在质子交换膜燃料电池中通过 Zr 掺杂促进 ZIF-8 衍生的 Fe-N-C 氧还原催化剂：耐久性和活性增强,ACS Catalysis

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在质子交换膜燃料电池中通过 Zr 掺杂促进 ZIF-8 衍生的 Fe-N-C 氧还原催化剂：耐久性和活性增强
ACS Catalysis ( IF 11.3 ) Pub Date : 2023-03-13 , DOI: 10.1021/acscatal.2c06118
Bin Chi ₁ , Longhai Zhang ₁ , Xiaoxuan Yang ₂ , Yachao Zeng ₂ , Yijie Deng ₃ , Mingrui Liu ₁ , Junlang Huo ₁ , Chaozhong Li ₁ , Xiaorong Zhang ₁ , Xiudong Shi ₁ , Yijia Shao ₁ , Lin Gu ₄ , Lirong Zheng ₅ , Zhiming Cui ₁ , Shijun Liao ₁ , Gang Wu ₂

Affiliation

原子分散的铁位点和氮共掺杂碳催化剂 (Fe-N-C) 在质子交换膜燃料电池的酸中取代 Pt 进行氧还原反应 (ORR) 方面表现出良好的性能。然而，Fe-N-C 催化剂的耐久性不足严重阻碍了它们的实际应用。在此，我们报道了将 Zr 和 Fe 双金属位点共掺杂到 ZIF-8 衍生的中孔碳中显示出显着改善的 ORR 耐久性。特别是，来自 ORR 阴极催化剂的膜电极组件在恒定电流密度下连续运行 20 小时后仅损失 25% 的电压。经过长达 100 小时的延长测试后，Zr 掺杂的 Fe-N-C 催化剂保留了其初始性能的 40%，优于未掺杂 Zr 的催化剂，仅 20 小时后活性损失超过 70%。阴极还显示出显着改善的 ORR 活性，实现了 0.72 W cm 的最大功率密度^–2在 H ₂ /空气条件下。广泛的实验表征和密度泛函理论计算表明，促进的催化活性和稳定性是由于形成了 Zr 基活性位点，与单个 Fe 位点相比具有增强的酸性耐受性。_{此外，Zr 的掺杂可以抑制 H 2} O ₂和其他自由基的形成，从而减轻活性位点的降解。可能的 Fe/Zr 双金属活性位点，即 N ₂ (N)–Fe–N ₂ –Zr–N ₂ (O ₂ )，相对于传统的 FeN _x位点，可能具有增强的固有 ORR 活性。

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Promoting ZIF-8-Derived Fe–N–C Oxygen Reduction Catalysts via Zr Doping in Proton Exchange Membrane Fuel Cells: Durability and Activity Enhancements

The atomically dispersed iron site and nitrogen co-doped carbon catalysts (Fe–N–C) have demonstrated promising performance in replacing Pt toward the oxygen reduction reaction (ORR) in acids for proton exchange membrane fuel cells. However, the insufficient durability of Fe–N–C catalysts prohibitively hinders their practical applications. Herein, we report that the co-doping of Zr and Fe dual metal sites into a ZIF-8-derived mesoporous carbon exhibited significantly improved durability for the ORR. Especially, a membrane electrode assembly from the ORR cathode catalyst only lost 25% voltage after 20 h of continuous operation at a constant current density. After an extended test of up to 100 h, the Zr-doped Fe–N–C catalyst retained 40% of its initial performance, superior to the catalyst without Zr doping with more than 70% activity loss after only 20 h. The cathode also showed significantly improved ORR activity, achieving a maximum power density of 0.72 W cm^–2 under H₂/air conditions. Extensive experimental characterization and density functional theory calculations suggested that the promoted catalytic activity and stability are due to the formation of Zr-based active sites with enhanced acidic tolerance than the individual Fe sites. Also, the doping of Zr could suppress the formation of H₂O₂ and other free radicals, thus mitigating active site degradation. The possible Fe/Zr dual-metal active sites, i.e., N₂(N)–Fe–N₂–Zr–N₂(O₂), likely have enhanced intrinsic ORR activity relative to conventional FeN_x sites.

更新日期：2023-03-13

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