bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electrochemical Oxidation of Synthetic Wastewater Sludge on Ni Foam for Nutrient Recovery
Authors: Barrera Luisa , Sahin Elif Selin , Botte Gerardine G , Hatzell Marta 
Published: February 2024

Continued growth of the world’s population as well as shifting socio-economic trends have been tied to increasing demands for food and water. Due to upcoming worldwide environmental crises, there needs to be a shift towards a circular economy, where key nutrients are not lost but repurposed. For example, high-yield food crops depend on the application of nitrogen and phosphorus-based fertilizers, which are respectively made using highly energy intensive methods, like the Haber-Bosch process, and non-renewable limited resources, such as phosphate rock. In addition, water that has been contaminated by human activity is being treated in a multitude of manners, with the overarching drawbacks being high energy consumption and, in some cases, the production of a secondary waste stream. In particular, wastewater sludge is a nutrient-rich waste stream with high levels of nitrogen and phosphorus stored in organic bonds that is most commonly sent to landfills for disposal.
In this talk, we focus on the electrochemical oxidation of wastewater sludge for the recovery of ammonia and other nutrients. We used a synthetic wastewater sludge composition to better understand the contributions of each component on the formed end-products. We probed the potential dependence of these end-products by conducting fixed-potential tests in a H-cell with Ni foam electrodes. This work contributes to the ongoing efforts in the Center of Advancing Sustainable and Distributed Fertilizer Production (CASFER).
Considerations of Reference Electrodes and Liquid Junction Potentials for Accurate Electrocatalysis Studies
Authors: Kawashima Kenta , Marquez-Montes Raul A. , Son Yoon Jun , Milton Antony Elvin Fernando , Le Thuy Vy , Guo Clarissa , Smith Lettie A. , Chukwuneke Chikaodili E. , Vaidyula Rinish Reddy , Mullins Charles Buddie 
Published: February 2024

For lab-scale electrocatalysis studies, one typically uses a three-electrode system, which consists of working, counter (auxiliary), and reference electrodes, an electrolyte solution, and a reactor. In this system, it is important for accurate electrochemical studies to select an appropriate reference electrode for a particular electrolyte solution and recognize the presence/absence of liquid junction potential at the frit of a reference electrode. For instance, in alkaline water electrocatalysis experiments, Hg/HgO, Ag/AgCl, or saturated calomel electrode (SCE) is generally used as a reference electrode, and 1 M KOH/NaOH aqueous solution is utilized as an electrolyte solution.1 In this regard, the Ag/AgCl electrode and SCE are unsuitable for electrochemical studies with alkaline electrolytes, and among them, only the Hg/HgO electrode can be used instead.1 Furthermore, if the internal solution of a reference electrode and the external electrolyte solution are different in constituent and/or concentration, the liquid junction potential will be established at the frit of a reference electrode. In this case, to accurately know the potential applied to a working electrode, this liquid junction potential as well as the iR drop caused by solution resistance need to be considered and corrected appropriately. However, the liquid junction potential has so far been ignored in most of the electrocatalysis studies.
In this work, we will discuss a method to experimentally estimate the liquid junction potential at the reference electrode frit using three-electrode systems with different combinations of electrolytes and reference electrodes. Herein, we will deal with alkaline water electrolysis systems as representatives. The as-estimated values of various liquid junction potentials will be compared with the theoretical values obtained using the Henderson equation2 and the stationary Nernst–Planck equation.3 Additionally, the guideline for selecting an appropriate reference electrode depending on the types of external electrolyte solutions will be discussed briefly. We believe that these findings can improve the accuracy of reporting potential-related parameters (e.g., overpotential, half-wave potential, onset potential, etc.) in three-electrode system-based electrocatalysis studies.

References

K. Kawashima et al., ACS Catal., 13, 1893–1898 (2023).

R. G. Bates, Determination of pH, 2nd ed., p. 36–44, A Wiley-Interscience Publication, New York, New York, (1973).

M. Marino, L. Misuri, and D. Brogioli, (2014) https://arxiv.org/abs/1403.3640v2.
Gas-Phase CuPd Bimetallic Cluster-Modified Electrodes as Model Electrocatalysts for CO2 Conversion
Authors: Papamichail Dimitra , Balalta Deema , Abbas Imran , Song Jason , Altantzis Thomas , Bals Sara , Pant Deepak , Janssens Ewald , Grandjean Didier , Lievens Peter 
Published: February 2024

Copper-based electrocatalysts possess the unique ability to convert CO2 to multicarbon products such as ethylene – a precursor in many industrial processes. However, their stability and product selectivity remain insufficient. A promising approach to overcome these shortcomings and design better CO2RR electrocatalysts is to tune Cu selectivity by forming bimetallic Cu-M systems [1] while establishing their detailed structure-selectivity relationship. To achieve this, we used laser ablation Cluster Beam Deposition (CBD) [2] to produce well-defined bimetallic cluster-modified electrodes [2]. More specifically, CuPd clusters with an original average size of 2.5 nm and mass loadings of 1-3 µg cm-2 were deposited onto a carbon support. To produce a model catalyst which allows the independent investigation of the electronic and geometric structural effects induced to Cu by the second element, a Cu0.9Pd0.1 composition was selected [3]. CuPd cluster-decorated electrodes were tested for CO2 electrolysis and methane (C1), and ethylene (C2) were found among the products. Observed from the electrocatalytic activity trends, the evolution of C2 products is correlated with the cluster mass loading. In addition, the cluster coverage has an effect on the onset of the competitive H2 evolution (HER); with the lowest cluster-loaded electrodes presenting more intense HER due to limited cluster coverage of the carbon substrate. High resolution (Scanning) Transmission Electron Microscopy ((S)TEM) coupled with Energy-dispersive X-ray spectroscopy (EDX), and X-ray Photoelectron Spectroscopy (XPS) analyses of the as-prepared cluster-modified electrodes, show that the clusters feature some degree of CuPd alloying in the ambient. CuPd cluster-based systems will then be investigated in-situ using X-ray absorption spectroscopy to unravel their structure-catalytic performance relationship.

References:

[1] X. Zhang et al., Materials Today Advances, 7, 2020
[2] V. C. Chinnabathini, et al., Nanoscale, 2023, DOI: 10.1039/D2NR07287D
[3] L. Zaza et al., ACS Energy Letters, 7, 4, 1284–1291, 2022
Temperature-Dependent Investigation of ORR Kinetics on Non-Precious Metal-Free Catalysts in Alkaline Media - Doping Effect on Electrocatalysis
Authors: Das Rubul , Neergat Manoj 
Published: February 2024

The kinetic analysis of oxygen reduction reaction (ORR) on non-precious catalysts is cumbersome due to the formation of more than one major products ( and ). In the present study, ORR is investigated on Vulcan XC-72 (C) and a metal-free nitrogen-doped (~≤ 1%) carbon (N/C-900) catalysts in 0.1 M KOH [1]. The experiments are conducted in the temperature range of 293–323 K using a rotating ring disk electrode (RRDE) assembly to quantify the product distribution, viz., and . The measured kinetic current () is partitioned into and on the basis of the potential-dependent product distribution ( and ) .and is used in the estimation of kinetic parameters [2]. The α values are derived from Butler-Volmer (B-V) theory, Tafel equation at high overpotentials (η), and from the derivative of the change in Gibbs free energy of activation () with respect to η. The α values obtained from all the three methods are different. Therefore, the origin of the difference in the α values is the subject of the present investigation. The seemingly unreasonable values of (> 1.0)on N/C-900 may be due to the alternative lower energy path for the formation of activated complex along with the change in the free energy of the reactant [3,4]. On C, it does not provide any alternative pathway for the formation of activated complex and perhaps η influences only the energy state of the reactant. Therefore, the free energy of activation for the formation of activated complex is a stronger function of η on N/C-900 and an indication of strong electrocatalysis.

References

B. Bera, T. Kar, A. Chakraborty, M. Neergat, J. Electroanal. Chem., 805, 184–192 (2017).

R. Das, D. Choudhury, R. Maurya, S. Sharma, M. Neergat, Langmuir,39 (12), 4351–4361 (2023).

U. Stimming, J. Wang, A. Bund, ChemPhysChem, 20 (22), 3004–3009 (2019).

R. Maurya, R. Das, A. K. Tripathi, M. Neergat, Phys. Chem. Chem. Phys., 25, 700–707 (2023).

*Corresponding author:

Tel.: +91 22 2576 7893; Fax: +91 22 2576 4890
E-mail: nmanoj@iitb.ac.in (M. Neergat)
Charge Carrier Trapping in the Surface Region of BiVO4 Photoanodes
Authors: Kaya Sarp 
Published: February 2024

Photoelectrochemical water splitting is a promising method for converting solar energy into chemical energy stored in molecular hydrogen and oxygen. However, the efficiency of this process is heavily dependent on the properties of the photoelectrode materials used. Metal oxide semiconductors, such as BiVO4, are commonly used as photoanode materials, but they have poor charge transport properties and surface catalytic activity, which can limit their efficiency.
To address these limitations, catalysts are often incorporated onto the surface of the photoanode to improve its surface activity. However, the overall efficiency of the photoelectrochemical process is also influenced by charged defect sites present both in the bulk and on the surface of the semiconductor. These defect sites can trap charges and hamper the kinetics of the process in the millisecond time scale. To address this issue, covalently coordinated catalyst layers and surface doping can be used to eliminate these trapped charges. Moreover, the bulk charge carriers are not entirely decoupled from the surface processes and can be influenced by surface treatments. Therefore, a multi-folded approach that considers both the surface and bulk properties of the photoanode, as well as the role of the catalysts, is necessary to improve the overall efficiency of photoelectrochemical water splitting.
We have investigated interfacial charge trapping and transfer processes through a CoOx catalyst layer deposited on BiVO4 by atomic layer deposition (ALD) and cobalt incorporated into the subsurface region. We have shown, by the combination of activity studies and spectroscopy investigations, that oxygen vacancies modified by cobalt incorporation have a remarkable impact on the water oxidation activity and charge injection efficiency. We further demonstrated by transient photocurrent measurements performed by fast LED light pulses (within ms time scale) that the CoOx catalyst layer reduced the number of trapped electrons and improved the rate of charge utilization. Cobalt ions in the subsurface region on the other did not act as catalytic centers but they eliminated the trapping process. We have also confirmed these observations by transient absorption spectroscopy investigations and showed that cobalt incorporation had a much bigger effect on the charge recombination lifetime.
Understanding Performance Limitations in Water Splitting Photoelectrodes at the Nanoscale
Authors: Wolz Lukas , Balakrishnan Harishankar , Zhou Guanda , Sharp Ian D. , Hartschuh Achim , Eichhorn Johanna 
Published: February 2024

Photoelectrochemical (PEC) water splitting is a promising route for efficient conversion of solar energy into chemical fuels. In this context, economically viable photosystems are often based of semiconductor thin films which are polycrystalline or nanostructured with highly complex architectures e.g. with boundaries between differently orientated grains, different crystal facet orientations, as well as locally varying composition or phase. These nano- to micrometer properties often control critical processes, such as efficiency and stability, of the macroscale system. To understand the impact of nanoscale properties on the macroscopic performance, we aim at resolving local structural, chemical, and optoelectronic heterogeneities and at elucidating their effect on light-driven processes.
In this work, we use a correlative approach to elucidate the nanoscale properties of polycrystalline BiVO4 thin films – a promising material for solar water splitting. Mapping of the local charge transport properties by photoconductive atomic force microscopy (pc-AFM) reveals the tolerance to grain boundaries.[1] Interestingly, scanning nearfield infrared microscopy shows strongly varying absorption from VO4 stretching modes between grains and at grain boundaries which correlate with the heterogeneities in the local photoconductivity across the polycrystalline thin films. Furthermore, local temperature-dependent current-voltage spectroscopy show that the low intrinsic bulk conductivity of BiVO4 limits the electron transport through the film, and that the transport mechanism can be attributed to space charge limited current (SCLC) in the presence of trap states.[1] Performing the same measurements in-situ in controlled gas-phase environment reveals the influence of chemical interactions of adsorbed oxygen and water on charge transport and interfacial charge transfer.[2] For BiVO4, we demonstrate that adsorbed oxygen acts as a surface trap state for electrons, which enhances the built-in potential and depletes the BiVO4 layer. Overall, combining insights from different nanoscale techniques generates a comprehensive picture of charge separation, transport, and transfer at the nanoscale. The gained nanoscale understanding of energy materials enables the rational design of durable and efficient solar fuel devices.
[1] Eichhorn et al., Nat. Commun. 9, 2597(2018).
[2] Eichhorn et al., ACS Appl. Mater. Interfaces, 10, 41, 35129 (2018).
Carbon and Energy Efficient Ethanol Electrosynthesis By Acidic CO2 Reduction
Authors: Shayesteh Ali , Li Feng , Alkayyali Tartela , Shirzadi Erfan , Arabyarmohammadi Fatemeh , Dorakhan Roham , O'Brien Colin P. , Gabardo Christine M. , Ozden Adnan , Zargartalebi Mohammad , Fan Lizhou , Papangelakis Panagiotis , Zhao Yong , Sargent Edward H. , Sinton David 
Published: February 2024

The electrochemical CO2 reduction reaction (CO2RR) is one way of mitigating the rising levels of anthropogenic CO2 emissions. Most of the advancements in the CO2RR field have been implemented in basic or neutral electrolytes where a major fraction of the input CO2 converts to carbonate ions through reaction with OH– (Science 360, 783-787 (2018); Nat. Catal. 5, 564-570 (2022)). These approaches result in low carbon efficiency (the percentage of CO2 converted per total CO2 input), typically below 20% toward multicarbon products, resulting in severe energy and cost penalty (Nat. Sustain. 5, 563-573 (2022)).
Performing CO2RR in acidic conditions reduces reactant loss to carbonates. In this condition, the (bi)carbonate ion crossover/formation is countered by the high proton concentration in the electrolyte. However, the unshielded cathode surface favors the hydrogen evolution reaction (HER) over CO2RR due to the high availability of protons and the fast kinetics of the HER (Science 372, 1074-1078, (2021); Nat. Catal. 4, 654-662 (2021)).
Here, we have developed an interfacial cation matrix (ICM) to modulate the local microenvironment on the cathode surface. The ICM increases the local pH and electric field, promoting multicarbon production. Additionally, we have designed a Copper-Silver catalyst to tune the selectivity towards alcohol production. We improved the ethanol FE to 45% at 200 mA/cm2, which, to our knowledge, represents the highestethanol FE in membrane electrode assembly literature. The system maintains a high carbon efficiency (60%) resulting in a total energy cost of 263 GJ/tonne ethanol, which is the lowest value among current ethanol-producing CO2 electrolysers.
In Situ Investigation of Electrochemically Mediated Carbon Capture and Release Via Quinone Chemistry in Aqueous Media
Authors: Amini Kiana , Cochard Thomas , Jing Yan , Sosa Jordan D. , Xi Dawei , Alberts Maia , Gordon Roy G. , Aziz Michael J. 
Published: February 2024

The development of devices capable of capturing and sequestering carbon dioxide emissions directly from air or at point sources is motivated by mitigating climate change. Electrochemically driven carbon capture and release at ambient temperature and pressure through the formation of complexes with organic redox active molecules [1,2] or via pH swing caused by proton-coupled electron transfer during molecular redox events [3,4] has shown promising results for carbon capture and release in terms of energy cost, scalability and safety compared to the state of the art amine scrubbing technologies [5].
Quinones are organic molecules containing an unsaturated six-member ring with two carbonyl groups. They exhibit two potential mechanisms of CO2 capture. (a) Upon electrochemical reduction, the carbonyl groups within quinones provide sites for nucleophilic addition of carbon dioxide which results in the formation of a quinone-CO2 adduct (CO2reversibly bound by quinones). (b) Depending on the pKa of the quinone and the local pH, the electrochemical reduction of the compound can be proton-coupled, creating hydroxide, which captures CO2 as carbonate or bicarbonate.
In this work, we introduce in situ electrochemical characterization and in situ fluorescence microscopy to separately quantify the two aforementioned contributions toward capture of CO2 at partial pressures ranging from 0.1 bar to 0.4 mbar. The non-invasive in situ analytical methods introduced in this work are used to distinguish, with sub-second time resolution, between the oxidized, reduced and adduct species by their electrochemical and fluorescence signatures. The results of this study permits us to understand the underlying simultaneous contributions of quinone-CO2 adduct path and the pH-swing path toward carbon capture and release and, additionally, introduces powerful non-invasive methods for gathering insights on similar systems.

1X. Li, X. Zhao, Y. Liu, T.A. Hatton, and Y. Liu, "Redox-tunable lewis bases for electrochemical carbon dioxide capture", Nature Energy
7, 1065 (2022).

2Y. Liu, H.Z. Ye, K.M. Diederichsen, T. Van Voorhis, and T.A. Hatton, "Electrochemically mediated carbon dioxide separation with quinone chemistry in salt-concentrated aqueous media", Nat Commun
11, 2278 (2020).

3S. Jin, M. Wu, Y. Jing, R.G. Gordon, and M.J. Aziz, "Low energy carbon capture via electrochemically induced pH swing with electrochemical rebalancing", Nat Commun
13, 2140 (2022).

4S. Jin, M. Wu, R.G. Gordon, M.J. Aziz, and D.G. Kwabi, "pH swing cycle for CO2 capture electrochemically driven through proton-coupled electron transfer", Energy & Environmental Science
13, 3706 (2020).

5G.T. Rochelle, "Amine scrubbing for CO2 capture", Science
325, 1652.
Visualizing pH and Mass Transport at Hydrogen Evolving Electrodes with Fluorescence Lifetime Microscopy
Authors: Bleeker Jorrit , Vermaas David , Jager Wolter 
Published: February 2024

The chemical industry needs electrochemical solutions to avoid large CO₂ emissions. However, many of these electrochemical processes suffer from poor mass transport around the catalyst. To optimize these technologies, we need to gain a better understanding of the local processes at the electrode. This could give us ideas of new catalyst and reactor designs to enhance mass transport.
The pH is a parameter that helps us to understand these processes. This is because the catalyst stability and selectivity of many reactions is strongly dependent on the local pH. You need a non-invasive technique to measure in operando spatial maps of pH. Optical techniques are a logical route for this.
Fluorescence Lifetime Imaging Microscopy (FLIM) is a technique that measures the fluorescence lifetime of a probe molecule. It is friendly to use, as it is self-referencing (i.e. you do not need to calibrate your system for every new measurement). Many electrochemical applications, like seawater electrolysis, CO2 reduction and alkaline water electrolysis, tend to work in alkaline conditions (pH >8). Unfortunately commercial FLIM probes are only available in neutral and mildly acidic pH (4 to 8), owing to their use in biological systems.
We have developed new fluorescence lifetime probes based on the 1-methyl-7-amino-quinolinium fluorophore molecules, that allow pH measurements in the range of pH 5.5-13. We have used the probes to visualise the local pH around a hydrogen evolving electrode and can show the boundary layer that forms close to the electrode and investigate how it is disturbed by gas bubbles at a rate of 3 fps and resolution of 4 μm.

Figure 1
Probing of Near-Surface Cations during the Oxygen Evolution Reaction (OER) Using Operando XAS
Authors: Deka Nipon , Mom Rik 
Published: February 2024

Electrified solid-liquid interfaces are ubiquitous in technologies ranging from colloidal science to electrochemistry. Hence, an atomic-level characterization of the electrode-electrolyte interface is crucial for total control and optimization of the processes involved. While the electrode side of the interface has been quite extensively studied, the electrolyte side is comparatively poorly understood1. Specifically probing the near-surface electrolyte species during an electrochemical reaction is a major technical challenge in the field of catalysis and surface chemistry.
We have developed an interface-sensitive X-ray absorption spectroscopy (XAS) approach which allows us to directly probe the near-surface cations and anions of the electrolyte under applied potentials. In this approach, we employ a mesoporous electrocatalyst film coated on a 𝑆𝑖𝑁𝑥 X-ray window. These mesoporous films exhibit an extremely high electrode-electrolyte interface area, enabling us to specifically probe the behaviour of interfacial ions via their K-edge spectra. Using this approach, we have recently investigated the interaction of Na+ cations with IrOx during the oxygen evolution reaction (OER), which is a bottleneck in major electrochemical processes like green hydrogen production and CO2 reduction. The cations and anions of the electrolyte reportedly influence the OER activity of electrodes during OER2,3. We used operando Na K-edge XAS to directly probe the concentration and coordination environment of the near-surface Na+ cations. Simultaneously, operando O K-edge XAS monitored the interfacial water structure and the evolution of catalyst’s surface structure. Contrary to expectations, we discovered that the positively charged Na+ ions are drawn to the IrOx surface by more positive potentials only at alkaline pH. This finding cannot be explained by any of the electrolyte theories4 put up thus far, emphasizing the necessity of a detailed investigation of interfacial electrolyte structures.
References:

Arminio-Ravelo et al.
ChemPhysChem
20, (2019).

Tymoczko et al.
Catal. Today
244, (2015).

Ganassin et al.
Phys. Chem. Chem. Phys.
17, (2015).

Waegele et al.
J. Chem. Phys.
151, (2019).

Figure 1