In recent years, the conversion of 5-hydroxymethylfurfural (HMF) into 5-ethoxymethylfurfural (EMF) and ethyl levulinate (EL) has become an attractive biomass transformation route due to their potential applications in the energy and chemical industries. In this study, we have developed an effective method to prepare a catalyst for this reaction. Sulfonic-acid-functionalized carbon nanomaterials (C-SO₃H), prepared from the direct pyrolysis of Metal-Organic Frameworks (MOFs) precursor Cu-benzene-1,3,5-tricarboxylate (Cu-BTC) followed by acidification with sulfuric acid, show excellent catalytic activity with a total yield higher than 90%. It is interesting that, different from the previous catalysts, a different major product—EMF or EL—can be selectively obtained by controlling the reaction temperature and time.

Magnetoelectric composites have attracted much attentions due to their excellent multiferroic properties at room temperature. In this paper, CoFe₂O₄-PbZr_0.52Ti_0.48O₃ (CFO-PZT) composite ceramics with different molar ratios (CFO/PZT = 1:4, 1:5, 1:6 and 1:7) were prepared by conventional solid reaction method. Effects of molar ratio on the structure, dielectric, ferroelectric and magnetic properties were comparatively investigated. X-ray diffraction patterns confirmed bi-phase structures of the composites, which can be indexed as CFO and PZT, no other obvious phase can be found with the limitation of the XRD resolution. Scanning electron microscopy (SEM) images show that the surface of the prepared samples is not dense enough and many pores are formed, the mean grain size is about 200 nm. The same relaxation behavior was observed in the intermediate temperature range of PZT-CFO composite ceramics. At room temperature, the dielectric constant and dielectric loss of the specimen 1:4 are the highest. The leakage current of the sample 1:4 is the lowest while the sample 1:6 has the largest value. As the CFO content in the composite decreases, both the saturation (Ms) and the remnant (Mr) magnetization decrease. Among them, the sample 1:4 presents better ferroelectric and magnetic properties, the remnant polarization is 1.13 μC cm⁻², the saturation magnetization and remnant magnetization are 11.01 and 3.28 emu g⁻¹, respectively. The sample 1:6 has the largest coercive field (945.27 Oe) while the sample 1:7 show the smallest value (681.19 Oe). Interface interaction between CFO/PZT may be applied to explain this phenomenon.