A high-temperature anion-exchange membrane fuel cell

In the past few years, developments in anion exchange membranes (AEMs) have led to a significant increase in hydroxide conductivities, ultimately yielding striking improvements in the performance of anion exchange membrane fuel cells (AEMFCs) at low operating temperatures, usually at 40–80 °C. Aside from these remarkable achievements, the literature is void of any work on AEMFCs operated at temperatures above 100 °C, despite the consensus from various models remarking that working at higher cell temperatures may lead to many significant advantages. In this work, we present the first high-temperature AEMFC (HT-AEMFC) tested at 110 °C. The HT-AEMFC exhibits high performance, with a peak power density of 2.1 W cm−2 and a current density of as high as 574 mA cm−2 measured at 0.8 V. This initial work represents a significant landmark for the research and development of the fuel cell technology, opening a wide door for a new field of research we call hereafter, HT-AEMFCs

CoO_x-Fe₃O₄/N-rGO Oxygen Reduction Catalyst for Anion-Exchange Membrane Fuel Cells

Platinum group metal (PGM)-free oxygen reduction reaction (ORR) catalysts are of utmost importance for the rapid development of anion-exchange membrane fuel cell (AEMFC) technology. In this work, we demonstrate the improved ORR performance and stability of Co and Fe oxide-decorated/N-doped reduced graphene oxide (CoOx-Fe3O4/N-rGO) prepared via a hydrothermal method at the low temperature of 150 °C. The catalysts were characterized thoroughly using transmission electron microscopy, high-angle annular dark field-scanning electron microscopy, X-ray diffraction, N2 physisorption, Raman spectroscopy, and X-ray photoelectron spectroscopy to obtain information about morphology, elemental distribution, phases, porosity, defects, and surface elemental compositions. Significant ORR activity improvement (130 [email protected] mA cm−2) was achieved with this catalyst compared to the pristine graphene oxide, and the ORR limiting current was even 12%@0.5 V higher than the commercial Pt/C. The enhanced ORR activity of CoOx-Fe3O4/N-rGO was attributed to the uniform dispersion of Co, Fe, and N on reduced graphene oxide (rGO) sheets. Furthermore, ORR accelerated stress tests revealed excellent durability, suggesting that this material could be a promising and durable catalyst. With a cathode layer of the CoOx-Fe3O4/N-rGO catalyst, we achieved a peak power density of 676 mW cm−2 in an operando H2-O2 AEMFC. To the best of our knowledge, this is the highest reported power density per cathode catalyst mass in a reported PGM-free cathode catalyst. Finally, we quantified the various cell polarization losses as a function of cathode catalyst loadings to obtain insights for future work with AEMFCs based on this catalyst. The improvement in the AEMFC performance using CoOx-Fe3O4/N-rGO as a cathode catalyst can be attributed to the synergistic effects of (i) the high turnover frequency of the transition metals (Co and Fe) for ORR and (ii) the enhancement provided by N doping to the metal distribution and stability

A High-Temperature Anion-Exchange Membrane Fuel Cell with a Critical Raw Material-free Cathode

•First time CRM-free cathode AEMFC evaluated at temperatures > 100 °C•At 105 °C, the AEM reaches an OH‾ conductivity of 201 mS cm−1•Highest performing CRM-free cathode HT-AEMFC – 1.14 W cm−2 peak power densityWe present a first high-temperature anion-exchange membrane fuel cell (HT-AEMFC, operating at 105 °C) based on a critical raw material (CRM)-free cathode catalyst; at the same temperature, the anion-exchange membrane (AEM) has an ex-situ high hydroxide conductivity value of 201 mS cm−1. Our HT-AEMFC, containing a highly active nitrogen-doped carbon (N-doped-C) cathode catalyst, also features low polarization resistances, high catalytic activity and stability with retention of 81% of the catalyst layer capacitance after an initial 10 h longevity test, and 1.14 W cm−2. This is one of the highest power densities reported for a CRM-free AEMFC cathode. This work shows the potential of the new field of HT-AEMFCs, opening opportunities for developing and using novel CRM-free catalysts; highly active at these high operating temperatures.[Display omitted

Isoindolinium Groups as Stable Anion Conductors for Anion-Exchange Membrane Fuel Cells and Electrolyzers

Anion-exchange membrane (AEM) fuel cells (AEMFCs) and water electrolyzers (AEMWEs) have gained strongattention 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 commonly used in the AEMs and ionomers. Therefore, new highly stable QAs are needed to withstand the strong alkaline environment of these electrochemical devices. In this study, a series of isoindolinium salts with different substituents is prepared and investigated for their stability under dry alkaline conditions. We show that by modifying isoindolinium salts, steric effects could be added to change the degradation kinetics and impart significant improvement in the alkaline stability, reaching an order of magnitude improvement when all the aromatic positions are substituted. Density functional theory (DFT) calculations are provided in support of the high kinetic stability found in these substituted isoindolinium salts. This is the first time that this class of QAs has been investigated. We believe that these novel isoindolinium groups can be a good alternative in the chemical design of AEMs to overcome material stability challenges in advanced electrochemical systems.</p

Data of bifunctional oxygen electrocatalysis on mixed metal phthalocyanine-modified carbon nanotubes prepared via pyrolysis

This dataset contains the data presented in the figures of the published paper "Bifunctional Oxygen Electrocatalysis on Mixed Metal Phthalocyanine-Modified Carbon Nanotubes Prepared via Pyrolysis" ACS Appl. Mater. Interfaces 2021, 13, 35, 41507–41516 (https://doi.org/10.1021/acsami.1c06737