Lanthanum-Induced Quasi-Covalent Bonding and Chemical Potential Bridging in Pt ₃ Co Intermetallic Catalysts for Durable Fuel Cells

Pt-based intermetallic compounds represent the most promising catalysts for oxygen reduction reaction (ORR). However, they still face stability challenges, primarily due to component segregation and oxidation/dissolution of both transition metal and Pt atoms under harsh electrochemical conditions. Herein, we strategically incorporate electron-donating La into the L1 2 -Pt 3 Co intermetallic catalyst to steer a quasi-covalent Pt–M interaction and bridge the core–shell chemical potential gradient, enhancing ORR durability. Combined experimental and theoretical analyses elucidate that the transition from metallic to quasi-covalent bonding strengthens Pt–Co/La interactions, which effectively suppresses Pt leaching. Furthermore, La-mediated electronic modulation reduces the core–shell chemical potential difference, thus inhibiting Co migration from the core to the outermost surface and the subsequent oxidative dissolution. Due to these properties, the as-developed catalyst demonstrates high ORR activity under H 2 –air conditions, achieving a peak power density of 1.27 W cm –2 and high mass activity (MA) of 1.29 A mg Pt –1 . More importantly, it exhibits exceptional stability with 87% MA retention and only 12 mV voltage loss at 0.8 A cm –2 after 30k accelerated durability cycles, outperforming DOE 2026 targets (60% MA retention and voltage loss <30 mV). This study proposes a new structural engineering strategy for enhancing catalytic robustness in harsh electrochemical environments.