Performance optimization of PGM and PGM‑free catalysts in anion‑ exchange membrane fuel cells

Authors: John C. Douglin, Ramesh K. Singh, Eliran R. Hamo, Mohamad B. Hassine, Paulo J. Ferreira, Brian A. Rosen, Hamish A. Miller, Gadi Rothenberg, Dario R. Dekel This study focuses on H2-O2 operando AEMFC performance based on several platinum group metal (PGM) and PGM-free catalysts. Specifically, we evaluate the AEMFC performance of commercial PtRu/C, as-synthesized PtRu/C, and Pd-CeO2/C catalysts as anodes and commercial Pt/C and as-synthesized N-doped carbon catalysts as cathodes. The evolution of cell performance with varying cathode catalyst layer compositions, back pressure, and dew points is underscored. The as-synthesized PtRu/C catalyst is characterized by advanced transmission electron microscopy and showed significantly

Authors: Kanika Aggarwal, Songlin Li, Elisa Ivry, Dario R. Dekel, and Charles E. Diesendruck Metallopolymers are intriguing prospective materials for use as anion exchange membranes (AEMs) in fuel cells and water electrolysis applications. Metallopolymers potentially offer high ion conductivity due to the multivalent nature of metal cations; however, similar to organic cations, the durability of the organic component can be compromised by the alkaline environment. To develop AEMs with long operational lifetimes, the fundamental relationship between the metal–ligand pair and alkaline stability needs to be understood. Here, we synthesize metallopolymers with different N-heterocyclic carbene ligand side chains that are connected to

Authors: Marian Chatenet, Bruno G. Pollet, Dario R. Dekel, Fabio Dionigi, Jonathan Deseure, Pierre Millet, Richard D. Braatz, Martin Z. Bazant, Michael Eikerling, Iain Staffell, Paul Balcombe, Yang Shao-Horn and Helmut Schafer Replacing fossil fuels with energy sources and carriers that are sustainable, environmentally benign, and affordable is amongst the most pressing challenges for future socio-economic development. To that goal, hydrogen is presumed to be the most promising energy carrier. Electrocatalytic water splitting, if driven by green electricity, would provide hydrogen with minimal CO2 footprint. The viability of water electrolysis still hinges on the availability of durable earth-abundant electrocatalyst materials and the

Authors: Zi-Ye Xiao, Charles E. Diesendruck, Viatcheslav Freger, and Dario R. Dekel We successfully electropolymerize homopolymer and copolymer from vinylbenzyltrimethylammonium chloride (VBTMA) and divinylbenzene (DVB) by cyclic voltammetry to form ultra-thin anion-conducting polymer films with significant anion conductance. The morphologies of electropolymerized polymers with different monomer compositions are analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). In-situ electrochemical impedance spectroscopy (in situ EIS) is performed to track the electropolymerization (EP) process and film properties. High anion conductance of up to 2 mS is found in the electropolymerized thin films, suggesting that this technique can be suitable for making anion-conducting

Authors: Tamar Zelovich, Cataldo Simari, Isabella Nicotera, Dario R. Dekel and Mark E. Tuckerman Exposing anion exchange membrane (AEM) fuel cells to ambient air is known to decrease fuel cell efficiency significantly due to the presence of CO2. In this combined theoretical and experimental study, we examine the hydration conditions that promote reactions between CO2 and hydroxide ions in nano-confined AEMs, and we explore the effect of the carbonation process on the solvation structure and diffusion of hydroxide ions. Using fully atomistic ab initio molecular dynamics (AIMD) simulations, we find that increasing hydration can delay the carbonation reaction between OH− and CO2. Once reacted, HCO3− ions

Authors: Julian Lorenz, Holger Janßen, Karam Yassin, Janine Leppin, Young-Woo Choi, Jung-Eun Cha, Michael Wark, Simon Brandon, Dario R. Dekel, Corinna Harms, and Alexander Dyck Although substantial improvement of the performance of anion exchange membrane fuel cells (AEMFCs) was achieved, longevity is still the main challenge for the AEMFC technology, which is attributed to the degradation of the functional groups of applied membranes and ionomers. Contrary to ex situ material stability studies, we demonstrate here the application of ion chromatography to quantify the amounts of degradation products in the exhaust water during different fuel cell operation conditions on the example of

Authors: Kanika Aggarwal, Nansi Gjineci, Alexander Kaushansky, Saja Bsoul, John C. Douglin, Songlin Li, Ihtasham Salam, Sinai Aharonovich, John R. Varcoe, Dario R. Dekel, and Charles E. Diesendruck Anion-exchange membrane (AEM) fuel cells (AEMFCs) and water electrolyzers (AEMWEs) have gained strong attention of the scientific community as an alternative to expensive mainstream fuel cell and electrolysis technologies. However, in the high pH environment of the AEMFCs and AEMWEs, especially at low hydration levels, the molecular structure of most anion-conducting polymers breaks down because of the strong reactivity of the hydroxide anions with the quaternary ammonium (QA) cation functional groups that are

Authors: Carlo Santoro, Alessandro Lavacchi, Piercarlo Mustarelli, Vito Di Noto, Lior Elbaz, Dario R. Dekel, and Frédéric Jaouen As highlighted by the recent roadmaps from the European Union and the United States, water electrolysis is the most valuable high-intensity technology for producing green hydrogen. Currently, two commercial low-temperature water electrolyzer technologies exist: alkaline water electrolyzer (A-WE) and proton-exchange membrane water electrolyzer (PEM-WE). However, both have major drawbacks. A-WE shows low productivity and efficiency, while PEM-WE uses a significant amount of critical raw materials. Lately, the use of anion-exchange membrane water electrolyzers (AEM-WE) has been proposed to overcome the limitations of the

Authors: Xin Liu , Na Xie, Jiandang Xue, Mengyuan Li, Chenyang Zheng, Junfeng Zhang , Yanzhou Qin, Yan Yin, Dario R. Dekel and Michael D. Guiver Through-plane (TP) conducting pathways in anion-exchange membranes (AEMs) are desirable for AEM fuel cells as they serve as short and efficient routes for hydroxide ion transport between electrodes, improving power output. Electric and magnetic fields have previously been used to create TP-oriented structures in AEMs, but with modest performance gains. Here we use paramagnetic ferrocenium polymers to prepare TP-oriented AEMs under a magnetic field. The magnetic field induces a mixed-valence state, which effectuates higher anion dissociation

Authors: Zhicong Liang, Feng Yang, Yang Li, Jiali Tang, Dario R. Dekel, Xuezhong He Highly CO2 permeable membranes with good selectivity are ideal candidates for CO2 separation. Herein, we, for the first time, designed different polymeric membrane systems for CO2 removal from the air-fed anion-exchange membrane fuel cells (AEMFCs) by UniSim simulation under different operating conditions. The results indicate that the operations with higher feed pressure and permeate vacuum degree reduce the required membrane areas but increase the power demands. In addition, the single-stage facilitated transport membrane system (CO2 permeance of 3000 GPU) with an area of<10 m2 is feasible to reach a low CO2 content of < 5 ppm for automotive AEMFCs with