Hydrochars derived from macroalgae Sargassum horneri were characterized physically and chemically to elucidate their potential as a valuable resource. Hydrochars were prepared by hydrothermal carbonization (HTC) of Sargassum horneri at temperatures of 180−210 °C with citric acid. The hydrochars were found to form mainly through a dehydration reaction pathway and had carbon contents of 36.8−50.5% and higher heating values of 19.0−25.1 MJ kg −1 . The BET surface area of hydrochars remained low, in the range of 0.6−31.8 m 2 g −1 . On the basis of Taguchi's experimental design, reaction temperature, reaction time, and particle size of feedstock were found to be the most important control factors for the chemical and physical properties of the hydrochars.

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One-dimensional H2Ti3O7 nanowires (NWs) supported by Au, Ag, and Pd monometallic nanoparticles (NPs) and Au–Pd bimetallic NPs were prepared and used for photochemical benzyl alcohol oxidation. Techniques, such as XRD, TEM, XPS, N2 physisorption, and diffuse reflectance ultraviolet–visible (DRUV–vis), were used to characterize the obtained catalysts. These results showed that the Pd/H2Ti3O7 NWs catalyst under light irradiation displayed an enhanced photocatalytic performance, nearly 2.6 times higher than that for the catalyst without irradiation and about 1.5 times higher than that for Pd/TiO2(P25) with irradiation. The enhanced benzyl alcohol oxidation activity for Pd/H2Ti3O7 NWs might be due to the favorable synergetic effect between Pd and H2Ti3O7 NWs. Particularly, highly dispersed Pd NPs with about 10.2 nm on H2Ti3O7 NWs can promoted the light harvesting ability. The well-matched contact boundary between H2Ti3O7 NWs and Pd NPs might promote separation for the photoinduced electron and hole pairs. After 5 recycle utilization cycles, there was no evident decline in activity and selectivity for the Pd/H2Ti3O7 NWs catalyst, which still maintained its original structure of H2Ti3O7 NWs. The current study provides a potential application in the green and highly efficient photocatalytic synthesis of other organic compounds and other environmental applications.

The preparation and characterization of carbon nanotubes (CNTs)/epoxy composites were studied for microwave absorption, which frequency is from 2 to 6 GHz. The absorbing coating with a loading of 15 wt % CNTs/epoxy resin, which thickness is 3 mm, exhibited an absorbing peak of 10.5 dB at 3.85GHz. After being treated by HNO3–H2SO4 acid at the temperature of 100 °C, the real and imaginary part values of permittivity of CNTs have a larger increase in quantity, and the absorbing peak position moves to lower frequency of 3.35 GHz showing an increasing the dielectric loss in lower microwave frequency. Two-layer coating with CNTs/epoxy resin and graphite/epoxy resin composites have been also investigated in order to widen the frequencies range of CNTs microwave sorbent in the low microwave frequency application. The results indicated that two-layer coating (15 wt % loading CNTs/epoxy resin and 9 wt % loading graphite/epoxy resin) can obtain 2.4 GHz broad frequencies band for absorption of 5.0 dB. The absorbing peak intensity and position can be adjusted by changing the thickness of each layer coating in the case of fixed total thickness. The two-layer coating of 15 wt % loading CNTs/epoxy resin (dtop=2 mm) and 9 wt % loading graphite/epoxy resin (dbottom=1 mm) has a strong absorbing peak at 5.52 GHz and achieves an absorbing value of 20.79 dB.