Functional Materials Letters

We synthesized SiC nanorods/Ni core-shell structure (SiC_R-Ni) by a facile solution method and researched their dielectric and microwave absorption properties. The dielectric and microwave absorbing properties of SiC_R-Ni are superior to SiC nanorods (SiC${}_{\text{R}})$. The maximum absorption peak of SiC_R-Ni is almost three times that of SiC_R. The bandwidth of effective absorption of SiC_R-Ni covers 64% of $X$-band. The improved properties of SiC_R-Ni originate from multi-polarization in the special core-shell structure of SiC_R-Ni.

To prepare the novel plate-like nanocomposite Co^IIITMPyP/Nb₃O₈, the cationic cobalt (III) tetrakis–5, 10, 15, 20–(N–methyl–4–pyridyl) porphyrin (Co^IIITMPyP) was intercalated into the interlayer of the perovskite structural material KNb₃O₈ via the electrostatic self-assembly of the positively charged Co^IIITMPyP molecules and the electronegative Nb₃O${}_8^{-}$ nanosheets. The Nb₃O${}_8^{-}$ nanosheets was obtained by exfoliating the protonated product of niobate KNb₃O₈ in the tetrabutyl ammonium hydroxide (TBA${}^{+}$OH${}^{-}$) aqueous solution. The zeta potential was measured to indicate the stability and uniformity of the Nb₃O${}_8^{-}$ nanosheet colloidal dispersion, and the structure and component of the parent material KNb₃O₈, the acidified product HNb₃O₈, and the interlayered nanocomposite Co^IIITMPyP/Nb₃O₈ were characterized using XRD, FT-IR, SEM and AFM. Furthermore, the electrocatalytic activity toward the oxygen reduction reaction (ORR) of Co^IIITMPyP/Nb₃O₈ hybrids modified GCE was investigated by the cyclic voltammetry (CV) measurements. The modified GCE exhibited good electrocatalytic activity toward ORR in consideration of the peak shift from $-$0.723V to $-$0.300V. The linear correlation of the reduction peak current and the square root of the scan rate suggested a diffusion controlled process.

Oxide precursors NdCaCo${}_{1-x}$Ni_xO_n ($x=0;0.2;0.4;0.6;0.8;1$) are obtained by the solid-state synthesis method at 1100${}^{\circ }$C. According to XRD analysis, the main components of these precursors are complex oxides with K₂NiF₄-like structure at $x\le 0.8$ and with rhombically distorted K₂NiF₄ structure at $x=1$. A thermal decomposition of these precursors in the mixture of CH₄/O${}_2=2$ at T $\ge$ 800${}^{\circ }$C results in the formation of dense metal-oxide nanocomposite particles. As-obtained nanocomposites demonstrated a considerable catalytic activity and selectivity in the reaction of partial oxidation of methane; their catalytic properties vary non-monotonously with Co/Ni ratio. The maximum CH₄ conversion and CO selectivity at 820${}^{\circ }$C is demonstrated by the composite comprising Nd₂O₃, CaO, NiO and Ni metal nanoparticles.

This paper reports the synthesis of MgO-based nanosheets loaded with UV-light absorbed, wurtzite Zn_xMg${}_{1-x}$O nanoparticles based on calcining Zn${}^{2+}$-adsorbed Mg(OH)₂ precursor, as evidenced by X-ray diffraction, UV-visible, X-ray photoelectron spectroscopy analyses, etc. The surface modification of magnesium oxide (MgO) sheet-like adsorbents by Zn–Mg–O alloys generates photocatalytic activity for the degradation removal of cationic dye Rhodamine B and anionic dye methyl orange under UV light irradiation. These findings provide a route to chemically controlled synthesis of new and highly robust MgO–Zn_xMg${}_{1-x}$O materials for water purification. The endowed photocatalysis function of MgO makes it be easily recovered via photodegradation of adsorbed dyes rather than high-temperature calcination, thus extending the applications of MgO in dye wastewater treatment.

The study compares thick-film NTC thermistor devices, produced by the screen-printing (and firing) technique and by the Aerosol Deposition Method (ADM) at room temperature. The devices are compared with respect to film quality (optical, mechanical) and to the negative temperature coefficient of resistance (NTCR) parameters ${\rho }_{25}$ and $B$. While the screen-printed films are porous, the Aerosol Deposited (AD) films are characterized by high tightness, mechanical stability, and a production at room temperature. The electrical analysis shows that the AD films reach the ${\rho }_{25}$- and $B$-values of bulk NTCRs from literature after a moderate tempering step below 400${}^{\circ }$C in air. The screen-printed films show $B$-values that are comparable to the values of bulk NTCRs from literature and ${\rho }_{25}$-values that are significantly higher.

In this paper, we have synthesized LiNi${}_{0.5}$Mn${}_{1.5}$O₄ with P4₃32 space group by carbonate co-precipitation. TG/DSC, TG*, ICP-OES, a gas displacement pycnometer using He gas, XPS, and XRD refinement results show that oxygen vacancies exist in the LiNi${}_{0.5}$Mn${}_{1.5}$O${}_{4-\delta }$ with a P4₃32 space group. There is a mixture of Mn${}^{3+}$ and Mn${}^{4+}$ in the P4₃32 structured LiNi${}_{0.5}$Mn${}_{1.5}$O${}_{4-\delta }$. Despite the large amount of Mn${}^{3+}$ in the spinel structure, no 4.0V plateau appears in charge–discharge curves. This result indicates that the Mn${}^{3+}$ in LiNi${}_{0.5}$Mn${}_{1.5}$O${}_{4-\delta }$ does not participate in electrochemical reactions during the charge–discharge process.

Fe₃O₄ hollow microspheres with good dispersibility and high saturation magnetization were synthesized through a facile one-step solvothermal method. The formation mechanism of the hollow structure was studied by taking time-dependent experiments. Porous $\alpha$-FeOOH and $\alpha$-Fe₂O₃ nanosheets were firstly fabricated. Fe₃O₄ solid spheres aggregated by small particles were obtained from the transition of $\alpha$-FeOOH and $\alpha$-Fe₂O₃. Finally, the solid sphere is transferred to hollow sphere through Ostwald ripening. The maximum saturation magnetization of the hollow spheres is $115.4\pm 0.1$emu/g, which is higher than some results reported in references. The Fe₃O₄ hollow spheres show potential applications in microwave absorption and photocatalysis.

Co-based anode materials are regarded as high capacity anode for alkaline secondary batteries. Their application, however, is limited by poor cycling stability. Herein, flower-like Co hierarchitectures with hcp crystal structure were synthesized by a simple chemical reduction method. The as-prepared Co electrode shows a high maximum discharge capacity of 509mAh/g at 100mA/g and good rate capability. Nevertheless, the discharge capacity decreased to 337mAh/g after 50 cycles due to dissolution of the Co electrode into the electrolyte. The addition of Na₂S₂O₃ in the electrolyte can restrain this dissolution and contributes to significant improvement in the cycling stability. A high reversible discharge capacity of 480mAh/g was retrained after 50 cycles when the electrolyte with 0.02M Na₂S₂O₃ addition was employed, yielding an excellent cycling performance.

Electrode materials with high performance and low cost are demanding in supercapacitor applications. Novel V₂O₃ nanofoam@activated carbon composites have been prepared simply and cost-efficiently. Due to the mesoporous structure and high specific surface of V₂O₃ nanofoam and the good electric conductivity of activated carbon, the obtained composites exhibit an obviously improved specific capacitance as high as 185F/g, which overpasses bulk V₂O₃ (119F/g) and activated carbon (113F/g). The rate capability of V₂O₃ nanofoam@activated carbon composites has also been improved, owing to the increased electron transport accelerated by the activated carbon and the fast electrolyte ion intercalation/deintercalation facilitated by mesopores of V₂O₃ nanofoam. The composites retain 56% of initial specific capacitance when the current density increases from 0.05A/g to 1.0A/g. Therefore, the obtained V₂O₃ nanofoam@activated carbon composites are low-cost electrode materials with obviously improved electrochemical performance, which are idea for supercapacitor application.

Novel black phosphorus quantum dots/attapulgite (BPQDs/ATP) nanocomposites were prepared via a facile hydrothermal-deposition method. TEM showed that BPQDs dispersed evenly on the surface of ATP with uniform particle size about 5nm. UV-Vis revealed that the BPQDs/ATP composite showed wider visible light absorption range as compared with pure ATP. The photocatalytic activity was evaluated by degradation of bisphenol A (BPA). Results showed that BPQDs/ATP reached 90% degradation rate under solar light irradiation for 180min. The coherent heterostructure formed by BPQDs and ATP was responsible for the enhanced photocatalytic performance, due to the sensitization effect of BPQDs and the facilitation of charges separation.

Series of plasmonic MoO${}_{3-x}$ particles have been prepared by a facile solvothermal method to produce hydrogen via hydrolytic dehydrogenation of ammonia borane. Interestingly, the as-prepared MoO${}_{3-x}$ particles present various morphologies, i.e. flower, schistose and nanorod by simply tuning the reaction temperature and solvent volume ratio of distilled water and acetic acid. More importantly, these MoO${}_{3-x}$ particles with different morphologies exhibit various catalytic performances of NH₃BH₃ under the irradiation of visible light. Particularly, the flower-like MoO${}_{3-x}$ microstructure possesses the best catalytic activity for hydrogen production probably owing to the relatively large surface area and strong LSPR in the visible region.

Here, a series of cellular-structured and predominantly mesoporous carbons were prepared via carbonization of glucose–fructose syrup (GFS) with sulfuric acid and subsequent calcination between 400${}^{\circ }$C and 700${}^{\circ }$C. Comparative results on the microstructure, chemical and textural properties of the newly produced carbons are presented. Furthermore, their adsorption performance for removal of acetaminophen from water was tested and it was found that the carbon calcined at 700${}^{\circ }$C has a maximum adsorption capacity (98.7mg$\cdot$g${}^{-1}$) among all samples due to its suitable textural properties (BET surface area of 418m${}^2\cdot$g${}^{-1}$ and total pore volume of 0.2cm${}^3\cdot$g${}^{-1}$). This study demonstrates the potential use of GFS as a precursor in the preparation of carbonaceous materials for removal of biologically-active micropollutants from water.

We here report a superconcentrated potassium acetate (KAC) solution (75wt.%, K : H₂O $=$ 1 : 1.8, called as “water-in-salt”) as an aqueous electrolyte to improve the working voltage and increasing capacitance in enhancing the energy density of the active carbon-based aqueous supercapacitor. The stability potential window of the superconcentrated electrolyte realizes an AC//AC symmetric supercapacitor with operating voltage of 2.0 V and excellent cyclic performance. Meanwhile, the energy density of such supercapacitor achieves about twice as high as that of the supercapacitor using normal concentration of electrolyte.

The Mo-, W-incorporated Sm${}_{0.5}$Sr${}_{0.5}$CoO${}_{3-\delta }$ ceramics were prepared by the tape casting and high temperature sintering method. The effects of Mo and W concentration on the structure and optical properties of Sm${}_{0.5}$Sr${}_{0.5}$CoO${}_{3-\delta }$ were investigated in detail. It was found that the Mo-, W-incorporated Sm${}_{0.5}$Sr${}_{0.5}$CoO${}_{3-\delta }$ exhibited extraordinary emittance property in the 3–5$\mu$m and 8–13$\mu$m (especially in the 11–13$\mu$m) wavelength ranges. The results suggest that the novel infrared emittance property of Mo- and W-incorporated Sm${}_{0.5}$Sr${}_{0.5}$CoO${}_{3-\delta }$ could find potential applications in solar thermal or radiative cooling systems.

A bilayered TiO₂/CuO photoelectrode was fabricated on a fluorine-doped tin oxide FTO substrate by spin-coating and pulsed laser deposition methods. The prepared bilayered system was assessed as a photoelectrode for solar water splitting. The fabricated TiO₂/CuO photoelectrode exhibited a higher photocurrent density (0.022mA/cm² at 1.23V vs. RHE) compared to bare TiO₂ photoelectrode (0.013mA/cm² at 1.23V vs. RHE). This photocurrent density enhancement was attributed to the improved charge separation combined with the improved sunlight harvesting efficiency of a bilayered structure.

A new molecule with dithieno[3,2-b:2’,3’-d]pyrrole (DTP) as central moiety and two terminal diketopyrrolopyrrole (DPP) units named DPP-DTPC8 has been designed and synthesized. The push–pull molecule exhibits excellent thermal stability, strong absorption in visible region, and matched energy levels. Devices fabricated from DTPC8:PC${}_{71}$BM blend films exhibit the maximum power conversion efficiency of 2.75%, with Voc of 0.63 V, Jsc of 9.94 mA$\cdot$ cm${}^{-2}$, and FF of 43.8%. The active layers undergo thermal annealing or solvent vapor annealing treatments, exhibiting inconspicuous influence on the aggregation of the molecule. This study demonstrates that the new molecule DPP-DTPC8 tailored with DTP and DPP units could affect the thermal stability, absorption, energy levels and morphology that manage the photovoltaic performances.

A facile strategy is described for general synthesis of MCo₂O₄@CeO₂ ($\mathrm{\text{M}}=\mathrm{\text{Ni}}$, Cu, Zn, Mn) core@shell nanospheres. First, uniform M,Co–glycerate were prepared and served as precursor to produce MCo₂O₄ spheres by calcination, followed by a reflux process to obtain MCo₂O₄@CeO₂ core@shell spheres. As expected, due to the synergetic effect at the interface between the two components, most of the as-prepared MCo₂O₄@CeO₂ core@shell spheres exhibited enhanced catalytic activities toward CO oxidation compared with the corresponding MCo₂O₄ spheres and CeO₂ nanoparticles.