Stabilization of potassium ferrate cathodic material coated with tetraphenylporphyrin

In this paper, K2FeO4 cathodes were coated with tetraphenylporphyrin (TPP) to improve their stability. Analyses involving a scanning electron microscope (SEM), an energy dispersive spectrometer (EDS) and Fourier transform infrared spectroscopy (FT-IR) indicated that the K2FeO4 cathodes were successfully coated with the TPP overlayer. Discharge performance tests were conducted after soaking the cathodes in a 10 M KOH electrolyte for 0–6 h. The discharge properties of the 8 wt% TPP coated K2FeO4 cathodes indicated that they were stable, and their discharge capacity increased to 160 mAh g−1 from 75 mAh g−1 for the uncoated electrodes after soaking in a 10 M KOH electrolyte solution for 6 h. In addition, adding 5 wt% sodium bismuthate (NaBiO3) to the tetraphenylporphyrin coated K2FeO4 electrode can further improve its discharge performance by increasing the discharge capacity from 275 mAh g−1 to 316 mAh g−1.