Dung Tran Phuong, Nguyen Nguyen Pham Tran, Chihaia Viorel, Son Do Ngoc
Department of Chemistry, University of Science, Vietnam National University Ho Chi Minh City Vietnam.
Department of Chemistry, Ho Chi Minh City University of Education Ho Chi Minh City Vietnam.
RSC Adv. 2025 Mar 26;15(12):9254-9264. doi: 10.1039/d5ra00814j. eCollection 2025 Mar 21.
The efficiency of the oxygen reduction reaction (ORR) on the cathode plays a crucial role in determining the performance of proton exchange membrane fuel cells. Porphyrin, distinguished by its cost-effectiveness, eco-friendly nature, and efficient utilization of its metal, stands out as a promising candidate for a metal single-atom catalyst in fuel cell cathodes. The metal and support modifications significantly impact the porphyrin's ORR activity. Nevertheless, the effects of Ni, Co, and Fe metals in tetramethyl metalloporphyrin/MoS, named MeTMP/MoS, catalyst on the mechanisms and activity of the ORR remain unknown. This study elucidates the topic using van der Waals dispersion-corrected density functional theory (DFT) calculations and thermodynamic model. Results showed that the rate-limiting step is located at the first and second hydrogenation steps in the associative mechanisms for Ni and Co (Fe) substitutions, respectively. For the dissociative mechanisms, the dissociation of molecular oxygen to two oxygen atoms is the rate-determining step on all the NiTMP/MoS, CoTMP/MoS, and FeTMP/MoS catalysts. The presence of the MoS support significantly reduces the thermodynamic activation barrier of the ORR, and hence improves the ORR activity in the dissociative mechanisms. This activation barrier is 3.45, 0.92, and 1.82 eV for NiTMP/MoS, CoTMP/MoS, and FeTMP/MoS, which is much better compared to 4.85, 3.34, and 2.19 eV for NiTMP, CoTMP, and FeTMP, respectively. CoTMP/MoS is the best candidate among the considered catalysts for the ORR. Furthermore, we provide a detailed explanation of the physical insights into the interaction between the ORR intermediates and the catalysts.
阴极上氧还原反应（ORR）的效率在决定质子交换膜燃料电池的性能方面起着至关重要的作用。卟啉以其成本效益、环境友好性以及对金属的高效利用而著称，是燃料电池阴极金属单原子催化剂的一个有前景的候选材料。金属和载体修饰对卟啉的ORR活性有显著影响。然而，四甲基金属卟啉/MoS（称为MeTMP/MoS）催化剂中Ni、Co和Fe金属对ORR的机理和活性的影响仍然未知。本研究使用范德华色散校正密度泛函理论（DFT）计算和热力学模型阐明了这一主题。结果表明，限速步骤分别位于Ni和Co（Fe）取代的缔合机理中的第一步和第二步氢化步骤。对于解离机理，分子氧分解为两个氧原子是所有NiTMP/MoS、CoTMP/MoS和FeTMP/MoS催化剂上的速率决定步骤。MoS载体的存在显著降低了ORR的热力学活化能垒，从而提高了解离机理中的ORR活性。NiTMP/MoS、CoTMP/MoS和FeTMP/MoS的这一活化能垒分别为3.45、0.92和1.82 eV，与NiTMP、CoTMP和FeTMP的4.85、3.34和2.19 eV相比要好得多。CoTMP/MoS是所考虑的ORR催化剂中最佳的候选材料。此外，我们对ORR中间体与催化剂之间相互作用的物理见解提供了详细解释。
