Efficient bifunctional cerium-zeolite electrocatalysts for oxygen evolution and oxygen reduction reactions in alkaline media

Four cerium-zeolites were examined as low-cost bifunctional electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in an alkaline solution. Cerium-exchanged zeolites, synthetic 13X and natural clinoptilolite were employed as prepared and calcined (cal). Four samples (Ce-13X cal, Ce-13X, CeCli cal, and Ce-Cli) were characterized by X-ray powder diffraction analysis (XRPD), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR) spectroscopy, fluorescence spectroscopy and Brunner-Emmet-Teller (BET) method. All four zeolites exhibited activity for the two studied reactions. Ce-13X cal gave the lowest onset potential accompanied by the highest OER current density. Furthermore, Ce-13X cal showed the most positive ORR onset potential value of 0.84 V and the most positive ORR half-wave potential of 0.75 V (ca. 50 mV more positive than value for the other three cerium-zeolite electrodes) accompanied by the lowest Tafel slope of 80 mV dec 1. Koutecky-Levich analysis indicated that ORR follows 2-electron pathway. Overall, Ce-13X cal showed the best OER/ORR performances in alkaline solution.

Automated summary

Four cerium-zeolites were tested as economical bifunctional electrocatalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) in an alkaline solution. Characterization of the four samples was carried out using various methods, and all four zeolites exhibited activity for the studied reactions. Ce-13X cal showed the best performance in terms of OER/ORR, with the lowest onset potential, highest current density for OER, and positive onset and half-wave potentials for ORR.