Facile Synthesis of Hierarchical Tin Oxide Nanoflowers with Ultra-High Methanol Gas Sensing at Low Working Temperature

Abstract

In this work, the hierarchical tin oxide nanoflowers have been successfully synthesized via a simple hydrothermal method followed by calcination. The as-obtained samples were investigated as a kind of gas sensing material candidate for methanol. A series of examinations has been performed to explore the structure, morphology, element composition, and gas sensing performance of as-synthesized product. The hierarchical tin oxide nanoflowers exhibit sensitivity to 100 ppm methanol and the response is 58, which is ascribed to the hierarchical structure. The response and recovery time are 4 s and 8 s, respectively. Moreover, the as-prepared sensor has a low working temperature of 200 °C which is lower than that for other gas sensors of such type has been reported elsewhere. The excellent sensitivity of the sensor is caused by its complex phase mixture of SnO, SnO 2 , Sn 2 O 3 , and Sn 6 O 4 revealed by XRD analysis. The proposed hierarchical tin oxide nanoflowers gas sensing material is promising for development of methanol gas sensor. Graphical Abstract The as-obtained hierarchical tin oxide nanoflower (HTONF) gas sensor shows excellent gas-sensing performance at low working temperature (200 °C) and high annealing temperature (400 °C).

Improving Gas-Sensing Performance Based on MOS Nanomaterials: A Review

“…Their structure stability is better than that of zero-dimensional nanostructures. When these nanostructures are close to each other, the adsorption sites could be sheltered owing to their complex morphologies [ 39 , 44 , 45 ]. Thus, we need to prevent them from forming clusters and hindering the gas adsorption in the manufacturing process.…”

“…[33][34][35]. The morphology of nanostructures has been classified into four kinds: zero-dimensional nanostructures [33], one-dimensional nanostructures [36,37], two-dimensional nanostructures [38], and three-dimensional nanostructures [39]. Next, we will focus on several typical types of nanostructures.…”

Micro/nanostructured gas sensors: the physics behind the nanostructure growth, sensing and selectivity mechanisms

“…For example, a transition metal oxide like TiO 2 offers wide energy band gap of 3.0 eV, 3.2 eV and 3.14-3.40 eV for rutile and anatase, and brookite, respectively. [33][34][35][36][37] However, surface properties can be further improved by adding noble metals like Ag, Au, Pd and Pt for increasing reaction centre and reducing the activation energy required for oxidation and reduction of target species.…”

“…For example, anatase crystalline phase of TiO 2 (as shown in Figure 2b) are more reactive towards gas than the rutile crystallographic (shown in Figure 2a) whereas brookite is insensitive to gases. [33][34][35][36][37][38][39] Brookite and rutile crystallinity have more stable phase even at higher temperature. Therefore, a trade-off between sensor response and crystallographic phase necessitate one to choose based on the sensor application.…”

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