Local dipole enhancement of space-charge piezophototronic catalysts of core-shell polytetrafluoroethylene@TiO2 nanospheres.

This study demonstrates the hydrothermal treatment of core-shell polytetrafluoroethylene (PTFE) nanoparticles decorated with TiO 2 (h -PTFE@TiO 2); this material exhibits strain-induced local dipole enhancement of the space-charge piezopotential that improves the photocatalytic effect. Under acoustic cavitation, dielectric barrier discharge and electric dipole formation are initiated in voids within the PTFE nanoparticles and at the TiO 2 –PTFE interface. The h -PTFE@TiO 2 nanoparticles (NPs) have exceptionally high catalytic activity in organic dye degradation because of the local dipole enhancement of photoinduced charge separation with a carrier lifetime of 3.14 ns. The observed rate constant of the h- PTFE@TiO 2 NPs in the piezophototronic reaction reaches 0.1388 min⁻¹, which is 17 times that of the photocatalytic reaction (0.0084 min⁻¹) and 66 times that of the piezocatalytic reaction (0.0021 min⁻¹). Computational simulation reveals that large strain-induced space charge piezoelectric polarization induces an internal electric field between the unsaturated PTFE (fluorine vacancies) and TiO 2 surface. The piezopotential has a critical role in band bending at PTFE-TiO 2 interfaces to enhance the electron-hole separation when PTFE is constrained in TiO 2 shells. Results of piezoresponse force microscopy reveal that the piezoelectric coefficient d 33 of PTFE is approximately 79.77 pCN⁻¹. The findings provide insights into catalytic activity for environmental remediation. This study demonstrates the hydrothermal treatment of core-shell polytetrafluoroethylene (PTFE) nanoparticles decorated with TiO2; this material exhibits strain-induced local dipole enhancement of the space-charge piezopotential improves the photocatalytic effect. Computational simulation reveals that large strain-induced space charge piezoelectric polarization induces an internal electric field between the unsaturated PTFE (fluorine vacancies) and TiO2 surface. Considerable local dipole enhancement was observed in the fluorine vacancies of the PTFE, further enhancing the space-charge piezophototronic effect that benefits the performance of the material when used as a photocatalyst. [Display omitted] • Space charge piezoelectric polarization occurs between the fluorine vacancies of PTFE and TiO 2 surface. • The piezoelectric coefficient d 33 of PTFE is approximately 79.77 pCN⁻¹. • A local dipole enhancement of PTFE@TiO 2 photoinduced charge separation with a carrier lifetime of 3.14ns. • Piezopotential modulates the band bending at PTFE-TiO 2 interfaces to enhance electron-hole separation. [ABSTRACT FROM AUTHOR]