Enhanced piezotronics by single-crystalline ferroelectrics for uniformly strengthening the piezo-photocatalysis of electrospun BaTiO3@TiO2 nanofibers

Abstract

Turning the built-in electric field by modulating the morphology and microstructure of ferroelectric materials is considered a viable approach to enhancing the piezo-photocatalytic activity of the ferroelectric/oxide semiconductor heterojunctions. Here, hydrothermally synthesized single-crystalline BaTiO₃ nanoparticles are employed to construct BaTiO₃@TiO₂ hybrid nanofibers by sol–gel assisted electrospinning of TiO₂ nanofibers and annealing. Because of the obvious enhancement of the synergetic piezo-photocatalytic effect under both ultrasonic and ultraviolet (UV) light irradiation, the piezo-photocatalytic degradation rate constant (k) of BaTiO₃@TiO₂ hybrid nanofibers on methyl orange (MO) reaches 14.84 × 10⁻² min⁻¹, which is approximately seven fold that for piezocatalysis and six fold that for photocatalysis. Moreover, BaTiO₃@TiO₂ core–shell nanoparticles are also synthesized for comparison purposes to assess the influence of microstructure on the piezo-photocatalysis by a wet-chemical coating of TiO₂ on BaTiO₃ nanoparticles. Such a high piezo-photocatalytic activity is attributed to the enhancement of the piezotronic effect by the single-crystalline ferroelectric nanoparticles and the nanoconfinement effect caused by the one-dimensional boundary of nanofibers with high specific surface areas. The mechanically induced uniform local built-in electric fields originated from the single-crystalline ferroelectric nanoparticles can enhance the separation of photogenerated electron and hole pairs and promote the formation of free hydroxyl radicals, resulting in a strong piezotronic effect boosted photochemical degradation of organic dye. This work introduces the single-crystalline ferroelectrics to construct ferroelectric/oxide semiconductor heterojunctions, and the enhanced local piezotronic effect uniformly strengthens the photochemical reactivity, which offers a new option to design high-efficiency piezo-photocatalysts for pollutant treatment.