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In this work, an obvious enhancement of pyroelectrically-driven catalytic activity is found in BaTiO3@ZnO heterostructures synthesized hydrothermally and then calcined. The pure BaTiO3 is able to decompose up to 45% of the RhB dye in aqueous solution (5 mg/L) under 30–54 °C cold-hot cycle. As the ZnO content coating on the surface of the BaTiO3 nanofibers is increased from 0 to 5 wt%, the decomposition ratio of the BaTiO3@ZnO heterostructures for RhB dye in aqueous solution first increases and then decreases, giving a maximum value of 97% at 2.5 wt%. The kinetic rate constant (K = 0.06384 cycle−1) of the catalytic reaction for BaTiO3 @2.5%ZnO is 4 times higher than that of pure BaTiO3. The enhancement of catalytic activity of BaTiO3@ZnO may be due to the formation of a semiconductor junction in which the electric field effectively separating the pyro-induced electron-hole pairs and further accelerates carrier migration. The ferroelectric heterostructures of BaTiO3@ZnO show pyroelectrically-driven-catalysis and may hold potential for use in decomposing dye wastewater through harvesting cold-hot alternation thermal-energy.

ZnO is one of the most promising materials for both photocatalytic and antibacterial applications, but its wide bandgap requires the excitation of UV light which limits their applications under visible and NIR bands. Herein, we demonstrate a facile approach to synthesize core-shell-shell hybrid nanoparticles consisting of hexagonal NaYF4:Yb,Tm, amorphous SiO2 and wurtzite ZnO. The upconversion nanocrystals are used as the core seeds and sequentially coated with an insulting shell and a semiconductor layer. Such hybrid nanoparticles can efficiently utilize the NIR light through the upconverting process, and display notable photocatalytic performance and antibacterial activity under NIR irradiation. The developed NaYF4:Yb,Tm@SiO2@ZnO nanoparticles are characterized with TEM, XRD, EDS, XPS and PL spectra, and their working mechanism is also elucidated.