A novel one-step preparation of sonochemical method was applied to synthesize Co/Zn co-doped TiO₂ nanoparticles using a sonicator of 750 W, 20 kHz for 30 min at room temperature. The formation of the anatase TiO₂ phase for all as-prepared samples was observed from XRD results with a crystalline size in nanoscale. The use of ultrasound allowed for the successful doping of both Co and Zn into the TiO₂ lattice, which was confirmed by Synchrotron light including X-ray near edge structure (XANES) and Extended X-ray absorption fine structure (EXAFS) spectroscopy. Ti K-edge, Co K-edge, and Zn K-edge XANES spectra exhibited the dominating +4, +2, and +2 valence state of Ti, Co, and Zn in as-prepared samples, respectively. A detailed XANES and EXAFS data analysis give strong evidence that the Co/Zn dopants partially replace the Ti atom of the TiO₂ host. The Co/Zn co-doping extends the light absorption of the host to the visible region and restricts the e⁺/h⁺ recombination. The photocatalytic activity of samples was tested for degradation of Rhodamine B dye solution under visible light irradiation. The as-synthesized of the co-doped catalyst was presented as highly efficient, with 2.5 and 5 times dye degradation compared with single-doped and bare TiO₂.

In this work, Er-doped BiVO₄/BiFeO₃ composites are prepared using the sonochemical process with a difference of rare earth loading compositions. The crystallinity and chemical and morphological structure of as-synthesized samples were investigated via X-ray diffraction, Raman scattering, and electron microscopy, respectively. The diffuse reflectance technique was used to extract the optical property and calculate the optical band gap of the composite sample. The piezo-photocatalytic performance was evaluated according to the decomposition of a Rhodamine B organic compound. The decomposition of the organic compound was achieved under ultrasonic bath irradiation combined with light exposure. The Er-doped BiVO₄/BiFeO₃ composite heterojunction material exhibited significant enhancement of the piezo-photocatalytic activity under both ultrasonic and light irradiation due to the improvement in charge generation and separation. The result indicates that Er dopant strongly affects the phase transformation, change in morphology, and alternation in optical band gap of the BiVO₄ matrix. The incorporation of BiFeO₃ in the composite form with BiVO₄ doped with 1%Er can improve the photocatalytic performance of BiVO₄ via piezo-induced charge separation and charge recombination retardment.

Piezoelectric-assisted photocatalysis technology is one of the efficient ways to achieve enhancement in photocatalytic performance by facilitating the separation of photoinduced electron and holes via internal field initiated via piezoelectricity. Herein, bi-piezoelectric integrated effect was generated by the combination of piezoelectric semiconductor photocatalyst ZnO/Cu and piezoelectric polymer polyvinylidene fluoride (PVDF). Firstly, ZnO/Cu nanoparticles were prepared by facile co-precipitation method. Then, nanoparticles (at 10–30 wt%) were loaded in PVDF for fabricating nanofibers by electrospinning technique. All PVDF–ZnO/Cu nanofibers were characterized by XRD, FE-SEM, FTIR, XAS, and UV–Vis DRS. The structural study indicates that the β- and α-phase PVDF is observed in all the prepared nanofibers. XANES technique confirms the oxidation state of 2+ for Zn and Cu ions in both nanoparticles and nanofibers. Furthermore, under the synergy action of ultrasonic and visible light irradiation, PVDF–ZnO/Cu nanofibers exhibit superior piezo-photocatalytic degradation of rhodamine B dye when compared with single light or mechanical excitation. Effects of ZnO/Cu concentration on optical, piezoelectric, and photocatalytic properties are discussed.

This study focuses on the synthesis and characterization of polyvinylidene fluoride (PVDF) membranes enhanced with nanocellulose (NCs) and TiO2 for the removal of rhodamine b (RhB) dye. PVDF/NCs/TiO2 membranes were fabricated with varying TiO2-P25 contents (0.18, 0.36 and 0.72wt%). Initially, PVDF and NCs were separately dissolved in dimethylacetamide (DMAc), followed by the addition of TiO2-P25 nanoparticles. The resulting solutions were cast into membranes using the doctor blade technique and dried at room temperature. Fourier transform infrared spectroscopy (FTIR) confirmed the successful incorporation of both NCs and TiO2 into the PVDF matrix. Water flow rate measurements were conducted to assess membrane permeability. Photocatalytic activity was evaluated using RhB dye solutions at pH 4, 7, and 10. The results indicated that membranes containing NCs and TiO2 exhibited superior water permeability and dye removal efficiency compared to pure PVDF membranes. These findings suggest that PVDF/NCs/TiO2 membranes are promising candidates for the treatment of dye-contaminated wastewater.