bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reaching PEM Performance Parity with Anion Exchange Membrane Electrolyzers
Authors: Perez Bakovic Sergio Ivan , Keane Alex , Carmo Marcelo , De Porcellinis Diana 
Published: September 2023

Anion exchange membrane (AEM) electrolyzers promise to combine the benefits from proton exchange membrane (PEM) electrolyzers and liquid alkaline electrolyzers. They offer both the compact stack design and high current densities that PEM electrolyzers provide, while also taking advantage of using non-platinum-group-metals (non-PGM) and titanium-free components similar to traditional alkaline electrolyzers. However, AEM stacks and systems must demonstrate competitive performance and durability to allow widespread commercial adoption.
As part of AEM development efforts, a comprehensive study has been conducted on the morphology of different porous plates and their impact on the cell performance. The key results demonstrate comparable performance of AEM electrolyzers to PEM electrolyzers under optimized conditions. Different ink formulation and processes have also been evaluated for a series of non-PGM catalysts, while testing their impact on performance and durability. In addition, commercially available AEMs have been evaluated for long term durability in short cell stacks, demonstrating comparable degradation rates to PEM electrolyzer technology.
On the Acid Stability of PGM-Free OER Catalyst for H2 Production in PEMWE
Authors: Liu Di-Jia 
Published: September 2023

Low temperature proton exchange membrane water electrolyzer (PEMWE) represents a critical technology for green hydrogen production. It offers the advantages of significantly higher current density and higher H2 purity, rendering it a preferred technology when high energy efficiency and low footprint are essential.
Working in the oxidative and acidic environment under high polarization voltage, however, adds substantial demand to the electrode catalyst and the support. This is particularly the case at anode where the oxygen evolution reaction (OER) takes place. At present, the platinum group metal (PGM) materials such as Ir black or Ir oxide are catalysts of choice. Their high cost and limited reserve, however, adds a significant cost to PEM electrolyzer, which contributes to the overall expense of hydrogen production next only to the cost of electricity. Replacing Ir with earth-abundant transition metal oxides could help to reduce the electrolyzer system cost.
Argonne National Laboratory has recently designed and prepared a new family of PGM-free OER catalyst for PEM electrolyzer. The new catalysts have high porosity and unique nanoarchitecture, and have demonstrated very promising activity and durability in both rotating disk electrode (RDE) and in operating PEMWE.
The most challenging aspect of PGM-free OER catalyst is its stability in the acidic media. To this end, we conducted extensive structural characterizations as well as computational modeling. Particularly, in situ X-ray absorption spectroscopy combined with high resolution imaging revealed insightful information on the electronic and surface structural changes during the electrochemical reaction. Computational Pourbaix diagram also elucidated the catalyst stability under the acidic OER operating condition.

Acknowledgement: This work is supported by U. S. Department of Energy, Hydrogen and Fuel Cell Technologies Office through Office of Energy Efficiency and Renewable Energy and by Office of Science, U.S. Department of Energy under Contract DE-AC02-06CH11357.
Enhancing Effect of Boron-Doping on the Activity of Nife-MOF-74 Towards Oxygen Evolution Reaction in Alkaline
Authors: Xing Jiale , Bliznakov Stoyan , Bonville Leonard J. , Maric Radenka 
Published: September 2023

Water splitting has drawn significant attention due to the capability of mass-producing hydrogen, which is considered a promising alternative to fossil fuels in the future.[1] The development of electrochemical energy conversion and storage technologies, such as water electrolyzers, metal-air batteries, and regenerative fuel cells, is of great importance to support the transition to clean and renewable energy.[2] Based on the merits of high surface area, 3D periodic porous structure, large porosities, diverse composition and well-defined metal centers, metal–organic frameworks (MOFs) and their derivatives have been widely exploited as OER electrocatalysts.[3]However, MOFs have some limitation to be used as a OER catalysts, considering their poor stabilities (in water, especially basic/acidic conditions) and low electrical conductivities. Incorporation of boron atoms into an aromatic carbon framework offers a wide variety of functionalities. [4] In this work, the flower-like bimetallic NiFe-MOF-74 dopped with boron were fabricated, and they exhibit superior catalytic activity with a very low overpotential of 318 mV for OER at a laboratory grade current density of 10 to 100 mA/cm2 and fast reaction kinetics with a small Tafel slope of 89 mV dec-1 in 1.0 M KOH using a catalyst fabrication process that is scalable to commercial levels. Additional work is required to demonstrate current densities at commercial levels.

Reference

[1] L. Fan, Z. Kang, M. Li, D. Sun, Recent progress in pristine MOF-based catalysts for electrochemical hydrogen evolution, oxygen evolution and oxygen reduction, Dalton Trans. 50 (2021) 5732–5753. https://doi.org/10.1039/D1DT00302J.
[2] Bimetallic metal–organic frameworks and MOF-derived composites: Recent progress on electro- and photoelectrocatalytic applications - ScienceDirect, (n.d.). https://www.sciencedirect.com/science/article/pii/S0010854521005385 (accessed April 27, 2022).
[3] J. Du, F. Li, L. Sun, Metal–organic frameworks and their derivatives as electrocatalysts for the oxygen evolution reaction, Chem. Soc. Rev. 50 (2021) 2663–2695. https://doi.org/10.1039/D0CS01191F.
[4] Y. Xie, Z. Meng, T. Cai, W.-Q. Han, Effect of Boron-Doping on the Graphene Aerogel Used as Cathode for the Lithium–Sulfur Battery, ACS Appl. Mater. Interfaces. 7 (2015) 25202–25210. https://doi.org/10.1021/acsami.5b08129.
Transition Metal Carbides and Nitrides As Electrocatalysts for Hydrogen and Oxygen Evolution Reactions
Authors: Kang Jin Soo 
Published: September 2023

Global demand to achieve carbon-neutral energy production and utilization has raised a trend of searching for a fuel that minimizes the production of CO2. From this viewpoint, hydrogen is considered as an ideal fuel as it does not contain carbon in its formula. Meanwhile, the challenge remains in the process for hydrogen production, as it is energetically up-hill and thereby produces CO2 unless a combination of renewable energy and water splitting is used.
There are a number of components that constitute a water electrolyzer, but its economic feasibility is largely challenged by noble metal electrocatalysts used for facilitation of hydrogen and oxygen evolution reactions. For this reason, significant efforts have been put to develop low-cost materials that could substitute costly catalysts. In-depth understandings on correlations between the electronic structure and the electrocatalytic activity led to the interest toward transition metal carbide and nitride materials, as they own electronic structures that mimic those of catalytic noble metals. These materials did manifest decent performances, though there are some remaining issues including the energy-intensive synthetic process.
Herein, nanostructured transition metal carbide and nitride produced by facile preparation methods are introduced. Self-supported carbides synthesized via electrochemical structuring followed by thermal carburization are applied in hydrogen evolution reaction, wherein decent catalytic activity and excellent durability are achieved. In addition, nitrides prepared at an ambient-temperature and environmentally-benign condition are utilized for oxygen evolution reaction, which manifested high performance both in terms of activity and long-term stability. Based on thorough characterization of carbides and nitrides, their physicochemical properties and electrochemical behaviors, and the relationships among them are discussed.
Core-Shell Structured Water Oxidation Anode for Minimum Platinum Group Metal Usage in Proton Exchange Membrane Water Electrolyzer
Authors: Jeong Hui-Yun , Oh Jinho , Yi Gyu Seong , Park Hyun S. 
Published: September 2023

The development of enhanced electrocatalysts and optimization of electrode structures are of great importance for the practical and widespread deployment of proton exchange membrane water electrolyzers (PEMWEs). In particular, the scarcity and high price of Ir are considered to be bottlenecks inhibiting the large-scale commercialization of PEMWEs. Even compared with Pt, a rare-earth metal with a low production rate of 150~200 tons per year, Ir availability is extremely limited, as only a few tons per year are produced [1]. Therefore, It is envisioned that the Ir loading on the anode should be lowered (e.g., to 0.05 mg/cm2) to meet the annual demand for the PEMWE system installation on the scale of ≈5 GW by 2040 [2].
To reduce the usage of rare-earth metals in PEMWEs, a highly active water-oxidizing anode was fabricated by depositing a core–shell structured catalyst on a titanium porous transport layer (Ti PTL). Earth-abundant metal-based iron-nitride (Fe2N) nanostructure was deposited on a Ti PTL by sequential hydrothermal and nitridation reaction. The prepared Fe2N nanostructure was then passivated by thin, electrodeposited iridium-oxide films (EIROF). Fe2N@EIROF core-shell structured anodes exhibited substantially low ohmic and mass-transfer resistances, leading to a high current density of 4.50 A/cm2 (@1.9 Vcell). The unique Fe2N@EIROF core-shell structure enhanced PEMWE performance in terms of Ir mass activity by substituting inner Ir atoms with earth-abundant metal-based iron nitride. A high Ir mass activity of 103 A/mgIr (@1.9 Vcell) was achieved by reducing Ir loading amount to 0.064 mg/cm2 on the anode. The chemical instability of transition metal-based supports in a PEMWE operating condition was overcome by the passivation with Ir catalyst layers. As a result, the prepared core–shell-structured catalysts were stable under the PEMWE operating condition achieving high Ir mass activities.
[1] K. Nose, T.H. Okabe, Chapter 2.10 - Platinum Group Metals Production, in: S. Seetharaman (Ed.) Treatise on Process Metallurgy, Elsevier, Boston, 2014, pp. 1071-1097,
[2] C. Minke, M. Suermann, B. Bensmann, R. Hanke-Rauschenbach, Is iridium demand a potential bottleneck in the realization of large-scale PEM water electrolysis?, Int. J. Hydrogen Energy, 46 (2021) 23581-23590
(Digital Presentation) Electrospun Bimetallic Cu/Zn Selenide @ Carbon Nanofiber Electrocatalysts for Oxygen Evolution and Oxygen Reduction
Authors: Velpandian Muthuraja , Meduri Praveen 
Published: September 2023

Electrochemical water splitting and fuel cells are intriguing ways to achieve a potentially sustainable and clean energy1. A greater focus on these energy technologies necessitates the design and development of highly active, cost-effective electrocatalysts that can substitute state of the art noble metal based materials2. In this context, metal selenide-based materials are important owing to their superior stability and electrical conductivity3. Their high specific surface area and abundant active sites on the surfaces make them strong candidates for use as electrocatalysts. Herein, heterostructured copper selenide and zinc selenide encased in carbon nanofibers (CZSe@C-450) synthesized using electrospinning and selenization techniques are used as bifunctional electrocatalysts. The novel architecture and tunable confinement of bimetallic selenides with the carbon matrix results in improved electrochemical performance in both oxygen evolution (OER) and oxygen reduction reactions (ORR)4. CZSe@C-450 exhibits a low overpotential of 260 mV at 10 mA cm−2 for oxygen evolution reaction and exhibits a half-wave potential (E1/2) of 0.88 V for oxygen reduction reaction. Further, the creation of a heterogeneous phase boundary between copper selenide and zinc selenide in the CZSe@C-450 enhances the built-in potential, local atomic disorder, and mismatch in the lattice that leads to lowering the surface energy. This gives rise to creation of catalytically active edge sites and phase boundaries, which contribute to the enhanced performance and good stability in both OER and ORR5,6.
References:
(1) Gielen, D.; Taibi, E.; Miranda, R. Hydrogen: A Renewable Energy Perspective. Abu Dhabi: International Renewable Energy Agency
2019.
(2) Han, L.; Dong, S.; Wang, E. Transition‐metal (Co, Ni, and Fe)‐based Electrocatalysts for the Water Oxidation Reaction. Advanced materials
2016, 28 (42), 9266–9291.
(3) Feng, W.; Pang, W.; Xu, Y.; Guo, A.; Gao, X.; Qiu, X.; Chen, W. Transition Metal Selenides for Electrocatalytic Hydrogen Evolution Reaction. ChemElectroChem
2020, 7 (1), 31–54. https://doi.org/10.1002/celc.201901623.
(4) Velpandian, M.; Ummethala, G.; Malladi, S. K.; Meduri, P. Heterogeneous Interface Induced Electrocatalytic Efficiency Boosting of Bimetallic Cu/Zn Selenides for Stable Water Oxidation and Oxygen Reduction Reactions. Catalysis Science & Technology
2022.
(5) Gbadamasi, S.; Mohiuddin, M.; Krishnamurthi, V.; Verma, R.; Khan, M. W.; Pathak, S.; Kalantar-Zadeh, K.; Mahmood, N. Interface Chemistry of Two-Dimensional Heterostructures – Fundamentals to Applications. Chem. Soc. Rev.
2021, 50 (7), 4684–4729. https://doi.org/10.1039/D0CS01070G.
(6) Zhao, R.; Li, Q.; Jiang, X.; Huang, S.; Fu, G.; Lee, J.-M. Interface Engineering in Transition Metal-Based Heterostructures for Oxygen Electrocatalysis. Mater. Chem. Front.
2021, 5 (3), 1033–1059. https://doi.org/10.1039/D0QM00729C.
Quantification of the Stability of ALD-Grown TiO2 Protective Coatings on Photoanodes for Solar Water Splitting
Authors: Kollmann Jiri , Kriegel Herman , Raudsepp Ragle , Pourmahdavi Maryam , Klassen Thomas , Schieda Mauricio 
Published: September 2023

Semiconducting photoabsorbers used in photoelectrochemical applications often exhibit low stability under operating conditions. One strategy implemented in recent years to prevent corrosion of photoelectrodes is the application of thin films of titanium dioxide (TiO2), coated by atomic layer deposition (ALD). However, the stability of these coatings under photoelectrochemical conditions is also limited. We are using spectroscopic ellipsometry (SE) and in-situ atomic force microscope (AFM) characterization[1, 2] in order to quantify the influence of the coating process parameters and of post-deposition treatments on the degradation of these protective layers. Here we show our recent investigations under anodic operation in acidic environment. For fully amorphous TiO2 layers, a significant contributor to the corrosion is a purely chemical process, with an activation energy of 57 kJ/mol. Furthermore, the degradation rate doubles upon illumination under simulated sunlight. With increasing pH, the stability increases significantly. Partially crystalline protective coatings exhibit improved stability under operating conditions in sulfuric acid.
References:
[1] Kriegel H. et al. J. Mater. Chem. A, 2020, 8, 18173.
[2] Raudsepp R. et al. (in preparation).

Figure 1
(Invited) New Approaches to Photoelectrochemical Cascade Reactions and Protection of Photoelectrodes
Authors: Greenaway Ann L 
Published: September 2023

A half-century of research has positioned direct photoelectrochemical (PEC) fuel generation as a promising technology that still requires substantial development. Work on the hydrogen evolution reaction (HER) has provided a strong basis for realizing the generation of more complex fuels through the carbon dioxide reduction reaction (CO2RR), but multiple challenges remain. The CO2RR requires larger driving forces and integration of multiple catalysts in order to selectively generate multi-carbonproducts, while still presenting many unsolved issues from HER, such stabilizing photoelectrodes under operation. In this talk I will discuss advances in the integration of multiple catalytic microenvironments in a single photoelectrochemical device, and progress toward the stabilization of photoelectrodes for fuel generation.
First, I will highlight the adaptation of three-terminal tandem (3TT) photovoltaic technology to photoelectrochemical applications. In our 3TT devices, a two-junction III-V solar cell device has an additional contact, enabling two unique catalyst sites operating at different voltages under the same illumination. Idealized circuit modeling shows the promise of these 3TT devices compared to traditional two-terminal, two-junction devices, particularly with respect to spectral tolerance. We have adapted the structure of 3TT photovoltaics to function as PEC devices and developed multiple catalysts for integration into the two solution contact sites. We demonstrate progress toward light-driven cascade catalysis for multi-carbon CO2RR products.
Second, I will highlight our approaches to protective schemes for photoelectrodes: one which is independent of semiconductor chemistry, and one which is driven by that chemistry. In the first approach, transparent conductive encapsulants (TCEs) are demonstrated as photoabsorber-agnostic protective layers. Unlike many protection schemes, these TCEs can be applied to semiconductors post-processing and without substantial modification, providing facile and robust protection. We have characterized the electrochemical performance of TCEs and demonstrate their integration with multiple semiconductors for the reduction of methyl viologen as a proxy for PEC fuel formation. In the second approach, we use the knowledge generated over fifty years of photoelectrode research to develop a new material, ZnTiN2, which can be directly integrated with established semiconductors and which will degrade under PEC conditions. We leverage this degradation to create protective layers which may be self-healing, and demonstrate rapid refinement of ZnTiN2 optoelectronic properties enabling integration with other semiconductors in tandem configurations.
(Invited) Sustainable Nitrate Production by Photocatalytic Oxidation of Air
Authors: Zaim Abdelkarim , Pashkova Aneta , Burek Bastien O. , Bloh Jonathan Z. 
Published: September 2023

Nitrates are essential compounds for the chemical industry and in particular fertilizer production and are therefore critical for our global food production. They are nowadays almost exclusively produced in centralized plants by burning ammonia, which presents a major energetic detour in which the majority of ammonia’s high energy content is lost as heat. It would be much more efficient to synthesize nitrates directly from the elements (i.e., air) instead.
It has been shown already that air can be oxidized using heterogenous photocatalysis in aqueous suspensions to yield nitrate. However, the low nitrogen solubility and the fact that nitrate will also be available as electron scavenger (back-reaction) limit the overall efficiency and performance. We have recently demonstrated that this reaction is also possible in the gas phase.[1] Air can be directly oxidized over illuminated TiO2 surfaces to nitrogen oxides, predominantly NO2, which can then subsequently be adsorbed into water to form nitric acid.[1] This approach circumvents the limitations of the aqueous phase as nitrogen and water content can be more freely controlled and nitrates are only formed on the subsequent step, suppressing the back-reaction.
Overall, this presents and interesting new synthesis approach to nitrates in a decentralized manner, which could then be the basis for sustainable (solar) fertilizers which are produced directly in the areas in which they are needed.[2] This circumvents the energetic retour via ammonia and also saves on storage and transportation costs and emissions.
In this talk we will present results of our first studies on this reaction, in particular which reaction parameters (such as humidity and light intensity) are critical for the reaction and what influence they have. This reveals first insights into possible reaction mechanisms which will then be discussed. Based on our screening experiments, we will also show which catalyst materials and potential co-catalysts are suited and discuss why that may be the case, further elaborating about the reaction mechanism and potential active sites. This information is then used to predict ideal catalyst materials in a knowledge-based catalyst design approach.
References:
[1] Pashkova, A.; Burek, B. O.; Bloh, J. Z. Sustainable Nitrate Production out of Thin Air: The Photocatalytic Oxidation of Molecular Nitrogen. Catal. Sci. Technol.
2022, 12 (9), 2755–2760, http://dx.doi.org/10.1039/D2CY00350C
[2] Comer, B. M.; Fuentes, P.; Dimkpa, C. O.; Liu, Y. H.; Fernandez, C. A.; Arora, P.; Realff, M.; Singh, U.; Hatzell, M. C.; Medford, A. J. Prospects and Challenges for Solar Fertilizers. Joule
2019, 3 (7), 1578–1605, http://dx.doi.org/10.1016/j.joule.2019.05.001
Coupled Lead Halide Perovskite Photoelectrode for Unbiased Photoelectrochemical Water Splitting
Authors: Rhee Ryan , Park Jong Hyeok 
Published: September 2023

In search for new technology to preserve global warming caused by fossil fuel, solar energy driven devices have been high in demand. For instance, photovoltaics (PV) are a promising technology that can produce high power conversion efficiency (PCE). In addition, photoelectrochemical (PEC) water splitting, a promising artificial photosynthesis method, is a potential alternative technique to generate renewable fuel. PEC devices can generate renewable energy sources such as hydrogen, which can alleviate CO2 emission from fossil fuels. However, most readily employed PEC devices require external bias to function as a hydrogen producer. Thus, utilizing PV active layer as a photo absorber, PEC system is a suitable approach to the breakthrough of efficient hydrogen production.
In the past decade of PV technology advances, organic-inorganic lead halide perovskite (LHP) can be arguably the most progressive research because of its tunable bandgap, fast charge separation, broad light absorption spectra, low cost, facile fabrication, and high efficiency. These advantageous properties led LHPs to be used as an active layer of water splitting devices. However, LHP-based PECs have flaws to be addressed to be viable material for PEC. LHP are known for their fragile nature from exposure to water. Hence, LHP-based PECs are commonly protected with metal foil encapsulation while covering the edges with epoxy resins. However, the metal foil provides poor contact with the LHP leading to poor charge transfer for water splitting. To solve this problem, we applied carbon conductive powder (CCP) as the interlayer to successfully facilitate charge transfer.
With the proposed device modeling, monolithic PEC device that is capable of generating hydrogen in presence of low external applied bias is fabricated. Nonetheless, single monolithic PEC devices still need external applied bias to function as water splitting device which seek for further research. Therefore, adding another photoelectrode will eliminate the necessity of external bias resulting in an only solar powered water splitting device. Herein, we report unassisted solar to hydrogen conversion by using inverted and planar type LHP solar cells as photocathode and photoanode, respectively. With the integration of catalyst, 3D Ni.NiFe and NiPCoP, LHP-based PEC with exceptional performance was attained. We demonstrated unbiased PEC water splitting using a coupled LHP-based photoelectrode under alkaline conditions. Each LHP-based photoelectrode exhibited a outstanding performance of 22.42 mA cm-2 at 1.23 VRHE and 21.96 mA cm-2 at 0 VRHE for the photoanode and photocathode, respectively. Thus, we achieved solar to hydrogen (STH) of 10.64% and unassisted photo-current density of 8.65 mA/cm2. In addition, unbiased catalytic reactivity over 20 h retaining about 60% of photo-current density was attained.