bluuebunny/crossref_metadata_2025 huggingface dataset:
Expanding the Scope of Electrosynthesis through Catalyst Design and Operando Spectroscopy
Authors: Kornienko Nikolay
Published: November 2022

Electrochemical conversion of abundant feedstocks to fuels and value-added chemicals is rapidly gaining significance as a promising method to harness renewable electricity. To this end, research group develops heterogeneous catalysts (e.g. nanomaterials, MOFs) geared for the reduction of CO2 and oxidation of biomass platforms to fuels and value-added chemicals. Further, we establish strategies in emergent areas of electrocatalysis such as electrochemically forming and cleaving C-N bonds. Because the design of new catalytic systems is inherently linked to a precise understanding of how these reactions proceed on heterogeneous surfaces, we put considerable efforts in developing methodology for operando probing of these systems with vibrational spectroscopy. In all, I show how using these experiments provides key mechanistic information on surface reaction mechanisms that enhance our understanding of functional interfaces and how the research provides avenues for future materials design within the context of renewable energy electrocatalysis.
(Invited) High-Temperature Electrosynthesis of Hydrogen and Syngas - Technology Status and Development Needs
Authors: Minh Nguyen Q. , Yoon Kyung Joong
Published: November 2022

High-temperature solid oxide electrolysis cell (SOEC) technology has been considered and developed for production of hydrogen (from steam) and syngas (from mixtures of steam and carbon dioxide). The SOEC, a solid oxide fuel cell (SOFC) in reverse or electrolysis operating mode, is traditionally derived from the more technologically advanced SOFC. The SOEC uses the same materials and operates in the same temperature range (600˚-800˚C) as the conventional SOFC. The SOEC therefore has the advantages shown by the SOFC such as flexibility in cell and stack designs, multiple options in cell fabrication processes, and choice in operating temperatures. In addition, at the high operating temperature of the SOEC, the electrical energy required for the electrolysis is reduced and the unavoidable Joule heat is used in the splitting process. SOEC technology has made significant progress toward practical applications in the last several years. To date, SOEC single cells, multi-cell stacks and systems have been fabricated/built and operated. However, further improvements are needed for the SOEC in several areas relating to the key drivers (efficiency, reliability and cost) to enable commercialization. This paper provides an overview on the status of SOEC technology, especially zirconia based technology, and discusses R&D needs to move the technology toward practical applications and widespread uses.
Improving the Selectivity of Nitrogen Reduction Reaction through the Mars-Van Krevelen Mechanism
Authors: Johnson Denis , Djire Abdoulaye
Published: November 2022

The electrochemical nitrogen reduction reaction (NRR) process is an attractive alternative to minimizing the energy and greenhouse gas footprint from current ammonia (NH3) production processes. Most NRR catalysts operate through utilizing an associative or dissociative mechanism, during which the NRR competes with the hydrogen evolution reaction (HER), resulting in low selectivity. In this presentation, we report on a new active catalyst for NRR that operates through the Mars-van Krevelen (MvK) mechanism to increase the selectivity of NRR towards NH3. This new catalyst, two-dimensional (2D) Ti2N nitride MXene, was synthesized via an oxygen-assisted molten salt fluoride etching technique. We confirmed its phase purity and stability in aqueous electrolytes using various characterization techniques, including Raman, X-ray diffraction, and UV-Vis. The Ti2N nitride MXene catalyst achieved a high Faradaic efficiency (FE) of 19.85% towards NH3 at an applied potential of –250 mV vs. RHE with a yield of 11.33 μg/cm2/hr in a 0.1 m hydrochloric acid (HCl) N2-saturated electrolyte. Electrocatalytic activity and selectivity obtained in an Ar-saturated electrolyte confirm that the new catalyst operates through an MvK mechanism. These results can be expanded to a broad class of systems enabling the MvK mechanism and constitute the foundation of NRR technology based on MXenes.
Coupled CO2 reduction and Alcohol Oxidation for Fuel Synthesis and CO2 Utilization
Authors: Fields Jacob , Singh Nirala , Jawahar Hussaini Syed Mubeen
Published: November 2022

Electro-conversion CO2 to fuels like formic acid, methanol, and ethanol is an attractive method to recycle CO2 and close the carbon cycle associated with these fuels, which could benefit the environment, national energy security

Many CO2 electrolyzers oxidize water or hydroxyl ions as a counter reaction which releases oxygen. However, this can lead to a large cell potential due to oxygen’s large, positive reduction potential. Further, oxygen is a relatively low-value product. These systems also use an ion exchange membrane to prevent crossover of CO2 reduction products to the anode while conducting ions between the electrodes.

Instead of oxygen evolution, the partial oxidation of alcohols could serve as the anodic counter reaction to synthesize oxygenated fuel additives. Partial alcohol oxidation could be coupled with CO2 reduction which could regenerate the alcohol. Coupling the anodic and cathodic reactions in this way could preclude the need for an ion exchange membrane, and lower required energy input by decreasing the thermodynamic cell voltage. Our system is also capable of high-pressure operation, which could allow higher concentrations of CO2 in the electrolyte. This study examines the use of alcohol/water mixtures as a working fluid for a CO2 electrolyzer, and the effect of pressure and catalyst composition on the current density and product selectivity. Linear sweep voltammetry and chronoamperometry will be used to evaluate the current densities and cell voltages for different catalysts at pressures up to 90 bar. Gas and liquid products will be analyzed following chronoamperometry studies to determine the faradaic efficiencies. Noble and transition metal catalysts will be used at the cathode and anode based on their purported ability to drive CO2 reduction to alcohol and partial oxidation of alcohols.
Large Raw Powder Production of Proton Conductor Electrolyte Materials for Hydrogen Production in Proton Conducting Solid Oxide Electrolysis Cells
Authors: Wang Min , Yang Yingchao , Ding Dong
Published: November 2022

Solid oxide protonic electrolyte materials make protonic ceramic electrochemical cells (PCECs) viable to be operated at reduced temperatures (400~600 oC) because of its high conductivity and low activation energy. Barium zirconate and/or cerate are representative candidates which are mainly synthesized via conventional solid state reaction (SSR) method. Currently, synthesizing a pure phase of BZCYYb4411 in a large batch is still challenging with desired particle size for scaled manufacturing of PCECs. By optimizing and developing the SSR process, we successfully demonstrated large batch fabrication of these powders enabled by micro-sized mediates in the ball milling profiles. It can result in excellent powder quality including high phase purity, and favorable particle size and distribution with demonstration for subsequent cell manufacturing. More importantly, establishing such a protocol of kilogram-scale mass production by shortening the overall fabrication time and increasing the manufacturing efficiency has pronounced implication in the reduction of overall cost and carbon footprint, which is proven by Technoeconomic analysis (TEA) and life cycle assessment (LCA). It represents a critical step for PCEC advancement with serious consideration on supply chain development.
Formaldehyde Self-Condensation Reaction for C-C Coupling on CuP2 Electro Catalyst Reducing CO2 to Multi-Carbon
Authors: Choi Minjun , Lee Jaeyoung
Published: November 2022

Use of electrochemical method for reduction of carbon dioxide (CO2) convert into valuable organic compounds, is a great solution to solve the problem of CO2 accumulation. The most advantage of electrochemical conversion is to elect reaction to produce a few organic compounds from carbon dioxide depending to types of catalyst. Among many types of catalyst, metal catalysts based on Copper element or alloy metals offers the route to synthesize multi-carbon fuels and chemicals from CO2 (e.g., ethylene, ethanol and n-propanol). [1], [2]
, [3]

In this study we focused on the autonomous nonfaradaic reaction of C-C coupling using CuP2 electrode. In our previous study, the generation of 1-butanol from carbon dioxide (CO2) on a phosphorus-rich copper cathode was first reported, based on a combination of faradaic and autonomous nonfaradaic reactions.[
4] The faradaic efficiency of the obtained formate and acetaldehyde intermediates led us to propose a mechanism for the formation of 1-butanol that does not include a *CO dimerization step. 13C labeling experiments confirmed that the origin of each product was from dissolved CO2. This study provides a perspective on the C–C coupling reaction on Cu-based electrocatalysts for the electroreduction of CO2 into high-value multicarbon products.

References

[1] Park G, Hong S, Choi M, Lee S, Lee J*, Catalysis today, 355, 340-346 (2020)

[2] Lee S, Choi M, Lee J*, The Chemical Record, 20, 89-101 (2020)

[3] Choi M‡, Kim J‡, Chung S, Lee Y, Bong S, Lee J*, Chemical Engineering Journal, 430, 132563 (2022)

[4] Choi M, Bong S, Kim J, Lee J*, ACS Energy Letters, 6, 2090-2095 (2021)

Figure 1
Determining Substrate Oxygen Transport Resistance at Limiting Current Using Pore Network Modelling
Authors: Guan Raymond , Bazylak Aimy
Published: November 2022

The polymer electrolyte membrane (PEM) fuel is a promising technology to supplant traditional, greenhouse gas emitting energy conversion devices. However, widespread commercial adoption of the PEM fuel cell is hindered by the high cost of the precious metals required for its catalyst (1). The amount of catalyst required in a PEM fuel cell can be reduced if the reactant (oxygen) is delivered more efficiently to the catalyst. Therefore, previous studies have sought to characterize the mechanisms affecting oxygen transport in PEM fuel cells (2)(3)(4)(5). In past studies, the oxygen transport resistance of a PEM fuel cell was measured at limiting current, and this value was further decomposed into contributions from individual PEM fuel components using empirical modelling. By resolving each PEM fuel cell component’s contribution to oxygen transport resistance, an informed approach can be undertaken to design next generation components with enhanced oxygen transport capabilities.

In this study, we employed pore network modelling to quantify the oxygen transport resistance arising from the presence of liquid water within the substrate region of the gas diffusion layer (GDL). First, we captured the operando liquid water distribution within a PEM fuel cell operating at limiting current using synchrotron X-ray radiography. Next, we used a combination of invasion percolation and an in-house water invasion inlet selection algorithm to partially saturate the representative pore network of the substrate and to reproduce the mean water saturation. Finally, we obtained substrate oxygen transport resistance values by performing transport simulations on the partially saturated pore network and compare our findings with the experimental observations.

References

X. X. Wang, M. T. Swihart, and G. Wu, Nature catalysis, 2, 7 (2019).

D. R. Baker, D. A. Caulk, K. C. Neyerlin, and M. W. Murphy, J. Electrochem. Soc., 156, B991 (2009).

T. Reshtenko, J. St-Pierre, J. Electrochem. Soc., 161, F1089 (2014)

D. Muirhead, R. Banerjee, M. G. George, N. Ge, P. Shrestha, H. Liu, J. Lee, A. Bazylak, Electrochimica Acta, 274 (2018).

N. Ge, P. Shrestha, M. Balakrishnan, D. Ouellette, A. K. C. Wong, H. Liu, C. H. Lee, J. K. Lee, A. Bazylak, Electrochimica acta,
328 (2019).
Noble Metals (Pd, Ag, Pt and Au) Doped Bismuth Oxybromide (BiOBr) Photocatalysts for Improved Visible Light Driven Catalysts for the Degradation of Phenol
Authors: Malathi Arumugam , Praserthdam Piyasan
Published: November 2022

In this study, the synthesis of noble metals Pd, Ag, Pt, and Au doped bismuth oxybromide (BiOBr) photocatalysts with a micro-flower like morphologies by an ethylene glycol a solvothermal process. The various physico-chemical characterization results show the successful incorporation of Pt, Ag, Pt, and Au elements on the BiOBr. The synthesized Pd, Ag, Pt, and Au doped BiOBr photocatalysts were tested for phenol degradation in the presence of visible light. The Pd-doped BiOBr photocatalyst showed higher phenol removal efficiency than the pure BiOBr. This improved efficiency of the Pd-doped BiOBr photocatalyst was owing to the good optical absorption and lower recombination rate of charge carriers. Also, the Pd-doped BiOI photocatalyst exhibited good photo-stability up to 3 cycles. The phenol degradation mechanism over Pd-doped BiOBr was offered under visible light. This present work offers the fabrication of noble metals-doped photocatalysts for environmental applications.
Tuning the Selectivity of Liquid Products during CO Electroreduction
Authors: Hasa Bjorn
Published: November 2022

The electrochemical carbon dioxide reduction (eCO2RR) into value-added chemicals and fuels offers a sustainable route to close the anthropogenic carbon cycle and store the renewable sources' excess energy into chemical bonds. Typically, eCO2RR/eCORR studies employ reactant reduction in the cathode and oxygen evolution reaction in the anode. The membrane (membrane electrode assembly configuration) facilitates the ion transport between the two electrodes and chemically isolate the occurring electrochemical half-reactions. It should be noted that investigators have conceptualized the use of ion-exchange membranes in order to improve the reaction energy efficiency and rate. However, the impact of membrane properties on reaction selectivity, stability, and efficiency remains unexplored.

Herein, we investigated the role of anion exchange membrane on the CO reduction performance using a membrane electrode assembly configuration. This talk will provide insights into the ion-exchange membrane's role in the electrocatalytic reduction of CO. We will show how the membrane properties determine the product crossover, product selectivity, and stability. For example, we will discuss: i) the impact of membrane thickness on the product crossover and applied potential, ii) the role of the membrane on the cell stability, iii) the possibility of various membrane functional groups to tune the reaction selectivity and stability, and iv) the role of counter-ion, ion exchange capacity (IEC), and membrane reinforcement on the cell performance. This work will provide a first step toward designing an ion-exchange membrane with the desired characteristics for CO electroreduction.
Structure-Property-Transport Relationships of Miscible Ionomer Blend Systems
Authors: Sulikowski Sylwia , Senathiraja Thivani , Cornelius Chris
Published: November 2022

Systematically designing the spatial arrangement is a key to understanding the structure and property relationships of proton-exchange membranes (PEM)/ionomers. Miscible polymer blends provide a cost-effective method for developing new materials in polymer science industries instead of synthesizing new polymers. In this study, commercially available Pentablock Copolymer (PBC(1.0)) ionomers were blended with poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) in varying blend ratios. The FTIR studies showed composition-dependent interaction between the methyl group of PPO and phenyl rings of Polystyrene blocks in PBC(1.0). However, the sulfonate peaks at PBC(1.0): PPO (50:50) blend ratios were significantly reduced . The reduction in the peak intensity at this blend ratio may be attributed to specific interactions within this blend composition. The miscibility of the blends was confirmed by the single glass transition temperature from the DSC studies. And the application of the Fox rule to the experimental glass transition confirmed the conformational rearrangements of the blends. At the same time, applying the Kwei equation to the glass transition temperature confirmed the presence of specific interactions in the PBC(1.0): PPO (50:50) blend ratio observed in FTIR studies. The thermal stability studies demonstrated morphology dependence behavior with the rule of mixtures with the highest stability of 454oC at PBC(1.0): PPO (50:50) blend ratio. Higher stability at the PBC(1.0): PPO (50:50) blend ratio may be attributed to the specific interactions within this composition. High water uptake correlated with enhanced conductivity for the blend membranes, which strongly depended upon the PBC composition in the blend. Gas permeation studies exhibited that the blending can significantly reduce the permeability of H2 without altering its selectivity compared to pure membranes and Nafion, indicating the desired low fuel cross-over during the fuel cell operation. In conclusion, the gas transport and physical properties of the miscible blends showed strong dependence on composition. The morphological transitions that occur due to the compositional changes will be investigated in future studies.
Study on Key Parameters of Reverse Electrodialysis (RED) Cell-Stack Performance Based on Equivalent Circuit Model
Authors: Ryoo Won Sun , Yoo Jinsu
Published: November 2022

Reverse electrodialysis (RED) is a direct process to convert salinity-gradient energy to electricity utilizing ion exchange membranes. The current density of a unit cell based on normal area of ion exchange membrane is well related to the membrane resistances, channel structure, flowrates and salinities of dilute and concentrate water feed. Alternate stacking of cation and anion exchange membranes enables directional control of ion migration relaxing the concentration gradient, and it increases the voltage in proportion to stack number. High salinity of concentrate water often causes parasitic currents between adjacent cells, and this complicates the power charateristics of a RED cell stack. In order to evaluate the effects of key parameters and to optimize the efficiency of energy harvesting, various equivalent circuit models are developed for typical structures of RED cell stacks. Input parameters are resistances of membranes and electrodes, structure of flow channels, stack number, and salt concentrations. The electrical potential across a membrane is calculated from Nernest equation and used as electromotive force for each unit cell. Output such as power density, short-circuit current, open-circuit voltage, and the distribution of parasitic currents can be estimated by the model. The internal resistance of a cell stack, which is most affected by dilute water concentration, is the critical parameter influencing the power efficiency. Parasitic currents that degrade the overall power characteristics were also considered. Those effects evaluated by the model agree with experimental measurements with varying concentrations, the thickness of water channels, and stack number.

Figure 1
Electrochemical Air Separation and Emergency Power Fuel Cell for Aircraft
Authors: Darling Robert M. , Yang Zhiwei
Published: November 2022

The crash of TWA Flight 800 in July 1996 was attributed to an explosion in the center fuel tank. Since then, commercial airliners have been equipped with inerting systems to prevent explosive mixtures of air and kerosene vapor from forming in fuel tanks. The incumbent technology is based on hollow-fiber membrane (HFM) separation modules that split air into an oxygen-enriched air (OEA) stream and a nitrogen- enriched air (NEA) stream. The nitrogen enriched air used to inert kerosene contains less than 12% oxygen. Other methods for separating air like cryogenic distillation and pressure swing absorption producer purer oxygen than HFM, but they do not scale down well. Another alternative is electrochemical air separation. High-temperature air separation units using solid oxide cells have been investigated for large-scale applications like oxy-combustion to facilitate carbon dioxide sequestration. However, high-temperature technologies may be less suitable for transportation applications. Electrochemical air separation at low temperatures can be accomplished with relatively compact polymer-electrolyte cells that evolve oxygen at the anode and reduce oxygen at the cathode. The effluent from the cathode is nitrogen enriched. This presentation discusses proof of concept tests and uses these to explore the relative merits of this approach versus incumbent HFM. The electrochemical air separation stack can be fed hydrogen to provide power during emergencies, potentially performing the functions of two components on commercial aircraft.
Highly Active and Durable IrRuOx Electrode with Facile Electroplating for Green Hydrogen Generation in PEM Electrolyzer Cells
Authors: Ding Lei , Wang Weitian , Xie Zhiqiang , Banner Jane , Gage Adam , Paxson Adam , Zhang Feng Yuan
Published: November 2022

Highly efficient electrodes with facile fabrication, enhanced reaction sites, low cost, and acceptable durability are of paramount significance for the development of gigawatt-scale proton exchange membrane electrolyzer cells (PEMECs).1-4 In this study, IrRuOx catalysts with high activity are firstly electroplated on titanium liquid/gas diffusion layers via a facile electroplating process at room temperature, serving as highly efficient integrated anode electrodes in PEMECs. When assembled with a PEMEC, low cell voltages of 1.620 and 1.867 V are achieved at 2 and 6 A/cm2, respectively, achieving high cell efficiency of above 91% at 2 A/cm2, superior to the commercial CCM. Moreover, the IrRuOx integrated electrode shows low-performance loss during a 500-h operation at a high current density of 5 A/cm2, and a degradation rate of less than 40 μV/h is observed in the last 250 h, as shown in the figure. The remarkable performance and stability of the IrRuOx integrated electrode are mainly due to the excellent electrode design, high intrinsic activity of amorphous IrRuOx catalysts exposing abundant active sites and a well-controlled Ir and Ru ratio.

References

Mo, Jingke, Zhenye Kang, Scott T. Retterer, David A. Cullen, Todd J. Toops, Johney B. Green Jr, Matthew M. Mench, and Feng-Yuan Zhang. "Discovery of true electrochemical reactions for ultrahigh catalyst mass activity in water splitting." Science advances 2, no. 11 (2016): e1600690.

Xie, Zhiqiang, Shule Yu, Xiaohan Ma, Kui Li, Lei Ding, Weitian Wang, David A. Cullen et al. "MoS2 nanosheet integrated electrodes with engineered 1T-2H phases and defects for efficient hydrogen production in practical PEM electrolysis." Applied Catalysis B: Environmental 313 (2022): 121458.

Yang, Gaoqiang, Shule Yu, Zhenye Kang, Yifan Li, Guido Bender, Bryan S. Pivovar, Johney B. Green Jr, David A. Cullen, and Feng‐Yuan Zhang. "Building electron/proton nanohighways for full utilization of water splitting catalysts." Advanced Energy Materials 10, no. 16 (2020): 1903871.

Kang, Zhenye, Jingke Mo, Gaoqiang Yang, Scott T. Retterer, David A. Cullen, Todd J. Toops, Johney B. Green Jr, Matthew M. Mench, and Feng-Yuan Zhang. "Investigation of thin/well-tunable liquid/gas diffusion layers exhibiting superior multifunctional performance in low-temperature electrolytic water splitting." Energy & Environmental Science 10, no. 1 (2017): 166-175.

Figure 1
(Digital Presentation) Assessment of the Cyclic Stability of a Bench-Scale TiFe-Based Hydrogen Storage Tank
Authors: Kuhnert Eveline , Stepanov Dmytro , Hacker Viktor , Bodner Merit
Published: November 2022

Hydrogen storage devices comprising of low-cost and flexible metal hydrides have recently regained vivid interest as basic elements in energy conversion systems. Among many intermetallic compounds, TiFe-based alloys are one of the most promising candidates to hold atomic hydrogen because of their significant storage capacity of about 1.9 wt.% and moderate operating conditions. However, the alloy degradation in repeated hydriding- and dehydriding cycles inevitably affects the performance of the hydrogen storage system. In this work, the intrinsic degradation behavior of a bench-scale TiFe-based alloy tank has been investigated. Thermal cyclic life tests were performed between 5°C and 45°C, and the heat transfer properties of the storage device were tested over repeated cycles by obtaining temperature histories. A thermal imaging device was used for the internal heat transfer mapping and the charging time and pressure-composition isotherms were recorded for the hydriding- and dehydriding reactions. In Figure 1 thermal images of the discharge reaction at Begin of Life (BoL) and End of Life (EoL) of the storage device are shown. The hydrogen storage capacity was observed to decrease by almost 90% after 100 cycles. Heat transfer mapping revealed that the excess portion of degradation occurs in the middle of the storage device and is attributed to the formation of inactive TiFe clusters based on the measurements.

Acknowledgment: Financial support by the Austrian Research Promotion Agency (FFG) through the 8th Call of “COMET-Projects” is gratefully acknowledged.

Figure
1
. Thermal image of the TiFe storage device at Begin of Life (BoL) a) and End of Life (EoL) b) after discharging for 240s respectively.

Figure 1
Nanostructured Lscf-GDC Cathodes Via a Sol–Gel Method for High Performance Solid Oxide Fuel Cells
Authors: Joh Dong Woo , Hussain Amjad , KIM TAE-Hun , Hong Jong-Eun , Lee Seungbok , Lim Tak-Hyoung , Song Rak-Hyun
Published: November 2022

Cobaltite-based perovskite materials such as La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF), Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) which have rapid surface activation and mixed ionic and electronic ionic conductivity (MIEC) usually mixed with ionic conducting electrolyte material to lower cathodic polarization resistance. Moreover, decreasing the particulate size of the cathode at nanoscale can effectively enhance the ORR activity of the cathode by extending the electrochemically active sites due to its high surface area. However, due the high surface energy, the nanoparticles easily aggregate before mixing into homogeneous heterophase nanoparticles, resulting in significant coarsening between adjacent particles during high-temperature sintering. In this study, GDC and LSCF-GDC composite powders were synthesized via advance sol-gel method. The physicochemical properties such as sintering behavior, phase stability, etc. of the synthesized nanopowders were investigated. The optimal sintering conditions of GDC nanopowders were evaluated based on the relative density and total conductivity of the sintered GDC pellets. Furthermore, the electrochemical performances of the LSCF-GDC nanocomposite cathodes were measured by the electrochemical impedance spectroscopy (EIS). The microstructural characteristics of the LSCF-GDC nanocomposite cathode were quantified via a 3D reconstruction techniques and related to electrochemical performance of the Ni-YSZ anode supported SOFC single cell.
Pyrochlore Oxide Decorated with Exsolved Metal Nanoparticles for Enhanced Water Splitting Reaction
Authors: Ju Hyun , Park Jinho , Stern Ilan , Lee Seung Woo
Published: November 2022

Recently, we reported hybrid catalysts consist of metal nanoparticles on a metal oxide support for water splitting reaction, which is synthesized through an in situ exsolution process of metallic nanoparticles on pyrochlore oxide material.1,2 Specifically, we prepared Ni substituted lead ruthenate pyrochlore oxide (Pb2Ru1.6Ni0.4O6.5) via sol-gel crystallization and reduce the samples at different temperatures. Ni nanoparticles supported pyrochlore oxide catalyst significantly accelerate the conversion of Ni to NiOOH due to favorable electron transfer during the oxygen evolution reaction. The hybrid catalyst of pyrochlore oxide with NiRu alloy nanoparticles exhibits superior hydrogen evolution reaction performance, resulting from the bifunctional reaction mechanism, modified electronic structure, and efficient electron transport. Consequently, remarkable water electrolysis performance with superior long-term stability was obtained at the hybrid catalysts.

References

[1] S. W. Lee et al., Energy Environ. Sci., 2021, 14, 3053-3063.

[2] S. W. Lee et al., Advanced Materials, 2019, 31, 1901977.
Luminescence Thermometry - Crossing the Limits of Operating Range
Authors: Sójka Małgorzata , Piotrowski Wojciech , Marciniak Łukasz , Carlos Luis D. , Zych Eugeniusz
Published: November 2022

Temperature is one of the fundamental thermodynamic parameters that affects and regulates the rate and nature of the chemical, physical and biological processes. A precise and accurate measurement of temperature is essential across a broad spectrum of areas, such as nanomedicine, electronics, aerospace, climate, food storage, etc. Therefore, there is a great variety of temperature sensors (which currently account for ≈80% of the worldwide sensor market), and their operating modes can be divided into two main groups: contact and noncontact techniques. However, in some specific cases, only non-contact systems may provide accurate information about temperature and its distribution over an area. These are as follows: harsh environments (for example inside turbines), fast-moving objects (gas jets), intense magnetic fields that prevent the use of metals or materials with free electric charges (NMR therapies) or when the size of the system to measure is smaller than 10 μm (cellular tracking or microelectronic circuits). One promising solution that can break through those limitations is luminescence thermometry (LT). LT is a non-contact and non-invasive spectroscopic technique based on the changes in a phosphor emission when temperature changes (e.g., the intensity of a band, relative intensities, band shapes, excited-state lifetimes, etc.).

We shall present our original approach to use intra- and inter- configurational transitions of Pr3+ ion for accurate temperature reading with high relative sensitivity over an outstandingly wide range of temperatures. Studies were focused on Y2SiO5:0.05%Pr and its chemically modified version by a bandgap engineering approach (replacing Si with Ge). The addition of Ge to replace Si was expected to decrease the host bandgap – energetic separation of its valence and conduction bands. Consequently, we expected that the 5d→4f luminescence would be more susceptible to temperature quenching. This, in turn, allowed to control the range of temperatures within which the 5d→4f/4f→4f emission intensity ratio could be utilized for thermometry. Furthermore, possibilities to further improve such sensors will be discussed by widening the operating range of distinct thermometers.

This presentation will show that luminescence thermometers working in unprecedented board operating range can be effectively constructed and managed. Further analysis of such an approach will be carefully discussed.

This research was supported by the National Science Centre, Poland under grant #2020/37/N/ST5/02507

Figure 1
(Digital Presentation) Tailored Rare Earth-Doped Nanomaterials Toward Information Storage and Deep Learning Decoding
Authors: Sun Lining
Published: November 2022

Lanthanide-doped nanoparticles have been considered as one of the most promising luminescent materials due to their excellent properties such as high photochemical stability, long-lived (μs-ms) luminescence, narrow emission band, and low toxicity.Moreover, benefiting from a unique electronic structure (4fn5s25p6
, n = 0-14), lanthanides have discrete energy levels and exhibit practical wavelength conversion via downshifting and upconversion processes. Hence, their emissions cover the spectral regions from ultraviolet (UV) to near-infrared (NIR).[1,2]

Here, my talk is mainly devoted to our recent developments, including (1) recently, we present a new composition of Er3+-based upconversion nanoparticles with color-switchable output under irradiation with 980, 808, or 1535 nm light for information security. The variation of excitation wavelengths changes the intensity ratio of visible (Vis)/near-infrared 1535 nm (NIR-II) emissions. Taking advantage of the Vis/NIR-II multi-modal emissions of upconversion nanoparticles and deep learning, we successfully demonstrated the storage and decoding of visible light information in pork tissue.[3] (2) we construct heterostructured nanocomposites based on upconversion nanoparticles and EuSe semiconductors by using cation exchange method. It is generally considered that epitaxial growth is difficult when the lattice mismatch is large between two materials. In this case, the cation exchange of Eu3+ ions and other rare-earth ions could promote the formation of buffer layers to reduce the lattice mismatch and promote the heterogeneous epitaxial growth of EuSe on the upconversion nanoparticles. The heterostructured nanocomposites can emit tunable multicolor fluorescence under excitation of UV, continuous NIR, and pulsed NIR light. Based on the advantage of multiple tunable luminescence, the nanocomposites are designed as optical modules to load optical information. This work enables multi-dimensional storage of information and provides new insights into the design and fabrication of next-generation storage materials.

References

[1] L. N. Sun, R. Wei, J. Feng, and H. J. Zhang, Tailored lanthanide-doped upconversion nanoparticles and their promising bioapplication prospects, Coordination Chemistry Reviews, 2018, 364, 10-32.

[2] G. Sun, Y. Xie, L. N. Sun, and H. J. Zhang, Lanthanide Upconversion and Downshifting Luminescence for Biomolecules Detection, Nanoscale Horizons, 2021, 6(10), 766 – 780.

[3] Y. Song, M. Lu, G. A. Mandl, Y. Xie, G. Sun,J. Chen, X. Liu,J. A. Capobianco, and L. N. Sun, “Energy Migration Control of Multimodal Emissions in an Er3+-Doped Nanostructure for Information Encryption and Deep-Learning Decoding”, Angewandte Chemie International Edition
, 2021, 60(44), 23790–23796.
(Invited, Digital Presentation) Surface Engineering of Fluorescent CsPbBr3 and Carbon Quantum Dots By Perfluorocarboxylic Acid
Authors: Isobe Tetsuhiko , Iso Yoshiki
Published: November 2022

CsPbX3 (X = Cl, Br, I) perovskite quantum dots (QDs) are an extremely attractive material with a narrow fluorescence peak and tunable emission color by halogen composition. Surface ligands have a variety of effects, including control of size and shape, uniform dispersion through good affinity with solvents and matrices, elimination of quenching sites due to surface defect capping effects and subsequent improvement of luminescent properties, and improvement of stability through surface protection. CsPbX3 QDs can be synthesized by hot injection and room temperature precipitation methods, using oleic acid (OA) and oleylamine (OLA) as surface ligands. One of the problems with these QDs is their low stability; the mechanism of degradation of QDs is the easy proton transfer between the carboxylate groups of OA and the ammonium groups of OLA on the surface of the QDs, resulting in the desorption of OA and OLA from the QD surface. Ligand desorption creates halogen vacancies, which act as trap levels that cause nonradiative recombination; therefore, it is important to design ligands that hardly desorb from the QD surface to suppress degradation of the QDs. In this talk, we will introduce our results on surface ligand of perfluorocarboxylic acid that improves thermal stability of CsPbBr3 QDs [1].

Fluorescent carbon quantum dots (CQDs) are attracting attention as an alternative material to toxic QDs. In order to synthesize CQDs with a variety of fluorescent colors, it is effective to select aromatic compounds as carbon sources. The fluorescence color of CQDs changes depending on the polarity of the dispersant. This fluorescence solvatochromism is attributed to the change in the HOMO-LUMO energy gap of CQDs through the dipolar and hydrogen bonding interactions between CQDs and the dispersant molecules. In this talk, we will show that fluorescence solvatochromism of CQDs synthesized from p-phenylenediamine can be modulated by surface modification with perfluorocarboxylic acid [2].

[1] D. Sato, Y. Iso, T. Isobe, ACS Omega, 5, 1178-1187 (2020).

[2] K. Sato, R. Sato, Y. Iso, T. Isobe, Chem. Commun., 56, 2174-2177 (2020).
(Invited, Digital Presentation) Novel Technology for Halide Phosphors
Authors: Toda Kenji
Published: November 2022

Many people believe that an ionic-diffusion in an ionic crystal is very slow around room temperature. Therefore, a conventional solid-state reaction (SSR) method requires a high temperature to synthesize the ceramic materials. Synthesis of morphology controlled phosphors can be categorized in two ways namely, chemical and physical methods. Various methods such as the sol-gel, hydro-thermal, or the polymerized complex methods are usually used to synthesize phosphor materials. However, these methods require expensive and special experimental equipment, raw materials, or solvents.

In order to perform inexpensive mass-production for new phosphor materials, we have applied novel soft chemical synthesis technique, water-assisted solid-state reaction (WASSR) method. The WASSR method is very simple and can synthesize nano-materials just by storing or mixing raw materials added a small amount (typically 10wt%) of water at low temperature below 500 K. Typical particle sizes (10 - 100 nm) of the samples prepared by the WASSR method were smaller than that (2 - 10 micrometer size) of the sample prepared by the SSR method. The most probable mechanism is new type water accelerated solid acid-base reaction on the surface. We successfully synthesized various phosphor materials ((Cs,Rb)VO3, YVO4:Eu, Ba2SiO4:Eu, LaPO4:Ce,Tb) by the WASSR method. In this study, we report the synthesis of non-oxide halide phosphors (CsPbX3, K2SiF6:Mn).

For example, a stoichiometric mixture of CsBr, PbCl2 was mixed for the WASSR synthesis of CsPbBr3 quantum dot phosphor. Then, a small amount (10 wt%) of water was added to the mixture and mixed using mortar for 1 min to synthesize a single phase of CsPbBr3. The XRD pattern of the products are in good agreement with that of single phase CsPbBr3. The QD dispersed hexane solution shows strong green emission under the excitation of UV light. Our proposed WASSR synthesis technique is a powerful tool for rapid screening and mass-production of phosphor materials.

Acknowledgment

This research was partly supported by the Ministry of Trade, Industry and Energy(MOTIE) and Korea Institute for Advancement of Technology(KIAT) through the International Cooperative R&D program(P0006844_Development of color conversion nanocrystal luminescence materials for next generation display).

References

[1] T. Kaneko, S. W. Kim, A. Toda, K. Uematsu, T. Ishigaki, K. Toda, M. Sato, J. Koide, M. Toda, Y. Kudo,T. Masaki, and D. H. Yoon, Sci. Adv. Mater., 7, 1502 (2015).

[2] S-W. Kim, T. Hasegawa, M. Watanabe, M. Muto, T. Terashima, Y. Abe, T. Kaneko, A. Toda, T. Ishigaki, K. Uematsu, K. Toda, M. Sato, E. Kawakami, J. Koide, M. Toda, Y. Kudo, T. Masaki and D. H. Yoon, Appl. Spect. Rev., 52, 1 (2017).
Mechanochemical Synthesis As a Green Route: Cs3Cu2X5 (X = Cl, Br, I) and CsCu2I3 and Their Reversible Phase Transitions
Authors: Han Joo Hyeong , Im Won Bin
Published: November 2022

Cesium copper halides (CCHs) show promise for optoelectronic applications, and their syntheses usually involve high-temperatures and hazard solvents. Herein, the synthesis of highly luminescent and phase-pure Cs3Cu2X5 (X = Cl, Br, and I) and CsCu2I3 via a solvent-free mechanochemical approach through manual grinding is demonstrated. This cost-effective approach can produce CCHs on a scale of tens to hundreds of grams. Rietveld refinement analysis of the X-ray diffraction patterns of the as-synthesized CCHs reveals their structural details. Notably, the emission characteristics of green-emitting, chloride-based CCHs remain stable even at elevated temperatures──maintaining 80% of initial PL efficiency at 150 °C. Lastly, a postsynthetic reversible transformation between zero- and one-dimensional CCH materials is demonstrated, indicating the labile nature of their crystal structure. The proposed study suggests that mechanochemistry can be an alternative and promising synthetic tool for fabricating high-quality lead-free metal halides.
Designing Enzymatic Redox Mediators: Quantifying the Impact of Molecular Structure on Biocatalytic Activity
Authors: Mtemeri Lincoln , Hickey David
Published: November 2022

Enzymatic bioelectrocatalysis involves the application of enzymes to facilitate the conversion of chemical to electrical energy. This approach has been widely applied in the fields of biosensing, biofuel cells, and to a lesser degree the synthesis of fine chemicals. While direct electrochemical communication between the enzymes and electrodes is generally preferable, it is often the case that efficient electron transfer rates can only be achieved when redox mediators are employed to shuttle electrons reversibly from the redox site of the enzyme to the electrode interface. Unfortunately, there still exist many oxidoreductases for which no effective exogenous mediator is known. This may be due to insufficient understanding of the role that molecular structure of the mediator plays in determining its ability to facilitate electron transfer to a given enzyme. Consequently, selection and/or design of novel redox mediators remains a challenge that is often accomplished using a “guess and check” approach to maximize electron transfer rates. Developing a rapid, and convenient method of predicting the role played by other structural and chemical features beyond redox potential of a mediator is an important goal in advancing mediated bioelectrocatalysis. This talk will describe our recent efforts in identifying structure - function relationships of redox mediators that control efficient electron transfer rates. I will highlight results from stopped-flow spectrophotometry experiments which review the nature of electron transfer events between quinone redox couples in altering bioelectrocatalytic activity.
Electrochemical Analysis Reveals Chlorpyrifos-Induced Dysregulation of Net Astrocytic Glutamate Uptake
Authors: Xu Kaixuan , Miller Dusty R , Tuladhar Pragun R , Ward Patricia A , Neely M. Diana , Cliffel David E
Published: November 2022

Chlorpyrifos (CPF), an organophosphate pesticide widely used on food crops and in households, has been a critical public health concern due to its neurotoxic effects. Investigations of CPF-induced neurotoxicity have focused on dysregulation of acetylcholinergic signaling but recent work suggests that alterations in glutamatergic neurotransmission and astrocytic glutamate metabolism may occur. L-glutamate is a major excitatory neurotransmitter that is mostly removed from the synaptic cleft by astrocytic glutamate transporters. Here we assessed the effects of CPF on net glutamate uptake by human-induced pluripotent stem cell derived astrocytes using electrochemical analysis. Our microclinical analyzer (µCA) paired with screen-printed electrodes (SPE) offers an automated sensing system that can be used to monitor cellular metabolism and signaling. In this work, a platinum based SPE combined with the µCA was used to electrochemically quantify glutamate uptake in human astrocytes. Immobilized glutamate oxidase on electrode surfaces provided stable and sensitive glutamate detection. The temperature modification of these electrodes (37°C) led to a nearly four-fold improvement in sensitivity (0.84±0.04 nA/µM), with low limits of detection (2.8±0.1 µM), and quantitation (9.3±0.5 µM). The linear range of the sensor (1-667 µM) is on the same order as typical extracellular glutamate concentrations. These sensors were used to assess the net glutamate uptake efficiency by using escalating concentrations of glutamate (10-200 µM). Glutamate uptake was most efficient when astrocytes were exposed to 50 µM glutamate for 30min (50% net uptake). We are investigating acute and chronic effects of net glutamate uptake using sublethal doses of CPF (0-100 µM). Identifying these cellular mechanisms affected by CPF is critical for the understanding of the impact of organophosphate toxicity.
Electrochemical Detection of Nitrite Ions Using PEDOT Based Films
Authors: Lucero Gisella Liliana , Bund Andreas
Published: November 2022

Poly (3,4-ethylenedioxythiophene) (PEDOT) is an important conducting polymer that is widely studied for applications in photovoltaic devices, thermoelectric materials, batteries, capacitors and sensors [1]. In the field of sensors, PEDOT and PEDOT composites synthesized by chemical and electrochemical methods have been used for the detection of organic and inorganic analytes [2]. In particular, the performance of the composites of PEDOT with nanomaterials (mono and bi-metallic nanoparticles, graphene and nanotubes) has been thoroughly investigated in the last years because the incorporation of those nanostructures can significantly improve the sensing properties of the pristine polymer [3,4]. However, to the best of our knowledge the effect of the content of hollow PdAu nanoparticles in PEDOT composites for the detection of nitrite, an important environmental pollutant, has not been reported before.

In this work, PEDOT films were prepared by cyclic voltammetry and under amperometric and potentiostatic conditions from a solution of EDOT, LiClO4 and SDS (sodium dodecyl suphate). The films were characterized by scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDX). 500 nm- and 300 nm-thick PEDOT films deposited on glassy carbon were used for the electrochemical detection of nitrite by differential pulse voltammetry. 500 nm-thick films shown a higher sensitivity towards NO2
- ions (0.027 μA μM-1). Hollow nanoparticles of gold and palladium were synthesized by a galvanic replacement reaction using Na2PdCl4. PEDOT films were codeposited with the hollow PdAu nanoparticles at constant potential. The performance of the composites with different contents of the bimetallic nanoparticles (3,6,12,15,24 and 30% of the total mass of nanoparticles) were evaluated for the detection of nitrite ions in the range of 50 to 250 μM nitrite. All composites exhibited a higher performance in comparison to PEDOT films mainly in the range of 50 to 112.5 μM.

Figure 1.- SEM PEDOT films produced by (a) potentiostatic deposition, (b) constant current, (c) cyclic voltammetry and (d) DPV curves of nitrite detection with PEDOT + 15% mass percent of PdAu nanoparticles suspension

Figure 1