Preparation of LaCoO3 catalytic thin film by the sol–gel process and its NO decomposition characteristics

LaCoO3 and LaMnO3 gel films were deposited by dip-coating technique on yttria-stabilized zirconia (YSZ) substrate using the precursor solution prepared from La(O-i-C3H7)3, Co(CH3COO)2 or Mn(O-i-C3H7)2, 2-methoxyethanol, and polyethylene glycol. By heat-treating the gel films, electrochemical cells, LaCoO3|YSZ|LaCoO3 were fabricated. The effect of polyethylene glycol on the microstructure evolution of LaCoO3 and LaMnO3 thin films was investigated, and NO decomposition characteristics of LaCoO3 powders and the electrochemical cells were investigated at 600–800°C. In the absence of oxygen, the LaCoO3 powder was active both in decomposition of NO and reduction of NO by C2H4. It was found that they lost their catalytic activity in the presence of 2% oxygen. By applying a direct current to LaCoO3|YSZ|LaCoO3 electrochemical cell, a good NO conversion rate could be obtained at relatively low current value even if excess oxygen is included in the reaction gas mixture.