Search

This article reports the successful fabrication of a lightweight CoNi/C nanocomposite as an electromagnetic wave absorber, which has excellent microwave absorption performance in the X-band and Ku-band.

The optical properties and stability of metal halide perovskites can be improved by reducing their dimensionality. Because defects at the perovskite film grain body and boundaries cause significant energetic losses by nonradiative recombination, perovskite films with manageable crystal size and macroscopic grains are essential to improve the photovoltaic properties. Through theoretical calculation models and experiments, we show that the carboxyl group of 4-ammonium butyric acid-based cation (4-ABA

Defects at the interface and grain boundaries of perovskite solar cells (PSCs) will result in severe non-radiative recombination and open-circuit voltage (Voc) loss. Herein, we reported a zwitterionic ionic liquid imidazolium tetrafluoroborate (IMBF

Developing low-cost and highly efficient electrochemical materials toward supercapacitor applications is crucial for energy conversion systems. In the present work, dual S, N-doped activated CoFe2O4@CNTs was successfully synthesized using carbamide and sodium thiosulfate as N and S precursors and CNTs as a substrate via a convenient two-step hydrothermal activation procedure, which presents good performance for supercapacitor. The characterization results indicate that activity S and N atoms can be successfully doped into the framework of CoFe2O4@CNTs with little impact on the inner morphology and structure. However, the electrode material of N2S1–CoFe2O4@CNTs exhibits a superior electrochemical performance with 1053.60 F g−1 at 1 A g−1 in KOH electrolyte due to synergistic effects between spinel-type metal oxides, heteroatoms and sp2 lattice of graphitic carbon. In addition to high energy and power densities, the capacitance retention of charging-discharging reaches 93.15% at a current density of 30 A g−1 after 5000 cycles, exhibiting an outstanding cycle stability and potential lifetime in an alkaline electrolyte.

Typical magnetic three-phase alloys-modificated graphene nanoplatelets (GNPs) synthetic nanocomposites (FeCoNi@GNPs) were prepared by liquid-phase reduction method and precursor-assisted high-temperature sintering technique. FeCoNi@GNPs nanocomposites exhibit superior magnetic properties with the saturation magnetization and coercive force 58.4 emu/g and 197.25 Oe, respectively. Furthermore, the GNPs encapsulated by FeCoNi increase of 48.2% in antioxidation performance compared with original GNPs due to surface passivation layers. Additionally, it also shows superior electrochemical performances with a capacitance of 538 F/g at 1 A/g, which provides great application in the fields of magnetocaloric device, high-temperature heat-insulating coatings, electromagnetic material and electrochemical sensors, etc.

Low dimensional interface passivation has been proved to be an efficient method to lessen the nonradiative recombination loss in perovskite solar cells. To overcome the limitation of Phenethylammonium (PEA+) for carrier transport and water molecule intrusion, we developed a modification strategy by functioning the typical PEA+ with the 4-methoxy to optimize the interface defects and carrier transport performance, thus maximizing the synchronous improvement of device efficiency and stability. Our results indicate that the 2 mg ml−1 4-methoxy-phenethylammonium (MeO-PEA+) modified device could achieve a best power conversion efficiency of 19.64% with improved shelf-life stability in ambient conditions. The new passivation molecule of MeO-PEA+ could possess the capability of defect passivation, carrier transfer, and moisture blocking, demonstrating that rationally designed organic components for interface passivation could help to achieve efficient and stable PSCs.

The trap-assisted nonradiative recombination at grain surface and grain boundary (GB) of perovskite films impede the further improvement of power conversion efficiency (PCE) and stability of perovskite solar cells (PSCs). In addition, the poor moisture stability of perovskite films hinders the commercial application of PSCs. Herein, we report a multifunctional GB modification strategy where the wide-bandgap hydrophobic PbSO4 modification layer is in situ formed at the GBs of perovskite films through the reaction between methylamine sulfate and PbI2. It is revealed that multiple functions are achieved after the formation of PbSO4 modification layer, including crystallization improvement, defect passivation, and hydrophobicity improvement. As a result, the PbSO4 modified device exhibits a PCE enhancement from 19.53% to 21.90% as compared to the control device. Moreover, up to 71% of its initial PCE is maintained for the unencapsulated PbSO4 modified device after aging under a relative humidity of 80 ± 5% for 250 h. This work proposes an effective multifunctional approach to modify the GBs of perovskite films for the purpose of simultaneous increasement of PCE and stability.

NiZn ferrite/reduced graphene oxide (Ni 0.8 Zn 0.2 Fe 2 O 4 /rGO) nanocomposite and Al 3+ and Cu 2+ substituted NiZn ferrite/reduced graphene oxide (Ni 0.8 Zn 0.2 Al 0.1 Fe 1.9 O 4 /rGO and Ni 0.6 Cu 0.2 Zn 0.2 Fe 2 O 4 /rGO) nanocomposites were directly synthesized by one-step hydrothermal route. XRD and FTIR confirmed the formation of Ni 0.8 Zn 0.2 Fe 2 O 4 /rGO, Ni 0.8 Zn 0.2 Al 0.1 Fe 1.9 O 4 /rGO and Ni 0.6 Cu 0.2 Zn 0.2 Fe 2 O 4 /rGO nanocomposites. The average crystallite size was found to be 16.9–20.4 nm. The substitution of Al 3+ /Cu 2+ for Fe 3+ /Ni 2+ ions promotes a variation in unit cell due to the difference of ionic radius between Al 3+ /Cu 2+ and Fe 3+ /Ni 2+ , which leads the lattice parameter to vary from 8.353A to 8.394 A. Magnetic measurements reveal the saturation magnetization to vary with the replacement of Al 3+ /Cu 2+ for Fe 3+ /Ni 2+ ions. The variations of saturation magnetization in Al and Cu substituted NiZn ferrite/reduced graphene oxide nanocomposites have been explained in the light of Neel's two-sublattice theory. A maximum specific capacitance of 136.91 F/g and energy density of 16.80 W h/kg were obtained in Ni 0.8 Zn 0.2 Al 0.1 Fe 1.9 O 4 /rGO nanocomposite at a current density of 1 A/g. The enhanced electrochemical performances could be related to the high electronic conduction of Ni 0.8 Zn 0.2 Al 0.1 Fe 1.9 O 4 /rGO nanocomposite.

NiInxFe2−xO4 (x=0.0, 0.1, 0.2, 0.3, 0.4) ferrite nanoparticles have been synthesized by sol-gel autocombustion technique. The effect of In3+ substitution on the structural and magnetic properties of nickel ferrite has been analyzed by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), Field emission scanning electron microscopy (FESEM) and Vibrating sample magnetometer (VSM). The XRD results confirmed the formation of single cubic spinel phase for 0 ≤ x ≤ 0.3 and the appearance of secondary phase of In2O3 for x=0.4. The lattice parameter increases (from 8.3152 to 8.4336 A) with indium content. The FTIR results illustrated that the absorption intensity of peak at about 594 cm−1 increases with increasing the In3+ ions. The saturation magnetization increases and then decreases while the coercivity decreases along with In3+substitution. The maximal saturation magnetization emerged at the composition of NiIn0.2Fe1.8O4 (42.111 emu/g).

The demand for low-cost and high-performance energy storage supercapacitors is continuously promoting as a result of the rapid development of portable electric vehicles and electronic devices. Here, a high-performance MnCo alloy nanoparticles decorated boron-doped carbon nanotubes (MnCo–B/CNTs) electrode was obtained by a facile heteroatom hydrothermal and subsequent liquid-phase reduction methods, which yields improved performance for supercapacitor. In this process, boron doping led to extra oxygen graft into carbon surface, leading to the improved durability and wettability of the fabricated carbon-based electrodes, which presented both increased capacitances and rate capability due to electrolyte ion penetration and interactions with carbon surface. In addition, boron doping led to smaller size and higher dispersion of MnCo nanoparticles, facilitating more metallic alloy and new electroactive sites formation and promoting supercapacitive activity, which was attributed to increased MnCo alloy nucleation rate with boron-doped, electron donation from boron to alloy, and extra chemisorption sites. The constructed electrode exhibited all-round performance improvements of specific capacitance (1175 F g−1 at 0.5 A g−1) and capacitance retention (94.48% at a current density of 20 A g−1 after 5000 cycles), providing a novel insight for designing high performance supercapacitors.

The increasing demands for green sustainable energy have motivated much interest and attention in energy conversion systems. In this work, 3D hierarchical network porous CNS@Ag0.5@Co-180-10/GNPs hetero-nanostructure hybrid was successfully designed and fabricated via a multistep transformation approach of liquid-phase reduction procedure and subsequent hydrothermal activation pathway, through using a facile heteroatoms synergistic-doping cobalt-based AgCo hybrid and precursor assisted-templating strategy. Here, the chemical compositions, structure parameters and electrochemical performances of C, N, S-tri-doped Ag@Co composites precursor can be simply tuned by adjusting the requirement of Ag content in alloys, hybridization temperature and activation time. It was found that the typical CNS@Ag0.5@Co-180-10/GNPs material possessed a molar ratio of 0.5:1 of Ag and Co, hybridized at 180 °C and activated for 10 h is endowed with large specific surface area (1370 m2g−1), suitable porosity (wider mesopores and narrow micropores), unique morphology (porous 3D hierarchical network structure) and outstanding electrochemical performance (657.6 F g−1 at 1 A g−1 for specific capacitance, 97.11% at a current density of 15 A g−1 after 5000 cycles for capacitance retention), providing a new insight to design a promising electrode materials for high-performance supercapacitors.