oa Comparative Short-Term Stability of TiO2- and SiO2-Coated Fuel-Cell Catalysts in Acid Electrolytes: A Systematic Review

Fuel cells for heavy-duty applications have garnered significant attention. Decades of advancements in stable oxygen reduction reaction (ORR) catalysts must now be leveraged to meet the increased cyclability demands of the heavy-duty vehicle market. The deposition of metal oxide coatings on Pt-based catalysts for ORR is hypothesized to balance high initial surface area with short-term electrochemical surface area (ECSA) retention in acid electrolytes. To explore this potential, a literature review covering 2001–2023 was conducted. Between-study heterogeneity was assessed through regression analyses at a 5% significance level. A total of 24 studies evaluated the electrochemical properties of metal oxide-coated Pt-based catalysts. Regression analyses indicated that 4-9 wt.% TiO2-coated catalysts on thin-film rotating disk electrodes degrade in a systematic manner, making their properties more predictable. In contrast, 11-55 wt.% SiO2-coated catalysts exhibited higher active surface area retention in comparison to TiO2-coated catalysts but with less consistency. Our findings suggest that thinner, atomically-grown MO2-type metal oxide coatings with more ionic M–O bonds, such as TiO2, provide the optimal balance between active site accessibility and catalyst stability under potential cycling. Furthermore, metal oxide coating shows potential for protecting and stabilizing platinum particles against dissolution and coalescence, presenting a promising avenue for further research to optimize ORR activity and long-term performance.