BaTiO₃ has a giant electrocaloric strength, |ΔT|/|ΔE|, because of a large latent heat and a sharp phase transition. The electrocaloric strength of a new single crystal, as giant as 0.48 K·cm/kV, is twice larger than the previous best result, but it remarkably decreased to 0.18 K·cm/kV after several times of thermal cycles accompanied by alternating electric fields, because the field-induced phase transition and domain switching resulted in numerous defects such as microcracks. The ceramics prepared from nano-sized powders showed a high electrocaloric strength of 0.14 K·cm/kV, comparable to the single crystals experienced electrocaloric cycles, because of its unique microstructure after proper sintering process. Moreover, its properties did not change under the combined effects of thermal cycles and alternating electric fields, i.e. it has both large electrocaloric effect and good reliability, which are desirable for practical applications.

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 (S_BET > 125 m² g⁻¹) and high pore volumes (V_p > 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.