Recently, metal–organic frameworks (MOFs), which are porous inorganic–organic hybrid materials consisting of metal ions (clusters or secondary building units) and organic ligands through coordination bonds, have attracted wide attention because of their high surface area, huge ordered porosity, uniform structural cavities, and excellent thermal/chemical stability. In this work, durian shell biomass carbon fiber and Fe3O4 functionalized metal–organic framework composite material (durian shell fiber-Fe3O4-MOF, DFM) was synthesized and employed for the adsorption removal of methylene blue (MB) from wastewater. The morphology, structure, and chemical elements of the DFM material were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), transmission electron microscope (TEM), and X-ray photoelectron spectroscope (XPS) techniques. Adsorption conditions such as pH, adsorption time, and temperature were optimized. The adsorption isotherm and kinetics results show that the adsorption process of DFM material to MB is more in line with the Freundlich model and pseudo-second-order kinetic model. Using these models, the maximum adsorption capacity of 53.31 mg/g was obtained by calculation. In addition, DFM material could be easily reused through an external magnet and the removal rate of MB was still 80% after five adsorption cycles. The obtained results show that DFM composite material, as an economical, environmentally friendly, recyclable new adsorbent, can simply and effectively remove MB from wastewater.

Using solar energy to efficiently decompose water to produce hydrogen under visible light is a kind of promising green energy. A great number of hybrid materials have been developed as catalysts for photolysis of water to hydrogen. However, these photocatalysts are still limited by fast electron–hole recombination or their low quantum efficiency. In this study, novel N,S-organic dots (NSOD) were combined with g-C3N4 (CN) by ultrasonic self-assembly to form a new NSOD/CN van der Waals heterojunction photocatalyst. Photocatalytic hydrogen production of the NSOD/CN van der Waals heterojunction reached 1369.5 μmol h–1 g–1, and the efficiency is 4.25 times higher than CN. The improvement in performance is due to the formation of the van der Waals heterojunction between NSOD and CN, which effectively promotes charge separation and electron transfer. Meanwhile, the introduction of NSOD is beneficial for the visible light response of the photocatalyst. This paper reports an effective reference to construct a novel van der Waals heterojunction for applications in the field of energy conversion.

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