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In this work, N-doped carbon microtubes have been synthesized using MoO3 microrods as the sacrificial template. Then, the Fe3O4 nanoparticles were integrated into N-doped carbon microtubes to obtain triple-walled Fe3O4@N-doped carbon@Fe3O4 microtubes via a high temperature decomposition process. Due to the coordination ability of nitrogen and the unique structures of the N-doped carbon microtubes, the Fe3O4 nanoparticles were closely attached to both the external and internal surfaces of the N-doped carbon microtubes and thus, assured a relatively good response to an external magnetic field. All these features make the nanocomposites well fitted for adsorption, catalysis, energy storage etc. Moreover, the N-doped carbon microtubes can be used as versatile templates to synthesize other triple-walled composites M@N-doped carbon@M microtubes (such as M = Cu(Cu2O), MnO2, MoS2), which greatly widens the applications of N-doped carbon microtubes. [ABSTRACT FROM AUTHOR]

The photo-transformation of graphene oxide (GO) nanosheet and the photo-reduction of uranyl ion (U(VI)) have been widely studied separately. However, little attention has been given to the simultaneous photo-degradation of GO nanosheets and the photochemical reduction of U(VI) under ultraviolet (UV) illumination. In this study, the relationships among the UV-induced degradation of GO, the U(VI)-induced aggregation of GO, the adsorption of U(VI) on GO, and the UV-induced reduction of U(VI) as well as their roles in the UV-induced simultaneous photo-degradation of GO and photo-reduction of U(VI) were elucidated. These results indicated that the UV-induced transformation of GO occurred more quickly than the adsorption of U(VI) on GO. The presence of low concentration of U(VI) could promote the UV-induced transformation of GO at the initial stage, while UV irradiation weaken the efficiency of U(VI) ions in destabilizing GO nanosheets at the subsequent stage. Our findings are crucial for developing a highly efficient method to accomplish the simultaneous removal of GO and U(VI) in the actual environmental cleanup. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni@IHC hybrids were synthesized by combining the solvothermal method with a one-step pyrolysis. • Ni@IHC hybrids held extraordinary structural merits. • Ni@IHC hybrids showed the superior catalytic performance for Cr(VI) reduction with formic acid. • The magnetically separable Ni@IHC hybrids were very cheap and scalable. Magnetic carbon materials promise distinct advantages in the decontamination of heavy metal ions. In this work, a novel interconnected hierarchical nickel-carbon (Ni@IHC) hybrid was synthesized by combining the solvothermal method with a one-step pyrolysis under argon atmosphere. Benefitting from 3D flower-like morphology, interconnected porous nanosheets, large surface area, and abundant Ni nanoparticles, Ni@IHC hybrids can remove Cr(VI) within 25 min by using formic acid (FA) as a reductant at 25 ℃. Furthermore, the experimental parameters that can affect the material catalytic performance such as initial Cr(VI) concentration, catalyst dosage, FA concentration, and temperature were also investigated in detail. It was found that highly dispersed Ni nanoparticles contributed significantly to the reduction process. More importantly, the embedded Ni nanoparticles favor fast separation by a magnet and were helpful for the recycles use. This Ni@IHC hybrid was obtained by a facile and easy scale-up method, resulting in the fast transformation of Cr(VI) into Cr(III). [ABSTRACT FROM AUTHOR]

• 3D flower-like few layer MXene modified NiFe-LDH (MNFL) composites were fabricated. • The added amount of MXene played a significant role in the physicochemical properties of MNFL. • MNFL-60 has excellent removal performance for both Cr(VI) and 1-naphthol. • The addition of LDH decreased the bio-toxicity of MXene. The application of few-layer MXene combined with layered double hydroxides (LDH) as adsorbent for the removal of pollutant is scarce. Herein, a series of novel flower-like MXene modified NiFe-LDH composites (MNFL) were fabricated via in situ growth of LDH on the MXene substrate. The results demonstrated that the added amount of MXene played a significant role in the physicochemical properties of MNFL. Among them, the formed MNFL-60 possessed wonderful dispersion, appreciable surface area (64.04 m2/g) and saturation magnetization (∼10 emu/g). The maximum removal capacities of MNFL-60 were highest, with the value of 372.9 mg/g for Cr(VI) and 201.8 mg/g for 1-naphthol at 288 K. Furthermore, the removal capacities of MNFL-60 for Cr(VI)/1-naphthol increased with the rise of temperature, indicating that the adsorption processes were more favorable under a higher temperature. The addition of LDH decreased the bio-toxicity of MXene, with mortality rates of more than 76 % for E. coli and 48 % for S. aureus at 100 mg/L MNFL-60 and 80 % for E. coli and 57 % for S. aureus at 200 mg/L MNFL-60. Based on the results of XPS, the removal of 1-naphthol was ascribed to the inter-reaction with N/O–containing groups, whereas the eliminate of Cr(VI) was attributed to the electrostatic attraction, complexation and partial reduction of Cr(VI) to Cr(III). Additionally, the outstanding reusability and easy recyclability could make MNFL-60 can be a promising material for remediating organic and inorganic pollutants from wastewaters. [ABSTRACT FROM AUTHOR]