bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Exploring the Safe Operational Boundary for High Temperature Solid Oxide Electrolyzer
Authors: Huang Kevin , Wen Yeting
Published: July 2022

High temperature water splitting through solid oxide cells (SOCs) has fundamental advantage in efficiency and rate over its low temperature counterparts. However, fast performance degradation of high temperature SOCs is a major challenge to scale up the technology to the hydrogen market. One leading cause for the degradation is the delamination of oxygen electrode (OE) under high current densities. In this presentation, we show our effort to determine critical conditions under which OE can safely operate without delamination. We particularly apply DC-biased electrochemical impedance spectroscopy (EIS) method to a three-electrode symmetrical cell to delineate OE polarization resistance RP and overpotential h as a function of current density and time under both oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). We then correlate exchange current density (io) with the time of delamination using ohmic resistance Rohm as an indicator of delamination, from which the boundary that OE can safely operate without delamination is established for SOC-based electrolyzers operation.
(Invited) From Nano-Bulk Interplayed Composites to Industrial Standard Devices: A Length Scale Evolution of Heterogeneous Functional Materials for Solid Oxide Electrochemical Cells at Intermediate Temperatures
Authors: Ding Dong
Published: July 2022

Heterogeneous functional materials play very important roles in solid oxide electrochemical cells in intermediate temperatures (400-600oC). At this temperature regime, the solid oxide electrochemical cells can compromise the disadvantages from lower and higher temperature counterparts by adopting more cost-effective catalysts and materials as the cell components while mitigating the fast degradation to achieve optimal reaction kinetics. More importantly, it allows many nano-sized catalysts to be functioning that can be ultimately integrated into the real device through advanced manufacturing technologies. At Idaho National Laboratory, we developed a series of strategies to accommodate heterogeneous functional materials for a range of applications, including hydrogen production via water electrolysis, CO2 conversion and ammonia electrosynthesis using protonic ceramic electrochemical cells (PCECs). The special emphasis is placed on the effect of structure, composition, morphology, and defects of these materials on electrochemical performance of PCECs and respective product for a given feedstock.
Hybrid Manufacturing of a Single-Layer Ceramic Fuel Cell Utilizing 3D Printing and Laser Scribing
Authors: Asghar Muhammad Imran , Lund Peter D.
Published: July 2022

Single-layer ceramic fuel cells are developing as a promising fuel cell technology [1-3]. Since 3D printing can create both the dense and the porous structures with good mechanical and electrochemical properties, it has the potential to revolutionize the manufacturing of fuel cells. We recently reported a 3D printed single-layer ceramic fuel cell fabricated through an extrusion-based 3D printing, which generated a power density of 230 mW/cm2 at 550oC [1]. A comprehensive investigation into the influence of sintering temperatures ranging from 700oC to 1000oC assisted us in optimizing the density of the functional layer for acceptable electrochemical performance while maintaining adequate mechanical properties. We noticed that the performance of the single-layer cells was limited by the mass transport losses due to low porosity of the single-layer. The best printed cell suffered from a high ohmic loss (0.46 Ω.cm2) and a polarization loss (0.32 Ω.cm2) [1]. In this work, we used a hybrid of a 3D printer and a laser scriber to fabricate the patterned single-layer ceramic fuel cells. Interestingly, the performance of the patterned single-layer ceramic fuel cell was 30% better as compared to a conventional single-layer fuel cell without any patterns. The patterned structures on the surfaces of the cell obtained through the laser scribing, considerably improved the electrode processes. In the patterned 3D printed fuel cells, we studied several electrode materials such as CuFe2O4, LSCF, LSC, NiCoAlLi-oxide, and LiNiZn-oxide and synthesized pastes appropriate for extrusion-based 3D printing. The rheological characteristics of the pastes were investigated using several characterization techniques such as dynamic light scattering, viscometry and tensiometry. Electrochemical impedance spectroscopy and current-voltage measurements were used to assess the electrochemical performance of the cells. Furthermore, high-temperature XRD demonstrated the composite materials' excellent structural stability. To further understand the processes in the cells, additional spectroscopic and microscopic investigations (HR-TEM, SEM-EDX, XPS) were performed.

Acknowledgement. Dr. Asghar thanks Academy of Finland (Grant No. 13322738, 13329016) and the Hubei overseas Talent 100 program for their support.

References

[1] M. I. Asghar, P. Mäkinen, S. Virtanen, A. Maitre, M. Borghei and P. D. Lund, P.D., Nanomaterials 11 (2021) 2180.

[2] M. I. Asghar, X. Yao, S. Jouttijärvi, E. Hochreiner, R. Virta and P. D. Lund, Materials International Journal of Hydrogen energy, 45 (2020) 24083.

[3] M. I. Asghar, S. Jouttijärvi, R. Jokiranta, A. Valtavirta and P. D. Lund, Nanoenergy, 53 (2018) 391.

Figure 1
Ultrafast Fabrication of Protonic Ceramic Electrochemical Cells Via Rapid Co-Sintering Process
Authors: Kim Dongyeon , Lee Kang Taek
Published: July 2022

Ceramic-based fuel cells have continued to attract attention due to their high energy conversion efficiency. Among them, proton ceramic electrochemical cells (PCECs) using barium-based proton conducting oxides have been considered as promising candidates for future energy devices. Because they can operate at low temperature (< 650 ℃) compared to other ceramic based fuel cells through the low activation energy. However, PCECs have problems about the secondary phase of proton conducting oxides due to the relatively high calcination/sintering temperature and annealing time. This issue has a detrimental effect on the electrochemical performance of PCECs. Herein, to overcome these hurdles, we suggest innovative approach using rapid co-sintering process (Microwave-assisted sintering method), which dramatically reduces the sintering time (< 10min). Our device exhibited higher electrochemical performance than the conventionally sintered PCECs processed at 1500 ℃ for 5 h. Our results provide effective pathway in fabricating PCECs with an optimal performance.
Metal Supported Thin Film SOFC Fabrication Via RF Sputtering
Authors: Park Chan ho , Lee Ki Yun
Published: July 2022

Thin film solid oxide fuel cell (TF-SOFC) has been studied for past few decades to lower its operating temperature to intermediate temperature range (400℃-700℃). However, it is a challenge to deposit a pinhole free electrolyte thin film on a conventional porous ceramic support. In the case of the Ni-Fe based metal support, even if NiO-Fe2O3 is manufactured as a dense structure, it is reduced to Ni-Fe in a hydrogen atmosphere and forms pores. In this study, Ni-Fe based metal support has been introduced as TF-SOFC support to deposit pinhole free electrolyte. Metal support was fabricated as 290㎛ thick porous bulk(34% porosity) with 10㎛ thick dense layer(<1% porosity) by using tape casting process. Ni-Fe ratio (9:1. 7:3, 5:5, 3:7) and sintering condition (1300℃-1500℃) of metal support were optimized to minimize a mismatch of TEC with thin film and improve microstructure stability of support. After that, NiO-YSZ anode functional layer (AFL) and YSZ electrolyte were continuously deposited on metal support through RF sputtering. By tailoring sputtering condition (substrate temperature, operating pressure, reactive gas flow), 39vol%NiO-YSZ composition AFL and 8.6mol%YSZ pinhole free electrolyte were deposited. Annealing was performed at a temperature of 1100℃ or less to improve the crystallinity of the thin film and suppress Ni agglomeration of Ni-YSZ AFL while minimizing diffusion of Fe in the AFL. In cell operating condition (600℃-H2 atmosphere), the dense layer of metal support and NiO-YSZ AFL formed 28% and 24% of pores, respectively. By using LSM-YSZ cathode through the screen printing process, Metal support (300㎛) / Ni-YSZ (1.3㎛) / YSZ (0.8㎛) / LSM-YSZ (20㎛) button cell was fabricated, and electrochemical analysis was performed.

Key wards: Sputtering, Thin film, Metal Support, Ni-Fe, YSZ, Ni-YSZ
Redox-Active Organic Molecules and Modified Graphene-Based Materials As Active Material Composites for Supercapacitor Applications
Authors: Noor Navid , Lee Hyejin Jin , Rego Arjun , Baker Thomas , Ibarra Espinoza Alejandra , Schouten Anja , Higgins Drew
Published: July 2022

Green and sustainable energy demand has directed the modern world toward producing clean energy storage devices to cut down fossil fuel consumption. Supercapacitors are energy storage devices that have attracted much attention due to owning outstanding properties. Supercapacitors use two main mechanisms to storge charge: I) electrical double layer II) pseudocapacitance. Graphene-based materials have shown promising performance in supercapacitors due to their high surface area and proper electrical conductivity. One of the challenges of working with graphene is the restacking of the graphene sheets, leading to poor performance and lower capacitance. Studies have used doping graphene with different heteroatoms as one of the techniques to overcome the restacking and enhancement of its electrochemical performance. Moreover, redox-active organic molecules, including anthraquinones, phenols, and phenathrequinones, also can be employed to modify graphene.

In this work we develop composite active material structures consisting of modified graphene-based materials and organic molecules containing redox active functional groups to provide pseudo-capacitance capabilities. By combining these materials, specific capacitance values above 600 F/g were obtained (at cyclic voltammetry scan rates of 50 mV/s) along with good capacitance retention following repeated electrochemical cycling. In this presentation we will discuss the influence of synthesis route and processing parameters and the resulting structures and performance of the active supercapacitor materials. By correlating these results, we provide insight into the energy storage mechanisms and durability considerations pertaining to these hybrid materials.
(Invited) Engineering Polypeptides for Controlled Assembly of Ionomer Thin Films: Expanding Beyond Typical Assembly Tools
Authors: Renner Julie N. , Su Zihang , Pramounmat Nuttanit , Arges Christopher G.
Published: July 2022

Control of ionomer thin film structures on metal surfaces is pivotal for efficient performance in electrochemical devices such as fuel cells and electrolyzers. Unfortunately, the assembly of these thin film structures is difficult to control using conventional methods and ideal arrangements remain unknown. Engineered polypeptides have emerged as powerful biomolecular tools in electrode assembly because binding sites and polypeptide structures can be easily modulated by changing the amino acid sequence. However, no studies have been conducted showing polypeptides can be engineered to interact with ionomers, attach them to metal surfaces, and control their arrangement. Our lab has recently developed this technology, using an elastin-like polypeptide to bind to metals, and bind to acidic and basic ionomer via ionic interactions. We use a quartz crystal microbalance with dissipation to provide detailed information about the loading, thickness, and binding behavior of the polypeptide and ionomer layers. We also use atomic force microscopy and grazing-incidence small-angle X-ray scattering to understand the impact of the biomolecules on ionomer phase separation. Finally, we have analyzed the performance (ionic conductivity) of the assembled films using interdigitated electrodes and electrochemical impedance spectroscopy. Through these techniques, we show that 1) our biomolecular system is highly flexible, easily adapting to different materials, 2) the polypeptide sequence can dictate ionomer phase separated structures, and 3) this system can be used to improve the performance of ionomer thin films and gain structure-function understanding. Finally, alternative ionomer assembly techniques are discussed for future exploration. Generally, our results demonstrate that engineered polypeptides are promising tools for ionomer control in electrode engineering.
(Digital Presentation) Heat Transfer Enhancement in Room-Temperature Metal Hydride Storage Systems
Authors: Kuhnert Eveline , Bodner Merit , Stepanov Dmytro , Hacker Viktor
Published: July 2022

Among the existing methods of short- and long-term storage of renewable energy, reversible metal hydrides (MH) are considered safe and volume efficient. They provide efficient hydrogen storage capacity for various applications, including Low Temperature PEM Fuel Cells (LT PEMFCs) [1]. The heat transfer in the MH reactor has a substantial influence on the efficiency of the storage process. In order to achieve the established goals for tank filling times, enhanced heat transfer techniques will be essential [2]. Therefore, this work investigates technical solutions for thermal conductivity enhancement in MH storage systems. Different tank designs are assessed in terms of their applicability and the effect of different solid matrices in the storage system on the internal heat transfer is studied. With the help of thermal imaging, the impact of the geometry of the solid matrices on the uniformity of gas distribution along the MH bed is analysed. The MH tanks are operated with room temperature (RT) metal hydrides that achieve a hydrogen storage capacity of up to 105 kgH2 m−3 in a wide range of temperatures (from 50 to -40°C). The tests are carried out within a limited pressure range of 1 to 0.1 MPa to reduce the reliance on additional H2 compressors when used in stationary applications.

[1] M. V. Lototskyy et al., „Metal hydride systems for hydrogen storage and supply for stationary and automotive low temperature PEM fuel cell power modules“, Int. J. Hydrog. Energy, Bd. 40, Nr. 35, S. 11491–11497, Sep. 2015.

[2] K. C. Smith, Y. Zheng, T. S. Fisher, T. L. Pourpoint, und I. Mudawar, „Heat Transfer in High-Pressure Metal Hydride Systems“, J. Enhanc. Heat Transf., Bd. 16, Nr. 2, S. 189–203, 2009.
(Invited) Green Hydrogen Technologies: Status and Trends
Authors: Soloveichik Grigorii L.
Published: July 2022

There is growing societal consensus that hydrogen is an absolutely necessary part of energy portfolio to reach the COP26 goal to secure global net-zero by mid-century. Hydrogen will play a major role in hard to decarbonize sectors such as industrial (production of steel, cement, and chemicals including ammonia) and heavy-duty, long-haul transportation. By different estimations, hydrogen production volume will be anywhere from 240 to 800 million metric tons per year (MMTY). More realistic predictions are in the range 500 – 600 MMTY that is 7 – 8.5 times more than current global hydrogen production, which predominantly uses fossil fuels and emits around 830 MMTY of carbon dioxide. It is assumed that hydrogen produced by water splitting became predominant by 2050.

With less than 0.1% of current global hydrogen production delivered from water electrolysis, electrolytic hydrogen has tremendous potential for growth. Two commercial (alkaline and PEM) and two emerging (SOEC and AEM) will be compared based on current status and trends of technology (catalysts, membranes, system manufacturability, and capital cost). These technologies could benefit from the integration with energy sources (e.g., nuclear power) or downstream utilization (e.g., ammonia production). Suitability of these technologies for exemplary environments with different energy inputs, electricity prices, and capacity factors will be analyzed. In addition, the effect of different pathways for hydrogen delivery (pure and in the form of a hydrogen carrier) on the levelized cost of hydrogen will be considered.

Development of advanced green hydrogen technologies including early stage research will be illustrated with projects funded by DOE Advanced Research Projects Agency (ARPA-E) and Hydrogen and Fuel Cell technologies Office (HFTO), and their role in DOE Hydrogen Program and Hydrogen Earthshot will be discussed.
(Invited) Advanced Electrode and Electrolyte Materials for Proton Conducting Solid Oxide Electrolysis Cells
Authors: Ding Hanping , Regalado Vera Clarita Yosune , Tang Wei , Ding Dong
Published: July 2022

Hydrogen production by using proton-conducting solid oxide electrolysis cells (SOECs) has been acknowledged as a promising approach to effectively utilize the clean renewable energies and nuclear heat and to decarbonize. To deliver fast and durable hydrogen production during intermediate-to-low temperature (400~600○C) operation, some critical components such as oxygen electrode and electrolyte are important for achieving high electrolysis performance under realistic conditions, particularly in high steam pressure. In this presentation, the recent developments on praseodymium cobaltite-based PrNixCo1-xO3-δ electrode and Sc-doped BaZrO3-based electrolyte are respectively introduced. The triple conductive electrode demonstrates high activity and stability towards water splitting reaction, and to down-select the optimal composition, a series of optimization study have been carried out to understand structure-property relationship, chemical/performance stability in high steam condition, and interfacial stability. For electrolyte, the hydration behavior, proton conductivity, transference number, and chemical stability are studied to disclose the effect of dopant on increasing effective proton concentration, and the underlying mechanism is also investigated by experimental characterizations.
Suppressing Hydrogen Crossover and Scavenging Radicals By Incorporation of Pt and Cerium-Zirconium Oxide for Polymer Electrolyte Water Electrolyzers
Authors: Zhang Zheyu , Han Zongyi , Testino Andrea , Gubler Lorenz
Published: July 2022

Polymer electrolyte water electrolysis (PEWE) is one of the key technologies for green hydrogen production. It has the advantages of operating at relatively high current densities and differential pressures. The hydrogen gas produced, under high cathodic pressure and with a thin membrane, tends to cross over to the anode chamber, forming explosive H2/O2 gas mixture and posing severe safety concerns for the device. Literature has shown that one effective solution is the use of Pt as the recombination catalyst. On the other hand, radical attacks to the PFSA-based membrane leads to possible thinning and pinhole formation, which deteriorates the electrochemical performance and eventually causes cell failure. To this end, ceria is often employed as a radical scavenger. In this work, we report the co-incorporation of Pt and cerium-zirconium oxide in solution-cast Nafion membranes for the dual functions of suppressing hydrogen crossover and scavenging of radicals. We show that the hydrogen in oxygen content in the anode gas stream is significantly reduced with the incorporation of Pt, and the inclusion of cerium-zirconium oxide inside the membrane is able to decrease fluoride release rate in a 100-hour constant-current water electrolysis measurement. This study provides guidance in developing proton exchange membranes with enhanced durability and safe operating range.
(Invited) Electrifying CO2 into Fuels and Chemicals in a Solid Electrolyte Reactor
Authors: Wang Haotian
Published: July 2022

Electrochemical CO2 reduction, with the energy input from renewable electricity, provides a green and alternative route for the generation of chemicals and fuels. However, its practice is currently challenged at two systematical levels: the lack of selective electrocatalysts to combat the strong completion from water reduction, and the lack of novel reactors for large-scale reaction rates and efficient product separation. In this talk, I will introduce the rational design of both catalytic materials and reactors towards practical CO2 reduction performances. By dispersing transition metals into isolated single atoms with electronic structures significantly different from their bulk counterparts, we can dramatically suppress the competing hydrogen evolution and deliver an ultra-high CO2 reduction selectivity of more than 95% under ambient conditions in water. Scaled-up synthesis and efficient reactors demonstrated the potential for practical applications. Furthermore, by designing a solid electrolyte reactor, we successfully demonstrated a continuous generation of pure liquid fuel solutions via CO2 reduction. This technology eliminates the product separation process required in traditional CO2 reduction electrolyzers, opening up its practical applications in the future.
Water Oxidation to Hydrogen Peroxide on Carbonaceous Materials
Authors: Pangotra Dhananjai , Csepei Lénárd-István , Roth Arne , Sieber Volker , Vieira Luciana
Published: July 2022

Hydrogen peroxide (H2O2) is one of the most important chemicals used in the chemical industry. It has been widely utilized in pulp and paper manufacturing, chemical synthesis, wastewater management, and disinfection.1 The primary industrial approach to producing H2O2 is via the fossil-based anthraquinone process - an energy-demanding multi-step process requiring high-cost catalysts and generating substantial volumes of waste. Another route to the classic anthraquinone process is the electrochemical production of H2O2 from oxygen (O2) and water (H2O). This electrochemical route based on renewable energy is an appealing “green” alternative.

Our research group has been extensively working on the electrochemical production of H2O2 through anodic water oxidation using various electrode materials, including metal oxides, commercial carbon materials, and boron-doped diamond (BDD). Besides the electrode material, a suitable electrolyte is equally essential to achieve high H2O2 concentrations and production rates. The role of carbonate ions (HCO3
- and CO3
2-) for producing H2O2 has been investigated using commercial carbon fiber paper (CFP). The electrolyte pH was correlated with the activity of CO3
2- ions in enhancing H2O2 production. Thereby, a cyclic mechanism of H2O2 generation involving the oxidation of CO3
2- ions to peroxodicarbonate (C2O6
2-) species has been proposed.2

The role of the CO3
2- ions in enhancing the anodic H2O2 production was further studied in a continuous flow reactor using BDD anodes. The flow rate and setup configuration for 2e- water oxidation to H2O2 have been optimized at current densities up to 700 mA cm-2, with an impressive H2O2 production rate and faradaic efficiency. Additionally, the role of a chemical stabilizer in avoiding the H2O2 decomposition in the flow system has been addressed. The importance of electrolyte composition, pH, operating parameters, and cell setup to enhance the production of H2O2 at the anode was shown. Finally, outstanding H2O2 yields were obtained in continuous flow for at least 30 hours.

References

Perry, S. C.; Pangotra, D.; Vieira, L.; Csepei, L.-I.; Sieber, V.; Wang, L.; Ponce de León, C.; Walsh, F. C., Electrochemical synthesis of hydrogen peroxide from water and oxygen. Nat. Rev. Chem.
2019,
3 (7), 442-458.

Pangotra, D.; Csepei, L.-I.; Roth, A.; Ponce de León, C.; Sieber, V.; Vieira, L., Anodic production of hydrogen peroxide using commercial carbon materials. Appl. Catal. B Environ.
2022,
303, 120848.
Nitrate Reduction By Hydrophobic, Negatively, and Positively Charged Peptide-Coated Au Electrode
Authors: Emdadi Arash , Renner Julie N. , Greenlee Lauren F
Published: July 2022

Nitrate has been considered as a source of water pollution with harmful effects on human health. Compared to other removal techniques, electrochemical reduction of nitrate is capable of delivering products such as ammonia and nitrogen which are valuable and harmless, respectively. However, it is challenging to control nitrate reduction pathway through catalyst design alone. Our research goal in this work is to understand how peptide chemistry influences nitrate reduction pathway and electrocatalyst activity for a suite of peptide-functionalized electrocatalyst surfaces. To analyze the electrocatalytic reduction of nitrate, three types are peptides, including V (hydrophobic), E (negatively charged), and K (positively charged), were coated on the gold electrodes and their performance compared with the bare gold electrode. In all the experiments, the effective area of the Au electrode was 1 cm2. An electrochemical cell with the gold electrode (working electrode), platinum (counter electrode) electrode, and a background solution (0.5 M Na2SO4) were used for electrochemical experiments. Cyclic voltammetry (CV) was used to assess the reduction of nitrate by different peptide-coated Au electrodes in the presence of nitrate ions (0.5 M Na2SO4 +0.1 M NaNO3, pH∼7.1), with a scanning rate of 20 mV/s. Chronoamperometry (CA) was applied to investigate the conversion of nitrate to different products and the pathway of nitrate reduction at different operational conditions. UV–visible spectrophotometry was employed to analyze the conversion of nitrate into nitrite and ammonia in the solution. Results of CV indicate that gold electrodes coated with V and E type peptides have promising responses to the applied voltage in the presence of nitrate ions. Based on the results, reduction of nitrate takes place at the onset potentials of -0.37 V and -0.23 V versus reversible hydrogen electrode (RHE) for E and V types of peptide-coated Au electrodes, respectively. To assess the pathway of nitrate reduction, CA experiments were done for 60 minutes on the hydrophobic peptide-coated Au and bare Au electrodes by applying a constant potential of -0.37 V versus RHE. Initial CA results of the V peptide coated-Au electrode indicate the reduction of nitrate into both nitrite and ammonia compared to a bare gold electrode which is only capable of nitrate reduction to ammonia. Based on the initial results, 0.92 mg ammonia, and 0.78 mg nitrite were produced by a V-type coated-Au electrode after 60 minutes CA experiment.
The Role of Atomically Dispersed Transition Metal Centers for the Electrochemical Nitrate Reduction Reaction Towards Ammonia Synthesis
Authors: Murphy Eamonn , Liu Yuanchao , Matanovic Ivana , Ly Alvin , Huang Ying , Guo Shengyuan , Wang Hanson , Zenyuk Iryna V. , Spoerke Erik D. , Atanassov Plamen
Published: July 2022

The electrochemical reduction of oxidized nitrogen species, nitrate (NO3
-) and nitrite (NO2
-), both of which are environmental pollutants, to benign nitrogen gas (N2) has been extensively researched for water remediation applications. Recently, a large research focus has shifted to reducing these oxidized nitrogen species to ammonia (NH3).1 In this way, a dual benefit is achieved by eliminating the environmentally hazardous nitrates, while also creating a value-added product, ammonia. Moreover, the nitrate reduction reaction (NO3RR) can aid in closing the nitrogen cycle, by reforming nitrates introduced into the environment through nitrate-based fertilizers originating from the Haber-Bosch process, back into NH3, in a carbon neutral fashion.

The NO3RR is a complex, 8e-, 9H+ transfer process with multiple possible intermediate species (NO2
-, NO, N2O, N2H4, NH2OH, NH3) and rate limiting steps. The NO3RR mechanism and its activity descriptors over various metals is not fully understood, and this is especially true over atomically dispersed sites, where less than a handful of studies exist.2,3 Our previous work found that atomically dispersed nitrogen coordinated Fe-N4 and Mo-N4 sites displayed distinct associative adsorption and dissociative adsorption of the nitrate molecule in the NO3RR pathways, respectively. Specifically, Fe-N4 sites adsorb and reduce NO3
- into NH3through an 8e- pathway on the surface, while Mo-N4 sites dissociate NO3
- and release NO2
- into the bulk electrolyte. These active sites were then integrated into a single bi-metallic catalyst (FeMo-N-C), creating a catalytic cascade yielding a significantly improved yield rate and Faradaic efficiency for NH3.4

In this talk, building on our previous work, we will present a series of transition metal atomically dispersed nitrogen doped carbon (M-N-C) electrocatalysts (M = Mn, Fe, Co, Ni, Cu...) for the systematic investigation of NO3RR activities over the different metal centers. In this work we leverage physical (ICP-MS, gas physisorption), electrochemical (e.g., NO3RR) and computational (DFT) characterization to create a set of NO3RR activity descriptors. A detailed set of activity descriptors can aid in the selection of atomically dispersed metals for creating efficient reaction cascades to synergize favorable reaction pathways.

Figure 1
(Digital Presentation) Enhanced Electrochemical Phosphate Recovery from Wastewater: Implications of Pulsating Anode Potential
Authors: Sultana Ruhi , Greenlee Lauren F
Published: July 2022

Electrochemical recovery of phosphorus (P) as struvite (or magnesium ammonium phosphate hexahydrate, MgNH4PO4.6H2O) fertilizer using a sacrificial pure magnesium (Mg) anode is considered a sustainable strategy to deal with the limited availability of rock phosphate. However, the formation of an electrically passive film of magnesium hydroxide (Mg(OH)2) and/or struvite on the surface of Mg upon immediate immersion in aqueous phosphate solution limits the release of divalent Mg ions and decreases struvite precipitation. The present work highlights struvite recovery by an electrochemical method upon application of a dynamic voltage with a sinusoidal waveform. Our results demonstrate that a dynamic potential, when compared to a constant potential, can enhance the rupture of the passivating film, and facilitate the release of Mg2+ from the metal thereby overcoming the problems related to electrical passivation.Aqueous solutions of ammonium dihydrogen phosphate (NH4H2PO4, 10 mM) at neutral pH were used as test solutions. Mg2+ release was notably increased by ~48% relative to constant voltage applications, which subsequently led to ~20% higher phosphate recovery. Characterization studies including X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated the presence of struvite in the recovered precipitate. Surface characterization of electrodes using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) also confirms a higher extent of passivating film breakdown in the presence of dynamic voltage.
Ptirm (M=Zn, Ni) Ammonia Oxidation Catalysts for Anion-Exchange Membrane Direct Ammonia Fuel Cells
Authors: Li Yi , Wang Teng , Yan Yushan , Wu Gang
Published: July 2022

Low-temperature direct ammonia fuel cells (DAFCs) use carbon-neutral ammonia as a fuel, which has attracted increasing attention recently due to ammonia's low source-to-tank energy cost, easy transport and storage, and wide availability. However, current DAFC technologies are greatly limited by the kinetically sluggish ammonia oxidation reaction (AOR) at the anode. Herein, we report an AOR catalyst, in which ternary PtIrZn nanoparticles with an average size of 2.3 ± 0.2 nm were highly dispersed on a binary composite support comprising cerium oxide (CeO2) and zeolitic imidazolate framework-8 (ZIF-8)-derived carbon (PtIrZn/CeO2-ZIF-8) through a sonochemical-assisted synthesis method. The PtIrZn alloy, with the aid of abundant OHad provided by CeO2 and uniform particle dispersibility contributed by porous ZIF-8 carbon (surface area: ∼600 m2 g−1), has shown highly efficient catalytic activity for the AOR in alkaline media, superior to that of commercial PtIr/C. The rotating disk electrode (RDE) results indicate a lower onset potential (0.35 vs. 0.43 V), relative to the reversible hydrogen electrode at room temperature, and a decreased activation energy (∼36.7 vs. 50.8 kJ mol−1) relative to the PtIr/C catalyst. Notably, the PtIrZn/CeO2-ZIF-8 catalyst was assembled with a high-performance hydroxide anion-exchange membrane to fabricate an alkaline DAFC, reaching a peak power density of 91 mW cm−2. Unlike in aqueous electrolytes, supports play a critical role in improving uniform ionomer distribution and mass transport in the anode. PtIrZn nanoparticles on silicon dioxide (SiO2) integrated with carboxyl-functionalized carbon nanotubes (CNT–COOH) were further studied as the anode in a DAFC. A significantly enhanced peak power density of 314 mW cm−2 was achieved.
Electrochemical Reduction of Flue Gas CO2 in a Dual Methanol/Water Electrolysis System for the Synthesis of Methyl Formate
Authors: Spurgeon Joshua M. , Hofsommer Dillon , Gautam Manu , Grapperhaus Craig
Published: July 2022

The conversion of waste CO2 to value-added chemicals through electrochemical reduction is a promising technology for mitigating climate change while simultaneously providing economic opportunities. The use of the nonaqueous solvent methanol allows for higher CO2 solubility and novel products through the incorporation of methanol as an intermediate. In this work, the electrochemistry of CO2 reduction in acidic methanol catholyte at a Pb working electrode was investigated while using a separate aqueous anolyte to promote a sustainable water oxidation half-reaction. The selectivity among methyl formate (a product unique to reduction of CO2 in methanol), formic acid, and formate was critically dependent on the catholyte pH, with a faradaic efficiency for methyl formate as high as 75% measured in pH < 2. Tests with simulated flue gas as the feedstock have shown a high level of tolerance for the Pb-catalyzed electrolysis to SO2, NO, and dilute O2 contaminants.
(Digital Presentation) Interface Engineering of Transition Metal-Selenide Heterostructures for Application in Electrochemical Water-Splitting
Authors: Velpandian Muthuraja , Meduri Praveen
Published: July 2022

Transition metal selenides (TMS) have sparked great interest in energy storage and catalysis because they are direct bandgap materials, have a highly layered structure, high redox activity, abundant active sites at the edges, short diffusion paths, and large surface area1. However, low electrical conductivity and structural instability result in long-term performance degradation. The development of high-performance water electrolyzers and metal-air batteries requires the design and construction of efficient TMS electrocatalysts. In order to boost electrochemical activity, increasing emphasis has been devoted to interface engineering of TMS heterostructures through manipulation of composition, adjustment of crystal facets, and heteroatomic doping2. Interface engineering helps in optimizing reaction intermediates, modulating charge carrier characteristics, and preventing the aggregation of active components. Herein, we designed and studied the interface between hydrothermally synthesized tin selenide (SnSe2) and tungsten selenide (WSe2). The intimate electronic interaction between the bimetallic selenides leads to a rich interface boundary that reduces the surface energy and creates a larger number of active sites involved in both the hydrogen evolution and oxygen evolution reactions3. These heterostructures exhibited a low overpotential of 180 mV at 10 mA cm-2 and good stability of up to 12 hours for the hydrogen evolution reaction, and a low overpotential of 250 mV at 10 mA cm-2 and stability up to 12 hours for the oxygen evolution reaction. This study gives a better insight into the design of TMS heterostructures using interface engineering for high electrocatalytic activity.

References:

(1) Gbadamasi, S.; Mohiuddin, M.; Krishnamurthi, V.; Verma, R.; Khan, M. W.; Pathak, S.; Kalantar-Zadeh, K.; Mahmood, N. Interface Chemistry of Two-Dimensional Heterostructures – Fundamentals to Applications. Chem. Soc. Rev.
2021, 50 (7), 4684–4729. https://doi.org/10.1039/D0CS01070G.

(2) Zhao, R.; Li, Q.; Jiang, X.; Huang, S.; Fu, G.; Lee, J.-M. Interface Engineering in Transition Metal-Based Heterostructures for Oxygen Electrocatalysis. Mater. Chem. Front.
2021, 5 (3), 1033–1059. https://doi.org/10.1039/D0QM00729C.

(3) Chen, P.; Tong, Y.; Wu, C.; Xie, Y. Surface/Interfacial Engineering of Inorganic Low-Dimensional Electrode Materials for Electrocatalysis. Acc. Chem. Res.
2018, 51 (11), 2857–2866. https://doi.org/10.1021/acs.accounts.8b00266.
(Digital Presentation) Electrochemical and UV-VIS Spectroscopic Studies of Bismuth(III) Interactions with L-Cysteine
Authors: Schlessman Jamie , Huang Jonathan , Cheek Graham
Published: July 2022

Introduction

In an ongoing investigation of the interaction of bismuth(III) compounds with L-cysteiene1, recent work has involved more complete characterization of these interactions at lower pH levels in various aqueous media. Pharmaceutical medications2 such as bismuth subsalicylate (BSS) and bismuth citrate (BC) have now been investigated at pH 1.00 and 3.00 by both cyclic voltammetric and UV-VIS methods. Electrochemical methods have been used to evaluate the interaction of L-cysteine with bismuth compounds by observing shifts in the potential for bismuth reduction, and UV-VIS methods have allowed the observation of an absorbance peak at approximately 340 nm due to the bismuth(III) ion interaction with the L-cysteine thiol group.

Results and Discussion

Recent work has involved investigation of bismuth(III) nitrate (BN), BSS, and BC with L-cysteine at pH 1.00 and 3.00 in both HNO3 and HCl solutions. In general, complexation of BN is not quite as favorable at lower pH levels as in pH 7.00 MOPS (3-N-morpholino)propanesulfonic acid)3 buffer solution.1 This conclusion was based on the need for higher mole ratios of L-cysteine to BN to achieve the final state of the voltammograms. The UV-VIS behavior was also not as well-defined as in our previous work1, with higher molar ratios of L-cysteine needed to produce the 340 nm absorbance peak. These results support the competition of protons with bismuth(III) for the L-cysteine ligand, there being much higher proton levels at pH 1.00 and pH 3.00 than at pH 7.00. The behaviors of BC and BSS at pH 1.00 and pH 3.00 are in many ways similar to that of BN. Finally, some preliminary work on glutathione (cysteine-containing tripeptide) interactions with bismuth compounds is also planned for presentation.

References

T. Cheek and D. Peña, J. Electrochem. Soc.,
167, 155522 (2020)

Li, R. Wang, and H. Sun, Acc. Chem. Res.,
52, 216 (2019).

M. H. Ferreira, I. S. S. Pinto, E. V. Soares, and H. M. V. M. Soares, RSC Advances, 5(39), 30989 (2015).
(Organic and Biological Electrochemistry Division Manuel M. Baizer Award) A Perspective on Organic Electrochemistry
Authors: Little Dan
Published: July 2022

Manuel Baizer’s profound influence upon electrochemistry is undeniable. He was a pioneer and a visionary whose influence and insights continue to permeate scientific thought.

During his lifetime Baizer frequently expressed frustration at the slow pace at which electrochemistry’s attributes were accepted and utilized by the broader community of organic chemists. Even now, despite a tremendous surge and a steady increase in the number of researchers who are exploring the breadth of the field, the rate of its inclusion in textbooks lags far behind – a situation that appears to be on the cusp of a most appropriate change.

I was fortunate to have Manuel Baizer as my colleague at UCSB. His optimism, drive, curiosity and interest in the field was contagious. Without doubt, his arrival on the UCSB campus provided the spark needed to turn my passing interest into action. Several co-directed students and research projects resulted including, for example, work involving electrogenerated bases, the generation and utilization of superoxide, as well as various intramolecular electroreductive processes and their application to the total synthesis of natural products.

Today’s presentation will focus upon examples of these efforts and will then turn to ongoing research in the area of mediated electron transfer chemistry.
Electrochemically Generated Periodates As a Platform Oxidizer
Authors: Waldvogel Siegfried R
Published: July 2022

Periodates represent one of the most powerful and versatile oxidizers in organic synthesis. Common ways to generate it electrochemically employ lead dioxide anodes. The disintegration of these electrodes cause contaminations which impede sensitive applications.[1] The purification of periodates makes this reagent usually too costly for pharmaceutical applications. With the use of boron-doped diamond anodes, a direct conversion of the inexpensive sodium and potassium iodide within an eight-electron oxidation process renders periodate. The novel process is scalable, heavy metal-free and can be conducted in batch as well as flow electrolyzers.[2] This approach can also be used for the regeneration of periodates from iodates and other iodine sources (waste streams). The process was implemented in a new synthetic approach to levetiracetam, which demonstrates the technical application and recycling of iodates in API synthesis.[3] This reagent can also be employed to make sulfoximines and degrade lignins to elaborated building blocks. [4] The reactor concepts for the efficient preparation of multi-kg quantities will be presented.

References:

[1] D. Pollok, S. R. Waldvogel, Chem. Sci. 11 (2020) 12375–12592.

[2] S. Arndt, D. Weis, K. Donsbach, S. R. Waldvogel, Angew. Chem. Int. Ed.
132
,
(2020) 8112-8118.

[3] S. Arndt, B. Grill, H. Schwab, G. Steinkellner, U. Pogorevčnik, D. Weis, A. M. Nauth, T. Opatz, K. Donsbach, S. R. Waldvogel, M. Winkler, Green Chem. 23 (2020) 388–395.

[4] M. Klein, S. R. Waldvogel, Angew. Chem. Int. Ed. 60 (2021) 23197–23201.
Electrochemical Structure-Reactivity Relationships in NAD+ Mimetics: Towards Recyclable Cofactors for Protein-Catalyzed Reactions
Authors: Bruggeman Chase , Hickey David
Published: July 2022

The chemical engineering industry relies increasingly on enzyme-catalyzed reactions in the production of fine chemicals, value-added compounds, and commodity chemicals. However, many attractive transformations, such as the selective reduction of ketones and alkenes, depend on cofactors that are prohibitively expensive for application on an industrial scale. One such cofactor, nicotinamide adenine dinucleotide (NAD+/NADH), is utilized by >20% of all enzymes but is required in generally super-stoichiometric amounts and currently has no efficient means for recycling. Direct electrochemical reduction of NAD+ is an attractive approach for regeneration of the biological cofactor; however, electrolysis often results in relatively small amounts of biologically active NADH due to a parasitic dimerization. Recent work has demonstrated the ability of lower-cost NADH mimetics to exhibit enzymatic activity, sometimes exceeding that of NADH itself, although still required in at least stoichiometric amounts. Subsequently, we considered the possibility of designing NADH biomimetics to simultaneously maintain enzymatic activity and minimize deleterious side reactions, thereby allowing them to be electrochemically recycled. We will describe our recent progress in both measuring and modeling the electrochemical dimerization and regeneration rates of NADH mimetics. We have employed Electrochemical Impedance Spectroscopy to quantify rapid dimerization rates observed for electrochemically reduced NADH biomimetics. By combining this electroanalytical approach with density functional theory (DFT) modeling and machine learning algorithms, we are elucidating structure-function relationships to design more efficiently regenerable mimetics.
(Digital Presentation) Electrochemical Cyanosilylation of Carbonyl Compounds: Machine Learning-Assisted Exploration of Suitable Reaction Conditions
Authors: Suga Seiji , Sato Eisuke , Fujii Mayu , Tanaka Hiroki , Mitsudo Koichi
Published: July 2022

Cyanosilylation of carbonyl compounds provides protected cyanohydrins, which can easily be converted into various compounds such as amino alcohols, amides, esters, and carboxylic acids. We herein describe an electrochemically initiated cyanosilylation of carbonyl compounds using trimethylsilyl cyanide as the sole carbon source and its application to a microflow reactor. To optimize suitable reaction conditions, we demonstrate the machine learning-assisted exploration. Machine learning well supported us to adjust the current and flow rate at the same time and identify the conditions needed to achieve the best productivity.
(Digital Presentation) Evaluation on the Efficiency of Redox Reaction By Oxidation Potential Gap (ΔE
ox)
Authors: Okamoto Kazuhiro , Shida Naoki , Morizumi Haruka , Kitano Yoshikazu , Chiba Kazuhiro
Published: July 2022

Oxidative biaryl coupling of aryls with different electronic features generally fails. However, this has not been systematically studied via theoretical analysis, and thus, the crucial factor governing coupling efficiency remains unclear. Herein, we propose that the “oxidation potential gap (ΔE
ox)” is a key parameter in evaluating the efficiency of an intramolecular oxidative coupling reaction, with ΔE
ox defined as a difference in the oxidation potentials of the relevant aromatic rings. Our experimental and computational analyses revealed that the efficiency of an aromatic intramolecular coupling reaction correlates with the activation energy (ΔE‡
) of C–C bond formation of the radical cation intermediates. Furthermore, ΔE‡
correlates with ΔE
ox. Therefore, we demonstrate the tuning of ΔE
ox by attaching cleavable extra electron-donating/withdrawing groups, enabling the rational synthesis of a phenanthridone skeleton using aromatic rings with an electronic gap.

Figure 1
(Digital Presentation) Wavelength Controllable Multi-Color Firefly Luciferin Analogues
Authors: Kitada Nobuo , Kamiya Genta , Moriya-Saito Ryohei , Iwano Satoshi , Obata Rika , Hirano Takashi , Maki Shojiro
Published: July 2022

I will show you the multi-color luciferin analogues, and in particular the usefulness of near-infrared(NIR) luciferin analogues.

Firefly bioluminescent reaction requires luciferin, luciferase, Mg2+, ATP and O2, and emits light at 560 nm (green-yellow light). As the light emission efficiency of the firefly bioluminescence system is extremely high(ΦBL=41%), this system is attracting widespread attention as a bioimaging tool.

We have studied the relationship between structure modification and the firefly luminescence wavelength, where the luciferase of Photinus pyralis (Ppy) was used. As a result, we are able to control the wavelength of the luciferin analogues to some extent. An analog having the thiazoline ring connected directly to p-(dimethylamino)phenyl group exhibited blue shifted luminescence maximum. Furthermore, replacement of the dimethylamino group into a hydroxyl group caused blue shift of luminescence wavelength. On the other hand, Introduction of a double bond between the thiazoline ring and the benzene ring caused large red shift of luminescence wavelength.

Based on these structure-activity relationships, we have synthesized a number of luciferin analogs. The shortest emission wavelength of luciferin analogs is 430 nm, and the longest is 760 nm by using Ppy luciferase. Among them, near-infrared(NIR) light is expected to be applied to in vivo imaging because of its high living body permeability.

Therefore, Thus, AkaLumine, a luciferin analogue that produces light at 675 nm wavelength, was developed. This compound was shown to yield useful results when applied to the in vivo imaging of mice. We have improved the characteristics of AkaLumine to optimize this compound for use in in
vivo imaging, thus obtaining the compounds dubbed TokeOni and seMpai. In this way, bioluminescence imaging technology is undergoing constant innovation, and we continue to develop NIR luciferin analogues that can be used as imaging tools.

In this conference, I will present the characteristics of recently developed multi-color luciferin analogues, include NIR luciferin analogues.

Figure 1