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In this work, the microwave-assisted synthesis of manganese metal–organic framework (MOF) material is presented. Synthesis procedure is based on a microwave-assisted solvothermal reaction of manganese(III) acetylacetonate with biphenyl-4,4′-dicarboxylic acid (Bpdc) in N,N′-dimethylformamide at the temperature of 160 °C. The obtained Mn-based metal–organic framework, labeled as Mn-Bpdc, was used as a precursor for the preparation of a porous MnO/carbon nanocomposite, which was obtained via thermal transformation in a nitrogen atmosphere at 700 °C. It was found that this approach provides an effective and simple preparation pathway for porous carbon decorated with homogeneously embedded manganese(II) oxide nanoparticles. Both Mn-Bpdc and MnO/C nanocomposite materials were characterized by a variety of physicochemical methods. The prepared MnO/C nanocomposite material was deposited on a cathode surface of lithium-sulfur batteries and utilized as a shuttle suppressing layer. This electrode structure immobilizes polysulfides inside the cathode and improves the stability during cycling. The electrode with MnO/C nanocomposite shuttle suppressing layer maintains high stability during cycling in comparison with a standard electrode. The electrode with MnO/C composite layer exhibits 84.8% capacity retention after 50 cycles at different C-rates compared to 76.2% obtained for the standard electrode. [ABSTRACT FROM AUTHOR]

In this work, vanadium metal-organic framework derived VO x /carbon and VO x /N-doped carbon nanocomposites are presented. The methodology introduced here is based on a novel polyol synthesis of vanadium metal-organic frameworks (MOFs) involving a microwave-assisted solvothermal reaction of vanadyl acetylacetonate with biphenyl-4,4′-dicarboxylic acid (Bpdc) and/or 2,2′-bipyridine-4,4′-dicarboxylic acid (NBpdc) in diethylene glycol (DEG) at the temperature of 230 °C. The V-based MOFs, labeled as V-Bpdc and V-NBpdc, were used as precursors for the preparation of VO x /carbon and VO x /N-doped carbon nanocomposites with unique sponge-like nano-sheet and paperclip-like morphology, respectively. The nanocomposites were obtained via thermal transformation of as-prepared vanadium MOFs in the argon atmosphere at 600 °C. The VO x /carbon sample consists of nano-sheets with the thickness 5–20 nm while the VO x /N-doped carbon paperclip-like nanocomposite has a rod diameter 35–70 nm. It was found that the approach reported here provides an effective and simple preparation pathway of carbon-based nanocomposites containing homogeneously distributed VO x species. Both V-MOFs and V-MOF-derived nanocomposites were characterized by the variety of physicochemical methods. In the following step, the obtained nanocomposites were investigated as electrode materials in sodium-ion batteries. Based on the obtained results, high electrochemical activities of VO x /carbon and VO x /N-doped carbon nanocomposites were evidenced. Particularly, in the case of VO x /N-doped carbon-based electrode, high capacity and low irreversible capacity were achieved. Therefore, reported materials are found to be promising candidates for electrode materials in sodium-ion batteries. [Display omitted] • Novel microwave-assisted polyol synthesis of vanadium MOF materials introduced. • Original nano-sheet and paperclip morphologies of V-MOF derived nanocomposites. • VO x /Carbon and VO x /nitrogen-doped carbon successfully utilized in Na-ion batteries. • Improved electrochemical behavior of VO x /N-doped carbon due to nitrogen doping. • Low irreversible capacity and high performance V-MOF derived nanocomposites observed. [ABSTRACT FROM AUTHOR]

In this paper, we report the preparation of visible-light active direct Z-scheme Cu2O/WO3 nanocomposite photocatalyst by a solid-state reaction avoiding the otherwise inevitable formation of CuWO4 phase in wet syntheses. Structure, morphology, and thermal and optical properties of prepared WO3 nanoplatelets decorated by Cu2O were investigated by XRD, Raman spectroscopy, SEM/TEM, combined thermogravimetric (TG)/differential scanning calorimetry (DSC) analysis, and UV–VIS spectroscopy. The photocatalytic performance of the prepared samples under UV and visible light was studied through monitoring discoloration of methylene blue under illumination by selected wavelengths, allowing for the distinguishing between the contributions of the two semiconductive components. Experimental results showed that the decoration of WO3 nanoplates by Cu2O nanoparticles led to an improvement in photocatalytic performance, regardless of used LED (Light-Emitting Diode) wavelength, even at low concentrations. By using scavengers selectively blocking reactive species involved in the discoloration reaction, we determined that the Cu2O/WO3 nanocomposite exhibited the characteristics of direct Z-scheme-type photocatalyst. [ABSTRACT FROM AUTHOR]