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 TiO2 (h-PTFE@TiO2); 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 TiO2-PTFE interface. The h-PTFE@TiO2 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@TiO2 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 TiO2 surface. The piezopotential has a critical role in band bending at PTFE-TiO2 interfaces to enhance the electron-hole separation when PTFE is constrained in TiO2 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.

Automated summary

This study demonstrates the hydrothermal treatment of core-shell polytetrafluoroethylene (PTFE) nanoparticles decorated with TiO2 (h-PTFE@TiO2). The material exhibits enhanced photocatalytic effect due to the strain-induced local dipole enhancement of the space-charge piezopotential. The h-PTFE@TiO2 nanoparticles show exceptionally high catalytic activity in organic dye degradation.