Synthesis and chlorine sensing properties of nanocrystalline hierarchical porous SnO 2 by a phenol formaldehyde resin-assisted process

Nanocrystalline tin dioxide (SnO2) materials with very interesting architectures (well-defined pores, hierarchical pores) were synthesized by a suitable heat treatment of SnO2/phenol formaldehyde resin (PFR) nanocomposite. The composite was obtained through a facile hydrothermal approach by using tin(IV) tetrachloride pentahydrate (SnCl4·5H2O) as a raw material, hexamethylenetetramine (HMT) as a pore-forming agent and monomer (HCHO) source for polymerization with phenol. Compared with the fine porous SnO2 sensor, the hierarchical porous SnO2 sensor showed a higher response. Owing to the hierarchical porous structure, the as-prepared materials exhibit satisfactory selectivity to chlorine along with high-sensitivity (249.3 at 10 ppm), fast response (7 s), very short recovery time (15 s), long-term stability as well as low power. The excellent sensing performance was discussed concerning the architectures of the materials.