Vapor–Solid Growth of p‑Te/n-SnO₂ Hierarchical Heterostructures and Their Enhanced Room-Temperature Gas Sensing Properties

Abstract

We have synthesized brushlike p-Te/n-SnO₂ hierarchical heterostructures by a two-step thermal vapor transport process. The morphologies of the branched Te nanostructures can be manipulated by adjusting the source temperature or the argon flow rate. The growth of the branched Te nanotubes on the SnO₂ nanowire backbones can be ascribed to the vapor–solid (VS) growth mechanism, in which the inherent anisotropic nature of Te lattice and/or dislocations lying along the Te nanotubes axis should play critical roles. When exposed to CO and NO₂ gases at room temperature, Te/SnO₂ hierarchical heterostructures changed the resistance in the same trend and exhibited much higher responses and faster response speeds than the Te nanotube counterparts. The enhancement in gas sensing performance can be ascribed to the higher specific surface areas and formations of numerous Te/Te or TeO₂/TeO₂ bridging point contacts and additional p-Te/n-SnO₂ heterojunctions