Enhancing the Stability of a Pt-Free ORR Catalyst via Reaction Intermediates,Advanced Materials Interfaces

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Enhancing the Stability of a Pt-Free ORR Catalyst via Reaction Intermediates
Advanced Materials Interfaces ( IF 4.3 ) Pub Date : 2023-02-17 , DOI: 10.1002/admi.202202132
Naomi Helsel ₁ , Pabitra Choudhury ₁

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Finding a platinum-free cathode catalyst that effectively models the oxygen reduction reaction (ORR) of a proton-exchange membrane (PEM) fuel cell cathode better than the current commercial Pt/C catalyst has been a major shortcoming in fuel cell technology. Overall, a promising platinum-free cathode catalyst must offer great ORR activity, ORR selectivity, and acid stability. Due to their enticing ORR activity and selectivity to the preferred four-electron ORR pathway, the possible dissolution reactions and oxygen-intermediate reactions of iron phthalocyanine monolayer supported on a pristine graphene (GFePc) and boron-doped graphene substrate (BGFePc) have been studied to determine the stability as a function of potential and pH through spin-polarized density functional theory (DFT) calculations at both infinitesimally low (10⁻⁹m) and 1 m Fe²⁺/Fe³⁺ ionic concentrations. BGFePc offers higher stability in both concentrations than GFePc. In both cases, the oxygen-intermediates are more stable than the bare catalytic surface due to the metal d-band center shifting further away from the Fermi level in the valence band state (higher energy of antibonding). Moreover, at an Fe²⁺ ionic concentration, both catalysts would be stable in the potential and pH regions at the operating conditions of rotating disk electrode (RDE) experiments and PEM fuel cells.

中文翻译：

通过反应中间体提高无 Pt ORR 催化剂的稳定性

寻找一种比目前商用 Pt/C 催化剂更好地有效模拟质子交换膜 (PEM) 燃料电池阴极氧还原反应 (ORR) 的无铂阴极催化剂一直是燃料电池技术的主要缺点。总的来说，一种有前途的无铂阴极催化剂必须具有出色的 ORR 活性、ORR 选择性和酸稳定性。由于它们诱人的 ORR 活性和对首选四电子 ORR 途径的选择性，研究了负载在原始石墨烯 (GFePc) 和硼掺杂石墨烯基板 (BGFePc) 上的铁酞菁单层可能的溶解反应和氧中间反应通过自旋极化密度泛函理论 (DFT) 计算在无限低 (10^-9m ) 和 1 m Fe ²⁺ /Fe ³⁺离子浓度。BGFePc 在两种浓度下均比 GFePc 具有更高的稳定性。在这两种情况下，由于金属 d 带中心在价带状态下远离费米能级（更高的反键能），因此氧中间体比裸露的催化表面更稳定。此外，在 Fe ²⁺离子浓度下，两种催化剂在旋转圆盘电极 (RDE) 实验和 PEM 燃料电池的操作条件下的电位和 pH 范围内都是稳定的。

更新日期：2023-02-17

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