More and more metal oxide nanomaterials are being synthesized and investigated for degradation of organic pollutants through harvesting friction energy, yet the strategy to optimize their performance for this application has not been carefully explored up to date. In this work, three commercially available ZnO powders are selected and compared for tribocatalytic degradation of organic dyes, among which ZnO-1 and ZnO-2 are agglomerates of spherical nanoparticles around 20 nm, and ZnO-3 are particles of high crystallinity with a regular prismatic shape and smooth surfaces, ranging from 50 to 150 nm. Compared with ZnO-1 and ZnO-2, ZnO-3 exhibits a much higher tribocatalytic degradation performance, and a high degradation rate constant of 6.566 × 10⁻² min⁻¹ is achieved for RhB, which is superior compared with previous tribocatalytic reports. The stability and universality of ZnO-3 were demonstrated through cycling tests and degradation of different types of dyes. Furthermore, the mechanism of tribocatalysis revealed that h+ was the main active species in the degradation process by ZnO. This work highlights the great significance of high crystallinity rather than a large specific surface area for the development of high-performance tribocatalysts and demonstrates the great potential of tribocatalysis for water remediation.

A large quantity of ultrafine tetragonal barium titanate (BaTiO3) nanoparticles is directly synthesized at room temperature. The crystalline form and grain size are checked by both X-ray diffraction and transmission electron microscopy. The results revealed that the perovskite nanoparticles as fine as 7 nm have been synthesized. The phase transition of the as-prepared nanoparticles is investigated by the temperature-dependent Raman spectrum and shows the similar tendency to that of bulk BaTiO3 materials. It is confirmed that the nanoparticles have tetragonal phase at room temperature.

Here we report a very simple method to convert conventional CuO powders to nanoparticle interlinked microsphere cages by solution method. CuO is dissolved into aqueous ammonia, and the solution is diluted by alcohol and dip coating onto a glass substrate. Drying at 80 °C, the nanostructures with bunchy nanoparticles of Cu(OH)₂can be formed. After the substrate immerges into the solution and we vaporize the solution, hollow microspheres can be formed onto the substrate. There are three phases in the as-prepared samples, monoclinic tenorite CuO, orthorhombic Cu(OH)₂, and monoclinic carbonatodiamminecopper(II) (Cu(NH₃)₂CO₃). After annealing at 150 °C, the products convert to CuO completely. At annealing temperature above 350 °C, the hollow microspheres became nanoparticle interlinked cages.

The Curie point of barium titanate (BaTiO₃) has been a focal point of research since the discovery of its ferroelectric properties. Exploring methods to elevate the Curie point without relying on Pb as a dopant presents fresh opportunities for lead-free dielectric and/or piezoelectric materials. It is essential to avoid introducing ions like K[ ] and Na[ ], which could jeopardize the functional ceramic characteristics. This study delves into the stoichiometry of barium titanate, examining how impurities, point defects and doping techniques influence its Curie point, focus on the potential of doping and processing to enhance this property. BaTiO₃ nanopowders were synthesized directly with varying Ba:Ti ratios in an ethanol–water solution at 60^∘C, followed by sintering at 1280^∘C and characterization through dielectric spectroscopy. A comparison was made with samples doped with Si, vapor-doped with Bi and vapor-doped with Pb. Results revealed that even minimal Si doping could boost the ferroelectric properties and elevate the Curie point, while vapor-doping with trace amounts of PbO or Bi₂O₃ significantly increased the Curie point, particularly in samples with higher Ti content. The impact of vapor dopants of PbO and Bi₂O₃ was similar, with a nominal doping level of 1[ ]mol% shifting the Curie point above 140^∘C. Notably, in samples with a Ba:Ti ratio of 0.95 vapor-doped with PbO, the Curie point rose to 146^∘C, a notable increase of 16^∘C, surpassing the traditional doping efficiency. This study offers fresh insights into enhancing the Curie point of barium titanate-based materials, exploring the intricate connections among chemical stoichiometry, dopants, point defects and dielectric properties. It highlights the significant influence of chemical composition, impurities, defects and doping strategies on the dielectric characteristics of barium titanate.

The role of electric field is investigated in determining the structure, morphology, and crystallographic characteristics of CaCO3 nanostructures crystallized from solution. It is found that the lattice structure and crystalline morphology of CaCO3 can be tailed by the electric field applied to the solution during its crystallization. The calcite structure with cubic-like morphology can be obtained generally without electric field, and the vaterite structure with the morphology of nanorod is formed under the high electric field. The vaterite nanorods can be piled up to the petaliform layers. Both the nanorod and the petaliform layer can have mesocrystal structures which are piled up by much fine units of the rods with the size of several nanometers. Beautiful rose-like nanoflowers can be self-arranged by the petaliform layers. These structures can have potential application as carrier for medicine to involve into metabolism of living cell.