In situ ex-solution of CoFeRu solid solution nanoparticles from non-stoichiometric (La0.8Sr0.2)0.9Co0.1Fe0.8Ru0.1O3−δ perovskite for hydrogen gas sensor

Ex-solution process is a novel technology to grow uniformly distributed highly catalytic nanoparticles (NPs) on the surface of parent metal oxide solid support and has been recently applied to diverse engineering applications. Here, we study the effect of CoFeRu NPs which are ex-solved on the surface of Ru-doped La0.8Sr0.2Co0.1Fe0.9O3−δ (LSCF) perovskite at reduction temperature 350-550 oC. The shape and size of decorated CoFeRu NPs on the surface of the (LSCFRu, La0.8Sr0.2Co0.1Fe0.8Ru0.1O3−δ) sensing layer was studied for controlled hydrogen gas sensing. The results show that the ex-solved LSCFRu sensor leads to an enhanced gas response, long-term stability, and a smaller limit of detection (LOD=0.05 ppm) against H2 gas exposure at 450 oC. The hydrogen gas sensing properties of ex-solved LSCFRu, La0.8Sr0.2Co0.1Fe0.8Ru0.1O3−δ, is (Ra/Rg = 55) after reduction at 450 oC was enhanced to 20-folds compared to un-doped LSCF with a detection limit of 0.05 ppm. The high gas response is ascribed to the catalytic effect of uniformly embedded CoFeRu NPs ex-solved via p-to-n type transition of the LSCFRu parent oxide after reduction. The concept demonstrated here may serve in the development of potential ex-solved perovskite sensors for advanced and reliable hydrogen gas sensing.