Shape and composition effects of PdPt bimetallic nanocrystals on hydrogen sensing properties of SnO2 based sensors

Abstract

The efficient detection of hydrogen leakage is important for the development of hydrogen economy. Semiconductor-based hydrogen sensors still suffer from high temperature and low detection rate. Here, a hydrogen sensor using PdPt nanocrystals with different morphologies such as nano-octahedron, nanocube and nanoflower as sensitizers is proposed. The experimental results demonstrate that PdPt/SnO2 materials exhibit shape-dependent H2 sensing performances, and the response order is NOS (PdPt nano-octahedrons modified SnO2) > NCS (PdPt nanocubes modified SnO2) > NFS (PdPt nanoflowers modified SnO2). The superior H2 sensing characteristics of NOS can be ascribed to the higher catalytic activity of {111} facet of PdPt nanocrystals than {100} facet and abundant oxygen defects. Apart from the shape effect, the atomic ratio of Pd to Pt also affects the H2 sensing capability of PdPt/SnO2. Especially, NOS-3 (Pd3Pt nano-octahedrons modified SnO2) exhibits a superfast response/recovery rate (1/8 s) and ultrahigh response (22821) to 1000 ppm H2 at 25 ℃, which is superior to the MOS-based H2 sensing materials reported so far in terms of operating temperature, response speed and response value. This study establishes a practicable strategy for ultrafast detection of H2 at room temperature.