Cr- and Ti-Based Spinels as Materials for Anodic Catalyst Support in PEM Electrolysis Cells: Assessing Corrosion Stability and Support Role in Catalyst Activity of Corrosion Stable Ceramics

摘要

This work aims to determine the stability of Cr- and Ti-based spinels as catalyst supports for oxygen evolution reaction (OER) catalyst in PEM electrolyzers (PEMECs). Different compositions of MCr_2O_4 (M=Ni, NiFe, Zn, Mg) and MTi_2O_4 (Li, Mg, Mn) have been synthesized by solid state synthesis. Pure and doped Cr-based spinels exhibit low conductivities at the operating temperatures of PEMECs (<10~(-4) S cm~(-1)), while Ti-based spinels showed very high conductivities at room temperature (～10-100 S cm~(-1)). Cr-spinels proved to be very stable to chemical corrosion testing, while Ti-spinels manifested substantial weight loss. The most promising materials (LiTi_2O_4, MnCr_2O_4, Cu-MnCr_2O_4) showed redox activity at potentials >1.5 V vs SHE. LiTi_2O_4 is completely oxidized upon cycling up to 2.0 V vs SHE. Mixtures of IrO_2/oxide support deposited on glassy carbon were tested toward OER, which showed a 10% higher absolute current at 2.0 V vs SHE in the case of IrO_2/Cu-MnCr_2O_4 compared with pure IrO_2.