Composite Cathode based on Mn-doped Perovskite Niobate-Titanate for Efficient Steam Electrolysis

Redox-active Mn is introduced into the B site of redox-stable perovskite niobate-titanate to improve the electrocatalytic activity of composite cathode in an oxide-ion-conducting solid oxide electrolyzer. The XRD and XPS results reveal the successful partial replacement of Ti/Nb by Mn in the B site of niobate-titanate. The ionic conductivities of the Mndoped niobate-titanate are significantly improved by approximately 1 order of magnitude in reducing atmosphere and 0.5 order of magnitude in oxidizing atmosphere compared with bare niobate-titanate at 800 oC. The current efficiency for Mn-doped niobate-titanate cathode is accordingly enhanced by ～25% and 30% in contrast to the bare cathode with and without reducing gas flowing over the cathode under the applied voltage of 2.0 V at 800 oC in anoxide-ion-conducting solid oxide electrolyzer, respectively.