bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing Flexible Carbon Nitride Quantum Dots Decorated Polyaniline Nanocomposite Layer for a Non-Invasive Wearable Sweat Biosensor for Glucose Monitoring
Authors: Chiu Yi Hao , Guo Yi-Ting , Rinawati Mia , Chang Ching-Cheng , Chang Ling-Yu , Yeh Min-Hsin
Published: August 2024

Understanding dynamic biomarker fluctuations, particularly glucose, is vital for early diabetes therapy. Novel non-invasive wearable sweat biosensors are gaining appeal, enabling constant severity monitoring. Nevertheless, the key challenges are that multiplexed motions may result in undesirable metal cracking by the rigid electrocatalytic layer, leading to decreased sensitivity and stability. In this work, we designed carbon nitride quantum dots (CNQDs) decorated polyaniline (PANI) nanocomposite to realize flexible wearable biosensors with high detection accuracy. Upon the enhanced electron transfer by CNQDs, CNQDs/PANI nanocomposite offers greater sensitivity in H2O2 detection compared to pristine PANI, resulting in a sensitivity of 37.21 μA mM-1 cm-2. Therefore, after the glucose oxidase (GOx) immobilization, GOx/CNQDs/PANI-based biosensors is expected to show excellent performance for glucose detection in artificial sweat.

Figure 1
Investigation of Electrical Impedance of Human Breast Cancer Cells and Osteosarcoma Cells
Authors: Tsai Cheng-Feng , Li Yu-Ting , Lin Shu-Ping
Published: August 2024

Nanostructures exhibit a high aspect ratio and volume-specific surface area, endowing them with unique physical and chemical properties distinct from conventional bulk materials[1]. This study aims to develop cell-based biosensors (CBBs) for the non-invasive monitoring of MCF-7 (ATCC-HTB-22) and U2OS (ATCC-HTB-96) cell conditions. Vertically aligned nanostructures, coated with indium tin oxide (ITO), were employed as sensing substrates for cell growth. A polystyrene cylinder, attached to the (3-aminopropyl) trimethoxysilane (APTMS)-modified ITO sensing substrate using PDMS, was utilized to create a cell culture chamber. Impedance measurements were conducted with an E4980A precision LCR meter (Agilent Technologies) at 1 V, covering a frequency range of 20 Hz to 2 MHz, with 201 sample points. We verified the establishment of a functional biointerface by seeding MCF-7 and U2OS cells and monitoring impedance changes, indicative of cell attachment and growth. In conclusion, we successfully adopted the APTMS-modified ITO-coated sensing substrate to measure the impedance of MCF-7 and U2OS cells. Our goal is for this CBB platform to significantly contribute to the advancement of cancer drug development.

References

A. Gao et al., "Silicon-Nanowire-Based CMOS-Compatible Field-Effect Transistor Nanosensors for Ultrasensitive Electrical Detection of Nucleic Acids". Nano Lett.
11, 3974-3978 (2011).

Figure 1
Increasing Graphene Selectivity for H2O2 Electro-Production Using Phosphorus Doped Carbon Nitride Quantum Dots as Self-Antibiofouling Dissolved Oxygen Sensor
Authors: Chen Kung-Hsing , Aulia Sofiannisa , Rinawati Mia , Chang Ching-Cheng , Chang Ling-Yu , Yeh Min-Hsin
Published: August 2024

Dissolved oxygen (DO) is a crucial indicator of the aquatic environment. The electrochemical DO sensor is renowned for superior precision. However, the unfavorable biofilm growth on the electrode surface and affect its sensitivity. H2O2, generated from the 2e- pathway ORR, emerges as a potent for degrading the biofilm attached on the electrode surface. Developing electrocatalyst material for selective 2e- pathway ORR that is challenging, while most are work for 4e- pathway. Herein, we design P-CNQD attaching to functionalized graphene (P-CNQD/Gr) that possesses highly selective 2e- pathway ORR. Upon the combination, the P-CNQDs were successful in altering the H2O2 selectivity, resulting in 85% H2O2 selectivity inside neutral medium. The reliable electrocatalyst with outstanding sensitivity and self-antibiofouling performance to be employed in fish farming

Figure 1
(Invited) Tuning Chirality of Graphene Quantum Dots to Empower Medical Imaging and Theranostic Applications
Authors: Wang Yichun
Published: August 2024

Chiral nanostructures from metals and semiconductor, including graphene-based materials, are increasingly recognized for their potential in polarization-sensitive optoelectronics. Particularly, graphene quantum dots (GQDs) modified with L/D amino acids exhibit unique chiral properties due to edge-specific interactions, offering new possibilities in biomedicine. Our study delves into the interaction of these chiral nanomaterials with biological systems, revealing significant implications for their application in biology and medicine. We discovered that attaching L/D amino acid moieties to GQDs induces nanoscale chirality by helical buckling, influenced by the chiral interactions at the graphene edges. The chirality of GQDs affects their interaction at the nanoscale with cells and tissues. Molecular dynamics simulations show that D-GQDs are more likely to accumulate within cellular membranes compared to L-GQDs. Additionally, experiments on chiral GQD permeation through lipid membranes of extracellular vesicles demonstrated that optimizing chirality via ligand tuning and GQD size can significantly enhance their permeation efficiency into lipid bilayers, exceeding 80%. Leveraging this enhanced transmembrane transport, chiral GQDs have been applied in imaging and efficient drug loading for therapeutic extracellular vesicles. Furthermore, we explored how GQD chirality affects transport in tumor-like cellular spheroids. The results indicate that L-GQDs exhibit a 1.7 times higher apparent diffusion coefficient than D-GQDs, enhancing their transport into these spheroids. In summary, our research underscores the importance of controlling and engineering GQD chirality. This approach not only enhances the transport of drug carriers through biological barriers but also opens new avenues for advanced imaging and theranostic applications.
High Surface Area Metal Oxide Enhanced Self-Powered Microfluidic Device for Real-Time Pathological Detection
Authors: Kaswan Kuldeep , Lin Jia -Cheng , Fan Yu-Jui , Lin Zong-Hong
Published: August 2024

Biomarkers based sensing in the realm of disease prevention, its diagnosis, and drug development has shown its unique importance in health care. In particular, the platelet level in blood is strongly linked with the development of several kind of severe diseases like coronavirus disease 2019, diabetes, and microbial infections as well as individuals undergoing cancer diagnosis. Currently, commercial methods employed for platelet level determination in whole-blood are based on Coulter principle, flow cytometry, and image analysis. However, these technologies are intricate, time consuming, expensive, and require a trained operator as well as lack of portability. Considering these issues, we have developed a self-powered portable device for real-time platelet level monitoring, aimed towards point-of-care applications. The fabricated self-powered-microfluidic triboelectric nanogenerator (SPM-TENG) utilized test sample flow-resistance for sensing of platelet level and triboelectric voltage output as sensing signal. For the fine tuning of fabricated SPM-TENG, we compared the triboelectric voltage output from gold electrode measurement setup and terminal electrode measurement setup. In view of further improvement in stability, voltage output and to minimize the noise in sensing signals, the geometrical optimization of microfluidic channel was performed. In conclusion we have optimized the device as a terminal electrode measurement setup with copper tubes on terminals of microfluidic channel and copper oxide nanowires grown on the interior of copper tubes. These copper oxide nanowires provide a high surface area for solid-liquid contact separation and is responsible for enhanced sensing signal. The fabricated SPM-TENG has shown its great potential in platelet level sensing with plasma-based samples as well as whole-blood samples. The proposed device demonstrated its practicality towards real-time rapid sensing of platelet level and portability.
Phosphorus-Doped g-C3N4 Induces Self-Polarization PVDF for High-Performance Triboelectric Nanogenerator As Wearable Power Sources
Authors: Chiu Yen-Shuo , Chang Yu-Hsin , Chang Ching-Cheng , Chang Ling-Yu , Yeh Min-Hsin
Published: August 2024

In recent years, the requirement for wearable electronic energy has become increasingly popular, which can be seen from the creation of numerous energy harvesters and storage devices. Among them, a new type of energy harvesting technology named triboelectric nanogenerator (TENG) has gradually matured for nearly ten years. Increasing the output performance by enhancing the surface charge of the TENG is what most researchers have focused on recently. There are several ways such as changing the surface structures, improving the dielectric constant and spontaneous polarization, which is related to this work. Some papers mention that filling nanoparticles or adding 2-dimensional material will induce PVDF self-polarization to the beta phase, making it a highly electronegative state. Moreover, adding high electronegative atoms will also change the state of the PVDF. Therefore, we synthesize the PVDF film by adding phosphorus-doped g-C3N4 (PCN) in order to enhance the output performance. By introducing the P atom into the matrix of g-C3N4 via an annealing process, the P atom in g-C3N4 not only increases the electronegativity of the film surface but also induces PVDF to a polarized crystal b phase for absorbing more positive charges. Consequently, the TENG with PVDF/PCN displays a remarkable improvement in output performance compared to the pristine PVDF-based TENG with more than a 100 V increase. Furthermore, the flexibility and durability of PVDF/PCN thin film have the potential to be widely used in self-powered wearable sources.

Figure 1
Enhanced Detection of Klebsiella Pneumoniae Using Electric-Double-Layer FET Sensor: Rapid, Temperature-Boosted Probe-Target Binding Analysis
Authors: Kalaimani Vishal Mani , Zeng Guan-Cheng , Lin Chia Kai , Wang Yu-Lin
Published: August 2024

Klebsiella pneumoniae demonstrates versatility in its pathogenicity, leading to diverse infections in humans such as pneumonia, urinary tract infections, bacteremia, wound infections, meningitis, endocarditis, and sepsis. The severity of these infections is contingent upon the patient's immune status, the site of infection, and the existence of underlying medical comorbidities. A sputum or urine culture, on the other hand, typically takes between 24 and 72 hours to produce results. Over recent years, various innovative methodologies have emerged, including optical and electrochemical techniques and molecular detection via PCR. Despite the diversity of available techniques, concerns persist regarding their sensitivity and specificity. Moreover, fluorescence-based methodologies and Surface Plasmon Resonance (SPR)-based sensors have been explored for bacterial detection. However, these existing methods have drawbacks such as elevated costs, prolonged turnaround times, the need for sophisticated instrumentation, and a demand for skilled personnel. Field-effect transistor (FET) sensors have garnered considerable scientific attention since their inception due to their remarkable sensitivity, facile signal readout, and the capability for label-free assays. The aim of this research is to detect the detect Klebsiella pneumoniae bacteria in blood serum by double electric layer (EDL) extended-gate field-effect transistor (FET) sensor. In this study, a preliminary investigation employed a single-step surface functionalization approach to immobilize receptor probes, specifically single-stranded DNA (ssDNA). This strategy aimed to enable the rapid detection of complementary DNA (cDNA) across varying concentrations, leveraging differential gate voltages to modulate the sensitivity of this analytical platform. The designed probes were successfully immobilized onto a disposable chip housing a pair of gold electrodes. A handheld reader, integrating enhancement-mode N-channel MOSFETs, established connectivity with a laptop via a USB port to facilitate the measurement of sensor signals. By applying pulsed gate voltage to the input electrode, which modulates the channel conductivity which behaves as a function of the charge distribution within the EDL structure, consequently influencing the drain current of the MOSFET. The immobilized probe, positioned on the gate electrode, underwent testing using varying concentrations of cDNA introduced into TE buffer. Detection of probe-target binding occurred through fluorescence alterations and electrically by assessing changes in drain current. In order to improve the response time, we elevated the temperature near the Tm enhances sensitivity and binding rates, in shorter time period of 1 minutes.

Figure 1
Investigating the Catalyst/Ionomer Interface in PEM Water Electrolysis Using Microelectrodes
Authors: Anderson Grace C. , Tricker Andrew W. , Lee Jason Keonhag , Bell Alexis T. , Peng Xiong , Mukundan Rangachary , Weber Adam Z.
Published: August 2024

Low temperature zero-gap PEM water electrolyzers are promising devices which are still in development. Water electrolyzers have the potential to be a critical part of the energy transition as a method to use renewable electricity to produce hydrogen which can feed into the hydrogen economy. When paired with renewable sources of electricity, electrolyzers will be subjected to variable power loads, which places a large stress on the systems. This stress causes increased degradation of many components, including the catalyst layers. It can be challenging to study the impact of degradation of the catalyst layer in an electrolysis cell, due to the many coupled degradation phenomenon occurring in the full cell system. Microelectrodes can be used to investigate the catalyst layer under electrolysis operating conditions, but in a simplified system which can more easily isolate the catalyst layer and kinetics. One of the limiting factors in water electrolyzer performance is the oxygen evolution reaction (OER) due to the sluggish kinetics. If the OER kinetics could be improved, it would greatly reduce the cost of the electrolyzer system. The ionomer forms a thin film in the catalyst layer, and controls the local conditions surrounding the catalyst. The local conditions and interactions of the ionomer with the active catalyst sites still aren't well understood, as well as the contribution of the ionomer to catalyst degradation. In this study, cavity microelectrodes will be used to investigate the impact of ionomer on IrOx catalyst OER performance and durability.
Comprehensive Characterization of Porous Transport Electrodes with SEM, XPS, and Tof-SIMS
Authors: Stelmacovich Genevieve , van Eijk Lonneke , Foster Jayson , Walker Michael , Ding Lei , Zhang Feng Yuan , Paxson Adam , Pylypenko Svitlana
Published: August 2024

Advancements towards more efficient design and manufacturability of polymer electrolyte membrane electrolyzers include recent efforts to better integrate the porous transport layer (PTL) and adjacent anodic catalyst layer (CL), forming the porous transport electrode (PTE). It is well known that characterizations of the PTL alone, especially when combined with a protective coating, present numerous challenges. The PTE structure is even more complex, and it is difficult to comprehensively characterize all components and interfaces. In prior work, we established Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) as a characterization technique for the PTLs coated with protective coatings. This work demonstrates ToF-SIMS as a powerful technique for the characterization of PTLs integrated with CLs.

A series of sintered Ti PTLs were first coated with protective Pt coatings and then coated with various IrOx and IrRuOx catalysts via electrodeposition. Prepared PTE samples ranged in catalyst loadings and catalyst composition. Selected samples were also subjected to annealing post-treatments to further modify catalyst composition. X-ray photoelectron spectroscopy (XPS) was conducted to identify surface chemical speciation and states of the catalysts. ToF-SIMS analysis was conducted using Cs in both positive and negative modes to identify chemical species, including Ir, Ru, and their oxides as a function of catalyst layer depth. These two methods were complemented by Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy (SEM- EDS) analysis to evaluate morphology and distribution of catalysts. This comprehensive physical and chemical characterization of the PTEs provides insights that are useful for the characterization of as produced, modified, and degraded PTE samples.
Benchmarking Local pH of Electrocatalysts for Water Electrolysis Using the Rotating Ring-Disk Electrode Technique
Authors: Wu Wen Yu , Wilkinson David P. , Gyenge Elod L.
Published: August 2024

Water electrolysis is an important route for production of green hydrogen and remains a field of active research in pursuit of improved electrocatalytic activity and durability. Operating with a near-neutral feed is critical for this technology to be more widely adapted, because it allows the direct use of various water sources and imposes less stringent requirements on the components of the electrochemical cell.

During water electrolysis, the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) involving protons and hydroxides can experience a significant change in local pH at the surface of the catalyst, especially in near-neutral bulk conditions. This change in local pH is usually dictated by the reaction conditions such as electrolyte composition and mass transport within the system. Notably, there has been an increase in development of catalysts for water electrolysis with the ability to modulate their local pH in recent years. 1–6

However, comparing and quantifying the local pH modulation effects of these catalysts is challenging due to varying experimental techniques and protocols. The rotating ring-disk electrode (RRDE) with a potentiometric pH sensing ring has been presented as a promising and facile tool for in-situ local pH detection. 3,4,7,8 The local pH at the disk is estimated from the ring pH through solving the convective-diffusion equation under the well-defined mass transport conditions of an RRDE system. 8

In this study, we have investigated the local pH of iridium oxide during OER in both unbuffered and buffered electrolytes under near-neutral to alkaline bulk conditions using the RRDE technique. Our results provide benchmarks for future studies on the local pH modulation effects of catalysts and insights into the impact of electrolyte composition on local pH. In combination with mass transport modelling, we further examined the limitations of this technique and provide suggestions for best practices.

References

X. Liu et al., Appl. Catal. B Environ., 331, 122715 (2023).

Z. Li et al., Angew. Chemie Int. Ed., 62, e202217815 (2023).

J. Guo et al., Nat. Energy, 8, 264–272 (2023).

X. Zheng et al., Nat. Commun. 2023 141, 14, 1–13 (2023).

X. Wang, C. Xu, M. Jaroniec, Y. Zheng, and S. Z. Qiao, Nat. Commun. 2019 101, 10, 1–8 (2019).

H. Tan et al., Nat. Commun. 2022 131, 13, 1–9 (2022).

Y. Yokoyama et al., Chem. Lett., 49, 195–198 (2020).

W. J. Albery and E. J. Calvo, J. Chem. SOC., Faraday Trans. 1, 79, 2583–2596 (1983).

Figure 1
(Invited) Design Principles and Operation of PEM Electrolyzers for Power-to-Gas Technologies
Authors: Strasser Peter
Published: August 2024

This Tutorial addresses fundamental and practical principles of design and operation of Proton Exchange Membrane (PEM) Electrolyzers used in today’s emerging Power-to-Gas Technologies. Starting from thermodynamics and basic process schemes, this tutorial will concisely discuss mass transport processes and heat balances pertinent to the operation of PEM electrolyzers at cell, stack, and system level. The sensitivity of key performance indicators such as energy efficiency or the specific work to generate 1kg of hydrogen to the choice of material and operating parameters will be highlighted.

References

Smolinka, Garche eds., Hydrogen Production by Water Electrolysis, Elsevier,2022

Bessarabov, Millet eds., PEM Water Electrolysis Vol.1, 2, Hydrogen and Fuel Cells Primer Series, Elsevier academic Press, 2018

Geert Tjarks “PEM-Elektrolyse-Systeme zur Anwendung in Power-to-Gas Anlagen” Schriften des Forschungszentrums Jülich Reihe Energie & Umwelt / Energy & Environment Band / Volume 366 ISBN 978-3-95806-217-7 2017

Bessarabov, Wang, Li Zhao eds., PEM Electrolysis for Hydrogen Production, 2015
(Invited) Fruitful and False Analogies between Polymer Electrolyte Fuel Cells and Electrolyzers
Authors: Mittelsteadt Cortney , Yang Fan , Paxson Adam , Sweetland Matthew
Published: August 2024

In the past 20 years polymer electrolyzer membrane fuel cells (PEMFCs) received great attention as a clean alternative for powering mobility and stationary applications. Resultingly, there has been a rich amount of research by public, private and university investigators particularly focusing on membranes, catalysts, transport and cost. Yields of great advances were made, though scant attention was given to the generation of this hydrogen and polymer electrolyte membrane water electrolysis (PEMWE) was the neglected stepsister, sentenced to back chapters, footnotes, and small conference rooms. Now however the opportunity for hydrogen generated from renewables, "green hydrogen" has been widely seen as an opportunity to not only provide hydrogen for these PEMFC applications, but also seemingly intractable CO2 emitters as ammonia generation and steel and petroleum refining. As numerous government agencies have announced eye-popping targets for green electrolysis and the complementary research funding, the temptation is to take the beautiful evening gown woven of PEMFC research and adorn the overlooked stepsister. .

Zealous PEMFC researchers have not surprisingly reversed course and focused attention on making, rather than consuming hydrogen. Exploitation of the PEMFC and PEMWE analogy is tempting, as many of the materials and reactions are the same or similar. Noteworthy, there are the polymer electrolyte membrane, expensive PGM catalysts, a very fast hydrogen reaction and very slow oxygen reaction. Yearning for faster kinetics and facile heat management, both also have pushed operation to higher temperatures and suffer the accelerated degradation that goes with it. Using these analogies has has generated some benefits, particularly in lower catalyst loading and conductive membrane resistance. Keeping in mind the differences is key however, as PEMWE will generally need to operate at much higher currents, under higher pressures, for far longer durations.

This talk will look at what PEMWE has and has the potential to learn from PEMFC research. We will look at materials, their key aspects and how optimizing for each is different, with a focus on costs, the use of hydrocarbon materials, chemical and mechanical durability strategies and recycling. Use cases will also be explored, particularly how the need for high hydrogen production pressures (>30 bar) changes the electrode assembly as well as the balance of stack.
Investigating the Differences between the in-Situ Galvanostatic Test and Ex-Situ Fenton Test on Nafion Membranes for PEM Water Electrolysis
Authors: Patra Sudeshna , Gottschalk Torben , Heßling Janis , Trinke Patrick , Schweer Felix , Bittner Florian , Schönhoff Monika , Bensmann Boris , Hanke-Rauschenbach Richard
Published: August 2024

Perfluorinated sulfonic acid (PFSA) ionomer membranes (e.g Nafion) are widely employed as the benchmark materials for the electrolyte membranes in PEM water electrolysis (PEMWE). It is broadly acknowledged that the state of health of PFSA membranes is detrimentally impacted by the chemical degradation occurring during operation of PEMWE. The cross-over gases interacting with the catalytic surface lead to the generation of hydrogen peroxide. This compound can undergo homolytic cleavage or, in the presence of ferrous salts, yield reactive oxygen species such as hydroperoxyl (HOO.) and hydroxyl (HO.) radicals. These radicals attack the ionomer subsequently leading to chain scission, unzipping and loss of functional groups and release of HF in the effluent water. However, the degree of degradation differs when exposed to ex-situ conditions compared to real proton exchange membrane (PEM) water electrolysis conditions.

This work depicts a methodical investigation of degradation of catalyst coated Nafion membranes (CCM) using a Fenton's accelerated aging experiment and in-situ test. In the Fenton's approach, the durability of Nafion 117 and catalyst coated Nafion membrane with counter ions such as ferrous ions against H2O2 was explored as a degradation factor of polymer electrolyte water electrolyser. CCMs were submerged to a solution containing ferrous ions and peroxide. Accelerated aging experiments were conducted over a period of 3-7 days. An in-situ ageing test has been performed on a MEA with and without the presence of Ferrous ions by applying galvanostatic pulses for 7 days. Experimental confirmation of degradation mechanisms has been obtained by post-mortem analysis of the MEA using microscopy and chemical analysis and mechanical investigation. To quantify the effect of water activity in Nafion and CCM chemical structure on both water diffusion and interfacial transport, pulse field gradient spin echo nuclear magnetic resonance (PFGSE-NMR) technique has been employed. Morphological characteristics before and after aging tests were also investigated. Comparative estimation of the fluoride release rate in case of both in-situ and ex-situ test was also performed. This work offers a comprehensive dataset comparing the performance of degraded membranes both in situ and ex situ.
Materials Integration and Catalyst Interfaces in Anion Exchange Membrane, Low Temperature Electrolysis
Authors: Alia Shaun M , Kreider Melissa E , Volk Emily K. , Chan Ai-Lin , Ul Hassan Noor , Clauser Arielle L , Sugar Josh D
Published: August 2024

Hydrogen has unique advantages as an energy carrier due to its high energy density and abilities in long-term storage and to convert between chemical bonds and electricity. [1] Although hydrogen currently has a small role in energy pathways, decreasing electricity prices can allow for significant growth. Anion-exchange-membrane water electrolysis (AEMWE) holds promise for reaching reduced hydrogen production cost targets, particularly from a materials perspective, and is the primary technology pathway being studied under Low Temperature Electrolysis in the HydroGEN Energy Materials Network (EMN).

In AEMWE, it has been critical to explore the impact of materials and their integration on performance and durability, thereby demonstrating and enhancing use opportunities. [2] While platinum group (PGM) -free components, including catalysts and transport layer/separator coatings are readily available that can achieve high performance at a reduced cost, individual properties and their interactions create integration challenges.[3] Specifically in performance, the inclusion of ionomer and pore structures can be more complicated than for acidic systems and the use of PGM-free materials can add difficulties in electronic and ionic transport. While AEMWE can become extremely durable when targeted for low-cost applications, additional loss sources including ionomer oxidation, materials passivation (catalyst, transport layer, separator) further complicates identifying and separating irreversible loss mechanisms, and in developing accelerated stress tests. This presentation includes an overview of efforts in AEMWE and focuses on materials choices, catalyst-ionomer-transport layer interactions, and the variety of integration strategies being employed in the HydroGEN EMN.

References

[1] B. Pivovar, N. Rustagi, S. Satyapal, The Electrochemical Society Interface
2018, 27, 47.

[2] S. Alia, D. Ding, A. McDaniel, F.M. Toma, H.N. Dinh, Chalkboard 2-how to make clean hydrogen. The Electrochemical Society Interface
2021,
30 (4), 49.

[3] S. M. Alia, HydroGEN: Low Temperature Electrolysis, https://www.hydrogen.energy.gov/docs/hydrogenprogramlibraries/pdfs/review23/p148a_alia_2023_p-pdf.pdf 2023.

Figure 1
Surface Engineered Ni-Fe Foam As a Bi-Functional Electrode for Water Electrolysis in Alkaline Media
Authors: Aly Islam A , Abdelsalam Mohamed O , El Sawy Ehab N
Published: August 2024

Using fossil fuels as a main source of energy has resulted in various environmentally hazardous effects, including global warming, climate change, and environmental pollution. Consequently, the development of a sustainable and clean source of energy became of urgent need. Water electrolysis has captured considerable attention as the main technology of hydrogen fuel production. It is particularly enticing due to its eco-friendliness and sustainability. Self-supported electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) have prominent roles in water electrolysis. Growing self-supported metal oxides, hydroxides1, phosphates2, sulfides3, etc. that possess high electrical conductivity, electrocatalytic activity, and structural stability have attracted attention lately. FeNi-based catalysts are considered one of the most promising electrocatalysts for water electrolysis in alkaline solutions. However, improving their catalytic activity and stability is one of the research targets before further practical applications. Nickel foam is widely used as a self-supported electrocatalyst due to its high surface area, low cost, and exceptional catalytic activity, with several studies focused on the deposition of nickel-iron materials on nickel foam for the development of a bifunctional catalyst for water electrolysis4. However, very few studies used NiFe mesh or foam to grow a self-supported catalyst material5.

In this study, surface-engineered NiFe foam electrodes were developed by facile control of the Ni/Fe surface ratio via chemical leaching and oxidation with NaOH and NaClO4 followed by electrochemical activation, aiming to design a bifunctional electrocatalyst for both OER and HER. Results revealed that varying the ratios of NaOH and NaClO4 induced significant alterations to the surface composition (different Ni/Fe), and hence the active sites for OER and HER. The physicochemical and structural properties of the NiFe foam were characterized using glancing angle X-ray diffraction (GAXRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). Further, the catalytic activity of the modified electrode was assessed utilizing cyclic voltammetry, linear sweep voltammetry, chronopotentiometry, and electrochemical impedance spectroscopy.

References

F. Dionigi and P. Strasser, Advanced Energy Materials, 6, 1600621 (2016).

Y. Yu et al., Journal of Colloid and Interface Science, 607, 1091–1102 (2022).

A. Shankar, R. Elakkiya, and G. Maduraiveeran, New J. Chem., 44, 5071–5078 (2020).

H.-S. Hu, S. Si, R.-J. Liu, C.-B. Wang, and Y.-Y. Feng, International Journal of Energy Research, 44, 9222–9232 (2020).

C. Sun et al., ACS Appl. Energy Mater., 4, 8791–8800 (2021).
Selectivity Study of Anodic Seawater Electrolysis Catalysts Using the Rotating Ring-Disc Electrode Method
Authors: Horner Oliver , Gyenge Elod Lajos , Wilkinson David P.
Published: August 2024

Water electrolysis generating green hydrogen will play a vital role in achieving the net-zero 2050 goal; however, freshwater electrolysis will further strain an already strained supply of clean freshwater.1 If seawater electrolysis can be scaled successfully, it would provide an important source of green hydrogen. Current research on untreated, direct seawater electrolysis is limited, and only recently have studies emerged analyzing catalyst performance at near-neutral pH.2 At industrially-relevant current densities, the formation of corrosive hypochlorite must be considered as a secondary reaction.3 Hypochlorite forms through the chloride oxidation reaction (ClOR), which competes with the oxygen evolution reaction (OER) in seawater electrolysis.2 In this work, we discuss the limitations of the current methods for determining anodic catalyst selectivity between OER and ClOR. The short lifetime of hypochlorite can cause faradaic efficiency measurement methods such as titration or oxygen gas capture to become unreliable, as these tests require that the hypochlorite remain stable. Using a rotating ring-disc electrode (RRDE), we measure the selectivity of common OER catalysts in-situ (Figure 1a). Real-time hypochlorite sensing overcomes the challenge of measuring catalyst selectivity posed by the short lifetime of hypochlorite. Remarkably, a PtRu catalyst outperformed more common OER catalysts with the best in OER selectivity and low overpotential, a novel development in the field of near-neutral water electrolysis. We also determine that elevated heat and low chlorine concentration are conducive to improved OER selectivity on an IrO2 catalyst (Figure 1b). We hope this work will set the standard in catalyst benchmarking for seawater electrolysis catalysts and could lead to the development of catalysts for efficient, scalable, and sustainable hydrogen production from seawater.

H. Jin et al., Sci Adv, 9, eadi7755 (2023) https://www.science.org/doi/10.1126/sciadv.adi7755.

F. Dionigi, T. Reier, Z. Pawolek, M. Gliech, and P. Strasser, ChemSusChem, 9, 962–972 (2016) https://onlinelibrary.wiley.com/doi/full/10.1002/cssc.201501581.

J. Guo et al., Nature Energy 2023, 1–9 (2023) https://www.nature.com/articles/s41560-023-01195-x.

Figure 1. a) LSV profiles of common OER catalysts (solid line) and the corresponding faradaic efficiency (dashed line) for the OER, measured using the ring current of the rotating ring-disc electrode. Catalysts were tested in 0.5 M NaCl and buffered with KHCO3 to pH 8.5. b) A ternary plot depicting the effect of varying Cl concentrations and temperatures on the selectivity of an IrO2 catalyst at pH 8.5.

Figure 1
Low Ir-Containing Materials As Anode Catalysts for PEM Water Electrolysis
Authors: Surkus Annette-Enrica , Pham Trang Minh
Published: August 2024

The PEM electrolysis is based on the application of IrO2 as anode catalyst. Until now, there is no real alternative for this electrocatalyst, since the highly acidic and oxidative conditions at the anode lead to rapid corrosion.[1-3] With steadily increasing energy consumption, the demand for iridium will exceed the available resources in a few decades. As a result, the price of iridium as well as the technologies based on it will continuously increase. An enhancement of PEM electrolysis capacities on a large scale can therefore only be realized in the long term if the application of iridium is significantly reduced.[4] Therefore, our research aims at reducing the iridium content of PEM anodes while maintaining catalytic activity and stability.

In this work, two approaches to save iridium were applied. On the one hand the iridium content was reduced by supporting it, on the other hand an additional, readily available metal is incorporated that is protected from corrosion by the presence of iridium and at the same time assists the iridium in catalysis.

So, bimetallic included low-loading Ir and different transition metal (Ru, Sn, and Ag) nanoparticles on titanium nitride (TiN) were synthesized by using a chemical reduction method and thermal treatment. Experimentally, a IrSnOx/TiN sample in 0.5 M H2SO4 with an Ir loading of 0.05 mgIr/cm2 achieves a mass activity of over 450 A/gIr at 1.6 V vs RHE and an overpotential of 297 mV at 10 mA/cm2. The investigation includes stability tests at constant current density of 10 mA/cm2 and determination of impedance by electrochemical impedance spectroscopy (EIS).

As result, a suitable anode material was successfully achieved, which exhibits a similarly good activity and stability values compared to the IrO2 materials that have been used industrially so far, but with a significantly reduction of iridium to 24% of the usually applied amount.

[1] C. Minke, M. Suermann, B. Bensmann, R.H. Rauschenbach, Int. J. Hydrog.
Energy, 2021, 46, 23581-23590.

[2] F. Scarpelli, N. Godbert, A. Crispini, I. Aiello, Inorganics,
2022, 10, 115.

[3] J. Gao, Y. Liu, B. Liu, K.W. Huang, ACS Nano, 2022, 16, 17761-17777.

[4] T. Reier, H. N. Nong, D. Teschner, R. Schlögl, P. Strasser, Adv. Energy Mater., 2017, 7, 1601275.
Pristine Metal-Organic Frameworks for Efficient Oxygen Evolution Electrocatalysis
Authors: Šljukić Biljana , Paul Anup , Santos Diogo M.F
Published: August 2024

Green energy technologies propose the use of hydrogen as fuel instead of fossil fuels that have drawbacks of limited supplies and greenhouse gas emission during their combustion. Though hydrogen is the most abundant element on the Earth, hydrogen gas is commonly not found in pure form, but bound in compounds such as water or hydrocarbons. Thus, hydrogen gas is a synthetic fuel that needs to be produced. For the energy to be completely green, hydrogen should be produced using renewable energy. Currently, most of the hydrogen is produced using fossil fuels and only ca. 5% is produced using electrolytic water splitting. It is the high cost of the water-splitting process that limits its use on the wider scale. To reduce the associated high energy input to break a water molecule, resulting in high cost of hydrogen produced by water splitting, expensive electrocatalysts are typically used.

The aim of this work is to design novel and low cost metal-organic frameworks (MOF) or coordination polymers (CP) utilizing different ligands (for instance, amide functionalized ligands) towards their application in energy conversion reactions such as oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). MOFs are rarely used in their pristine form; literature reports typically focus on MOF-derived carbon materials. Moreover, herein special attention is given to OER as the efficiency-limiting reaction within the water electrolysis process.

The first part of the work focuses on the synthesis and characterization of ligands and MOFs/CPs based on transition metals, nickel and cobalt. The morphology and structure of these composites is examined using electron microscopy and X-ray diffraction analysis. The second part of the work focuses on the pristine materials’ electrocatalytic activity involving standard electrochemical techniques, i.e., voltammetry, impedance spectroscopy, and chronoamperometry to identify the material with the optimum performance and stability. Main reactions parameters including onset potential, overpotential at defined current density as well as current density at defined potential and Tafel slope, are determined.

This work presents step towards green hydrogen production within search for solutions for the current energy crisis.

Acknowledgments

This work was supported by the Science Fund of the Republic of Serbia, grant number 7750219, Advanced Conducting Polymer-Based Materials for Electrochemical Energy Conversion and Storage, Sensors and Environmental Protection-AdConPolyMat (IDEAS programme).
Effectiveness of Gas Recombination Catalyst Layers in Mitigating H2 Crossover in PEM Water Electrolyzers Operating at High Differential Pressure
Authors: Gawas Ramchandra , Lee Jason Keonhag , Dizon Arthur , Wang Guanzhi , Kushner Douglas I. , Peng Xiong , Mukundan Rangachary
Published: August 2024

Gigawatt-scale deployment of proton exchange membrane water electrolyzers (PEMWE) to produce green hydrogen at $1/kg of H2, the US department of energy’s (DOE) ultimate cost target, requires the use of thinner membranes to reduce ohmic losses at high current densities as well as differential pressure operation to improve the overall system efficiency.1 High differential pressure operation results in significant hydrogen crossover through PEMs leading to safety concerns due to the formation of a flammable gas mixtures at anode (> 4% H2 in O2).2 Therefore, the successful deployment of PEMWEs at scale relies on successful implementation strategies to reduce the hydrogen concentration at anode to enable safe operation at high efficiency. These strategies include incorporating gas recombination catalyst (GRC) in the membrane, PTL or downstream in the anode gas outlet. However, the impact of GRC layers on PEMWE performance and hydrogen crossover rates at high differential pressure is not well understood.

In this work, we employ in-operando gas chromatography coupled with thermal conductivity detector along with PEMWEs operating at differential pressures (up to 30 bar) to quantify hydrogen crossover rates through PEM at differential pressure. Using this setup, we evaluate the effectiveness of gas recombination layers incorporated in PEMWE membrane electrode assemblies (MEA) in mitigating the risk of formation of the flammable gas mixture. Further, we will also discuss implications of high differential pressure operation on PEMWE performance, durability, and operational safety.

References:

(1) Ayers, K.; Danilovic, N.; Harrison, K.; Xu, H. PEM Electrolysis, a Forerunner for Clean Hydrogen. Electrochem Soc Interface
2021, 30 (4), 67–72. https://doi.org/10.1149/2.F16214IF.

(2) Bernt, M.; Schröter, J.; Möckl, M.; Gasteiger, H. A. Analysis of Gas Permeation Phenomena in a PEM Water Electrolyzer Operated at High Pressure and High Current Density. J Electrochem Soc
2020, 167 (12), 124502. https://doi.org/10.1149/1945-7111/abaa68.
Bimetallic Ir-Ru 25:75 Catalyst for PEM-WE: Uncovering the Origin of Its Activity by Operando Wide Angle X-Ray Scattering
Authors: Hrbek Tomas , Kúš Peter , Mirolo Marta , Drnec Jakub , Nedumkulam Hridya , Martens Isaac , Matolínová Iva
Published: August 2024

Proton Exchange Membrane Water Electrolyzers (PEM-WEs) are entering the phase of commercial mass production. However, the issue of an iridium catalyst for the anode remains. Our previous work presented an iridium-ruthenium-based catalyst (25% Ir = 158 µg cm-2, 75% Ru) prepared as a thin film on the surface-enhanced PEM-WE-anode via magnetron sputtering. This catalyst demonstrated excellent activity and stability in single-cell PEM-WE (1 A cm-2 at 1.606 V, 80 °C, degradation rate – 1.3 µV h-1 at 1 A cm-2 for 500 hours). The origin of its outstanding electrochemical performance was, however, not known. We present a complete operando Wide Angle X-Ray Scattering (WAXS) study done at the European Synchrotron Radiation Facility (ESRF) using a dedicated PEM-WE cell. The structure of each sample is observed for several hours under PEM-WE conditions with increasing current density from 100 mA cm-2 to 600 mA cm-2. Consequently, we show the connection of the electrochemical performance of the Ir-Ru 25:75 catalyst to its structural properties and uncover the interplay between the face-centered-cubic iridium and hexagonal-close-packed ruthenium.
Ruthenium-Zirconium Oxide Oxygen Evolution Electrocatalysts: Structure, Activity and Electrochemical Stability
Authors: Albiter Luis A , Salomon Fernando , Meehan Caroline , Rhodes Christopher P.
Published: August 2024

The cost of oxygen evolution reaction (OER) electrocatalysts is a hindrance to the large-scale utilization of proton exchange membrane water electrolyzers (PEMWEs). Iridium oxide (IrO2) provides a balance of high activity and stability; however, the high cost and scarcity of Ir necessitates the development of non-Ir OER catalysts. Ruthenium oxide (RuO2) has higher OER activity and lower cost compared to IrO2, but RuO2 is highly unstable in acidic media at high potentials and undergoes dissolution during PEMWE operation. We investigated incorporating zirconium (Zr) into RuO2 to improve the electrochemical stability of RuO2 OER catalysts. Ruthenium-zirconium oxides (Ru1-xZrxO2) were prepared using different synthesis methods and with different Zr concentrations, and we studied the effect of Zr on the structure, morphology, OER activity, and electrochemical stability. The Ru1-x ZrxO2 catalysts were studied by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and rotating disk electrode electrochemistry, and metal dissolution was analyzed by inductively coupled plasma mass spectrometry. Our results show that Zr can be incorporated into rutile RuO2 via different synthesis routes, and the OER activity and stability are affected by the incorporation of Zr. The understanding of the effects of substituents on OER activity and stability furthers the development of OER catalysts with high activity, high stability, and lower cost.
Reaction Induced Surface Restructuring in Electrocatalysts for OER
Authors: Feng Zhenxing
Published: August 2024

The search of efficient and stable electrocatalysts for oxygen evolution reaction (OER) in alkaline and acidic electrolytes is the key to enable the commercialization of electrolyzers and low hydrogen production price. However, there is a trade-off between activity and stability for catalysts due to the highly oxidative condition of OER, which induces the surface restructuring in electrocatalysts. This presentation will show couple of cases, including (Co, Ni)Sx and SrIrO3-based catalysts, go through irreversible restructuring and form (metal)stable phases that exhibit higher activity (better than commercial standards IrO2 and RuO2) and better stability. Using in-situ X-ray absorption spectroscopy (XAS) and other characterizations, we reveal the true catalyst phases that all contain octahedral oxide clusters, which are responsible for the improved activity and stability. The strategy to design and scale up such active phases will also be discussed.
Investigation of Iridium Catalyst Degradation in PEM Water Electrolyzers: Current Density or Cell Voltage?
Authors: Sun Qiang , Mittelsteadt Cortney , Buek Connor , Yang Fan , Jia Qingying
Published: August 2024

Proton exchange membrane (PEM) water electrolyzers represent a cornerstone technology in the sustainable production of green hydrogen. However, their large-scale commercialization is hindered by catalyst degradation, particularly the iridium-based anode, which compromises the efficiency and durability of the stack. This study delves into the degradation mechanism(s) of the Ir-based catalyst in the anode of PEM electrolyzers, focusing on the influence of operating conditions such as current density and cell voltage. We have utilized the state-of-the-art R&D platform “PEMI” at Plug Power to construct a rainbow stack that contains several 50 cm2 membrane electrode assemblies (MEAs) with different membrane thicknesses. This innovative approach enables identical current densities across different MEAs while varying the cell voltage on the anode catalyst layer, thereby isolating the effect of cell voltage from current on catalyst degradation.

Our investigation seeks to clarify the puzzle whether it is the current density or the cell voltage that determines the transition and degradation of iridium-based catalysts. Preliminary results indicate that different oxidation states of Iridium exhibit significantly different kinetics and conductivity at varied cell voltages. This is corroborated by our synchrotron-based in situ X-ray absorption spectroscopy experiments that unraveled evolution of the anode catalyst layer at elevated cell voltages. By systematically analyzing the degradation patterns of MEAs with different membrane thickness under controlled conditions, we pinpointed the operational parameter that drives catalyst degradation. The finding provides in-depth understanding of the underlying principles that govern the iridium-based catalyst durability and points to strategies mitigating the degradation. It will pave the way for more resilient and efficient PEM water electrolyzers.

Acknowledgement. This research used beamline 7-BM (QAS) of the National Synchrotron Light Source II, a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory Contract DE-SC0012704. Beamline operations were supported in part by the Synchrotron Catalysis Consortium Grant DE-SC0012335.

Keywords: PEM water electrolyzers, catalyst degradation, iridium, current density, cell voltage, MEAs.