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Due to the limitation of the theoretical specific capacity of traditional cathode materials, the key to improve the energy density of lithium-ion batteries (LIBs) is to develop high-performance cathode materials. As a promising cathode material for LIBs, Fe-containing lithium-rich manganese-based materials possess high specific capacity and high working voltage. At present, the research on the synthesis and electrochemical reaction mechanism of this kind of material is still imperfect. Here, a facile oxalate co-precipitation method is employed to prepare Li1.2Fe0.16Ni0.24Mn0.4O2 using different lithium sources. The effects of lithium source and electrochemical window on the specific capacity and cyclic stability of the materials are also systematically investigated. When applied in LIBs, the prepared material using LiNO3 as lithium source presents a micro-nano hierarchical structure and exhibits a high first discharge specific capacity of 337.7 mAh g−1 and a high reversible capacity of 208.4 mAh g−1 after 60 cycles at 0.1 C in the voltage range of 1.5 − 4.8 V. The results of this study can provide more selectivity for the lithium source of the electrode material during the preparation process, and select a suitable voltage test range for cathode materials to achieve specific properties. The outstanding performances make this oxalate co-precipitation process a prospective method to prepare high-capacity cathode materials for LIBs. [ABSTRACT FROM AUTHOR]

Organic solar cells (OSCs) have experienced a rapid progress in terms of efficiency in both single and tandem structures. Herein, two‐terminal (2T) tandem design is fabricated using PV2000:PCBM (1.65 eV) and PM6:Y6 (1.3 eV) blends as bottom and top cells, respectively. The role of transporting and recombination layers on photovoltaic (PV) parameters is studied. The impedance and transmittance results indicate that using SnO2 nanocrystals (NCs) as an electron transporting layer (ETL) in both subcells, the fill factor (FF) and the open circuit voltage (VOC) of the tandem device are increased drastically, mainly due to the lower resistance of the SnO2 layer and its higher transmittance as compared with the ZnO ETL. Moreover, it is found that the VOC and FF losses are reduced using poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/Ag (1 nm)/SnO2 NCs as a recombination layer in the tandem design. After proper optimization, a tandem OSC with a VOC of 1.61 V and an efficiency of 14.4% is achieved, which shows great operational stability as well. In addition, the current match and efficiency of the tandem device are increased up to 12.94 mA cm−2 and 15.2%, respectively, by applying a nanotextured anti‐reflection layer on the back of the device. [ABSTRACT FROM AUTHOR]

This work presents a simple method for the preparation of the Mg-doped nanocomposite copper silicates (Mgx-Cu1−x-SiO3) (x=0.25, 0.5, 0.75 and 0.9) using coal gangue waste as the silicon source for CO2 capture at low temperature. The as-prepared Mgx-Cu1−x-SiO3 was systemically characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Brunauer-Emmett-Teller surface area analysis (BET). The results suggest that all Mgx-Cu1−x-SiO3 possess large surface areas, micropores and mesoporous structures composed of the agglomerates of small nanoparticles. They exhibit high CO2 adsorption capacity at 298.15 K under 1 bar, and that of Mg0.9-Cu0.1-SiO3 was the highest with the value of 16.73 cm3/g. The Freundlich isotherm model fits the CO2 adsorption isotherm well. Thermodynamic analysis indicates that the CO2 adsorption on Mg0.9-Cu0.1-SiO3 is exothermic (ΔH°<0), chaotic (ΔS°<0), and spontaneous (ΔG°<0). This work highlights the low-temperature adsorption behavior of silicate materials on CO2, which can provide some research basis for the utilization of silica in coal gangue. [ABSTRACT FROM AUTHOR]

Structure and energy band engineering of 2D materials via selective doping or phase modulation provide a significant opportunity to design them for optoelectronic devices. Here, the synthesis of high‐quality MoxRe1–xS2 alloys with tunable composition and phase structure via chemical vapor deposition growth is reported, and their novel energy band structures and optoelectronic properties are explored. The phase separation and structure reconstruction, which are found to be two serious problems in the synthesis of these alloys, are successfully suppressed through tuning their growth thermodynamics. As a result, the obtained MoxRe1–xS2 alloys have uniform composition, phase structure, and crystal orientation. Together with X‐ray photoelectron spectroscopy analysis and first‐principle calculation, the Re/Mo doping‐induced Fermi level up‐shift/down‐shift, new electronic states, and "sub‐gap" formation in MoxRe1–xS2 alloys are revealed. Especially, a strong band bowing effect is discovered in the MoxRe1–xS2 alloys with structure transition between 1T′ and 2H phases. Furthermore, these alloys reveal tunable conduction behavior from n‐type to bipolar and p‐type in 1T′ phase, as well as novel "bipolar‐like" electron conduction behavior in 2H alloys. The results highlight the unique alloying effects, which do not exist in the single‐phase 2D alloys, and provide the feasibility for potential applications in building novel electronic and optoelectronic devices. [ABSTRACT FROM AUTHOR]

Recently discovered graphdiyne (GDY) is a unique two‐dimensional (2D) planar structure with a high‐degree π‐conjunction network composed of sp and sp2 hybridized carbon bonds. GDY has high carrier mobility, rich chemical bond properties, and having a bandgap of ≈2.1 eV. In this study, for the first time, g‐C3N4/NiFe‐layered double hydroxide (LDH) is decorated by GDY to obtain a new strongly coupled ternary nanocomposite g‐C3N4/GDY/NiFe‐LDH, which has hierarchical mesoporous layered structure, large surface area, and broad visible spectrum absorption. These properties make g‐C3N4/GDY/NiFe‐LDH nanocomposite an outstanding candidate for photoelectrochemical water oxidation. Therefore, the new architecture is analyzed and achieve a high photocurrent density of 178.66 µA cm−2 by applying 1.4 V, a maximum incident photon‐to‐current efficiency (IPCE) of 3.59% at wavelength of 350 nm and 2.05% at 420 nm under standard AM 1.5G condition, which are also the best reported values in the literature. More interestingly, the proposed nanocomposite indicates a great durability, where there is nearly no dropping on the photocurrent under continuous illumination after 3600 s. This work suggests that additive engineering using GDY is an effective approach for the fabrication of efficient photoelectrochemical water oxidation devices. [ABSTRACT FROM AUTHOR]

0.7BiFeO3-0.3BaTiO3-Y3Fe5O12 (BFO-BTO-YIG) composites were synthesized via a modified solid-sate route. The phase composition, microstructure, electrical, and magnetic properties of the composites were investigated. The results show that the BFO-BTO and YIG phases can coexist in the composites without any secondary phase. The electrical and magnetic properties BFO-BTO can be simultaneously improved by the introduction of YIG. Compared with BFO-BTO with weak magnetism, the 0.95(BFO-BTO)-0.05YIG composite shows an obviously enhanced ferromagnetic property with a Ms value of 1.4 emu/g, and a typical square polarization hysteresis loop with a Pr value of 19.3 μC/cm2, which is equal to that of BFO-BTO. [ABSTRACT FROM AUTHOR]

A series of BiOCl x I y solid solutions with bifunctional properties was prepared by a hydrolysis method. When used as potential adsorbents for removal of dyes in wastewater, the as prepared samples exhibited the excellent adsorption and photocatalytic abilities, which indicated that the removal ability had been restored completely without centrifugal separating or other chemical desorption methods. Especially to the sample 301 prepared with a 3:1 M ratio of Cl to I, its adsorption capacity could reach nearly 5.0 mg g −1 within 5 min, which was at least 3 times larger than that of the individual BiOX (ca. 1.3 mg g −1 ), and its degradation efficiency of high concentration (20 mg L −1 ) methyl orange (MO) was up to 100% after 50 min of visible light irradiation. The relevant characterization results revealed that not only high specific surface area but also the electron structure of interlayer could be the key factors for the high adsorption ability. The possible mechanism was also discussed. [ABSTRACT FROM AUTHOR]

A novel core-shell (ε-MnO 2 /CeO 2 )@CeO 2 composite catalyst with a synergistic effect was prepared by hydrothermal reaction and thermal decomposition and its application to high-efficiency oxidation removal of formaldehyde (HCHO) was systemically investigated. The (MnCO 3 /CeO 2 )@CeO 2 precursor was prepared first by the one-pot hydrothermal reaction of Mn 2+ and Ce 3+ solutions with a CO 2 -storage material (CO 2 SM) without any external templates or surfactants required. The thermal decomposition of the precursor afforded the core-shell (ε-MnO 2 /CeO 2 )@CeO 2 composite catalyst with excellent catalytic performance. HCHO in the feed gas (180 ppm HCHO, 21% O 2 , N 2 balanced) at a gas hourly space velocity of 100 L/(g cat h) is 100% converted over the catalyst at 80 °C. The conversion rate remains above 95% in 72 h and above 73.8% in 140 h, suggesting the strong stability of the catalyst at high gas flow rates and relatively low temperatures. The synergistic mechanism of the catalyst was explored by X-ray diffraction, Raman, Brunauer-Emmett-Teller, transmission electron microscopy, and X-ray photoelectron spectroscopy. The number of defects in the catalyst and the strength of the Mn-O bond in ε-MnO 2 can be tuned by adjusting the synthesis conditions. More oxygen vacancies on the surface of CeO 2 can make the synergistic effect of the catalyst stronger, which significantly improves the lattice oxygen (O latt ) activity on the surface of ε-MnO 2 . Our work has provided new insights into the preparation of the desired composite catalysts with excellent performances.