Synthesis and gas sensing properties of biomorphic SnO2 derived from loofah sponge and eggshell membrane

Abstract

Biomorphic SnO2 was synthesized through a sol–gel approach combined with an infiltration process and a calcination treatment. This synthesis route adopted loofah sponge (LS) and eggshell membrane (ESM) as a template respectively, which was proved low-cost and environmentally friendly. Based on TG/DTA analysis, the calcination temperature was decided to be 550 °C. XRD and TEM patterns confirmed the tetragonal rutile structure of SnO2. FESEM characterization revealed that the SnO2 fibers were made of nanoparticles (average particle size: ~8 nm) and faithfully duplicated the same confirmations of natural templates. The gas sensing properties of as-prepared SnO2 were investigated using different gases such as ethanol, methanol and acetone, etc. The optimal working temperature for LS-template SnO2 was 250 °C, which was relatively lower than the case of ESM-template SnO2 (300 °C). Compared with ESM-template SnO2, LS-template SnO2 showed higher response, better selectivity and stability to ethanol, which was mainly due to the three-dimensional, hierarchical and hollow structure. Synthesis mechanism and gas sensing mechanism of LS-template SnO2 were also discussed.