Direct Electrolysis Of CO₂ Based On Titanate Composite Cathode

Because the current efficiency based on perovskite titanate cathode for high temperature electrolysis of CO2 is low, this paper investigates the redox active element doped titanate, which set as a cathode of solid oxide electrolysis cell for direct electrolysis of CO2. On the one hand, the reversible exsolution of metal nanoparticle is achieved with anchored particles on the surface of titanate for enhancing the electrocatalytic activity of the cathode. On the other hand, the redox active element is introduced into the titanate to create oxygen vacancies in situ after high temperature reduction, chemical adsorption of CO2 by oxygen vacancies for improving the efficiency of CO2 electrolysis.Firstly, the paper indicates the reversible exsolution of Ni nanocatalyst anchored on the surface of La0.3Sr0.7TiO3 to enhance the electrocatalytic activity of the composite cathode. The synergetic effects of the Ni nanocatalyst and the redox-stable titanate contribute to the improved performance for direct CO2 electrolysis, the current efficiency with Ni-anchored titanate can be accordingly enhanced by 15% in contrast to the bare titanate with CO2 gas flowing over the cathode at 800℃. Secondly, it shows that the redox active Mn or Cr is introduced into the B site of redox stable perovskite Sr0.95Ti0.9Nb0.1O3 to create oxygen vacancies on the surface of sample. On the one hand, the ionic conductivities are improved; in addition, the high performance of adsorption of CO2 molecules is enhanced largely. The electrode polarizations and current efficiencies are observed to be significantly improved with the Mn or Cr doped titanate cathodes. Finally, the coupling of surface oxygen vacancies with nano-size metal can effectively improve the catalytic activity of heterogeneous catalysts, the high concentration of oxygen vacancies are created in Mn doped titanate cathode, then Fe nanoparticles are exsolved to anchor on the titanate surface and combine the surface oxygen vacancies to form heterogeneous catalysis clusters, which set as a cathode of solid oxide electrolysis cell for efficient electrolysis of CO2, the current efficiency reaches as high as 92%.