bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Water Electrolyzers for Green Hydrogen Production - a Tutorial on Catalyst and Electrode Development for Next Generation Devices
Authors: Carmo Marcelo , Capuano Christopher , Ayers Katherine E. 
Published: July 2022

Green hydrogen generation via electrolysis is at the forefront of international debates, with an unprecedent momentum within hydrogen technology. Various countries have already released their hydrogen strategy documents, recognizing the high propositional value of hydrogen as energy commodity of the future. Significant growth in water electrolysis has therefore occurred in recent years,` with the largest 20MW PEM electrolyzer being deployed for Iberdrola by NEL Hydrogen in Spain in 2021.
This project shows how commercial polymer electrolyte membrane (PEM) electrolysis has reached scales of several hundred kg/day, providing a relevant pathway for industrial scale hydrogen generation. PEM electrolyzers also have tremendous potential for continuing cost reduction, leveraging system and manufacturing scaling laws as well as leveraging advancements in nanomaterials, advanced manufacturing tools, and both in-situ and ex-situ analysis tools. Order of magnitude improvements in some of the highest cost elements have already been achieved, including by NEL Hydrogen. Many of the technology elements such as PFSA membranes, iridium electrodes, porous transport layers, etc. are known, but still need to be refined and validated in a manufacturing environment at scale, including modifications in materials and novel yet economical methods of fabrication. At the same time, classic KOH based alkaline electrolyzers (AEL) are showing renewed promise, as diaphragm structure has advanced and understanding of electrode processing has developed. The basic environment of the alkaline electrolysis cell enables a broader range of materials and the potential to eliminate the highest cost materials such as platinum group metals and commercially pure titanium from the stack.
However, for both AEL and PEM, complex interactions at the electrode level exist which need to be considered in catalyst and membrane/diaphragm development. First, the liquid electrolyte environment used for catalyst activity screening, where all the catalyst surface is accessible to the reactant is often not comparable to a complex, 3-dimensional, ionomer-based electrode. Therefore, in the same way that future alkaline electrode/diaphragm structures might resemble PEM catalyst coated membranes, novel PGM-free components still ought to show durability profiles similar to those shown by AEL stacks. This talk will describe some of the complex interactions that need to be considered, typical operating requirements, and stages of development where relevant conditions should be introduced.
(Invited, Digital Presentation) Regulating the Dynamic Surface Reconstruction of a Layered Cobalt Oxide Electrocatalyst for Water Oxidation
Authors: Wang Jian 
Published: July 2022

Water electrolysis conditions accelerate the dissolution and corrosion of electrocatalysts, changing their surface and/or bulk composition/structure from the original states. This dynamic reconstruction process redefines the catalytically active species. However, rational control of the in-situ surface reconstruction for electrocatalysts is tremendously challenging. Here, we proposed a novel redox-tuning method to precisely modulate the surface reconstruction and to favor the water oxidation activity. For a category of layered transition metal oxide (AMO2: A = alkaline metal, M = transition metal), redox of transition metal during the alkaline OER was in-situ tuned to engineer the catalyst leaching potential, manipulate the cation leaching amount, and redirect the dynamic catalyst reconstruction. Specifically, Cl doping lowered the cobalt valence state of LiCoO2 and the further OER potential for its in-situ cobalt oxidation triggering Li leaching. Operando XAFS and DFT calculations confirmed that such modulation bypassed the less favorable surface reconstruction by forming Li1-xCo2O4-type spinel structure, transforming the surface of LiCoO1.8Cl0.2 into a more catalytically-active (oxy)hydroxide phase. The proposed method could be potentially generalized to manipulate the surface reconstruction of other pre-catalysts.
References
1. Wang, J.; Gao, Y.; Kong, H.; Kim, J.; Choi, S.; Ciucci, F.; Hao, Y.; Yang, S.; Shao, Z.; Lim, J., Non-precious-metal catalysts for alkaline water electrolysis: operando characterizations, theoretical calculations, and recent advances. Chemical Society Reviews 2020, (49), 9154-9196.
2. Wang, J.; Kim, S.-J.; Liu, J.; Gao, Y.; Choi, S.; Han, J.; Shin, H.; Jo, S.; Kim, J.; Ciucci, F.; Kim, H.; Li, Q.; Yang, W.; Long, X.; Yang, S.; Cho, S.-P.; Chae, K. H.; Kim, M. G.; Kim, H.; Lim, J., Redirecting dynamic surface restructuring of a layered transition metal oxide catalyst for superior water oxidation. Nature Catalysis
2021,
4 (3), 212-222.
Oxygen Evolution Reaction Catalyst Development: Benchmarking IrOx Catalyst Activity and Stability
Authors: Murawski James , Yin Shuaihang , Zalitis Christopher , Stevens James , Rigg Katie , Clapp Mark , Smith Graham , Sharman Jonathan , Hinds Gareth , Stephens Ifan Erfyl Lester 
Published: July 2022

While PEM electrolyser catalyst cost may not be a significant portion of system costs1 it does represent a bottleneck for the ability to generate TW level of H2. This is primarily because of the reliance on IrOx as a stable oxygen evolution catalyst in order to meet future green H2 needs either replacement or reduction of iridium loading of at least 50 times is needed while maintaining a high level of stability2. IrOx based materials are the only oxygen evolution catalysts combining activity and stability under PEM electrolysis conditions; even so, they are insufficiently stable.
In the current work, we tailored the activity of IrOx catalysts synthesised by a variant of the Adams fusion reaction3 using decomposition of Iridium nitrate and varying temperature of synthesis to generate a series of catalysts with differing crystallinity and surface area. We benchmarked their stability using both accelerated degradation electrochemical measurements (30k cycles 1.2-1.7VRHE @ 500 mV s-1) and inductively coupled plasma-mass spectrometry(ICP-MS), both in rotating disk electrode(RDE) measurements and in a single cell PEM electrolyser.
We have compared several different methods for probing electrochemical surface area, including BET, double layer capacitance from cyclic voltammetry, adsorption capacitance using impedance spectroscopy and CO stripping using ultrasensitive on chip electrochemical mass spectrometry.
The results from the RDE measurements are shown in figure 1; they show that while the high surface area amorphous IrOx catalysts demonstrate higher activity normalised to geometric area, when normalised to specific activity the difference is insignificant. In addition to electrochemical performance losses, the amorphous IrOx shows an order of magnitude increase in iridium dissolution, determined via ICP-MS. Future studies will look at the ability to overcome the limitations of aqueous model studies for stability testing and utilising testing to select OER catalyst candidates that meet both activity and stability required for long term operation in PEM electrolyser systems.
1 L. Bertuccioli, A. Chan, D. Hart, F. Lehner, B. Madden and E. Standen, Study on development of water electrolysis in the EU, Fuel Cells and hydrogen Joint Undertaking, 2014, vol. 1.
2 P. S. Alexis Grimaud, Jan Rossmeisl, Research nees towards sustainable production of fuels and chemicals, Section 1: Water splitting and sustainable H2 Production, 2019.
3 D. F. Abbott, D. Lebedev, K. Waltar, M. Povia, M. Nachtegaal, E. Fabbri, C. Copéret and T. J. Schmidt, Chem. Mater., 2016, 28, 6591–6604.

Figure 1
Active Site Formation in Oxygen Deficient Cobalt Antimonate for Oxygen Evolution Reaction in Alkaline Media
Authors: Ham Kahyun , Hong Sukhwa , Kang Sinwoo , Cho Kangwoo , Lee Jaeyoung 
Published: July 2022

Electrochemical water splitting is the one of the promising ways to obtain hydrogen from aqueous media. Oxygen evolution reaction (OER) at the anode is the rate-determining step due to the sluggish kinetics, which leads to reducing energy efficiency. Recently, anion exchange membrane water splitting has been considered as an alternative way because of its capability of producing hydrogen of high purity and the availability of iron-triad element-based catalysts because of their thermodynamically stability in alkaline media. Besides, cobalt oxides such as spinel, layered double hydroxide are being investigated as active OER electrocatalyst. Among them, the spinel-type Co3O4, which contains one Co2+ in the tetrahedral site and two Co3+ ions in the octahedral site, exhibits outstanding OER performance in alkaline media and has been actively investigated.
In this study, we investigated oxygen-deficient cobalt antimonate oxide (CoSb2O6) as OER catalyst in alkaline media, which has unique crystal structure and contains abundant octahedral Co2+ compared to spinel-type cobalt oxide. Through in situ X-ray absorption near-edge structure analysis, we observed most of octahedral Co2+ ions were oxidized to Co4+ at OER potential, which leaded to increase the OER activity by extending the active site. We also carried out anion exchange membrane water splitting to confirm the availability as the anode catalyst to produce H2 gas.
Seacat - Catalysts for Direct Seawater Electrolysis
Authors: Moretti Enzo , Kiebach Ragnar , Kraglund Mikkel Rykær 
Published: July 2022

With current technology, the direct electrolysis of seawater struggles with ACSFRs (active chlorine species formation reactions), including the ClER (chlorine evolution reaction), competing with the formation of gaseous oxygen on the anode side. The corrosive and poisonous chlorine compounds produced in the ClER pose a significant issue, essentially destroying the electrolyser in a short period of time. Since the purification of seawater requires both energy and increased investment and maintenance costs, today water electrolysis is often not economically feasible in regions with no fresh water access.
This marks the starting point of this PhD project. The primary goal of this thesis is the development and demonstration of a catalyst suitable for direct electrolysis of seawater to hydrogen and oxygen, without the formation of Cl2.
Nickel based layered double hydroxides (Ni-LDH) and oxyhydroxides (Ni-OOH), particularly when doped with other transition metals, have shown very high catalytic activity with respect to the OER. If sufficient current densities under practical conditions (1A/cm2, < 80 °C, stable for several thousand hours) below the thermodynamic onset potential of the ClER of around 1.7 V could be reached, an active suppression of the ClER is not necessarily needed.
Initially, we investigate potential highly active mixed-metal LDH catalysts for the OER in sea water splitting, which are synthesized by a particularly simple, quick and efficient procedure proposed by Li et al. in 2020. Based on their work, we conduct a screening study of 36 unique compounds derived from abundantly available transition metals (Ni, Fe, Mn, Cr, Co, Cu, Zn, Al). The LDHs are coated onto a Ni foam substrate by a two-step dip coating process from metal nitrate solutions. In a first approach, we only consider compounds consisting of two transition metals with equal molar ratios. We then investigate their catalytic activity as well as the long term stability for up to 1000 hours in industrially relevant (60 – 80°C, 6M KOH) fresh water and sea water conditions, particularly regarding catalyst poisoning effects of the sea water constituents on the catalyst.
We then give an outlook on the next step in the project, which will be to make use of the simple synthesis procedure by implementing it into an autonomous lab robot setup. The robot platform will comprise all steps of the experiment from synthesis over electrochemical testing, data analysis and machine learning based optimization. This way, we will showcase the potential of combining high-throughput screening with AI-assisted materials discovery. As a proof-of-concept, the robot will reproduce the initial screening study that was carried out manually. Subsequently, autonomous data analysis and synthesis optimization functionality will be implemented and the robot will run several iterations of closed-loop catalyst optimization experiments without human interaction.
Quaternized Polybenzimidazole-Cross-Linked Poly(vinylbenzyl chloride) Membranes and Their Performance in HT-PEMFCs
Authors: Arslan Funda , Chuluunbandi Khajidkhand , Freiberg Anna , Kormanyos Attila , Sit Ferit , Cherevko Serhiy , Kerres Jochen Alfred , Thiele Simon , Böhm Thomas 
Published: July 2022

Quaternized Polybenzimidazole-Cross-Linked Poly(vinylbenzyl chloride) Membranes and Their Performance in HT-PEMFCs

Keywords: Proton-exchange membrane, ion pair, high-temperature, phosphoric acid, quaternary ammonium, hydrogen crossover
High temperature proton-exchange membrane fuel cells (HT-PEMFCs) are promising electrochemical energy conversion devices for the hydrogen economy. In this fuel cell type, phosphoric acid is immobilized as an electrolyte within a polybenzimidazole (PBI) membrane acting as a matrix. These membrane systems allow operating temperatures up to 200 °C, which is significantly higher than for sulfonated polymers that are used in low temperatures PEMFCs at around 80 °C.
Operating PEMFCs above 100 °C harbors advantages such as faster reaction kinetics, higher tolerances against fuel impurities, and easier cooling. Nonetheless, phosphoric acid doped membranes also is the main challenge and drawback of these systems due to leaching of the dopant over time. A high acid-oping level is desired since it ensures high proton conductivity. However, the mechanical properties of PBI-based materials generally deteriorate upon increasing acid doping levels. In this regard, cross-linking PBI with another polymer is a promising route to enhance the mechanical properties of acid-doped membranes. Further, polymers with specific functional groups, such as quaternary ammonium (QA), can be used as cross-linkers to enhance the retention of phosphoric acid by forming strong interactions with biphosphate anions.
Here, we present a new ion-pair-coordinated membrane (IPM) system decorated with QA groups. Poly(vinylbenzyl chloride) is used as a macromolecular cross-linker for PBI, and three different amines (Quinuclidine, Quinuclidinol, DABCO) are used as quaternizing agents. The performance of these membranes is evaluated ex-situ as well as electrochemically within HT-PEMFC operation and compared to a commercial m-PBI membrane (Dapazol). The IPMs show reduced swelling and better mechanical properties upon doping. Further, the commercial reference can be outperformed within HT-PEMFC operation at less acid doping than conventional PBI membranes. The best-performing IPM led to a 25% improved fuel cell performance. The peak power density of an HT-PEMFC incorporating a Dapazol membrane was 430 mW cm–2 at 180 °C under H2/air conditions and at ambient pressure, while the HT-PEMFC with the best-performing IPM yielded 530 cm–2 at equal parameters. Further, the hydrogen gas crossover of the IPMs is similar or less than that of the commercial reference even at lower membrane thicknesses, which renders these membranes as promising candidates for application in HT-PEMFC.
Influence of Three-Dimensional Flow Field Structures Consisting of Expanded Metal Meshes on the Physicochemical Loss Processes in Pemfcs
Authors: Raab Sebastian , Goosmann Tobias , Weber Andre 
Published: July 2022

To further increase the performance of polymer electrolyte membrane fuel cells (PEMFCs) at high current densities, a reduction of mass transport losses by an enhanced evacuation of water from the cell and an improved supply of gases to the reactive sites are necessary.
The application of three-dimensional flow field structures in PEMFCs is a promising measure to promote the evacuation of excess liquid water from the cell while boosting the transport of reactants from the gas channel in the direction of the cell. Expanded metal meshes offer a three-dimensional geometry, which predestines them to be used as flow field structures in PEMFCs. In the past, their application as flow fields has primarily been investigated for direct methanol fuel cells (DMFCs) [1, 2, 3] and electrolyzers [4, 5]. To gain a profound understanding of the impact of such three-dimensional flow field structures on the electrochemical properties of PEMFCs, the physicochemical loss processes of the cell have to be analyzed in detail.
In this contribution, the results of an in-depth analysis of the influence of three-dimensional flow field structures consisting of expanded metal meshes on the physicochemical loss processes in PEMFCs and their effect on the cell performance is presented. To assess the impact of expanded metal meshes in comparison to a conventional channel rib flow field design, the physicochemical loss processes were examined for both flow field designs. The operating conditions (j, RH, T, pO2) of the incremental PEM fuel cells (1 cm2 active cell area) [6] were varied systematically and the cells were analyzed by means of polarization curves and electrochemical impedance spectroscopy (EIS). The physicochemical loss processes of the cells were identified by a subsequent impedance data analysis by the distribution of relaxation times (DRT) [7, 8].
This investigation aims to determine the physicochemical loss process in PEMFCs with expanded metal meshes as flow field structures and compare them to the results of a conventional flow field design. Based on the physical interpretation of the results, consequences and conclusions for the further development of the expanded metal flow field geometries are discussed.

References:

[1] Yuan et al., International Journal of Hydrogen Energy
43, 19711-19720 (2018).
[2] Wang et al., Applied Energy
208, pp. 184-194 (2017).
[3] Mallick et al., Electrochimica Acta
243, pp. 299-309 (2017).
[4] Stiber et al., Adv. Energy Materials
11, 2100630 (2021).
[5] Lafmejani et al., J. Power Sources
397, pp. 334-342 (2018).
[6] M. Heinzmann et al., J. Power Sources
402, pp. 24-33 (2018).
[7] H. Schichlein et al., J. Appl. Electrochem. 32, pp. 875-882 (2002).
[8] E. Ivers-Tiffée et al., J. Ceram. Soc. Japan 125, pp. 193-201 (2017).
Manufacture and Performance of 3D Printed Carbonised Gas Diffusion Layers
Authors: Niblett Daniel , Guo Zunmin , Niasar Vahid J. , Holmes Stuart , Prosser Robert 
Published: July 2022

Proton exchange membrane fuel cells (PEMFC) electrochemically combine hydrogen and oxygen to produce electrical energy, heat and water. Therefore, PEMFC offer an alternative to vehicle electrification and reduction of greenhouse gas emissions. However, material limitations under high current density conditions limit the efficiency due to water flooding subsequent mass transport overpotential.
The cathode gas diffusion layer of PEMFC is conventionally a carbon paper material, due to its high electrical conductivity, permeability and mechanical strength. Whereas the porosity and thickness can be controlled, the exact microstructural features are unknown, resulting from the web of randomly orientated fibres. If the microstructural features of the porous layer can be designed, improvements in water flooding and mass transport could be established.
This research talk focuses on the series of studies from concept, simulation and manufacturing of designed microstructures using 3D printing and carbonisation. We investigate the potential improvements to electrical/thermal conductivity, permeability and reduction in the saturation using computational fluid dynamics. Furthermore, the impact of the porous microstructure in a lab scale set up is replicated to understand the effects of under-rib convection and oxygen consumption at the catalyst layer.
With a readily available 3D printing method, prototype materials; resembling those evaluated in the simulation studies are manufactured and carbonised into glassy carbon microstructures. The morphology of carbon was limited by the maximum temperature of the furnace. The resulting structures have in-plane dimensions of 2 cm x 2 cm and through-plane between 400 – 800 µm. They were tested for electrical conductivity with a value of approximately 130 S m-1.
Through a controlled carbonisation process, structural damage was minimised and the structures were introduced into a membrane electrode assembly (MEA) via spraying and hot pressing. The resulting MEA was tested in a lab cell to understand further considerations that limit the correct implementation of the 3D printed layers. In-homogenous MPL and CL formation along with membrane cracking are hypothesised to be causes of overpotentials.
Figure 1 – Design process of simulation to manufacture, with simulations of (a) electrical potential, (b) water flooding and (c) oxygen distribution in a designed carbon microstructure. (d) and (e) optical microscope images of printed precursor material and final carbonised structures.

Figure 1