Gas sensor based on Ni foam: SnO2-decorated NiO for Toluene detection

Dense nickel oxide layer on Ni foam was prepared via a facile heating method and SnO2 nanostructures was attached to NiO through a simple dip-coating process. Construction of optimized SnO2 thin layer, which achieved by rationally adjusting of dip-coating times of Sn(OH)4, leads to a prominently enhanced sensing properties to toluene. The sensor based on NiO foam with two times of dip-coating of SnO2 exhibits the best sensing performances with 9 and 8 seconds of response and recover time and a drastic selective response (Ra/Rg = 19.2) to 10 ppm toluene at 210 °C. Furthermore, an excellent linear dependence and a 30-day measurement with little decrease on response were observed. The superior sensing behavior of toluene and relevant sensing mechanism was explained by a large surface area of NiO foam, a unique structural sensitization and a common p-n heterojunction effect.