mAh g?1 at 1 A g?1. Owing to such excellent attributes, the as-assembled ASC NiCo//G-PANI exhibit the specific capacity of 84.7 mAh g?1 at 1 A g?1 and high energy density of 67.7 Wh Kg?1 at a power density of 800 W Kg?1 for the potential applications in electric energy storage technologies. As a result, this study promotes an innovative strategy to synthesize the metal oxides modified with carbon materials as positive electrode materials to assemble the new type of ASCs.
查看更多>>摘要：? 2022 Elsevier B.V.In this study, solute X (X = Li, Al, Mn, Zn, Y, Zr, Nd, and Gd) solution strengthening in Mg alloys have been screened by ab initio density functional theory calculations to quantify not only the substitutional stacking-fault configurations but also the solute ordering sequence as a function of local segregation. Interestingly, it has been found that the strengthening effects of single atom addition to a supercell made of 64 atoms can be mostly attributed to lattice distortions (Mn>Nd>Gd>Y>Zn>Al>Zr>Li), while the local ordering arrangements of Mg-X complex actually contribute most to the strengthening when the solute concentration rises. For example, Nd can induce a large local atomic ordering and significantly increase the basal critical-resolved shear stress (CRSS). A linear relationship between solute concentrations and ideal strength, and the quasi-quadratic relationship between solute atomic radii and ideal strength have been observed. Simultaneously, the higher the solute concentration, the higher degree of the solid solution strengthening, resulting in a smaller quasi-quadratic function curve opening. Based on the screening of the chemical (including stacking fault energy and atomic bonds) and strain (lattice distortion energy) energy calculations, we have discovered that the solute strengthening follows the ordering sequence of Nd> Mn> Gd> Y> Zn> Al> Zr> Li.
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