bluuebunny/crossref_metadata_2025 huggingface dataset:
Controllable Modification of NiMo-Based Electrocatalysts for Water Splitting in Alkaline Solution
Authors: Guan Yayu , Liu Yuyu , Zhang Jiujun
Published: July 2021

Pt modified NiMo-based nanomaterials with stable morphology and structure were prepared by simple and rapid operation. The introduction of small amounts of Pt can not only improve the adsorption and desorption of oxygen intermediates due to the accompanying defects, but also improve the conductivity and promote charge transfer. The synergistic effect of Pt and NiMo-based substance can make the nanomaterials give full play to the advantages of each component, and the catalyst shows good performance in alkaline solution by adjusting the amount of Pt introduced.

Under the current density of 10 mA cm-
2, the overpotential of 102 mV is required for hydrogen evolution reaction. And 399 mV is required for oxygen evolution reaction to generate 50 mA cm-
2. In addition, the effects of direct hydrothermal method and immersion method about introduction of Pt on properties of the materials were explored. It is worth noting that the immersion method is simpler and more effective. When used in a two-electrode system, it only needs a voltage of 1.58 V to achieve current densities of 10 mA cm-
2. What’s more, the nanomaterial shows excellent stability up to 45 hours without obvious decrease of current density, which makes it hopeful to be applied in practice and become a strong competitor of bifunctional electrocatalyst.
(Invited) Catalyst Assessments and Device Incorporation in Low Temperature Electrolysis
Authors: Alia Shaun M , Reeves Kimberly S. , Yu Haoran , Ha Mai-Anh , Larsen Ross E , Cullen David A.
Published: July 2021

Although hydrogen has a significant role in transportation and agriculture, its use in energy consumption overall has been limited, particularly when produced through electrochemical water splitting. With decreasing electricity prices, electrolysis cost reductions can be achieved and allow for an opportunity for greater use.(1) While load following renewable power sources can reduce feedstock cost, further cost reductions rely on minimizing the capital cost by reducing the platinum group metal (PGM) content.(2) Efforts are needed to understand and mitigate electrolyzer degradation, particularly when accounting for lower PGM loadings and intermittent operation.

Previous efforts have developed accelerated stress tests focused on catalyst layer and interfacial loss with standard material sets. (3) Expanded studies have incorporated advanced materials, including higher surface areas, different oxide compositions, supports, and multicomponents. Kinetic improvements were found to lessen load requirements and can mitigate catalyst loss. Cell performance loss during extended operation, however, tended to qualitatively correspond to ex-situ dissolution rates and less stable materials accelerated catalyst layer thinning, migration into the membrane, and interfacial tearing.

While individual components dictate cell-level performance and durability, how components are integrated into membrane electrode assemblies was found to have an impact on catalyst layer properties and electrolyzer performance/durability. (4) Catalyst layers were modified using an ultrasonic spray approach due to the number of variables that could be tuned. While changes to these variables affect several properties and loss mechanisms, trends were found with regards to how catalyst-ionomer integration and catalyst layer uniformity affected performance nonidealities and how losses grew during extended operation. These approaches are useful in diagnostics, to identify and mitigate lower performance and durability. Understanding catalyst layer formation and the relationship between catalyst layer properties and electrolyzer performance/durability is critical to establishing baselines and better informing catalyst development and fabrication efforts.

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

[2] K. Ayers, N. Danilovic, R. Ouimet, M. Carmo, B. Pivovar and M. Bornstein, Annual Review of Chemical and Biomolecular Engineering, 10, 219 (2019).

[3] S. M. Alia, S. Stariha and R. L. Borup, J. Electrochem. Soc., 166, F1164 (2019).

[4] S.M. Alia, K.S. Reeves, J.S. Baxter, D.A. Cullen, J. Electrochem. Soc., 167, 144512 (2020).
(Energy Technology Division Supramaniam Srinivasan Young Investigator Award) Rethinking Catalyst Layer Design: Interplay between Activity and Durability for Polymer Electrolyte Fuel Cells
Authors: Zenyuk Iryna V.
Published: July 2021

Polymer electrolyte fuel cell (PEFCs) technology has advanced to reach the commercialization stage with more automotive manufacturers announcing new PEFC-based light and heavy-duty vehicles. However, the life span and cost of such systems still remain challenges. Using the Department of Energy (DOE) cost-breakdown for the 80-kWnet stack for light-duty vehicles, the cost of precious metal electrocatalysts remains almost unchanged as production rate increases to 0.5 M PEFC stacks per year. The cost of the electrocatalysts amounts to 31% of stack cost, for 0.5 M systems per year production rate. Platinum (Pt) or Pt-alloys are used as electrocatalysts for the oxygen reduction reaction (ORR) on the cathode side and the hydrogen oxidation reaction (HOR) on the anode side of PEFCs. Pt or Pt-alloy electrocatalysts are dispersed as nanoparticles onto a carbon-black support. DOE set a target of reducing Pt loading to 0.125 mg cm-2 to achieve the goal of $12.6 kWnet
-1 for a stack with power density target of 1.8 W cm-2. MEAs with lower catalyst loading are less durable [1], thus, the cost issue cannot be resolved without focusing on the catalyst durability issue of the PEFC stack. To reach the activity and durability targets, overall understanding of the interfaces within the MEAs are needed and their evolution during ageing.

This presentation will summarize my group’s recent efforts within the three main directions for the MEA design: 1) catalyst layer durability studies, via advanced characterization [2], 2) Pt-ionomer interface understanding during the PEFC lifetime and its impact on activity and durability and, 3) ionic liquids and small molecule additives to tailor Pt-ionomer interface for activity. Using methodology of electrochemical characterization, including CO-displacement/stripping, double layer capacity studies, oxygen transport resistance measurements, and others, along with the computational modeling and advanced material characterization (synchrotron and lab-scale), we aim to build comprehensive understanding of transport properties, water management and interfacial properties during the PEFCs’ lifetime.

References:

S. Harzer, J. N. Schwämmlein, A. M. Damjanović, S. Ghosh, H. A. Gasteiger, J. Electrochem. Soc.
2018, 165, F3118–F3131.

Cheng, K. Khedekar, M. Rezaei Talarposhti, A. Perego, M. Metzger, S. Kuppan, S. Stewart, P. Atanassov, N. Tamura, N. Craig, et al., Adv. Energy Mater.
2020, 2000623, 1–7.

Avid and I.V. Zenyuk, Current Opinion in Electrochemistry, 2020, 25, 100634
Alloys of Cobalt Grafted with CNT Supported on N-Doped Carbon Heterostructure As Bifunctional Electrocatalysts
Authors: Sarkar Bidushi , Das Debanjan , Nanda Karuna Kar
Published: July 2021

Development of eco-friendly, stable, and affordable electrocatalysts is crucial for the sustainable energy production and storage units such as fuel cells, water electrolysis, and metal–air batteries. Metal organic frameworks (MOFs) are class of compounds in which metal ions are coordinated to an organic ligand. They have emerged as a great precursor for the synthesis of various electrocatalysts for Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER).

Carbon motifs derived from zeolitic imidazole frameworks (ZIFs), a subfamily of MOFs, have exceptional mechanical and chemical stability due to the presence of metal-nitrogen bonds. Amongst various synthesized ZIFs, ZIF-67 has cobalt ions (Co2+) coordinated to imidazolate-type linkers. The ZIF-67 derived carbon precursors are generally mesoporous, possess high degree of graphitization and large surface area.

Herein, we have tried to immobilize noble metals like Pd, Pt and Ru with short CNTs grafted on C matrix named as PdCo@NC, PtCo@NC and RuCo@NC, respectively. [1] We have synthesized a series of electrocatalysts by a novel H2-free method using simple one-step pyrolysis. The as-synthesized catalysts show excellent bifunctional catalytic activity towards HER as well as OER in alkaline medium. The catalysts show long cycle stability and compete with the state-of-the-art electrocatalysts like RuO2 and Pt/C. PtCo@NC and RuCo@NC shows the best HER and OER, respectively. Further, the excellent electrocatalytic activity is explained based on a synergistic effect between the noble metal and ZIF-67 derived N-doped carbon support.

References:

[1] Construction of noble-metal alloys of cobalt confined N-doped carbon polyhedra toward efficient water splitting, Green Chem, 2020, 22, 7884-7895.
Carbon Nanotube Encapsulated Metal Selenide Eelectrocatalyst for Oxygen Evolution Reaction
Authors: Singh Harish , Liyanage Wipula , Nath Manashi
Published: July 2021

The oxygen evaluation represents an important reaction in electrochemical water splitting and metal-air batteries. To deal with the increasing energy crisis, production of low-cost, high-efficiency, and robust oxygen evolution reaction (OER) electrocatalysts is urgently needed. Recently, transition metal chalcogenides (TMCs) have been used as active electrocatalysts for OER because of their high electric conductivity and enriched redox chemistry. These chalcogenide based electrocatalysts show unprecedented high activity surpassing state-of-the-art precious metal oxides or hydroxide-based catalysts. In the present work, nickel selenide nanorods (NRs) were grown inside carbon nanotubes (NiSe@CNT) through chemical vapor deposition (CVD) wherein, the carbon nanostructure formed in-situ wrapping around the growing nickel selenide nanorods. Electrocatalytic behavior was explored by various electrochemical studies, including linear sweep voltammetry (LSV), chronoamperometric experiments, electrochemical surface area determination, and Tafel slope calculation, under highly alkaline condition. It was observed that this NiSe@CNT composites showed enhanced electrocatalytic activity for OER. Our results indicate that the self-grown CNT around Nickel selenide increases catalytic activity of this hybrid due to an increased number of catalytic sites and electronic conductivity of the nanocomposite. The overpotential at 10 mA cm-2 current density for the as-synthesized NiSe@CNT catalyst is 270 mV which is much better than precious metal based electrocatalysts for OER, such as RuO2 and IrO2. In addition, before and after the 40 h chronoamperometry stability test, the LSV curves were almost similar confirming that the as-synthesized catalyst could give stable electrocatalytic OER activity in 1 M KOH medium for the extended time period. The as-synthesized catalyst was characterized by XRD, Raman spectroscopy, XPS and TEM for morphology, elemental and chemical compositions.
Localized Surface Plasmon Resonance Enhanced Oxygen Evolution on Nickel-Based Catalysts
Authors: Kendrick Ian , Kaufold Benjamin William , Mukerjee Sanjeev , Liu Yongmin , Wang Chuangtang
Published: July 2021

Electrochemical localized surface plasmon resonance (LSPR) is an emerging method with applications in sensing and catalysis. In terms of the latter, enhanced oxygen evolution has been demonstrated using nanostructured nickel hydroxide decorated with gold nanoparticles. However, the current state of alkaline oxygen evolution Ni-based transition metal catalysts have obviously expanded beyond monometallic Ni to include additional metals and are prepared using techniques to yield nanostructured catalysts. A variety of these nanostructures are known, with shapes and sizes that vary by synthetic method, and have been extensively studied as water splitting electrocatalysts; however, relatively few have been studied as photoelectrocatalysts which make use of the hot carriers generated by LSPR. We aim to maximize the potential of Ni-based oxygen evolution catalysts as photoelectrocatalysts by applying gold nanoparticle decoration to additional types of nanostructures. Furthermore, by comparing the plasmonic enhancement observed on additional binary and ternary Ni-based catalysts, we hope to elucidate the mechanism of oxygen evolution when the LSPR phenomenon is involved. Additional work may involve the decoration of NiFeLDH nanoplates or spherical structures, as opposed to ordinary nanosheets.
Understanding and Enhancing Catalyst Performance in AEM Electrolyzers Using a Statistical Approach
Authors: Ul Hassan Noor , Mercado Hector-Colon , Soucie Hanna , Kohl Paul , Mustain William
Published: July 2021

The behavior of the anode electrode in the Anion Exchange Membrane Water Electrolyzer (AEMWE) – where the oxygen evolution reaction (OER) occurs – is complex and influenced by several factors. Very few studies have been performed to understand OER electrode performance by optimizing contributing individual factors that influence the performance. This study highlights the individual effects of: catalyst loading, catalyst selection, gas diffusion layer (GDL) type and conductive additive content. The influence of each factor is elucidated through a Design of Experiments (DoE) approach with a full statistical analysis. Electrochemical data, alongside Pareto charts, parametric trends and their mutual interactions will be presented. Such a DoE approach is also helpful in making useful predictions, allowing new combinations to be discovered and tested. The end result is very high performance with a current density of 1 A/cm2 at 1.64 V in 0.1 M KOH being achieved. Furthermore, we extend our understanding from this electrolyzer work, coupled with our previous electrode engineering for AEM fuel cells [1-3] to design electrodes for an AEM-based Unitized Regenerative Fuel Cell (URFC). Good baseline performance was achieved, including a round trip efficiency of 40.7 % at 500 mA/cm2. This study will serve as a guide for optimal electrode design with insights into design-performance compromises, which can be especially helpful when making design choices and performing techno-economic analyses.

References

[1]. Xiong Peng, Devashish Kulkarni, Ying Huang, Travis J Omasta, Benjamin Ng, Yiwei Zheng, Lianqin Wang, Jacob M LaManna, Daniel S Hussey, John R Varcoe, Iryna V Zenyuk, William E Mustain, “Using operando techniques to understand and design high performance and stable alkaline membrane fuel cells”, Nature Communications, Volume 1, Pages 1-10 2020.

[2]. Noor Ul Hassan Mrinmay Mandal Garrett Huang Horie Adabi Firouzjaie Paul A. Kohl and William E. Mustain, “Achieving High‐Performance and 2000 h Stability in Anion Exchange Membrane Fuel Cells by Manipulating Ionomer Properties and Electrode Optimization”, Advanced Energy Materials, Volume 10, Issue 40 (2020).

[3]. Garrett Huang, Mrinmay Mandal, Xiong Peng, Ami C Yang-Neyerlin, Bryan S Pivovar, William E Mustain, Paul A Kohl, “Composite poly (norbornene) anion conducting membranes for achieving durability, water management and high power (3.4 W/cm2) in hydrogen/oxygen alkaline fuel cells, Journal of the Electrochemical Society, Volume 166, Pages F637, 2020.
Niobium Oxide Aerogel-Supported Bifunctional Oxygen Electrocatalysts for Unitized Regenerative Fuel Cells
Authors: Albiter Luis A , Godinez Salomon Jose Fernando , Urena Michael E. , Naymik Zachary G. , Rhodes Christopher P.
Published: July 2021

Proton exchange membrane unitized regenerative fuel cells (URFCs) combine the ability to both produce power (in fuel cell mode) and generate fuel and oxidant (in electrolysis mode) from the same cell. The further development and utilization of URFCs is hindered by the high costs and low stability of bifunctional oxygen electrocatalysts. Distributing the oxygen electrocatalyst on a high surface area support can reduce the loading of the active noble metal (e.g., platinum and iridium) and influence the efficiency and stability of the catalyst for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Carbon, which is typically used as a support material, is highly unstable under the conditions required for OER which makes carbon unfeasible for long-term use within URFCs. Therefore, alternative carbon-free catalyst supports are needed. Niobium oxide, Nb2O5, is stable in the oxidative potentials and highly corrosive acidic conditions of URFCs; however, the low electronic conductivity of Nb2O5 significantly limits its use as a catalyst support material. We investigated approaches to obtain high surface area and conductive niobium oxides, NbOx, as stable supports for bifunctional oxygen electrocatalysts. The effects of synthesis conditions, drying methods, and temperature/atmosphere treatments on the structure, morphology, surface area, and electronic conductivity were evaluated. The structure, morphology, composition, and surface area were determined by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, and nitrogen physisorption analysis. Sol-gel synthesis and supercritical drying resulted in a NbOx aerogel with high surface area and porous morphology. Thermal treatment of the NbOx aerogel under H2 increased the electronic conductivity of NbOx when compared to the as-prepared NbOx. Different methods to deposit noble metals on the NbOx support were evaluated. The NbOx-supported catalysts were tested as bifunctional ORR/OER electrocatalysts to determine their activity and stability. The development supported bifunctional oxygen electrocatalysts that can provide lower noble metal loadings, higher activity and improved stability under harsh acidic conditions and highly oxidizing potentials furthers the development of URFCs with lower cost, improved performance, and enhanced durability.
(Invited) Catalyst and Device Architectures for Pure and Dirty-Water Splitting with Alkaline Exchange Membrane Electrolyzers
Authors: Boettcher Shannon W. , Lindquist Grace , Krivina Raina A
Published: July 2021

Polymer-electrolyte-membrane electrolyzers are used commercially for hydrogen production from pure water. They offer a number of advantages over traditional liquid-alkaline systems in that they typically operate at higher current densities, better separate the produced H2 and O2 gases, and do not use corrosive liquid electrolyte. Commercial systems use Nafion, a proton exchange membrane, to conduct the ionic current from anode to cathode but require the use of precious metal catalysts that are stable in the presence of the high local acidities. Alkaline-exchange-membrane systems offer the possibility to achieve the same performance advantages as acidic-membrane systems while enabling the use of earth-abundant catalysts. In this presentation, I will discuss our effort to understand and design oxygen evolution catalysts for alkaline-membrane electrolyzers and build high-performance and durable systems that operate without added electrolyte at less than 1.9 V at 1 A cm-2. This includes the integration of reference electrodes into membrane-electrode assemblies. I will also discuss degradation phenomena associated with the ionomer and catalyst layers as well as the influence of feed-water impurities and the possibility to design dirty-water-tolerant alkaline-membrane electrolyzers.
(Invited) Oxide-Encapsulated (Photo)Electrocatalysts for Solar Fuels Production
Authors: Esposito Daniel V. , Beatty Marissa , Stinson Robert
Published: July 2021

Encapsulating active electrocatalysts with permeable oxide overlayers offers additional “control knobs” for tuning electrocatalyst selectivity and/or activity in ways that are not possible with conventional electrocatalysts.[1] In particular, nanoscopic oxide overlayers can possess selective transport characteristics that allow them to behave as ultrathin membranes that can block impurities and undesirable reactants while still permitting desired reactants and products to pass between the bulk electrolyte and active sites at the overlayer/catalyst buried interface.[1,2] In this presentation, I will describe recent investigations of silicon and titanium oxide-encapsulated thin film electrodes that allow for quantification of species permeabilities and to establish general design principles that govern the structure-property-performance relationships for nanoscopic oxide overlayers. First, I will show how the porosity and chemical composition of silicon oxide overlayers can be systematically tuned to control the relative permeabilities of protons and molecular oxygen, both of which are of great importance for water splitting.[3] Next, the selective transport properties of these coatings are reported in the presence of redox mediator species that are of interest for photocatalytic H2 production from Z-scheme water splitting.[4] Both silicon and titanium oxide overlayers are shown to be capable of selectively facilitating the desirable oxygen and hydrogen evolution reactions with selectivities of > 80% in the presence of a reversible redox mediator. Importantly, this work highlights the ability of ultrathin oxide overlayers to dramatically alter reaction selectivities, and presents design rules for overlayers that can be extended to many other (photo)electrocatalytic materials and reactions of interest to the solar fuels community.

References

[1] D.V. Esposito, ACS Catalysis, 2018, vol. 8, 457–465.

[2] N. Y. Labrador, et al.
,
ACS Catalysis, 2018, vol. 8, 1767–1778.

[3] M.E. Beatty, et al., ACS Applied Energy Materials, (Articles ASAP), doi.org/10.1021/acsaem.0c02359

[4] Bala Chadran, et al., Energy & Environmental Science, 2018. vol. 1, 115-135
(Invited) Prediction of Excited State Dynamics for Element-Specific Transient X-Ray Spectroscopy
Authors: Cushing Scott
Published: July 2021

Transient x-ray spectroscopy is evolving into a critical tool in photoelectrochemistry. X-rays can measure the coupled electronic and structural dynamics that underlie excited state polaron formation, molecular reaction dynamics, and hot carrier thermalization pathways. Element-specific responses can be used to measure electron or hole transport between each component of a photoelectrode (i.e. light absorber, oxide protection layer, catalyst). In this talk, we discuss progress towards the ab-initio prediction and interpretation of excited state x-ray spectra on a tens of femtoseconds to nanosecond timescale. The static and dynamic x-ray spectra are unique for each element or bonding scheme. It is typically unknown whether an element of choice will provide relevant dynamical information before performing the technically demanding transient x-ray experiment. We implement a Bethe-Salpeter equation approach with time-dependent electron and phonon populations from solving the Boltzmann transport equation. The calculation accurately includes core-hole excitonic effects in a range of test materials without needing to assume a model of the excited state processes (i.e. renormalization, lattice expansion, state-filling). The eventual goal is a distributable goal that can pre-screen transient x-ray experiments and interpret the measured excited state spectra.
High Throughput Evaluation of Multi-Element, Multi-Functional Coatings for Improved Photoanodes and Photocathodes
Authors: Haber Joel A. , Zhang Zemin , Liu Guiji , Shinde Aniketa , Zhou Lan , Guevarra Dan , Jones Ryan , Kan Kevin , Gregoire John M/ , Toma Francesca Maria
Published: July 2021

The development of efficient, stable photoanodes and photocathodes remains a primary materials challenge in the establishment of a scalable technology for artificial photosynthesis. The typical photoelectrode architecture consists of a semiconductor light absorber coated with a metal oxide that serves a combination of functions, including corrosion protection, electrocatalysis, light trapping, carrier transport, and elimination of deleterious surface recombination sites. We describe high throughput investigations of the variation in performance and photo-response of integrated photoanode and photocathode libraries. The photoanode assembly libraries consist of uniform BiVO4 light absorbers coated with films varying in composition and loading and evaluated at pH 9 and 13. The photocathode assembly libraries, for example, consist of uniform CuBi2O4 light absorbers coated with film libraries varying in composition and loading. Photoelectrode assemblies based on promising coating compositions and loadings were characterized in detail.
(Invited) CrOx-Mediated Stability and Performance Enhancement of Ni/NiO-Mg:SrTiO3 in Photocatalytic Water Splitting
Authors: Mul Guido , Mei Bastian , Crozier Peter , Cherevko Serhiy , Han Kai
Published: July 2021

In the field of photocatalytic water splitting to produce sustainable hydrogen, significant breakthrough in Apparent Quantum Efficiency (AQE) has been obtained by modification of SrTiO3-based semiconductors. Combining doping with aliovalent Al(III) and functionalization with CrOx-promoted Rh nanoparticles, AQEs of close to 100% have been reported upon UV excitation. In this study it is demonstrated that economically more viable Ni-based nanoparticles allow Mg-doped SrTiO3-based semiconductors to provide for AQEs >25%. A key and novel finding is that photodeposited CrOx not only promotes the performance of the Ni particles (AQY increases from ~10% to 26%), but also enhances the stability, allowing sustained cyclic operation (day-night cycles). In situ elemental analysis shows that CrOx significantly reduces dissolution of Ni from Ni/NiO-Mg:SrTiO3 by formation of a Ni-Cr mixed metal oxide. This is confirmed by state-of-the-art electron microscopy, which furthermore demonstrates that upon preparation, CrOx is photodeposited in the vicinity of several, but not all, Ni/NiO particles. Inhomogeneities in the interfacial contact between the Ni/NiO particles and the Mg:SrTiO3 substrate likely affect the probability of reduction of Cr(VI)-species during photodeposition, explaining the inhomogeneity. In addition it is revealed that the dopant Mg is essential in providing favorable interfacial contact with several NiO/Ni particles and effective promotion of these particles by CrOx. In general this presentation provides synthesis protocols that allow for intensification of interfacial contacts of Ni/NiO and (doped) SrTiO3, and stability enhancement by photodeposition of CrOx.
(Invited) How the Surface Chemistry of WO3 Influences Its Activity for the Oxygen-Evolution Reaction
Authors: Bartlett Bart M
Published: July 2021

Tungsten(VI) oxide (WO3) remains prominent in photoelectrochemical approaches toward the oxygen evolution reaction (OER) from water because of its stability in acidic solution (desirably for its redox partner, the hydrogen evolution reaction). Instability in the photocurrent density during the OER has previously been attributed to formation of destructive peroxide intermediates. Under constant illumination, repeated cycles of poising electrodes at 0.98 V vs Ag/AgCl in pH 1 sulfate solution followed by rest periods at open-circuit potential show reversibility in the photocurrent decay. This behavior is attributed to reversible proton deintercalation/intercalation in H
x
WO3. H+ intercalation with concomitant reduction of W6+ begins during the synthesis from annealing an ammonium metatungstate sol that is spin coated onto fluorinated tin oxide. The net result is that H
x
WO3 shows an increased donor density (1021 cm–3). The change in surface composition during the OER—specifically tungsten reduction, is measurable by XPS analysis, Mott-Schottky analysis of electrochemical impedance spectra, and a broad near-IR absorption band. The Faradaic efficiency for the OER (ηOER) is ~70% on H
x
WO3. When an amorphous FeOOH electrocatalyst layer is deposited on the surface, the photocurrent density stabilizes and ηOER increases to near 100%. Moreover, fast oxidation reactions such as chloride oxidation also show very stable photocurrent density on WO3, hinting that other redox partners for hydrogen evolution under acidic conditions are plausible.
Revealing the Critical Challenges in State-of-the-Art Electrochemical Nitrogen Fixation Research
Authors: Chen Yifu , Liu Hengzhou , Gu Shuang , Li Wenzhen
Published: July 2021

The energy-intensive Haber-Bosch process fixes around 140 million metric tons of molecular nitrogen (N2) annually worldwide into ammonia (NH3) despite its harsh conditions1. The electrochemical nitrogen reduction reaction (NRR) has been regarded as a promising alternative to the Haber-Bosch process, allowing for distributed and onsite NH3 production, and potentially can accelerate the decoupling of the ammonia industry with the use of fossil fuels2. The prosperity of NRR research under environmentally benign conditions in the past few years, however, has been challenged by the recent questioning on the source of produced NH3 in many systems3,4, due to the wide existence of active nitrogen species and the absence of direct evidence on the conversion of N2 (that is, quantitative analysis of 15NH3 production in the electrolytic experiments with 15N2).

In search of effective strategies as solutions to these critical challenges, here we propose a reliable protocol for impurities screening in NRR systems. In particular, suggested procedures to examine and eliminate the N-containing species in the electrolyte salts, catalyst materials, and feeding gases will be presented based on our experimental results. We also recommend a gas circulation system for cost-effective 15N2 experiments with improved accuracy in the determination of 15NH3 production as the true N2 fixation performance. Gas permeation and co-generation of hydrogen (H2) are taken into account to ensure that 15N2 can be well confined in the system for stable long-term operation. Such a system is adaptable to different types of electrochemical reactors, making it possible for measuring and reporting 15NH3 production as a routine activity in future NRR research.

References:

Apodaca, L. E. Nitrogen (fixed)—Ammonia. U.S. Geological Survey, Mineral Commodity Summaries (2020).

Soloveichik, G. Electrochemical synthesis of ammonia as a potential alternative to the Haber-Bosch process. Nat. Catal.
2, 377–380 (2019).

Andersen, S. Z. et al. A rigorous electrochemical ammonia synthesis protocol with quantitative isotope measurements. Nature
570, 504–508 (2019).

Chen, Y. et al. Revealing nitrogen-containing species in commercial catalysts used for ammonia electrosynthesis. Nat. Catal.
3, 1055–1061 (2020).
Electrocatalytically Denitrifying Wastewater Based on Unique Nitrate-to-Nitrite Selectivity on Ag
Authors: Liu Hengzhou , Park Jaeryul , Chen Yifu , Gu Shuang , Shanks Brent H , Li Wenzhen
Published: July 2021

In our study, an exceptionally high selectivity of the electrocatalytic nitrate-to-nitrite transformation was discovered on Ag surfaces, among eighteen metals screened. It was demonstrated that this electrocatalytic step on oxide-derived Ag (OD-Ag), which possesses extended surface area (13 times) and enhanced specific activity (3 times) relative to Ag foil, can be coupled with a catalytic nitrite-to-dinitrogen step on a Pd catalyst using renewable hydrogen generated on-site by a water electrolyzer. We thereby proposed and demonstrated a combined electrocatalytic-catalytic process as an alternative strategy for innovative nitrate removal from agricultural wastewater with high selectivity of >95%. With future research and development, the combined process may hold the potential of tackling the ever-increasing nitrate pollution in water bodies to address its linked environmental and health issues. Strategically returning reactive nitrogen from wastewater back to the atmosphere in the inert form, this combined process is well-positioned to help close the global nitrogen cycle, one of the grand engineering challenges in the 21st century. In parallel with the applications in wastewater treatment, the Ag-based electrocatalytic nitrate-to-nitrate conversion with ultrahigh selectivity may be widely employed for designing cost-effective and energy-efficient syntheses of various nitrogen-based compounds in a distributed manufacturing fashion. The kinetics studies and computational insights could also be beneficial to advancing nitrogen-centric electrochemistry, materials science, and technologies.

Figure 1
Electrochemical Detection of Drug Uptake and Retention in Bacteria and Cancer
Authors: Kuss Sabine , Luu Huy Tran Le , Islam Md Rafiqul , Salazar Vivien , Singh Vikram , Nachtigal Mark W.
Published: July 2021

Drug resistance in bacteria and cancer is a growing problem that severely increases the number of deaths worldwide.[1,2] According to the World Health Organization, drug resistance is present in every country, and various national and international health organizations have called for the urgent development of new treatment and diagnostic strategies.[3] This presentation outlines innovative and interdisciplinary approaches to recognize and quantify drug resistance in bacteria and cancer cells by electrochemistry. Electroanalytical techniques are cost efficient, sensitive and the transparency of a liquid sample is irrelevant, allowing direct in vitro analysis of blood, urine, and saliva samples. This presentation covers the characterization of some of the most important commercial drugs, and new investigational antibiotic hybrids by electrochemistry.[4] Building on this exploration of drug electrochemistry, the quantification of drug uptake and retention in biological cells is presented. This research forms the basis for the development of a point-of-care biosensors to identify drug resistance in patient samples. This technology will advance clinical treatment from the current trial-and-error approach to the prescription of evidence-based personalized drug regimens.

[1] J. Sun, A. R. Warden, J. Huang, W. Wang, and X. Ding, Anal. Chem., 91, 7524–7530 (2019).

[2] R. Article, J. Pathol., 205, 275–292 (2005).

[3] World Health Organization (WHO). Global action plan on antimicrobial resistance; (2015).

[4] R. Islam, H.T. Le Luu, S. Kuss, J. Electrochem. Soc., 167, 045501 (2020).
Insight into Direct and Indirect Electrocatalytic Dechlorination of Organic Chlorides By Ultrafine Pd Nanoparticles
Authors: Huang Binbin , Cao X
Published: July 2021

Electrocatalytic dehalogenation occurs via both direct and in-direct pathways at the cathode surface playing significant roles in the fields of organic synthesis and environmental remediation. To distinguish these two reduction routes and establish their quantitative relationships in the dehalogenation process are of fundamental interest for unraveling the electrocatalytic dehalogenation mechanisms. However, few studies have been conducted so far. In this work, we prepared ultrafine Pd nanoparticles (NPs) with high dispersibility by simply using N,N-dimethylformamide as solvent and metal-biding agent. The electrochemically active surface area of Pd NPs was 40 m2•g-1, 1.50 times higher than that of commercial Pd/C catalysts. By using the as-prepared Pd NPs as model catalyst, we first showed the direct and indirect reduction of 4-chlorophenol (4-CP) under aqueous conditions in the cyclic voltammogram. The dissociative electron transfer to 4-CP over the Pd NPs electrode was indicated to follow the concerted mechanism. The atomic hydrogen species exclusively existed in the forms of adsorbed hydrogen (H*ads) and absorbed hydrogen (H*abs), which all contributed to the excellent dehalogenation performance. A detailed voltammetric analyses allowed to establish the quantitative relationship between direct and indirect dehalogenation mechanisms, which showed comparable contributions to the electrocatalytic dehalogenation process. This discovery is very important and corrects the previous assertion that the indirect reduction pathway plays a predominant role in the dehalogenation process. This work provides insights into distinguishing the direct and indirect electrocatalytic dehalogenation pathways and successfully bringing the knowledge gap to quantitatively build connection between both dehalogenation routes.
Development of Visible Light Sensitive Photocatalyst Composed of Vitamin B12 and Metal Ions Modified TiO2
Authors: Shichijo Keita , Hisaeda Yoshio , Shimakoshi Hisashi
Published: July 2021

TiO2 is one of the most promising photocatalyst with excellent efficiency and stability in photocatalytic reaction. However, TiO2 can only be activated under UV light irradiation because of the wide band gap. Recently, several metal ions surface modified TiO2 (M–TiO2) has been developed as a visible light sensitive photocatalysis1. Visible light irradiation initiates effective charge transfer between metal ions and TiO2.Here, we report novel visible light driven photocatalyst (B12−M−TiO2) composed of the vitamin B12 derivatives which is unique cobalt complex and several M–TiO2 and introduce visible light-induced green molecular transformations mediated by B12-M-TiO2
2.

Reference

[1] M. Okazaki, Y. Wang, T. Yokoi, K. Maeda, J. Phys. Chem. C, 2019, 123, 10429.

[2] K. Shichijo, M. Fujitsuka, Y. Hisaeda, H. Shimakoshi, J. Organomet. Chem., 2020, 907, 121058.

Figure 1
Electroorganic Synthesis of Tertiary Cyanoformamide from Trichloroacetonitrile Catalyzed By B12 Complex
Authors: Mohammad Moniruzzaman , Hisaeda Yoshio , Shimakoshi Hisashi
Published: July 2021

Cyanoformamide is the key motifs of pharmaceuticals, agricultural chemicals, and component of the natural products, and it is vital building block in the synthesis of lactams,acrylonitriles, tetrazoles, unsymmetrical ketones, symmetric & asymmetric substituted ureas, and other heterocyclic compounds.[1] Herein the one-pot procedure for synthesis of tertiary cyanoformamide has been developed with electrochemical method by B12 complex[2] as catalyst under mild conditions, at room temperature under air. Over thirty examples of cyanoformamide were synthesized in moderate to good yields. This user-friendly strategy is compatible with a broad range of biologically active cyanoformamide and easily scalable with the cheap and simple experimental set-up.

References

[1] Y. Gao, Z. Zhang, Z. Li, T. Guo, Y. Zhu, Z. Yao, B. Liu, Y. Li, K. Gao, J. Org. Chem. 2020, 85, 1087.

[2] (a) Y. Anai, K. Shichijo, M. Fujitsuka, Y. Hisaeda, H. Shimakoshi, Chem. Commun., 2020, 56, 11945. (Inside front cover), (b) H. Shimakoshi, Z. Luo, T. Inaba, Y. Hisaeda, Dalton Trans, 2016, 45, 10173.

Figure 1
Electrochemical Investigations of Tau Protein Biochemistry
Authors: Martic Sanela
Published: July 2021

Proteins play important biological functions and are commonly associated with a variety of diseases. One such protein is tau protein, which maintains brain cell function and is linked to neurodegeneration. The complex tau protein biochemistry is composed of the post-translational modifications, interactions with binding partners and aggregation, among other pathways. To investigate the complex biochemistry of tau protein, we utilized electrochemical methods (cyclic voltammetry and electrochemical impedance spectroscopy. We demonstrated detection of protein-protein interactions (1), protein-ligand interactions (2), enzymatic catalysis and enzyme inhibition (3). For this purpose, tau protein film on Au surface was fabricated and characterized. Tau-Au films were used to probe interactions with heparin, ferritin, transferrin, antibodies, and protein kinases. Our data indicate that tau-Au films are functional surfaces which allow for monitoring biomolecular interactions, and enzymatic transformations.

References

(1) a) Carlin, N., Martic-Milne (2018) J. Electrochem. Soc. 165: G3018-G3025. b) Jahshan, A., Esteves, J.O., Martic-Milne (2016) J. Inorg. Biochem. 162: 127-134.

(2) Trzeciakiewicz, H., Esteves, J. O.V., Carlin, N., Martic, S. (2015) Electrochim. Acta 162: 24-30.

(3) Esteves, J.O.V., Martic-Milne, S. (2016) Anal. Biochem. 496: 55-62.
Polarization Behaviors of Biofilms on Metallic Materials By E.coli and S.Epidermidis, and the Applicability of Results
Authors: Kanematsu Hideyuki , Ogaki Sho , Sugino Noe , Hirai Nobumitsu , Wada Noriyuki , Kogo Takeshi , Yamada Hirohisa , Tsunashima Katsuhiko , Barry Dana M.
Published: July 2021

Biofilms are formed on materials by bacterial activities and bring about detrimental problems as well as beneficial ones in industrial fields and our daily lives. It is very important to establish effective countermeasures, to control biofilms properly and also to monitor the formation and growth. For any of those purposes, we have to know how the biofilms are constructed, what kind of components they have and also what is going on inside biofilms. Generally, we already know that biofilms are composed of dominated water, bacteria themselves and external polymeric substance (EPS) at the initial stages. From the academic viewpoints, the initial structures are illustrated very clearly and precisely and already well known. However, biofilms changes with time significantly. Inorganic and organic substances are introduced into biofilms from environments or substrates outside biofilms. They interact each other to form many new compounds or to decompose into new ones. And they break down due to many reasons. Since those interactions would be very complicated, lots of information about biofilms growth have been still missing. And the lack of information might bottleneck the development of countermeasure. Therefore, we need more effective investigations using various approaches. There is no doubt that electrochemical methods are very promising methods.

In this experiment, we chose two kinds of bacteria, E.coli and S.epidermidis. Each is representative gram-negative bacteria and gram-positive ones, respectively. Using those bacteria, biofilms formed on some metallic materials, such as copper and titanium. During the formation and growth of biofilms, the natural immersion potential (open circuit potentials) changed with time. However, the behaviors differed from substrate material to substrate material and also from bacteria to bacteria. And at some specific growth stages, the polarization curves were measured. The cyclic polarization curves depended also on the growth stage of biofilms.

The following results were obtained.

1. On the metallic materials forming biofilms easily such as copper, the natural immersion potentials shifted in the less noble direction with biofilm formation and growth significantly.

2. On the metallic materials with few biofilm formation/growth such as titanium, the natural immersion potentials did not change so much.

3. The polarization curves showed typical current peaks around 0.1-0.2V (versus Ag/AgCl in 3.3N KCl solution), when biofilms formed on metallic substrates.

4. In the case of few biofilm titanium specimens, polarization curves did not show any specific current peaks.

5. All of those electrochemical behaviors could be applied to monitor biofilms growth stages.
Interlocked Chalcogenide Lattice Showing High Sodium-Ion Conductivity and Facile Electrochemistry
Authors: Balijapelly Srikanth , Zhang Qi , Sundaramoorthy Santhoshkumar , Sandineni Prashanth , Chernatynskiy Aleksandr V , Choudhury Amitava
Published: July 2021

In this work, a new class of alkali ion containing quaternary chalcogenides with compositions Na3
MGaQ
4 (M = Zn, Fe, Mn; Q = S, Se) have been synthesized using building block approach. The crystal structure of these compounds is built up of three-dimensional (3-D) network of corner-shared supertetrahedral (T2) units, where two such 3-D networks are interlocked. The d-block metal and the main group metal, Ga, occupy same crystallographic site with 1:1 ratio making it a rare form of building unit. Na3ZnGaQ
4 (Q = S, Se) possess ionic conductivity of 3.74 × 10–4 and 0.12 mS/cm with activation energies of 0.38 and 0.42 eV, respectively, for sulfide and selenide analogues at 30 °C. To determine the possible Na-ion diffusion pathways, Nudged Elastic Band (NEB) calculation based on the DFT is performed. The defect formation energies of the two chemically inequivalent Na atoms is calculated. NEB calculations support the experimental findings that the sodium is more mobile in the selenide host than the sulfide. Na-ion electrochemistry of Na3FeGaQ
4 (Q= S, Se) as a cathode material in Na-ion batteries is evaluated. Preliminary results suggest that a modest capacity from 0.5 e/Fe redox reaction at a potential of 2.08 V (Na3FeGaS4) and 1.98V (Na3FeGaSe4) vs Na+/Na for Fe2+/3+ redox couple can be achieved with a very low polarization. Moreover, an excellent cycle life with more than 95% capacity retention for 100 cycles could be achieved at a moderately high rate of C/5, which can be attributed to the open framework structure with facile Na diffusion path.
(Student Battery Slam Best Presentation Award Winner) Combining Experimentation and Computation for Accelerated Understanding of Electrode Morphology in Redox Flow Batteries
Authors: Tenny Kevin M. , Chiang Yet-Ming , Brushett Fikile R.
Published: July 2021

Redox flow batteries (RFBs) hold promise as an electrochemical intermediary between intermittent renewable power generation and the grid.1 Within the RFB architecture, porous electrodes are an integral component, contributing to a myriad functions, such as providing surface sites for redox reactions, dispersing electrolyte throughout the void matrix, and shuttling electrons through its conductive network.2 Carbonaceous materials, such as cloths, papers, and felts, are commonly used in state-of-the-art RFB embodiments, despite their tailored morphologies in polymer electrolyte fuel cells. Consequently, these media engender suboptimal performance in RFBs, necessitating advancement of electrode structures specifically designed for flow battery operation.

While there have been previous systematic studies of RFB electrode structure/function relationships,3,4 most have been limited by manufacturing constraints, restricting the explorable design space. However, recent computational efforts have enabled broad sweeping property analyses,5 leveraging both data science and machine learning algorithms to identify key parameter values. These modeling and statistical pursuits, combined with advanced cell diagnostics, provide a platform for high-throughput material screening in the furtherance of electrode engineering.

In this presentation, we highlight some of the computational tools we have developed for simulated analyses of electrode functionalities in RFBs. We then present experimental tools for in situ and operando electrode benchmarking, which can also be simulated with the aforementioned computation toolkit. Finally, we conclude by demonstrating how this combined platform can be used across a wide variety of electrode domains, revealing performance comparisons and micron-scale designs to direct manufacturing avenues.

Acknowledgments

This work was funded by the Joint Center for Energy Storage Research, an Energy Innovation Hub of the U.S. Department of Energy, Office of Science, Basic Energy (De-AC02-06CH11357). K.M.T. recognizes additional support from the U.S. NSF Graduate Research Fellowship (1122374).

References

A. Z. Weber et al., J. Appl. Electrochem, 41, 1137 (2011).

K. J. Kim et al., J. Mater. Chem. A, 3, 16913–16933 (2015).

A. Forner-Cuenca, E. E. Penn, A. M. Oliveira, and F. R. Brushett, J. Electrochem. Soc., 166, A2230–A2241 (2019).

K. M. Tenny, A. Forner-Cuenca, Y.-M. Chiang, and F. R. Brushett, J. Electrochem. En. Conv. Stor, 17 (2020).

Z. Cheng et al., Applied Energy, 279, 115530 (2020).