The effect of noble metal (Au, Pd and Pt) nanoparticles on the gas sensing performance of SnO2-based sensors: a case study on the {221} high-index faceted SnO2 octahedra†
Abstract
Surface modification with noble metals is considered as an effective strategy to enhance sensitivity and selectivity of metal oxide-based gas sensors. This enhancement with noble metal decoration is generally attributed to the formation of a heterogeneous interface between the noble metal and metal oxide. However, the sensitization mechanism of noble metals on the specific facets of the metal oxide support lacks a unified understanding. In this work, three gas sensing hybrid nanostructures based on noble metal (Au, Pd and Pt) decorated {221} faceted octahedral SnO2 nanocrystals were specifically constructed. Our results showed that, on these {221} specific facets of SnO2, Au exhibited a positive effect for enhancing the sensitivity and selectivity of SnO2 sensors, while Pd and Pt played the opposite roles. It is considered that the sensitization effects of noble metals are related to their surface chemical states and interaction with the metal oxide support. The methodology demonstrated in this work is beneficial to probing into the sensitization mechanisms of noble metals in semiconductor/metal hybrid sensors.