Synthesis of porous SnO2 foams on SiO2/Si substrate by electrochemical deposition and their gas sensing properties

3-Dimensionally porous tin oxide (SnO2) foams were fabricated by an electrochemical deposition and their application for gas sensors was investigated. The electrochemical deposition was carried out in an electrolyte containing sulfuric acid and tin sulfate, and Sn film-coated SiO2/Si substrate was used as a cathode instead of conventional metal foil, which was deposited by a thermal evaporation. The porous Sn foam structure was formed during electrodeposition and its pore wall was composed of self-supported networked dendrites. The annealing at 700 °C converted the Sn foam into the corresponding metal oxide (SnO2) foam with preserving the structural integrity and pore structure. The porous SnO2 foam sensors responded to H2, CO, NH3, NOx, and C2H5OH gases. In particular, the foam sensors showed a significantly higher gas response toward C2H5OH, and the response time and working temperature were improved due to the rapid gas diffusion through 3D interconnected open porous structure.