bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Digital Presentation) Integrated Membrane Electrode Assembly in Proton Exchange Membrane Fuel Cells
Authors: 董 行 , Jiang Jia , Chen Qi , Ji Zhaoqi 
Published: August 2024

Proton exchange membrane fuel cells (PEMFCs), an electrical device with high energy conversion efficiency and zero-carbon emission, has attracted more attention. The membrane electrode assembly (MEA) is the core component of PEMFCs, mainly including proton exchange membrane (PEM), catalyst layer (CL), microporous layer (MPL) and carbon fiber gas diffusion layer (GDL), which has different structures and significantly affects its power density and durability [1].
Generally, MEA is fabricated by catalyst coated electrodes (CCE) and catalyst coated membrane (CCM) methods, which often results in a huge interface resistance between electrode and membrane, the weak adhesion and poor proton and electron transfer, limiting the electrochemical surface area (ECSA) and the power density of PEMFCs [2].
To solve this problem, many approaches have been adopted, such as improving sintering temperature for MEA, incorporating a guided cracked layer between cathode and membrane, double-layered catalyst and direct deposition method. Zhao et al prepared an integrated membrane electrode assembly structure to reduce the contact resistance between proton exchange membrane and catalyst layer, which significantly improves the efficiency and stability of water electrolysis [4]. At the same time, Klingele and Breitwieser developed a direct deposition of proton exchange membrane technology to improve high performance and long-term stability of PEMFCs. However, these methods are complex and almost impossible to industrialize [5].
In this study, integrated membrane electrode assembly (I-MEA) was prepared by combining casting and doctor blade method techniques. The results show that the casting method is more suitable for fabricating I-MEALT in low-temperature proton exchange membrane fuel cells. The power density of the I-MEALT cell is increased by 18% compared with that of the conventional MEALT (Fig. 1). The doctor blade method is more suitable for preparing I-MEAHT in high-temperature proton exchange membrane fuel cells. The maximum power density of I-MEAHT is increased by about 57% compared with that of the conventional MEAHT. The electrochemical impedance shows that this is mainly attributed to the reduced interface resistance between the electrode and the membrane, which facilitates the proton transfer.

References

[1] L. Zhao, J.B. Zhu, Y. Zheng, M.L. Xiao, R. Gao, Z. Zhang, G.B. Wen, H.Z. Dou, Y.P. Deng, A.P. Yu, Z.B. Wang, Z.W. Chen. Adv. Energy Mater. 12 (2021) 2102665.
[2] K. Jiao, J. Xuan, Q. Du, Z.M. Ba, B. Xie, B.W. Wang, Y. Zhao, L.H. Fan, H.Z. Wang, Z.J. Hou, S. Huo, N.P. Brandon, Y. Yin, M.D. Guiver. Nature 595 (2021) 361-369.
[3] X.D. Wang, W.B. Guan, R. Yu, W. Liu, W.L. Pei, X.D. Zhou. Int. J. Hydrog. Energy. 41 (2016) 22337-22343.
[4] L. Zeng, T.S. Zhao. Nano Energy 11 (2015) 110-118.
[5] M. Klingele, M. Breitwieser, R. Zengerle, S. Thiele. J. Mater. Chem. A. 3 (2015) 11239.

Figure 1
(Invited) Low Cost in Situ Electrosynthesis and Cycling of Quinone Negolytes in a Commercial Flow Battery Stack
Authors: Beh Eugene S. , Bahari Meisam , Symons Peter , Aziz Michael J. 
Published: August 2024

Aqueous organic redox flow batteries (RFBs) potentially offer greatly lower capital cost relative to vanadium RFBs or even lithium-ion batteries, as they use no critical materials and are instead derived from very inexpensive precursors. To date, the success of organic RFBs as a whole has been hampered by two factors. The first is the high cost of scaling up a new chemistry, as every synthetic step adds cost and complexity and creates waste that must be disposed of. The second is fast degradation of the reactants and has been largely mitigated through various strategies that have recently been reported. The recent results mean that low-cost compounds that may intrinsically have a fast degradation rate, now merit consideration since their fade rate can be lowered significantly.
We report the development of an in situ electrosynthesis process, from the lab scale to the ton scale, that creates the organic RFB negolyte from the starting reactants using commercial RFB stacks that have been repurposed as chemical reactors. The yield and purity are even higher than the equivalent chemical process and no further purification or downstream processing is required; the entire process is self-contained and produces zero waste which greatly simplifies scaleup, permitting, and implementation. Moreover, the as-produced material can be immediately cycled as a drop-in replacement for vanadium in RFBs with minimal modification of existing vanadium RFB designs.
This unique in situ strategy enables rapid scaling of a new chemistry in a way that supports local manufacture, which is of strategic importance to many governments. Further cost reductions are envisioned if it can be implemented at the customer site -- inside a completed flow battery system -- rather than at a centralized facility.
When combined with previous results on reversing the degradation of quinone RFB reactants, the electrosynthetic pathway to producing organic RFB negolytes is the final missing piece of the puzzle in the commercialization of an affordable, practical, and viable organic RFB chemistry.
(Invited) Commercialization of CO2 Electrolysis
Authors: Ma Sichao , Cooper Jason 
Published: August 2024

The atmospheric accumulation of greenhouse gasses such as carbon dioxide (CO2) is the primary cause of global climate irregularities. Over three trillion tons of greenhouse gasses have been emitted since the start of the industrial revolution, and natural disasters such as heatwaves, wildfires, and hurricanes have only increased in regularity. Decarbonization has become an important strategic priority for nations and industries worldwide. Numerous technologies have been developed to capture and store carbon dioxide from the atmosphere. However, most of these approaches do not address the ubiquitous demand for fossil fuel derivatives and their associated petroleum-based infrastructure, nor are these approaches capable of extracting value from the captured CO2.
Our company, Twelve, is developing a highly efficient and scalable electrochemical reactor that converts CO2 into valuable building blocks for chemicals and fuels such as carbon monoxide (CO). The resulting CO can be blended with green hydrogen from water electrolyzers to form syngas, enabling an ultra-low carbon pathway to sustainable aviation fuel (SAF) via the Fischer-Tropsch process. Twelve has previously produced SAF for the Air Force, where we demonstrated the first ever SAF pathway based on CO2 electrolysis. Beyond SAF, Twelve has completed commercial projects for chemicals and materials made from CO2 with global brands that include Procter & Gamble and Mercedes Benz. At scale, this technology can enable a closed loop ecosystem wherein CO2, water, and electricity are converted into manufacturing inputs that are currently derived from fossil fuels. We are presently translating the performance of our lab-scale prototypes to the industrial scale, focusing on SAF as our beachhead market.
In this talk, Twelve’s CO2 electrolysis technology will be used as a model to describe the commercialization challenges and market opportunities of industrial CO2 electrolysis. Key performance metrics and areas of active collaborative research between Twelve and academic institutions will be discussed. Finally, commercial demonstrations of our technology in the automobile, aviation, consumer chemicals, and apparel industries, as well as our company’s long-term vision and goals will be presented.
(Invited) Retinomorphic Motion Detector and Supercapacitors Based on Organic Semiconductors
Authors: Ng Tse Nga 
Published: August 2024

Organic retinomorphic sensors offer the advantage of in-sensor processing to filter out redundant static background and are well suited for motion detection. To improve this promising structure, here we studied the key role of interfacial energetics in promoting charge accumulation to raise the inherent photoresponse of the light-sensitive capacitor. Specifically, incorporating appropriate interfacial layers around the photoactive layer was crucial to extend the carrier lifetime, as confirmed by intensity-modulated photovoltage spectroscopy. Compared to its photodiode counterpart, the retinomorphic sensor showed better detectivity and response speed due to the additional insulating layer, which reduced the dark current and the resistor-capacitor time constant. Lastly, three retinomorphic sensors were integrated into a line array to demonstrate the detection of movement speed and direction, showing the potential of retinomorphic designs for efficient motion tracking.
In addition to discussing the development of organic optical sensors, this presentation will also show the use of the same class of organic semiconductors in energy storage applications, in particular for redox supercapacitors as portable power sources. We developed multifunctional structures, which combine load-bearing and energy-storage functions in one, resulting in weight savings and safety improvements. We demonstrated a gradient electrolyte design to facilitate high ionic conductivity at the electrode-electrolyte interfaces and transitioned to a composition with high mechanical strength in the bulk for load support. The gradient design enabled the multilayer structural supercapacitors to reach state-of-the-art performance matching the level of mono-functional supercapacitors. Finally, the structural supercapacitor was made into the hull of a model boat to demonstrate its multifunctionality.
(Invited) Scalable 2-Step Fabrication of Core-Shell GaN Micropillars
Authors: Davydov Albert V. , Krylyuk Sergiy , Bonevich John E. , Motayed Abhishek 
Published: August 2024

Group III-Nitride three-dimensional structures have gained substantial interest for application in optoelectronic, energy, and sensor devices with non-planar geometries [1-4]. The benefits of 3D structures, such as GaN-based nano-/micro-rods, compared to planar films include large surface area, high structural quality, non-polar-surface utilization, small footprint, mechanical flexibility, and enhanced light absorption/extraction efficiency. To advance the technology of non-planar III-Nitride semiconductors, it is necessary to optimize and scale up the fabrication of such structures with controlled geometries and desired electronic and optical properties. Here, we report the fabrication of wafer-scale periodic arrays of vertically aligned GaN core-shell micropillars using a combination of top-down etch and epitaxial overgrowth.
The two-step process consists of inductively coupled plasma (ICP) etching of lithographically patterned GaN-on-Si substrate to produce an array of micropillars followed by selective growth of GaN shells over these pillars using Hydride Vapor Phase Epitaxy (HVPE). The most significant aspect of the study is the demonstration of the sidewall facet control in the shells, ranging from truncated hexagonal pyramids with the (1-101) semi-polar sidewalls to hexagonal prisms with the (1-100) non-polar sidewalls, by employing a post-ICP wet chemical etch and by tuning the HVPE growth temperature. Optimization of both ICP etching and epitaxial overgrowth reduced dislocation density in the GaN shells, thus enhancing the transport and optical characteristics of these device platforms. Photo- and cathodoluminescence showed a substantial reduction of parasitic yellow luminescence as well as strain-relaxation in the core-shell structures, supported by Raman scattering, electron-backscatter-diffraction (EBSD), and X-ray-diffraction measurements. Transmission electron microscopy revealed improved crystal quality with reduced dislocation density in the epitaxially grown shells. This work demonstrates the feasibility of selective epitaxy on micro/nano-engineered 3D templates for realizing high-quality GaN-on-Si devices such as LEDs and p-i-n photodetectors.

References:

Zhao, Y.; Fu, H.; Wang, G.T.; Nakamura, S. Toward ultimate efficiency: progress and prospects on planar and 3D nanostructured nonpolar and semipolar InGaN light-emitting diodes. Opt. Photonics
2018, 10, 246-308.

Chen, F.; Ji, X.; Lau, S.P. Recent progress in group III-nitride nanostructures: From materials to Applications. Materials Science & Engineering R
2020, 142, No. 100578

Kazanowska, B.A.; Sapkota, K.R.; Lu, P.; Talin, A.A.; Bussmann, E.; Ohta, T.; Gunning, B.P.; Jones, K.S.; Wang, G.T. Fabrication and field emission properties of vertical, tapered GaN nanowires etched via phosphoric acid. Nanotechnology
2022, 33, No. 035301

Pandey, A.; Min, J.; Reddeppa, M.; Malhotra, Y.; Xiao, Y.; Wu, Y.; Sun, K.; Mi, Z. An Ultrahigh Efficiency Excitonic Micro-LED. Nano Letters
2023, 23, 1680-1687
Surface-Immobilized Ionophore Electric-Double-Layer (EDL) Extended-Gate Field-Effect Transistors for High Sensitivity to Detection of Mercury and Lead Ions
Authors: Zeng Guan-Cheng , Huang Hsuan-Wei , Lin Chia Kai , Kalaimani Vishal Mani , Kuo Tzu-Han , Wang Yu-Lin 
Published: August 2024

In the field of sensors, particularly in FETs (Field-Effect Transistors), they have emerged as a promising solution for detecting heavy metal ions. These sensors offer high sensitivity, rapid response, compact and portable device sizes, and the potential for low cost. These advantages have led to their successful application in monitoring drinking water, environmental samples, and industrial wastewater, enabling rapid on-site detection of heavy metal ions.
At the molecular level, certain organic molecules or coordination compounds can selectively bind to specific ions through specific chemical reactions or coordination interactions. Therefore, designing ionophores specifically for capturing or transporting particular types of ions is possible. Previous research has employed the mechanism of Ion Selective Membranes (ISM) for detecting heavy metals. However, ISMs are typically polymer coatings applied through spinning, resulting in a thick layer that leads to longer diffusion times, requiring 15 minutes or more to achieve baseline stability, with a detection limit of µM to nM .
Many studies have also utilized aptamers for detecting metal ions, but aptamers are typically expensive and require controlled formation of specific structures to bind with ions. They are susceptible to interference signals from pH value or salt concentrations.
In environmental or food samples, the presence of heavy metals often needs to be detected. Electric-Double-layer (EDL) sensors exhibit better stability, with a monolayer recognition layer providing shorter detection times and higher sensitivity. This study successfully developed FET (Field-Effect Transistor) metal ionophores based on a specially designed ionophore with a double-layer expanded gate, including mercury ionophore sensors and lead ionophore sensors. By defining a gate sensing area with dimensions of 500 μm x 500 μm, significant detection limits of nM to pM were achieved within minutes. The combination of FETs, EDL, and ionophores in this study's development has resulted in highly efficient, sensitive, selective, and portable detection instruments.

Keywords: MOSFET, EDL, Aptamer, Ionophore, Heavy metal

Figure 1
Solid-State Electrodes Towards a Real-Time Sensor Array for Health Monitoring
Authors: Brothers Michael , Leung Jennifer , Gazica Kiera E. , Chavez Jorge , Kim Steve 
Published: August 2024

The healthcare industry has been transformed by advances in biotechnology, resulting in improved health outcomes. Central to this has been advances in medical diagnostics that can both monitor patients as well as provide actionable data at the point-of-care. However, further improvements are needed to maximize the utility of diagnostics at times where acute care may be required, such as when individuals are unstable after experiencing physical trauma. When medical resources are limited, the ability to rapidly and effectively triage patients that have experienced trauma is critical to maximizing health outcomes. Notably, individuals that have experienced significant trauma can degrade quickly. Therefore, continuous monitoring approaches are needed that can provide critical biometric and biomarker information that will enable updating of the triage in real-time.
At present time, patients are assessed continuously using biometric monitoring. However, biometrics are often a lagging indicator to biochemical markers, and thus while easier to measure, less informative. Currently, the ISTAT-8 is a point-of-care unit to perform an automated, rapid biochemical panel that can assess the patient’s ability to maintain homeostasis by monitoring eight biomarkers. However, the ISTAT-8 captures biochemical data only at a point in time instead of continuously; this is a drawback, as the health of patients who have undergone trauma can improve or deteriorate rapidly. Therefore, a continuous biochemical monitoring solution is needed to allow for triage to happen in real-time.
Advances in biotechnology have for the first time made real-time biochemical sensing a reality. Unfortunately, commercial continuous biochemical sensors to-date are limited to subcutaneous continuous glucose monitors (CGMs). CGMs monitor glucose concentrations in the interstitial fluid (ISF), which strongly correlates to blood values. While the CGM is now commonly used, the current devices are not easily multiplexed. Therefore, a scalable, easy to insert system is needed to perform multiplexed measurements; microneedle-based platforms have the promise to enable sensing in the ISF leveraging five or more distinct sensors.
Here we present a solid-state platform that can enable multiplexed sensing leveraging hollow, wicking microneedles in fluidic contact with solid-state electrodes. Our approach leverages optimized sensor formulations and electrode materials fabricated onto a printed circuit board (PCB). The putative sensor array can be produced in a modular fashion leveraging scalable technologies and processes. Notably, this talk focuses on methods and approaches to fabricate an array of solid-state sensors that are capable of detecting ions and metabolites over extended periods (> 1 week) and can be readily integrated with microneedles for sensing interstitial fluid.
Electrokinetics with Surface-Enhanced Raman Spectroscopy for Bacterial Identification in Wastewater
Authors: Zhang Yirui , Herndon Liam , Padhy Punnag , Ogunlade Baba , Boehm Alexandria , Dionne Jennifer 
Published: August 2024

Bacterial presence in wastewater serves as a crucial bioindicator for monitoring population-level infections and offering early disease outbreak warnings [1,2]. However, identifying bacteria in wastewater presents outstanding challenges; notably, current culturing or fluorescence-based methods [3] to identify bacteria are slow and expensive, unsuitable for high-throughput screening of diverse bacterial species, and may not work well in the complex wastewater matrix. Here, we harness the potential of surface chemistry and electrokinetics to introduce an innovative electro-optical approach that has the promise to detect a broad spectrum of pathogenic bacteria in wastewater.
We combine surface-enhanced Raman spectroscopy (SERS) [4] with alternating current electric fields, complemented by machine learning models [5], to enable rapid and amplification-free bacteria detection in filtered wastewater, at cell concentrations as low as 104 cells/mL. First, we synthesize gold nanorods that can electrostatically bind to bacteria surfaces, allowing for SERS from cell surfaces. We collect SERS from bacteria spiked into filtered wastewater, including Staphylococcus aureus, Staphylococcus epidermidis, and Escherichia coli, spanning concentrations from 109 cells/mL to 104 cells/mL. Spectral clustering analysis shows that bacteria signals become more indistinguishable from wastewater as the concentrations decrease. Further, we incorporate electrokinetic effects into SERS by employing gold microelectrodes to apply electric fields, utilizing dielectrophoresis [6] to rapidly displace and concentrate bacteria based on their dielectric responses within minutes. The enrichment of bacteria with nanorods is directly visualized through microscopy, resulting in Raman signal intensities increased by up to tenfold under electrical fields for bacterial concentrations ranging from 106 down to 104 cells/mL. Such enhancement may enable the detection sensitivity to reach environmentally-relevant concentrations. Moreover, employing data science analysis, we identify biologically-relevant “fingerprint” Raman peaks characterizing proteins, nucleic acids, and lipids from bacteria surfaces, allowing for rapid identification of bacteria species in wastewater. This novel method exhibits potential for generalized pathogen detection and molecular recognition in complex liquid samples, such as wastewater, blood, and seawater.
[1] Hellmér, et al. Applied and environmental microbiology. (2014).
[2] Keshaviah, et al. The Lancet Global Health. (2023).
[3] Jahn, et al. Nature Microbiology. (2022).
[4] Tadesse, et al., Nano Lett. (2020).
[5] Ho, et al., Nat. Comm. (2019).
[6] Pethig. John Wiley & Sons (2010).
Key Role of Oxidising Species for Water Oxidation on Iridium Oxides Revealed By Time-Resolved Optical and X-Ray Spectroscopies
Authors: Liang Caiwu , Rao Reshma R , Svane Katrine Louise , Moss Benjamin , Scott Søren Bertelsen , Ryan Mary P. , Rossmeisl Jan , Durrant James , Stephens Ifan 
Published: August 2024

Iridium oxide is the state-of-the-art electrocatalyst for water oxidation in polymer electrolyte membrane (PEM) electrolysers, crucial for green hydrogen production. Despite its extensive industrial use, the water oxidation mechanism on this metal oxide and the key factors controlling the reaction rate remain unclear. Understanding these controls at a fundamental level on such benchmark metal oxides is vital for designing more active and stable electrocatalysts for water oxidation in PEM electrolysers.
In this talk, I will present our research on probing oxygen evolution reaction (OER) relevant species on iridium-based catalysts. This involves a combination of time-resolved operando optical spectroscopy, soft and hard X-ray absorption spectroscopy (XAS), and electrochemical mass spectrometry. Initially, I will discuss the intermediate and catalytically active states of iridium oxides. This is based on correlating optically detected states with oxygen molecular products identified through on-chip electrochemical mass spectrometry. Subsequently, I will demonstrate how we used optical spectroscopy to quantify these states as a function of potential. The nature of these states, including the Ir oxidation state and surface adsorbates on iridium sites, will be elucidated using a combination of time-resolved Ir-L edge XAS, O-K edge XAS, and supported by Density Functional Theory (DFT).
With these quantification results of active species for OER, I will compare the intrinsic kinetics of two state-of-the-art iridium oxide structures - amorphous IrOx versus crystalline rutile IrO2.[1] The effect of the electrolyte on the intrinsic activity of iridium oxides will also be discussed.[2]

Finally, based on this molecular-level understanding, I will present a modified volcano model for OER catalyst design. This model considers the impact of adsorbate-adsorbate interactions on binding energetics, demonstrating critical design principles for high intrinsic activity OER catalysts.
The authors acknowledge the funding support from the Imperial College-Chinese Scholarship Council Studentship and bp-ICAM 92, which made this research possible.
[1] Caiwu Liang, Reshma Rao, Karine Svane et al. Unravelling the effects of active site densities and energetics on the water oxidation activity of iridium oxides, 07 March 2023, PREPRINT (Version 1) available at Research Square [https://doi.org/10.21203/rs.3.rs-2605628/v1]
[2] Caiwu Liang, Yu Katayama, Yemin Tao, Asuka Morinaga, Benjamin Moss, Verónica Celorrio, et al. Role of electrolyte pH on water oxidation for iridium oxides. ChemRxiv. Cambridge: Cambridge Open Engage; 2023