CO‐Tolerant PEMFC Anodes Enabled by Synergistic Catalysis between Iridium Single‐Atom Sites and Nanoparticles

Abstract

Proton‐exchange membrane fuel cells (PEMFCs) are limited by their extreme sensitivity to trace‐level CO impurities, thus setting a strict requirement for H2 purity and excluding the possibility to directly use cheap crude hydrogen as fuel. Herein, we report a proof‐of‐concept study, in which a novel catalyst comprising both Ir particles and Ir single‐atom sites (IrNP@IrSA‐N‐C) addresses the CO poisoning issue. The Ir single‐atom sites are found not only to be good CO oxidizing sites, but also excel in scavenging the CO molecules adsorbed on Ir particles in close proximity, thereby enabling the Ir particles to reserve partial active sites towards H2 oxidation. The interplay between Ir nanoparticles and Ir single‐atom centers confers the catalyst with both excellent H2 oxidation activity (1.19 W cm−2) and excellent CO electro‐oxidation activity (85 mW cm−2) in PEMFCs; the catalyst also tolerates CO in H2/CO mixture gas at a level that is two times better than that of the current best PtRu/C catalyst.

High CO-Tolerant Ru-Based Catalysts by Constructing an Oxide Blocking Layer

“…So far, although a variety of noble metal catalysts have been exploited, 12,16−18,21−24 few of them can work stably for the HOR current at a potential lower than 0.10 V under 100−1000 ppm of CO impurity in rotating disk electrode (RDE) tests. Moreover, in PEMFC tests, even 20 ppm of CO in H 2 will cause a significant degradation of Ptbased catalysts within 1 h. 6 Recently, Ru-based 25 and Irbased 26,27 HOR catalysts have been developed, exhibiting evidently enhanced CO tolerance compared with Pt-based catalysts. However, the HOR stability under a CO environment beyond 1 h is still a great challenge in this field, which impedes the application in PEMFCs.…”

“…Moreover, in PEMFC tests, even 20 ppm of CO in H 2 will cause a significant degradation of Pt-based catalysts within 1 h . Recently, Ru-based and Ir-based , HOR catalysts have been developed, exhibiting evidently enhanced CO tolerance compared with Pt-based catalysts. However, the HOR stability under a CO environment beyond 1 h is still a great challenge in this field, which impedes the application in PEMFCs.…”

Facile synthesis of cobalt cluster-CoNx composites: synergistic effect boosts electrochemical oxygen reduction

“…Therefore, superior ORR performance of Co/CoN x -C with optimal 15 wt% Co composition should be mainly attributed to the good dispersion of Co species and the synergistic effect of CoN x sites and metallic Co clusters. [54][55][56][57] More importantly, the E 1/2 value of 15-Co/CoN x -C outperformed the commercial Pt/C (E 1/2 : 0.840 V vs. RHE) and the representative Co-based non-noble metal electrocatalysts towards ORR in alkaline media (Table S4 †). Notably, N-C shows a high HO 2…”

Recent Advances of Single‐Atom‐Alloy for Energy Electrocatalysis

“…Recently, the carbon supports doped with metallic single atoms, deliver a promoting effect on supported nanoparticles in several electrocatalytic reactions, which is lacked on the common carbon or N-doped carbon supports. For example, Yang et al [54] found that Ir NP @Ir SA -N-C catalysts with Ir single atoms and nanoparticles are highly active for hydrogen oxidation reaction in H 2 /CO mixture, while carbon-supported Ir and Pt nanoparticles are inactive due to the poisoning of CO. The Ru single atoms anchored by N-doped C and Ru or Ru alloyed nanoparticles also showed synergistic effects in promoting the HER activity.…”