Silver nanoparticles modified two-dimensional polarizative PbTiO3 nanoplates with high active plane and improved NH3 sensitivity at low temperature

Two-dimensional (2D) perovskite PbTiO 3 is an important ferroelectric material with spontaneous polarization below Curie temperature and readily adsorbs oxygen molecules in the atmosphere, a preliminary step for NH 3 response. However, the surface of 2D PbTiO 3 lacks enough active adsorption sites for NH 3 gas. Here, 2D PbTiO 3 nanoplates (NLs) with highly polarized (0   0   1) plane was synthesized by a two-step hydrothermal strategy without templates and surfactants, and Ag + ions on (0   0   1) plane were further in-situ reduced by an impregnation method. Specially, the negatively polarized surface (ζ (zeta potential) =  −22.3 mV) for (0   0   1) plane promoted the reduction of Ag + ions in AgNO 3 solution to Ag 0 nanoparticles (NPs). Where, Ag NPs with high density on (0   0   1) plane can produce spillover effect, promoting adsorption of O 2 in air and subsequent formation of O 2− . The response of PbTiO 3 -based gas sensor to 100 ppm NH 3 is 3.6 at room temperature (25 °C), while the response is improved by 2.6 times on 1.5 at% Ag/PbTiO 3 NLs with Schottky junctions. Even at 15 °C, the response reaches to 6. The ammonia sensor based on Ag/PbTiO 3 NFs is verified with high sensitivity, fast response-recovery and distinct selectivity at low operating temperature.