@article {1155,
	title = {Elucidating the Role of Hydroxide Electrolyte on Anion-Exchange-Membrane Water Electrolyzer Performance},
	journal = {Journal of The Electrochemical Society},
	volume = {168},
	year = {2021},
	month = {05/2021},
	pages = {054522},
	abstract = {Many solid-state devices, especially those requiring anion conduction, often add a supporting electrolyte to enable efficient operation. The prototypical case is that of anion-exchange-membrane water electrolyzers (AEMWEs), where addition of an alkali metal solution improves performance. However, the specific mechanism of this performance improvement is currently unknown. This work investigates the functionality of the alkali metal solution in AEMWEs using experiments and mathematical models. The results show that additional hydroxide plays a key role not only in ohmic resistance of the membrane and catalyst layer but also in the reaction kinetics. The modeling suggests that the added liquid electrolyte creates an additional electrochemical interface with the electrocatalyst that provides ion-transport pathways and distributes product gas bubbles; the total effective electrochemical active surface area in the cell with 1 M KOH is 5 times higher than that of the cell with DI water. In the cell with 1 M KOH, more than 80\% of the reaction current is associate with the liquid electrolyte. These results indicate the importance of high pH of electrolyte and catalyst/electrolyte interface in AEMWEs. The understanding of the functionality of the alkali metal solution presented in this study should help guide the design and optimization of AEMWEs.},
	keywords = {alkali metal solutions, anion-exchange-membrane water electrolyzers, Energy Sciences, energy storage, liquid electrolyte, solid-state devices},
	issn = {0013-4651},
	doi = {10.1149/1945-7111/ac0019},
	author = {Jiangjin Liu and Zhenye Kang and Dongguo Li and Magnolia Pak and Shaun M. Alia and Cy Fujimoto and Guido Bender and Yu Seung Kim and Adam Z. Weber}
}
@article {1158,
	title = {Influence of Supporting Electrolyte on Hydroxide Exchange Membrane Water Electrolysis Performance: Anolyte},
	journal = {Journal of The Electrochemical Society},
	volume = {168},
	year = {2021},
	month = {08/2021},
	pages = {084512},
	abstract = {Hydroxide-exchange-membrane water electrolysis (HEMWE) is an emerging hydrogen-production pathway that combines many advantages of incumbent alkaline water electrolysis (AWE) and proton-exchange-membrane water electrolysis (PEMWE). Advancement in HEMWE has been accelerated with the development of stable and conductive hydroxide exchange membranes (HEMs) and a more comprehensive understanding of alkaline gas-evolving kinetics. However, performance and durability without supporting electrolytes (SELs) remain inferior to PEMWE and AWE and little is known about the role and impact of the SELs. This study investigates the effects of SELs used as anolyte solutions in HEMWEs including cation-type, anion-type, SEL conductivity and pH, presence of carbonates and increased cation/OH- ratios on cell voltage and stability. We report our findings that (i) cell potential and high-frequency resistance did not correlate with anolyte SEL conductivity, (ii) cation-type influences cell voltage at low current densities (<50 mA cm-2) as predicted by half-cell measurements, (iii) increased cation/OH- ratio causes increased overpotentials, and (iv) carbonates are exchanged in the HEM but removed via self-purging at high current density. Overall, this study concludes that concentrated KOH is still the best SEL.},
	keywords = {hydrogen production pathway, Hydroxide exchange membrane, incumbent alkaline, proton exchange membrane, supporting electrolytes, water electrolysis},
	doi = {10.1149/1945-7111/ac1dcd},
	url = {https://doi.org/10.1149/1945-7111/ac1dcd},
	author = {Aleksandr Kiessling and Julie C. Fornaciari and Grace Anderson and Xiong Peng and Andreas Gerstmayr and Michael R. Gerhardt and Samuel McKinney and Alexey Serov and Yu Seung Kim and Barr Zulevi and Adam Z. Weber and Nemanja Danilovic}
}
@article {704,
	title = {Phenyl Oxidation Impacts the Durability of Alkaline Membrane Water Electrolyzer},
	journal = {ACS Applied Materials \& Interfaces},
	volume = {11},
	year = {2019},
	note = {{\textquoteright}doi: 10.1021/acsenergylett.0c01132\n - I.Am.Hydrogen{\textquoteright}
{\textquoteright}\n - jyoungstrom{\textquoteright}
{\textquoteright}Jason thinks this is great.\n~\n - jyoungstrom{\textquoteright}
{\textquoteright}\n - estechel{\textquoteright}
},
	pages = {9696-9701},
	abstract = {Published on March 13th, 2019.
The durability of alkaline anion exchange membrane (AEM) electrolyzers is a critical requirement for implementing this technology in cost-effective hydrogen production. Here, we report that the electrochemical oxidation of the adsorbed phenyl group (found in the ionomer) on oxygen evolution catalysts produces phenol, which may cause performance deterioration in AEM electrolyzers. In-line 1H NMR kinetic analyses of phenyl oxidation in a model organic cation electrolyte shows that catalyst type significantly impacts the phenyl oxidation rate at an oxygen evolution potential. Density functional theory calculations show that the phenyl adsorption is a critical factor determining the phenyl oxidation. This research provides a path for the development of more durable AEM electrolyzers with components that can minimize the adverse impact induced by the phenyl group oxidation, such as the development of novel ionomers with fewer phenyl moieties or catalysts with less phenyl-adsorbing character.},
	issn = {1944-8244},
	doi = {10.1021/acsami.9b00711},
	url = {https://doi.org/10.1021/acsami.9b00711},
	author = {Dongguo Li and Ivana Matanovic and Albert S. Lee and Eun Joo Park and Cy Fujimoto and Hoon T. Chung and Yu Seung Kim}
}
@article {1070,
	title = {Synthesis of Aromatic Anion Exchange Membranes by Friedel{\textendash}Crafts Bromoalkylation and Cross-Linking of Polystyrene Block Copolymers},
	journal = {Macromolecules},
	volume = {52},
	year = {2019},
	pages = {2139-2147},
	abstract = {<p><span style="color: $\#$111111; font-family: -apple-system, system-ui, {\textquoteright}Segoe UI{\textquoteright}, {\textquoteright}Helvetica Neue{\textquoteright}, Helvetica, Arial, sans-serif; font-size: 13px; white-space: pre-wrap; background-color: $\#$fafafa;">Published on March 12th, 2019. Elastomeric anion exchange membranes (AEMs) were prepared by acid-catalyzed Friedel{\textendash}Crafts alkylation of the polystyrene block of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) using bromoalkylated tertiary alcohols and triflic acid as a catalyst, followed by amination with trimethylamine. This simple one-step bromoalkylation allowed convenient control of both the degree of functionalization and cation tether length by changing the molar ratio and the structure of the bromoalkylated tertiary alcohol. The resulting quaternary ammonium-functionalized ionic triblock SEBS copolymers showed a microphase-separated morphology on the 35 nm length scale. A series of AEMs with different ion exchange capacities and ion tether lengths were systematically investigated by comparing swelling and anion conductivity. Because the SEBS AEMs showed high swelling and low dimensional stability in water due to the rubbery nature of SEBS, the hard segment PS units were cross-linked by 1,6-hexanediamine for practical use. The cross-linking of SEBS AEMs reduced water uptake significantly (e.g., 155\% vs 28\%) and enhanced their mechanical properties. Because the backbone of the SEBS AEMs are composed of all carbon{\textendash}carbon bonds, they showed good alkaline stability, preserving their IEC and OH{\textendash} conductivity after testing in a 1 M NaOH solution at 80 {\textdegree}C for 500 h. Alkaline membrane fuel cell performance was evaluated with the cross-linked SEBS AEM, and a peak power density of 520 mW/cm2 was achieved at 60 {\textdegree}C under H2/O2 conditions.</span></p>},
	issn = {0024-9297},
	doi = {10.1021/acs.macromol.8b02355},
	url = {https://doi.org/10.1021/acs.macromol.8b02355},
	author = {Yong Yeob Jeon and Sungmin Park and Junyoung Han and Sandip Maurya and Angela D. Mohanty and Ding Tian and Nayan Saikia and Michael A. Hickner and Chang Y. Ryu and Mark E. Tuckerman and Stephen J. Paddison and Yu Seung Kim and Chulsung Bae}
}
