Flame-spray-made metal-loaded semiconducting metal oxides thick films for flammable gas sensing

Flame spray pyrolysis (FSP) presents a new technique for metal (Pt, Sn, Ru, Nb and W)-loaded metal oxide (MOX) nanoparticle synthesis, which requires only a single step. FSP prepared MOX nanoparticles have recently widely employed for gas-sensing applications. In this work, the performance towards flammable gases of unloaded and metal (Pt, Sn, Ru, Nb and W)-catalyzed metal oxide (ZnO, WO3, SnO2 and TiO2) nanoparticle thick films fabricated by FSP and spin-coating is reviewed, discussed and compared to MOXs prepared by other methods. The gas-sensing characteristics towards H2, CH4, C2H2, C2H4, C2H5OH and CO gases of FSP-prepared MOXs are found to be significantly improved in terms of response, response time and selectivity with small Pt, Sn, Ru, Nb and W loading contents ranging from 0.2 to 5 mol% or at.%. In addition, Pt loading on WO3 and ZnO sensors results in excellent detection performances towards several flammable gases including H2, CH4 and C2H2.