Highly active and durable platinum group metal-free catalysts for the oxygen reduction reaction, such as Fe–N–C materials, are needed to lower the cost of proton-exchange membrane fuel cells. However, their durability is impaired by the attack of oxidizing radicals such as ·OH and HO₂· that form from incomplete reduction of O₂ via H₂O₂. Here we demonstrate that Ta–TiO_x nanoparticle additives protect Fe–N–C catalysts from such degradation via radical scavenging. The 5 nm Ta–TiO_x nanoparticles were uniformly synthesized on a Ketjenblack substrate using a high-temperature pulse technique, forming the rutile TaO₂ phase. We found that Ta–TiO_x nanoparticles suppressed the H₂O₂ yield by 51% at 0.7 V in an aqueous rotating ring disk electrode test. After an accelerated durability test, a fuel cell prepared with the scavengers showed a current density decay of 3% at 0.9 V_iR-free (internal resistance-compensated voltage); a fuel cell without scavengers showed 33% decay. Thus, addition of Ta–TiO_x provides an active defence strategy to improve the durability of oxygen reduction reaction catalysts.

需要用于氧还原反应的高活性和耐用的无铂族金属催化剂，例如 Fe-N-C 材料，以降低质子交换膜燃料电池的成本。然而，它们的耐久性会受到氧化自由基如·OH 和HO _{2 · 的攻击，这些自由基是由O 2}通过H ₂ O ₂不完全还原而形成的。在这里，我们证明了 Ta-TiO _x纳米颗粒添加剂可通过自由基清除保护 Fe-N-C 催化剂免受此类降解。使用高温脉冲技术在 Ketjenblack 基板上均匀合成5 nm Ta-TiO _{x纳米颗粒，形成金红石 TaO 2}相。我们发现 Ta-TiO _x在水性旋转环盘电极测试中，纳米粒子在 0.7 V 下将 H ₂ O _{2产率抑制了 51%。}在加速耐久性试验后，用清除剂制备的燃料电池在 0.9 V _iR-free（内阻补偿电压）下电流密度衰减 3%；没有清除剂的燃料电池显示出 33% 的衰减。因此，添加 Ta-TiO _x为提高氧还原反应催化剂的耐久性提供了一种主动防御策略。