A series of composites consisting of anatase TiO2 nanocrystals and three-dimensional (3D) graphene aerogel (TiO2–GA) were self-assembled directly from tetrabutyl titanate and graphene oxides via a one-pot hydrothermal process. TiO2 was found to uniformly distribute inside the 3D network of GA in the resulting composites with large surface areas (SBET > 125 m2 g−1) and high pore volumes (Vp > 0.22 cm3 g−1). In comparison with GA and TiO2, the composites possessed much higher adsorption capacities and visible light photocatalytic activity in the degradation of rhodamine B (RhB). With an initial concentration of 20.0 mg L−1 of RhB, the adsorptive decolourization of RhB was as high as 95.1% and the total decolourization value reached up to 98.7% under visible light irradiation over 5.0 mg of the resulting composites. It was elucidated that the physical and chemical properties of the TiO2–GA composites could be ascribed to their unique 3D nanoporous structure with high surface areas and the synergetic activities of graphene nanosheets and TiO2 nanoparticles.

A novel method to adjust the composition of a material while maintaining its morphology was described in this study. Nickel sulfide, the material investigated in this work, was found to be useful as a high surface area electrode material for supercapacitor applications. First, a nest-like Ni3S2@NiS composite electrode with 1D nanorod as structural unit was synthesized by simultaneously using Ni foam as template and Ni as a source through a one-step in situ growth method. Co and Se ions, which respectively acted as beneficial cation and anion, were successfully introduced into the nest-like Ni3S2@NiS material, resulting in the formation of Ni3S2@Co9S8 and NiS@NiSe2 composite electrodes with structures similar to those of the parent materials. The material structure was virtually retained and single-crystal-to-single-crystal transformation was achieved in the process. Introducing the cation and anion into the same type of material while maintaining topology could be important for the field of material synthesis and preparation of supercapacitor electrodes. Moreover, the electrochemical properties of these three materials were studied by cyclic voltammetry measurements and galvanostatic charge–discharge tests. The results indicated that the rate performance was improved significantly by ion exchange. In particular, the derived electrode with Se still showed superior oxidation and reduction ability at high scan rate of 10000 mV s–1. In addition, the second charge–discharge specific capacity also increased from 516 F g–1 to 925 F g–1 and 1412 F g–1 at the current density of 0.5 A g–1 and by Co and Se exchange, respectively. This work contributes to the knowledge on electrode materials for supercapacitors and can provide good reference for the fabrication of desired materials.

In this study, novel hierarchical rose-like Cu1.8Se microspheres with a porous three-dimensional (3D) framework were successfully synthesized by using a one-pot in situ growth method at low temperature (60 °C). The Cu1.8Se microspheres covered the surface of the 3D porous framework. The formation mechanism was investigated in detail by adjusting the volume ratio of DMF and EDA, as the blend solvents, and the reaction time. Then, the chemical composition of the Cu1.8Se microspheres was altered by Ag+ exchange without changing their morphology and structure. In this way, the binary Cu1.8Se was efficiently converted into the ternary CuAgSe. Notably, the band gap of materials was tuned continuously from 3.83 eV to 3.03 eV, and CuAgSe was produced continuously by adjusting the replacement time. This work provides a novel concept and a simple method that can serve as a good reference for improving the performance of tunable materials and the preparation of multielement alloy materials.

Novel hierarchical wool-ball-like copper sulfide (CuS) microflowers with a three-dimensional (3D) porous framework were successfully synthesized by the direct reaction of copper with sulfur powder using a one-pot in situ growth method at low temperature (60 °C). The CuS microflowers covered firmly the surface of the 3D porous framework. The formation mechanism was examined in detail by adjusting the amount of hydrochloric acid and reaction time. Most importantly, the chemical composition of the CuS microflowers was altered by the Se exchange without changing their morphology and structure. In this way, pure CuSe and Cu1.8Se crystalline materials were obtained on the surface of the porous microtube at different reaction times and the appropriate amount of Se powder. And interestingly, the core material remained as CuS. This behavior greatly affects the physical and chemical properties of the materials. The catalytic ability of the as-obtained CuSe@CuS and CuSe1.8@CuS composite materials to degrade methylene blue and rhodamine B is several times greater than that of the as-synthesized CuS microflowers.