bluuebunny/crossref_metadata_2025 huggingface dataset:
Anion Exchange Membrane Electrolyser Performance with Ni Ferrite Anodes Calcined at Different Temperatures
Authors: Caprì Angela , Gatto Irene , Monforte Giuseppe , Lo Vecchio Carmelo , Baglio Vincenzo
Published: September 2023

Hydrogen has a critical role in enabling European countries to achieve net-zero carbon targets. Hydrogen production via water splitting, using an electrolyser, is considered the "greenest" way because it does not produce any direct carbon emissions when powered by renewable sources. Among the different technologies of electrolysers (liquid alkaline, proton exchange membrane, etc.), there has been a recent surge in interest in that one based on anion-exchange membranes (AEMs). With respect to the state-of-the-art electrolysers that employ conventional acid polymer electrolyte separators (e.g., perfluorinated systems such as Nafion®), electrocatalysis with AEMs is much more promising. Accordingly, inexpensive catalysts can be used.

In this work, NiFe2O4 catalysts are prepared by an "oxalate route". Nickel and iron nitrates in suitable stoichiometric ratios are added in successive steps to the oxalic acid solution. An oxidizing solution of hydrogen peroxide is then added. The obtained precipitate is first filtered and then dried. Different calcination temperatures (350, 450 and 550°C) are applied to obtain the Ni Ferrite with different surface and bulk characteristics. The catalysts are then deposited by a spray technique onto a commercial FAA3-50 (from FuMa-Tech) anion-exchange membrane, combined with a Pt-based cathode electrode, and investigated for the water electrolysis process in a single cell of 5 cm2 geometrical area. A comparison between the performance recorded with the different anode catalysts is reported and discussed.

Acknowledgments

The authors thank the Italian Ministry for University and Research (MUR) for funding through the FISR 2019 project AMPERE (FISR2019_01294).
Exsolution of Iron Nanoparticles from LCTFeO3 for Oxygen Evolution Reaction
Authors: Zuo Shangshang , Naden Aaron , Irvine John Thomas Sirr
Published: September 2023

Perovskite oxides (ABO3) with stable structures and flexible compositions are considered to be alternative catalysts for the oxygen evolution reaction (OER). With A-site deficiency in a perovskite, the doping metals in the B-site may be exsolved by calcination in a reduction atmosphere, which is a promising approach to increasing the activity of the catalyst. Here, an iron doped La(0.2+x)Ca(0.7-x)Ti(1-x)FexO3 (x = 0.05, 0.3, LCTFex) perovskite is successfully synthesized by a mild sol-gel method, and the iron nanoparticles anchored perovskite (R-LCTFex) can be fabricated after reduction under 5% H2/N2 atmosphere in a tubular furnace, which can be seen clearly in SEM and STEM images. Notably, the onset overpotential of R-LCTFe0.3 is reduced by 130 mV compared with LCTFe0.3 and the current density of R-LCTFe0.3 is 12-fold higher than LCTFe0.3 at the overpotential of 530 mV. The enhanced OER performance is triggered by the exsolution of Fe nanoparticles. This study establishes that exsolution of metal nanoparticles from a perovskite is a useful tactic for enhancing OER performance.
The Mechanism of Hydrogen Evolution Reaction at the Buried Interface of Silica-Coated Electrocatalysts
Authors: Qu Jianzhou , Yu Zhou , Urban Alexander
Published: September 2023

Semipermeable oxide coatings can protect electrocatalysts in harsh environments without reducing the catalytic performance (Labrador, Esposito et al. ACS Catal. 8, 2018, 1767–1778), making them attractive for direct seawater electrolysis. We recently showed that the buried SiO2/Pt interface of silica-coated platinum electrocatalysts is environment-dependent and changes with the pH value of the electrolyte and the electrode potential (Qu and Urban, ACS Appl. Mater. Interfaces 12, 2020, 52125–52135). Here, we discuss the impact of silica membrane coatings on the hydrogen evolution reaction (HER) mechanism at the interface with different transition-metal surfaces. Stable configurations of the buried SiO2/TM interface at HER conditions were determined using density-functional theory (DFT) calculations. Computed Pourbaix diagrams for different transition-metal substrates show the pH and potential dependence of reaction intermediates and the hydrogen coverage on the metal surface. Our results indicate that the HER mechanism at the buried SiO2/catalyst interfaces may involve the silica membrane. Hence, besides the protective quality of silica membranes, this also points to the possibility of designing synergistic membrane-coated electrocatalysts that surpass the bare surfaces of earth-abundant transition metals in terms of catalytic performance (stability, activity, and/or selectivity).
Understanding the Role of Underlying Substrates on Hydrogen Evolution Reaction (HER) Catalytic Activity of Atomically Dispersed Pt Atoms
Authors: Kumar Bijandra , Muchharla Baleeswaraiah , Barbee Brianna , Darby Marlon , Sadasivuni Kishor Kumar , Adedeji Adetayo , Karoui Abdennaceur , Elahi Mehran
Published: September 2023

Electrochemical water splitting is an environmentally friendly way of producing hydrogen, but this process requires highly efficient catalysts. Platinum (Pt) is known the best catalyst for hydrogen evolution reaction (HER) in acidic media, but the scarcity and high cost of Pt limits its applicability in widespread technologies. In this work, we have uncovered the role of underlying substrate on the HER activity of atomically dispersed Pt atoms. A DC magnetron sputtering technique has been utilized to deposit transition metal (Cu, Mo, W, Ti and Ta) thin films as underlying substrates for atomically dispersed and extremely low loading of Pt (< 1.5 at%). As synthesized samples were characterized as electrocatalysts for the HER in both alkali and acidic media. In combination of standard electrochemical experiments (e.g., CV), the differential electrochemical mass spectrometry (DEMS) results show that despite low loading of Pt, the prepared catalysts produce hydrogen at a rate comparable with that of a pristine Pt. Based on the XPS study, the excellent performance is attributed to the modified electronic properties of the Pt atoms due to interaction with underlying substrates. Additionally, the performance of the Pt atoms is significantly governed by the physical properties of underlying substances. Our catalysts also displayed good stability for HER activity and found to be stable after 1000 cycles of continuous operation.
Performance Losses and Recovery from Cation Contaminants in PEM Water Electrolysis
Authors: Padgett Elliot , Adesso Anthony , Wrubel Jacob A , Pivovar Bryan S. , Alia Shaun M
Published: September 2023

Water contaminants are extremely common cause of failure for polymer electrolyte membrane (PEM) electrolyzers, potentially accounting for >90% of electrolyzer failures in the field. [1] Water contaminants also commonly impact PEM electrolysis devices in a research setting, confusing measurements of cell performance and durability if they are not recognized and properly addressed. Despite this, relatively little published literature has systematically investigated contaminants in PEM electrolysis cells specifically. Better understanding of contaminant impacts may lead to improved strategies to mitigate or recover performance losses as well as improve the consistency and rigor of electrolysis research.

Here we will present an investigation of the performance impacts of cation contaminants and their recoverability. This investigation focuses on cation contaminants that are abundant in tap/ground water, which may enter the cell through a failure of the water processing subsystem, and transition metals that may leach out of system components. We will report performance impacts for a representative selection of cations as a function of water concentration and accumulated contaminant dose, with impedance spectroscopy used to understand the origin of performance losses. We will also present multiple diagnostic signatures to help identify presence of contaminants in PEM electrolysis cells. Finally, we will address the recovery of cells with different contaminants and the prospects for improved recovery procedures.

[1] Capuano, Chris “Manufacturing Challenges, Opportunities, and Successes for PEM Electrolysis at Scale”, 3rd International Conference on Electrolysis, Golden, CO, 2022.
Effects of Bifunctional Oxygen Catalyst Layer Composition on Unitized Regenerative Fuel Cell Performance
Authors: Rhodes Christopher P. , Godinez Salomon Jose Fernando , Urena Michael E.
Published: September 2023

Proton exchange membrane unitized regenerative fuel cells (PEM-URFCs) can generate storable fuel (hydrogen) and oxidant (oxygen) which can then be used to produce power from the same cell. Combining electrolysis and fuel cell modes within the same cell allows PEM-URFCs to have the potential for lower mass, volume, and cost compared with discrete fuel cell and electrolyzer systems. The bifunctional oxygen catalyst layer (BOCL) catalyzes the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR) at the same electrode, and there are wide potential differences and opposing mass transport phenomena involved within the BOCL when operating in electrolyzer or fuel cell mode. The BOCL composition, structure and morphology significantly affect performance and stability of PEM-URFCs. In our prior work, we showed bimetallic nanoframes provide bifunctional oxygen electrocatalysts with significantly higher activity compared with monometallic structures, evaluated using a rotating disk electrode configuration.1 We will present our investigation of the effects of the BOCL composition, structure and morphology on URFC membrane electrode assemblies (MEAs) prepared using ultrasonic spraying. Catalyst composition and loading were determined to influence URFC performance, and there are tradeoffs between fuel cell performance, electrolyzer performance, and catalyst cost. In addition to the effects of the active catalyst (either Pt for ORR or IrO2 for OER), our work supports the non-catalytically active component influences MEA performance, which is in agreement with our finding of synergistic effects of Pt and IrO2 within rotating disk electrode measurements.1 We are also evaluating the effects of porous transport layers and different operating conditions on URFC MEA performance and durability over repeated cycling.

References

Godínez-Salomón, F.; Albiter, L.; Mendoza-Cruz, R.; Rhodes, C.P. Bimetallic Two-dimensional Nanoframes: High Activity Acidic Bifunctional Oxygen Reduction and Evolution Electrocatalysts. ACS Appl. Energy Mater.
2020,
3, 2404-2421.
Photo-Electrochemical Oxygen Evolution Activity in Nickel and Cobalt Antimonates
Authors: Bajdich Michal , Rao Karun K. , Zhou Lan , Yano Junko , Gregoire John M.
Published: September 2023

Renewable generation of fuels via solar energy offers promising pathways towards sustainable energy future. Its deployment hinges on the discovery of electrochemically durable materials with good solar-to-chemical conversion efficiency. Necessary visible spectrum photoresponse from electrochemically stable materials is however quite rare. On the other hand, the oxygen evolution reaction (OER) requires electrodes that are not only catalytically active, but also stable under harsh electrochemical environments. In this talk, we report on and theoretical understanding of photo-electrochemical behavior an amorphous and crystaline versions of Ni-Sb-Ox and Co-Sb-Ox oxide photoanodes discovered via high-throughput experimental screening [1,2]. The newly discovered amorphous phases meet the requirements of operational stability, visible photoresponse, and appreciable photovoltage. Guided by experimental X-ray absorption characterization of these systems we use density functional theory calculations to perform a prototype phase search to identify a broad family of stable and metastable mixed rutile and hexagonal-like phases for other compositions [3]. Detailed Pourbaix analysis of the identified phases show excellent electrochemical stability, consistent with experimentally measured electrolyte concentrations of photoelectrochemical cells. We analyze when he identified phases form favorable oxygen vacancies formation energies under the reducing synthesis conditions which match measured Ni K-edge x-ray absorption spectra. The calculated OER overpotentials for the most active sites decreases with increasing Ni/Co content, which captures the experimentally observed trend. Stable amorphous metal-antimonates photoanodes are important systems for computational understanding of both the structural and catalytic behavior of these complex oxides and elucidating the co-optimization of photo-electrochemical activity and durability. This material is based on work performed by the Liquid Sunlight Alliance, which is supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under award DE-SC0021266.

[1] Zhou, L., Peterson, E. A., Rao, K. K., Lu, Y., Li, X., Lai, Y., Bauers, S. R., Richter, M. H., Kan, K., Wang, Y., Newhouse, P. F., Yano, J., Neaton, J. B., Bajdich, M., & Gregoire, J. M. Addressing solar photochemistry durability with an amorphous nickel antimonate photoanode. Cell Reports Physical Science, 3(7), 100959. (2022).

[2] Zhou, L., Wang, Y., Kan, K., Lucana, D. M., Guevarra, D., Lai, Y., & Gregoire, J. M. Surveying Metal Antimonate Photoanodes for Solar Fuel Generation. ACS Sustainable Chemistry and Engineering, 21, 33. (2022).

[3] Rao, K. K., Zhou, L., Lai, Y., Richter, M. H., Li, X., Lu, Y., Yano, J., Gregoire, J. M. Bajdich, M., Resolving Atomistic Structure and Oxygen Evolution Activity in Nickel Antimonates, (under review).
(Invited) Emergent Absorbers, Interfaces, and Integration Methods for Chalcopyrite-Based Photoelectrochemical Water Splitting Devices
Authors: Gaillard Nicolas
Published: September 2023

Photoelectrochemical (PEC) water splitting has the potential to become an efficient method for renewable hydrogen production. However, the efficiency, projected cost, and durability of lab-scale systems are not yet at the level required to make this technology economically feasible. Amongst all materials studied to date, the chalcopyrite class is arguably one of the most promising classes for PEC water splitting, as it has already demonstrated low-cost and high photoconversion capabilities as a photovoltaic material. In the context of PEC, our group demonstrated that co-evaporated 1.65 eV bandgap (EG) CuGaSe2 is capable of evolving hydrogen with Faradaic efficiency greater than 85% and generate photocurrent densities over 15 mA.cm-2, as measured in a 3-electrode configuration in 0.5M H2SO4 under simulated AM1.5G illumination. Unfortunately, CuGaSe2’s narrow EG limits its integration as top absorber into a dual junction stacked PEC device (also known as hybrid photoelectrode, HPE). In the present communication, we report on our latest efforts to synthesize wide-EG (1.8-2.0 eV) chalcopyrites, compatible with the HPE integration scheme, and capable of generating saturated photocurrent densities greater than 10 mA/cm2. We present specifically results on EG tunable Cu(In,Ga)(S,Se)2, Cu(In,Ga)S2, CuGa(S,Se)2 and CuGa3Se5. We also discuss some of the strategies developed to improve their surface energetics for the hydrogen evolution reaction, including the use of bandgap tunable MgZnO n-type buffer layers. Finally, we introduce the concept of semi-monolithic tandems, a new integration scheme where wide- and narrow-bandgap chalcopyrites are first integrated on separate substrates and then exfoliated, and finally bonded to create fully functional tandem device.
Antimony Molybdate Photocatalysts for Nitrogen Fixation
Authors: Tang Chaoyun , Wu Nianqiang
Published: September 2023

Photocatalytic nitrogen fixation offers a pathway for clean, sustainable, and decentralized ammonia production, which can be an alternative to the capital and energy intensive Haber-Bosch process. Antimony molybdate (Sb2MoO6) is a promising material for photocatalytic nitrogen fixation. However, the typical hydrothermal synthesis method generally leads to poor crystallinity and consequent poor photoactivity. In this work, mechanical chemical method is adopted to massively synthesize highly crystalline Sb2MoO6. Defects and chemical composition of photocatalyst have been engineered to maximize photocatalytic activity toward nitrogen fixation. Findings of this work would help understand photocatalytic mechanism of metal oxides in nitrogen fixation, which has an implication in development of new photocatalysts.
(Invited) Photoelectrode Membrane Assemblies with Transparent Conductive Gas Diffusion Layers for Solar Fuel Production
Authors: Sivula Kevin
Published: September 2023

Gas diffusion electrodes are essential components of common fuel and electrolysis cells that use gas phase reactants and products, but are typically made from graphitic carbon or metallic materials, which do not allow light transmittance, and thus limit the development of photoelectrode membrane assemblies for gas-phase solar fuel production. In this presentation, the application of solar H2 production from humid air is motivated and the simple and scalable preparation of transparent gas-diffusion layers using F-doped SnO2 (FTO) coated SiO2 interconnected fiber felt substrates is introduced. The resulting substrates have a porosity of 90 %, a roughness factor of 15.8 and a Young’s Modulus of 0.2 GPa. A sheet resistivity of 20 ± 3 Ω sq−1 and a loss of incident light of 41% at an illumination wavelength of 550 nm is found with FTO coating. The application of various semiconductors on the substrates was established including Fe2O3 (chemical bath deposition), CuSCN and Cu2O (electrodeposition), and semiconducting polymers (dip coating) and the liquid-phase photoelectrochemical performance commensurate with flat FTO substrates was confirmed. Finally, gas phase H2 production was demonstrated with a polymer semiconductor photocathode membrane assembly at 1-Sun photocurrent density on the order of 1 mA cm–2 and Faradaic efficiency of 40%.
(Invited) Oxide-Water Interfaces from Ab Initio Based Deep Neural Network Simulations
Authors: Selloni Annabella
Published: September 2023

Photo-electrocatalysis involving complex oxide-water interfaces is a highly promising technology for the sustainable production of fuels. However, probing these complex interfaces and gaining atomistic insights is still very challenging for current experimental methods, and is often only possible through accurate computational simulations. While first principles-based simulations provide the best accuracy, they are also limited to small system sizes and time-scales due to their high computational cost. Machine learned potentials that reproduce the accuracy of first-principles methods, while at the same time allowing the exploration of larger systems and timescales, are a promising approach to circumvent this issue. In this talk, I will discuss recent applications of deep neural network based molecular dynamics simulations to understand the structure and dynamics of interfacial water on photoelectrochemically relevant oxide surfaces. Focusing on TiO2 and IrO2 surfaces, we examine interfacial proton transfer and discuss how the water dissociation fraction and hydroxyl lifetimes depend on the surface atomic and electronic structures.
(Invited) Cation and Anion Doping into Perovskite Lanthanum Titanium Oxides for Photocatalytic Water Splitting
Authors: Wu Nianqiang
Published: September 2023

Perovskite lanthanum titanium oxides have a great potential as photocatalysts for solar water splitting because of low cost, excellent operation stability and tunable surface chemistry. However, their solar energy conversion efficiency is low due to large band gap and the presence of surface trap states. This talk demonstrates our effort to dope nitrogen and metal ions into lanthanum titanium oxides to reduce the band gap and to suppress the surface trap states. Furthermore, the charge separation, migration and recombination processes have been studied.
(Invited) Electrochemical and in Situ FTIR Spectroscopic Studies of CO2 Reduction at 3D Nanostructured Catalysts
Authors: Chen Aicheng
Published: September 2023

There is a growing interest in developing high-performance catalysts for the electrochemical reduction of carbon dioxide (CO2) to address the increasingly serious impacts of global climate change. In this talk, we report on the design of advanced three-dimensional (3D) nanomaterials (e.g., nanoporous gold, Cu nanodendrites and Co nanodendrites) for the efficient electrochemical reduction of CO2. The morphology, composition and structure of the synthesized 3D nanomaterials were characterized with various imaging and spectroscopic techniques, including FE-SEM, XRD, EDX and XPS. The effects of an applied potential on the electrochemical reduction of CO2 were investigated using various electrochemical methods. The products generated from the CO2 electrochemical reduction were identified by gas chromatography and nuclear magnetic resonance (NMR) spectroscopy. The kinetics of the CO2 reduction reaction at the 3D nanomaterials was further studied using in situ electrochemical Fourier transform infrared (FTIR) spectroscopy. The critical roles of nanostructured surfaces in the electrochemical reduction of CO2 are discussed.
(Invited) Cascading Catalytic Microenvironments for (photo)Electroreduction of CO2
Authors: Houle Frances
Published: September 2023

Although copper is a useful electrocatalyst for generation of a variety of chemical products from CO2 and H2O, it has become widely recognized that the catalyst by itself is not capable of high selectivity for formation of pure streams of specific products. By controlling the local environment around the catalytic reaction center, and providing multiple types of catalysts that can perform a sequence of specific reactions, improved control over selectivity can be envisioned. The mesoscale design rules for such cascades are unknown, however. In this talk I will describe computational studies that begin to examine the molecular-level factors that control coupled reaction-diffusion processes involved in CO2 reduction via cascaded catalytic reactions, including interfacial reactivity and catalyst placement. Key design considerations and gaps in understanding that emerge from these calculations will be discussed.
(Invited) Single Atom Catalysts in Functionalized Carbon Nitride for Efficient Solar CO2 Reduction
Authors: St. John Allison , Ahmad Esraa , Jin Tianqi , Li Gonghu
Published: September 2023

Single atom catalysts (SACs) have demonstrated unique properties in a variety of chemical transformations. Using graphitic carbon nitride (C3N4) as a photoactive support, we have prepared different cobalt SACs for use in solar CO2 reduction. Functionalization of C3N4 was carried out to produce well-defined N4 binding sites for cobalt ions. Spectroscopic techniques and computational tools were employed to confirm the structures of the SACs. In these photosynthetic assemblies, C3N4 absorbs visible light and, in the presence of electron donor, transfers electrons to the cobalt sites for CO2-reduction catalysis.
(Invited) Tuning Electrochemical Fuel Synthesis by Controlling the Reaction Environment
Authors: Chu An , Surendranath Yogesh
Published: September 2023

The direct and selectivity reduction of CO2 and CO to hydrocarbon fuels could play a key role in closing the carbon cycle. However, many fuels are accessible over a narrow range in electrochemical potential, requiring general design principles for controlling kinetic branching in these reactions. We have uncovered the central role of the reaction environment in facilitating selective CO2 and CO activation reactions at electrode surfaces and have employed electrolyte design to alter the mechanistic profile of fuel synthesis. Our latest findings in this area will be discussed.
(Invited) Dynamics of Light-Matter Interactions in Plasmonic Optical Cavities for Characterizing Nanostructures Relevant to Energy Conversion and Photocatalysis
Authors: Wiederrecht Gary P.
Published: September 2023

Optical cavities are an established means to increase light-matter interactions with a wide range molecules, nanostructures and bulk materials. The use of an optical cavity to increase the likelihood of photon absorption by a material has clear potential for being of value for optical energy conversion and photocatalysis. Furthermore, optical cavities can significantly alter excited state dynamics due to the potential for Purcell effects that increase radiative rates of emission of a given material, molecule, or nanostructure. These dynamic changes can serve as a sensing mechanism of cavity impact to photoprocesses, making characterization tools such as transient absorption and time-resolved emission measurements an effective means to probe the degree of light-matter coupling. Taken a step further, these characterization tools can help establish the degree of light-matter coupling necessary to control excited state lifetimes for a particular purpose or application. Here, we explore the dynamics of nanostructured systems coupled to, or made out of, plasmonic materials. Importantly, plasmonic structures are well-known to serve as a type of optical cavity, and though plasmonic cavities are lossier than their dielectric counterparts, they can also confine light to a small mode volume which is very helpful for increasing photonic interactions with nanostructures. The focus of this talk is on materials and nanostructures of interest for solar energy conversion or photocatalysis, such plasmonic nanoparticles and semiconducting nanoparticles, which are interacting with or functioning as, a plasmonic cavity. The plasmonic cavity can be as simple as a thin metal film that supports a propagating surface plasmon polariton (SPP). We also explore refractory plasmonic systems due to their potential durability and reduced likelihood of melting under optical illumination as compared to noble metal nanostructures. The dynamics of nanostructure photoprocesses as a function of photon energy relative to the cavity resonance is explored in detail and impact on applications is described. Work performed at the Center for Nanoscale Materials, a U.S. Department of Energy Office of Science User Facility, was supported by the U.S. DOE, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
(Invited) Preparation of Inexpensive and Efficient Electrocatalysts for Water Electrolysis
Authors: Piao Yuanzhe
Published: September 2023

Water electrolysis has aroused extensive research efforts due to its potential applications of sewage disposal, microorganism treatment and direct electrolysis for large-scale hydrogen production. In this presentation, I will review our recent progress in the preparation of various electrocatalysts for water electrolysis[1-4]. In search of inexpensive and efficient electrocatalyst for water electrolysis, three strategies to bring out the full potential of the most earth abundant transition metal, iron, are explored: morphology control, secondary metal incorporation, and nitrogen doping.[2] An ultrafast microwave-assisted synthesis of FeMo-MIL-88B followed by self-templated calcination via soft-urea path is developed. The transformed 3D rod-shaped porous iron-molybdenum oxynitride (FeMoON) presents outstanding electrocatalytic performances in hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting. The FeMoON electrode affords high current densities of 850 mA-1 at an over- potential of merely 364 mV for OER and 750 mA-1 at an overpotential of 400 mV for HER. The overall water-splitting demeanor surpasses that of commercial noble metal pair in high current densities and shows potential for long-term stability.

[1] Xinyu Qin, Bingyi Yan, Dongwon Kim, Zhishun Teng, Tianyu Chen, Juhyung Choi, Lin Xu* and Yuanzhe Piao*, Interfacial engineering and hydrophilic/aerophobic tuning of Sn4P3/Co2P heterojunction nanoarrays for high-efficiency fully reversible water electrolysis, Applied Catalysis B: Environmental. 2022, 304, 120923.

[2] Yejung Choi, Tianyu Chen, Dongwon Kim, Sang Gu Ji, Hwichan Hong, Lulu Lyu, Myeongseok Jang, Yuanzhe Piao*, Transformation of microwave synthesized highly uniform FeMo-MIL-88B nanorod to oxynitride derivate for overall water splitting reaction, Applied Materials Today, 2021, 24, 101093.

[3] Juhyung Choi, Daekyu Kim, Weiran Zheng, Bingyi Yan, Yong Li, Lawrence Yoon Suk Lee,* Yuanzhe Piao*, Interface Engineered NiFe2O4-x/NiMoO4 Nanowire Arrays for Electrochemical Oxygen Evolution, Applied Catalysis B: Environmental. 2021, 286, 119857.

[4] Liwei Lin, Shuqing Piao,Yejung Choi, Lulu Lyu, Hwichan Hong, Dohyeong Kim, Jeongyeon Lee,* Wang Zhang,* Yuanzhe Piao,* Nanostructured Transition Metal Nitrides as Emerging Electrocatalysts for Water Electrolysis: Status and Challenges, EnergyChem, 2022, 4, 100072.
(Invited) P-Doped Hematite for Efficient Photoelectrochemical Water Splitting
Authors: Jang Ji-Hyun
Published: September 2023

In this talk, I would like to discuss about how a simple in-situ phosphorus (P) doping strategy improves the overall PEC performance of hematite. By introducing enriched FePO4 regions on the Ti-doped FeOOH surface and subsequent high-temperature annealing, P,Ti co-doped Fe2O3 (P,Ti-Fe2O3) nanorods were fabricated. P,Ti-Fe2O3 not only increased the conductivity by creating oxygen vacancies but also generated a porous structure inside the hematite. Benefiting from the efficient P doping effects, the resulting P,Ti-Fe2O3 photoanode exhibited 94% improved photocurrent density compared to that of Ti-Fe2O3 (@ 1.23 VRHE) under 1 sun illumination. After applying the co-catalyst, NiFeOx/P,Ti-Fe2O3showed significantly enhanced photocurrent density (3.54 mA cm-2 at 1.23 VRHE) with a 108 mV cathodic shift. Our study suggests a new approach for achieving porous hematite and a highly efficient PEC system by a simple and cost-effective nonmetal P-doping method.
Effective Photocatalytic Sea Water Splitting
Authors: Mann Rohit , Khushalani Deepa
Published: September 2023

The photocatalytic (PC) hydrogen production from water splitting is a promising route to fulfill the current energy demand in an eco-friendly and sustainable manner. For photocatalysis to become industrially viable, seawater should be used. This solvent owes its salinity due to various ions. To date, there are contradicting reports in the literature on the influence of these ions on the PC splitting of water. A variety of different neutral transition metal-oxide-based photocatalysts has been exploited. Although they might be effective in splitting deionized water[1], however, thus far, there has been a lack of a well-established route to effectively using any semi-conductor for seawater splitting. Presented here are the details of our work where an intriguing, ionized, low-cost semiconductor has been successfully evaluated for sea-water splitting. The structure consists of a modified carbon nitride such that it forms an ionized organic polymer-based system.[2] A detailed study has been done using this salt-type semiconductor in the presence of various ions (Na+, K+, Mg2+, Ca2+, Cl−, SO4
2-), and their role has been probed in modulating the photocatalytic activity. Photoelectrochemical measurements have provided insight as to how the presence of cations aids advantageously in forming an effective in-situ interface between catalyst/co-catalyst for improved charge transfer. This improved interfacial charge transfer rationalizes the 8-fold enhancement in the photocatalytic rate in the presence of simulated seawater compared to deionized water and provides an impetus for using these ionized carbon nitride structures for sustainable PC splitting of seawater.

References -:

1) Jining Zhang, Wenping Hu, Shuang Cao1, and Lingyu Piao Nano Research, 13(9) (2020) 2313–2322

2) Tanmay Banerjee, Filip Podjaski, Julia Kröger, Bishnu P. Biswal, and Bettina V. Lotsch. Nat. Rev. Mater., 6 (2020) 168–190.

Figure 1
Unravelling the Structure Change and Its Catalytic Consequence of CuO Nanowires Towards CO2 Reduction Reaction
Authors: Liu Ershuai , Wan Jiawei , Choi Woong , Wen Changlian , Bell Alexis T. , Zheng Haimei , Drisdell Walter S.
Published: September 2023

The CO2 reduction reaction (CO2RR) is a complex process with many possible products, and maintaining high selectivity for multi-carbon products remains a challenge. Currently, Cu-based catalysts are the only transition metal catalysts that can produce C2 products, and one of the popular Cu-based catalysts is CuO nanowires (NWs). We studied a series of CuO nanowires ranging from 50 to 200 nm for CO2RR using multiple characterization techniques including transmission electron microscopy(TEM), small angle X-ray scattering (SAXS) and in situ X-ray adsorption spectroscopy. We found that there could be an activation process required for such CuO NWs to serve as efficient CO2RR catalysts. The CuO can go through multiple steps resulting in the severe morphology changes during the activation process, confirmed by TEM and SAXS. In situ XAS results showed that the CuO NWs will be reduced from Cu(II) to Cu(0) during the reaction, consistent with our previous work(1). H-cell testing results also indicated the C2 production can be boosted after specific activation pathway, which highlights the importance of catalyst pre-treatment. These findings not only deepen our understanding of CO2RR mechanism but also provide fundamental insights for CO2RR catalysts synthesis.

References

(1) Soo Hong Lee, Ian Sullivan, David M. Larson, Guiji Liu, Francesca M. Toma, Chengxiang Xiang, and Walter S. Drisdell. ACS Catalysis,
2020,
10(14), 8000-8011

Acknowledgement

The authors acknowledge the funding support from the Laboratory Directed Research and Development Program of the Lawrence Berkeley National Laboratory under the U.S. Department of Energy Contract (No. DE-AC02-05CH11231).
(Invited) Artificial Photosynthetic CO2 Reduction through Microbial Membrane Re-Engineering with Nanostructures
Authors: Rozhkova Elena
Published: September 2023

The fusion of biological pathways with synthetic inorganic materials provides inspiring blueprints for sustainable fuel production1-4. Here, we use a top-down cellular engineering strategy to develop a new semi-artificial photosynthesis paradigm for carbon dioxide reduction by wrapping Halobacterium purple membrane-derived vesicles over Pd-deposited hollow porous TiO2 nanoparticles. In this biohybrid, the membrane protein, bacteriorhodopsin, not only retains its native biological function of pumping protons but also acts as a photosensitizer that injects light-excited electrons into the conduction band of TiO2. Thus, the photoinduced electrons and protons accumulated within the confined architecture act in concert to reduce CO2 emissions on the Pd cocatalyst through proton-coupled multielectron transfer processes. This study provides an alternative toolkit for developing robust semi-artificial photosynthetic systems for solar energy conversion.5

1. Balasubramanian, S.; Wang, P.; Schaller, R. D.; Rajh, T.; Rozhkova, E. A., High-Performance Bioassisted Nanophotocatalyst for Hydrogen Production. Nano Lett 2013, 13 (7), 3365-3371.

2. Wang, P.; Chang, A. Y.; Novosad, V.; Chupin, V. V.; Schaller, R. D.; Rozhkova, E. A., Cell-Free Synthetic Biology Chassis for Nanocatalytic Photon-to-Hydrogen Conversion. Acs Nano 2017, 11 (7), 6739-6745.

3. Chen, Z. W.; Silveira, G. D.; Ma, X. D.; Xie, Y. S.; Wu, Y. M. A.; Barry, E.; Rajh, T.; Fry, H. C.; Laible, P. D.; Rozhkova, E. A., Light-Gated Synthetic Protocells for Plasmon-Enhanced Chemiosmotic Gradient Generation and ATP Synthesis. Angew Chem Int Edit 2019, 58 (15), 4896-4900.

4. Chen, Z. W.; Rozhkova, E. A., Intracellular gold nanoclusters boost energy conversion. Nat Nanotechnol 2018, 13 (10), 880-881.

5. Chen, Z. W.; Zhang, H.; Guo, P. J.; Zhang, J. J.; Tira, G.; Kim, Y. J.; Wu, Y. M. A.; Liu, Y. Z.; Wen, J. G.; Rajh, T.; Niklas, J.; Poluektov, O. G.; Laible, P. D.; Rozhkova, E. A., Semi-artificial Photosynthetic CO2 Reduction through Purple Membrane Re-engineering with Semiconductor. J Am Chem Soc 2019, 141 (30), 11811-11815.

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Large-Scale Anodic TiO2 Nanotube Layers: Gas Phase Photocatalysis and Virus Killing
Authors: Sopha Hanna , Baudys Michal , Krysa Josef , Macak Jan M.
Published: September 2023

Self-organized TiO2 nanotube layers have attracted considerable scientific and technological interest over the past 15 years motivated for their wide range of applications including (photo-) catalysis, hydrogen generation and biomedical uses [1,2]. The synthesis of the 1D TiO2 nanotube layers is carried out by a conventional electrochemical anodization of valve Ti metal sheets in various electrolytes.

By now, the synthesis of TiO2 nanotube layers with different nanotube dimensions (diameter, length) and the application of these nanotube layers is well established on the laboratory scale. However, for real applications outside the laboratory scale, such as photocatalysis [3], TiO2 nanotube layers of much larger size are necessary. To date, just a few efforts were carried out to scale up the size of the nanotube layers to more than a few cm2 [3-7] due to the difficulty of controlling the parameters of the anodization process on a larger scale. The main challenge is the huge current received during the anodization of large substrates. This, in turn, leads to an increase in the electrolyte temperature that may result in dielectric breakdown of the growing nanotube layers.

In this presentation, the preparation of TiO2 nanotube layers on larger area titanium substrates (dozens of cm2) will be discussed, taking into account the control of the anodization parameters. The TiO2 nanotube layers with different thicknesses and nanotube diameters were employed for gas phase photocatalysis, following the ISO standards [3,8]. In addition, results from antivirotic tests of these layers will be demonstrated. Experimental details and photocatalytic results will be presented and discussed.

References

[1] J.M. Macak, H. Tsuchiya, A. Ghicov, K. Yasuda, R. Hahn, S. Bauer, P. Schmuki, Curr. Opin. Solid State Mater., 11 (2007) 3.

[2] K. Lee, A. Mazare, P. Schmuki, Chem. Rev., 114 (2014) 9385.

[3] H. Sopha, M. Baudys, M. Krbal, R. Zazpe, J. Prikryl, J. Krysa, J.M. Macak, Electrochem. Commun., 97 (2018) 91.

[4] S. Franz, D. Perego, O. Marchese, M. Bestetti, J. Water Chem. Tech., 37 (2015) 108.

[5] H.-I. Kim, D. Kim, W. Kim, Y.-C. Ha, S.-J. Sim, S. Kim, W. Choi, Appl. Catal. A: Gen., 521 (2016) 174.

[6] J.P. Ghosh, G. Achari, C.H. Langford, Water Environ. Res., 88 (2016) 785.

[7] C. Xiang, L. Sun, Y. Wang, G. Wang, X. Zhao, S. Zhang, J. Phys. Chem. C 121 (2017) 15448.

[8] H.Sopha, M. Baudys, L. Hromadko, M. Lhotka, D. Pavlinak,J. Krýsa, J. M. Macak, Applied Mater. Today 29 (2022) 101567.
Measuring Electrochemical Potentials for Health Monitoring of Redox Flow Batteries
Authors: Perry Mike L. , Alexandrescu Eric J.
Published: September 2023

Long-duration energy-storage (LDES) systems have the potential to transform the electric grid. Redox Flow Batteries (RFBs) have many unique attributes that make this battery architecture ideally suited for grid-scale LDES, namely: independent power and energy; long cycle life, even with deep cycles; inherently superior safety [1]; and easy recyclability. However, despite a recent renaissance in RFB technologies, assessing the durability of RFB cells is a topic that has not received much attention in the open literature, and further research is needed to better understand the performance and degradation mechanisms [2]. In-situ health monitoring of RFBs is critical for maximizing their lifetime and efficiency. Measurements of the electrochemical potentials of the electrodes and the electrolyte can provide insights into whether operating parameters are being adhered to and can potentially detect failure mechanisms occurring real-time within the battery. Since the electrochemical potential of both the positive and negative electrolytes exhibits Nernstian behavior, they are convertible to state-of-charge (SOC) measurements. Ensuring that the electrolyte stays within a desired SOC window during operation is essential for the mitigation of undesirable side reactions, such as the hydrogen-evolution reaction (HER) [3]. In addition, measurements of the potential difference between the electrode and the electrolyte, commonly known as overpotential, during charging and discharging processes allow for independent quantification of the reaction efficiency at each electrode. Factors affecting this reaction efficiency may include reaction kinetics, the mass transport of active species to the electrodes, the plating of impurities onto the electrode surface, and the mobility of ions across the ion-exchange membrane. Analysis of overpotential can also be useful in detecting failure mechanisms relating to these various factors [4]. Largo Clean Energy has developed multiple methods to measure electrochemical potentials in all-vanadium RFBs (VRFBs). The focus of this talk will be on how one can use these different measurements to assess the performance of VRFB cells.

References

R. Wittman, M. L. Perry, T. N. Lambert, B. R. Chalamala, and Y. Preger, “Perspective – On the Need for Reliability and Safety of Grid-Scale Aqueous Batteries,” J. Electrochemical Society, 167 (2020).

Y. Yao, J. Lei; Y. Shi; F. Ai; T. C. Lu, “Assessment methods and performance metrics for redox flow batteries,” Nature Energy, 6 (2021).

C. Tai-Chieh Wan, K. E. Rodby, M. L. Perry, Y.-M. Chiang, F. R. Brushett, “Hydrogen evolution mitigation in iron-chromium redox flow batteries via electrochemical purification of the electrolyte,” J. of Power Sources,
554 (2023).

M. L. Perry and R. M. Darling, “Development of a Simple and Rapid Diagnostic for Redox Flow-Battery Cells,” Symposium I02: Frontiers of Chemical/Molecular Engineering in Electrochemical Energy Technologies, 242nd
ECS Meeting, (2022).
Precipitation Mechanism of VOSO4 in Oversaturated Electrolytes of the Solid-Liquid Storage Method in Vanadium Redox Flow Batteries
Authors: Li Yuanchao , Abbey Joshua , Nguyen Trung Van
Published: September 2023

Redox flow batteries (RFBs)-based storage systems have the unique feature of separate power generating and energy storage units that can be individually sized. RFBs can be used for days-long energy storage, but because of the low solubility of most ions and molecules in both aqueous and non-aqueous solvents,[1,2] scaling these RFB systems for days-long applications requires a lot of storage tanks and floor area.

Our team has developed a new storage method that can significantly increase energy storage density while still maintaining the traditional flow battery design.[3] This method involves storing the reactants in both soluble ions and undissolved solid form, and only the liquid containing the soluble ions is circulated through the batteries. A larger than 4X improvement in storage energy density may be achieved with this strategy. The feasibility of this method was demonstrated in a hydrogen-vanadium (VI/V) RFB.[4] From the study, a major factor in achieving high performance with this hybrid storage system is the rates of the precipitation of the saturated electrolyte and dissolution of the solid precipitate. It was discovered that not all vanadium sulfate solids have precipitation rates fast enough to generate the active ions at the rate needed in the electrode reaction. Only the low crystallinity solid generated by rapid precipitation by the use of a suitable nucleation material was found to have the dissolution rate needed. This presentation will discuss the role of the molecule structures and the mechanism of the precipitation process in the formation of solids that have slow and fast dissolution rates.

References

[1] V. Singh, S. Kim, J. Kang, and H. R. Byon, Nano Res.,
12, 1988-2001 (2019).

[2] K. Gong, F. Xu, J. B. Grunewald, X. Ma, Y. Zhao, S. Gu, and Y. Yan, ACS Energy Lett.,
1, 89-93 (2016).

[3] Y. Li and T. V. Nguyen, Provisional US patent application number 62/941,064 filed 2019/11/27, International Application No. PCT/US20/61455 filed 2020/11/20 (WO2021108244A1).

[4] Y. Li and T. V. Nguyen, J. Electrochem. Soc., 169, 110509 (2022).
A Sensitivity Study of Key Parameters on the Efficiencies and Energy Losses of Organic Redox Flow Batteries
Authors: Chen Yunxiang , Zeng Chao , Fu Yucheng , Bao Jie , Xu Zhijie , Gao Peiyuan , Kim Soowhan , Wang Wei
Published: September 2023

Organic redox flow batteries (ORFB) are promising cost-competitive technologies for large-scale energy storage. At the unit cell scale, the battery performance is controlled by the combined effects of key parameters of microstructure design, physicochemical properties of organic molecules, mass transport, operating conditions, and membrane properties. However, a comprehensive study of how these parameters could affect the overall performance of ORFB has not been done. To address this gap, this work presents a sensitivity study of 12 key parameters on the battery efficiencies and energy losses of ORFB by using a validated numerical model for the Dihydroxyphenazine (DHP) family. The 12 key parameters include the specific area of microstructure; mass transfer rate; diffusivity, viscosity, reaction transfer coefficient, the reaction rate constant, standard potential, and electronic conductivity of DHP anolyte; operation conditions such as initial concentration of active species, pump rate, and applied current; and membrane electronic conductivity. In total, we generated 15,360 combinations of the 12 key parameters. These data are split into 15 groups with each having a fixed current density and flow rate and 1024 random parameter combinations of the remaining 10 parameters. All these parameters are then sent to the validated ORFB model developed in Comsol to predict the coupled flow, reaction, and transport processes at 38 pre-defined SOC between 0.025 and 0.85. We then output the total potential, equilibrium potential, activation potential, and concentration potential for charge (19 SOC) and discharge (19 SOC) from the model to further calculate the Coulombic Efficiency, Energy Efficiency, Voltage Efficiency, and System Efficiency as well as the energy losses contributed by equilibrium, activation, concentration, and ohmic losses. With these calculated efficiencies and the relative importance of energy losses, we used a deep neural network (DNN) to fit the relationship between the input 12 parameters (15,360 combinations), and the model calculated 4 efficiencies/relative ratios of energy losses. A sensitivity score is then calculated based on the DNN model and key factors controlling the ORFB performance are determined.
Iron Complex Posolyte Species Possessing Low Capacity Fade Rate Combined with Large Positive Redox Potential for Aqueous Organic Flow Batteries
Authors: Amini Kiana , Gao Jinxu , George Thomas Young , Jing Yan , Tsukamoto Tatsuhiro , Xi Dawei , Gordon Roy G. , Aziz Michael J.
Published: September 2023

Redox flow batteries are promising technologies for energy storage and conversion applications. Among different types of flow batteries, iron-based redox-active materials can have cost and environmental advantages. We introduce a high-potential tris(2,2'-bipyridine-4,4'-diyldimethanol) iron dichloride compound as a posolyte species with a redox potential more than 0.5 V more positive than that of ferro/ferricyanide. The new species, abbreviated Fe(Bhmbp)3, operating at near-neutral pH, was paired with bis(3-trimethylammonio)propyl viologen tetrachloride as the negolyte species. The resulting aqueous flow battery exhibits an open-circuit voltage of 1.36 V and it shows excellent cycling stability with a capacity fade rate of 0.0007% per cycle or 0.07% per day. In comparison with previously reported organic and metalorganic compounds, Fe(Bhmbpy)3 exhibits a superior combination of high positive redox potential and low capacity fade rate. We investigated the decomposition pathways during cell cycling to an unprecedented level of depth for an aqueous posolyte. We found that the compound degrades through self-discharge, dimerization and ligand dissociation. The proposed decomposition pathways explain the capacity fade phenomena and offer opportunities for future improvement of metalorganic posolytes with high redox potential and good cycling stability