Enhanced piezotronics by single-crystalline ferroelectrics for uniformly strengthening the piezo-photocatalysis of electrospun BaTiO 3 @TiO 2 nanofibers.

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 BaTiO 3 nanoparticles are employed to construct BaTiO 3 @TiO 2 hybrid nanofibers by sol-gel assisted electrospinning of TiO 2 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 BaTiO 3 @TiO 2 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, BaTiO 3 @TiO 2 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 TiO 2 on BaTiO 3 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.