Breaking the Pt Electron Symmetry and OH Spillover towards PtIr Active Center for Performance Modulation in Direct Ammonia Fuel Cell

• Published in: Small (Weinheim an der Bergstrasse, Germany) Germany), 2024-12, Vol.20 (49), p.e2406589-n/a
• Main Authors: Barik, Sidharth, Kharabe, Geeta Pandurang, Samal, Pragnya Paramita, Urkude, Rajashri R., Kumar, Sachin, Yoyakki, Athira, Vinod, C. P., Krishnamurty, Sailaja, Kurungot, Sreekumar
• Format: Article
• Language: English
• Subjects: Ammonia; ammonia oxidation reaction (AOR); Boehmite; Catalysts; Chemical synthesis; Dehydrogenation; density functional theory (DFT) study; direct ammonia fuel cells; d‐band center; Electrodes; Fuel cells; Graphene; hydroxyl spillover effect; Nanoalloys; XAS analysis
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202406589

The growing interest in low‐temperature direct ammonia fuel cells (DAFCs) arises from the utilization of a carbon‐neutral ammonia source; however, DAFCs encounter significant electrode overpotentials due to the substantial energy barrier of the *NH2 to *NH dehydrogenation, compounded by the facile deactivation by *N on the Pt surface. In this work, a unique catalyst, Pt4Ir@AlOOH/NGr i.e., Pt4Ir/ANGr, is introduced composed of PtIr alloy nanoparticles controllably decorated on the pseudo‐boehmite phase of AlOOH‐supported nitrogen‐doped reduced graphene (AlOOH/NGr) composite, synthesized via the polyol reduction method. The detailed studies on the structural and electronic properties of the catalyst by XAS and VB‐XPS reveal the possible electronic modulations. The optimized Pt4Ir/ANGr composition exhibits a significantly improved onset potential and mass activity for AOR. The DFT study confirms the OHad species spillover by AlOOH and Pt4Ir (100) facilitates the conversion of the *NH2 to *NH with minimal energy barriers. Finally, testing of DAFC at the system level using a membrane electrode assembly (MEA) with Pt4Ir/ANGr as the anode catalyst, demonstrating the suitability of the catalyst for its practical applications. This study thus uncovers the potential of the Pt4Ir catalyst in synergy with ANGr, largely addressing the challenges in hydrogen transportation, storage, and safety within DAFCs. In this article, a versatile catalyst, Pt4Ir/ANGr, is introduced composed of PtIr alloy nanoparticles decorated on AlOOH/NGr composite. The AlOOH provides an –OH‐rich surface conducive to the facile adsorption and decoration of the PtIr alloy nanoparticles and OHad species spillover from AlOOH to the Pt4Ir active center during AOR, further validating the higher experimental activity obtained in Pt4Ir/ANGr.