bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Nanomembrane Coating for Advanced Electrocatalysis
Authors: Takanabe Kazuhiro 
Published: February 2024

Advanced electrocatalysis that possesses higher selectivity and durability is more and more important for the electrification of chemical processes, which is expected in the renewable energy society in the future. Electrochemical reactions are often determined by the competition between the thermodynamic redox potential and the applied potential. Because the redox potential is characteristic for determining the product, it is often difficult to adjust the selectivity just by surface chemistry. Against this background, surface modification of electrodes is a well-studied field. Surface modification improves membrane functionality and selectivity, resulting in electrocatalysts with higher productivity and selectivity. Surface protective layers are also associated with material durability, as they prevent toxic and harmful substances from approaching the surface and prevent dissolution of the electrode material into the electrolyte. We are investigating the use of "nanomembrane" coatings on electrodes to achieve better selectivity and durability.
Electrochemical reduction deposition of ultrathin layers of Cr and Mo on Pt cathodes has been shown to yield O2-tolerant hydrogen-evolving electrodes in the appropriate pH range. Electrochemical measurements indicate that these surface layers act as a membrane film. Many bulky ions and O2 molecules cannot pass through these surface layers, but H2 molecules can, consistent with electrochemical and spectroscopic measurements. First, the electrochemical properties of Pt modified with other elements such as Cr and Mo were investigated and monitored for catalytic activity under different atmospheres. Next, in-operando X-ray absorption spectroscopy (XAS) was used to investigate the working state of the material: electrochemical measurements in H2 and O2 confirmed that the oxygen reduction reaction (ORR) was severely suppressed and the hydrogen evolution reaction (HER) was maintained. XAS results also showed that the oxidation state of Pt can be freely changed by a potential sweep with or without a coating layer. We extended this work to nanofilm coating on oxygen-evolving anodes for water splitting, and succeeded in anodic deposition of a thin Ce layer on Ni-Fe electrodes; the Ce layer not only prevents unwanted ions from reaching the electrode surfaces, but also prevents Fe ions from leaching from the electrodes, thus improving the durability of the electrodes. In this presentation, key findings of these nanomembrane coatings and future prospects for selective and durable electrodes will be discussed.
Disentangling pH Effects on Electrocatalytic Reactions
Authors: Eikerling Michael , Zhu Xinwei , Huang Jun 
Published: February 2024

Electrocatalysis is the key discipline to enable breakthrough advances in electrochemical energy technology and in the conversion of CO2 into renewable fuels and value-added chemicals. However, crucial electrocatalytic reactions are afflicted with sluggish kinetics and low selectivity. The electrolyte plays a vital role for the course of an electrocatalytic reactions and, in this realm, understanding the impact of the local pH is crucial for electrocatalyst development and design. The high interest in this topic in the research community is well-reflected in the recent literature, cf., e.g., Science
2022, 375 (6579). Explanations of pH effects remain controversial, even for the simplest model reactions, i.e., the hydrogen evolution/oxidation reaction and the formic acid oxidation reaction (FAOR), since a complex interplay of multiple interacting factors, centered around the local reaction environment and kinetic effects, must be disentangled. Theory and modeling are indispensable in this context. We will present a hierarchical framework that self-consistently couples the impacts of the microkinetics, mass transport and double layer charging effects (going beyond Frumkin corrections).1,2 In our modelling work, we will assess the role of distinct phenomena and parameters at play in a step-by-step fashion. The developed framework will be demonstrated for the FAOR and other electrocatalytic reactions.

References

[1] X. Zhuet al. (2021). ACS Catalysis
11, 14521-14532.
[2] X. Zhu et al. (2023). JACS Au XXXX, XXX, XXX−XXX.

Figure 1
Nanoengineered Bifunctional Porous Ni5P4 Electrocatalyst with Accelerated Bubble Departure and Reduced Overpotential for Solar-Driven Water Splitting
Authors: Lalwani Shubra , Lu Xinnan , Yuan Lin , Abbas Abdelsalam Mohamed , Zhang TieJun , Lalwani Shubra 
Published: February 2024

To achieve the global "carbon neutral" goal and low-carbon economy by 2050-2100, hydrogen has been considered as an ideal renewable and sustainable energy carrier.1,2 The electrochemical conversion of solar energy to energy dense hydrogen fuel ensures a promising approach to generate a clean and sustainable source of energy.3,4 The integrated solar powered water electrolyzers for green hydrogen production completely eliminate all sources of carbon emissions arising from the direct power supply, towards achieving a low-carbon economy.5,6 However, large-scale solar water splitting for green hydrogen production still remains a challenge due to expensive electrocatalyst. As a low-cost, earth-abundant catalyst Nickel phosphide shows enormous potential to effectively reduce water and generate hydrogen. We propose a low-cost and facile approach to fabricate nanoengineered hierarchically porous Ni5P4 as an electrocatalyst (p-Ni5P4) providing high surface area and enabling fast gas diffusion. Nickel phosphide (p-Ni5P4@NF) has pores ranging from 50-500 nm to 200-600 μm and enlarges the electrochemically-active surface area by 5 times. The porous structure of p-Ni5P4@NF offers abundant cavities to gas nucleation and fast growth of H2 bubble, and small bubbles (10-50 µm) depart quickly owing to reduced contact line. By enhancing gas transfer and reducing bubble overpotential by 30%, p-Ni5P4@NF achieves excellent electrocatalytic performance with a low HER (145 mV), OER (197 mV) and overall water splitting potential (1.54 V) at 10 mA cm-2. Powered by multijunction PV cell, the full electrolytic cell records a high solar-to-hydrogen efficiency of 14.5 %.

Keywords: Water splitting; Electrocatalysis; Green Hydrogen; Nickel Phosphide.

References

1. Agreement P. Paris agreement. Report of the Conference of the Parties to the United Nations Framework Convention on Climate Change. 2017, Retrieved December. 4.
2. Britain, G. Our energy future: creating a low carbon economy. Stationery Office. 2003.
3. Dunn, S. Hydrogen futures: toward a sustainable energy system. J. Hydrog. Energy 2002, 27, 235-264.
4. Turner, J. A. Sustainable hydrogen production. Science 2004, 305, 972-974.
5. Zeng, M.; Li, Y. Recent advances in heterogeneous electrocatalysts for the hydrogen evolution reaction. Mater. Chem. 2015, 3, 14942-14962.
6. Han, Y.; Chen, Y.; Fan, R.; Li, Z.; and Zou, Z. Promotion effect of metal phosphides towards electrocatalytic and photocatalytic water splitting. EcoMat. 2021, 3, e12097.
(Invited) First Principles Examination of Multiple Criteria of Organic Solvent Oxidative Stability in Batteries
Authors: Leung Kevin 
Published: February 2024

Oxidative instability of the liquid electrolyte at or near battery cathode oxide surfaces has significant detrimental effects on batteries. Organic solvent molecules are often the fuel and precurors of such degradation processes, releasing electrons and protons that react with cathode oxides and electrolyte anions. These reactions contribute to cathode electrolyte interphase (CEI) film formation, transition metal ion dissolution, and phase transformation of the surface regions of the cathode. Here we apply Density Functional Theory calculations to examine four criteria of oxidative stability (oxidation potential, hydrogen removal energies, and initial reactivity on two types of oxide facets) using four different solvent/additive molecules (ethylene carbonate, fluoroethylene carbonate, 1,3-dioxolane, and dimethyl ether). The ranking of molecular stability differs with each criterion. Surprisingly, the all-oxygen terminated basal planes of layered oxides exhibit lower reaction barriers than spinel surface facets with exposed transition metal cations, especially for ether solvents; the calculations also suggest basal planes contribute to the dissolution of transition metal ions. The structure-degradation relation complexity underscores the challenge of understanding the function of the CEI, but also offers a guide to future degradation-mitigation strategies including facet-engineering. Our predictions and models help establish a framework for future studies relevant to high voltage conditions.
Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This paper describes objective technical results and analysis. Any subjective views or opinions that might be expressed in the document do not necessarily represent the views of the U.S. Department of Energy or the United States Government.
(Invited) Application of Metal Oxide Active Supports for Enhancement of Electrocatalytic Reduction of Carbon Dioxide
Authors: Rutkowska Iwona A. , Chmielnicka Anna , Siamuk Olena , Sobkowicz Karolina , Rytelewska Beata , Kulesza Pawel J. 
Published: February 2024

Of particular interest to the preparation of advanced catalytic materials is efficient utilization of catalytic sites (metal and metal oxide nanostructures, their stabilization and intentional activation, as well as organization into two-dimensional arrays, ultra-thin films or three-dimensional networks (e.g. through sequential deposition) on electrode surfaces. They can form nanosized materials with well-defined composition, structure and thickness that exhibit desirable electrocatalytic properties (e.g. toward reduction of CO2). We explore here the ability of polynuclear inorganic metal oxo systems to stabilize and functionalize metal (e.g. copper) nanostructures. Here certain nanostructured metal oxides of zirconium, titanium, zinc or tungsten have been demonstrated to influence supported metal (e.g. Cu, Fe, Ag) centers in ways other than simple dispersion over electrode area. Evidence is presented that the support can modify activity (presumably electronic nature) of the above mentioned catalytic metal nanocenters thus affecting their chemisorptive and catalytic properties. Metal oxide cocatalysts can generate –OH groups at low potentials that induce proton mobility at the photo(electro)chemical interface.
Our research interests concern development of systems for the electrocatalytic reduction of carbon dioxide not only in neutral but also in acid media. For example, nanosized Cu or Fe catalytic centers immobilized within ultra-thin films of tungsten oxide or mixed ZrO2-WO3 films have been considered and demonstrated to exhibit synergism during CO2-reduction. Selectivity of the catalytic systems largely depends on the activing adsorptive (CO2) phenomena and the affinity of catalytic centers to the adsorbed carbon monoxide (CO) type intermediates leading to their protonation or hydrogenation. Reduction of carbon dioxide begins now at less negative potentials and is accompanied by significant enhancement of the CO2-reduction current densities relative to the competitive hydrogen evolution. Among other important issues is the ability of certain metal oxides (e.g., WO3) to affect hydrogen via intra-structural sorption of hydrogen molecules or atoms.
Exploring the Mechanism of the Electrochemical Polymerization of CO2 over CeO2(110)
Authors: Keller Florian , Döhn Johannes , Gross Axel , Busch Michael 
Published: February 2024

The reduction of CO2 is a promising route for the synthesis of renewable energy carriers and the removal of CO2 from the atmosphere to limit global warming. These negative emission technologies (NETs) require the conversion of carbon dioxide into a stable and easily storable form[1]. However, despite its potential, the development of suitable CO2 reduction catalysts is still in its infancy. Indeed state of the art catalysts suffer from high overpotentials, a low selectivity between possible products and a generally low yield of post CO products with two or more carbon atoms. Catalysts which even allow for the electrochemical polymerization of CO2 and thus, the direct formation of hard carbon were completely absent until the work of Esrafilzadeh et al.[2]. Using a liquid electrocatalyst consisting of Ga, In, Sn and Ce in a n,n-dimethylformamide (DMF) electrolyte they were able to polymerize CO2 electrochemically to a carbonaceous material. They hypothesized that the active catalyst consists of a cerium oxide which is reduced to metallic Ce in the process. However, no direct proof for this hypothesis was provided. Also a possible mechanism which could lead to the reported products is so far unknown.
In this contribution we will explore the reaction mechanisms for the electrochemical polymerization of CO2 using density functional theory (DFT) modelling. In the initial step, the most likely active sites at Ce oxide are identified. This is then followed by a detailed analysis of the reaction route which is based on well known mechanisms in organic chemistry. We find that an oxygen defect rich CeO2(110) surface is most likely present under reaction conditions. [3] The reaction over this surface is initialized at oxygen defect sites. Chain propagation is then achieved through an electrochemical aldol condensation type mechanism (Figure 1). [3]

References

1 J. Hilaire, J. C. Minx et al., Climatic Change, 2019, 157, 189.
2 D. Esrafilzadeh, A. Zavabeti et al., Nature. Commun., 2019, 10, 865.
3 F. Keller, J. Döhn, A. Groß, M. Busch, in preparation.

Figure 1
Zn-Based Catalysts for Selective and Stable Electrochemical CO2 Reduction at High Current Densities
Authors: Stamatelos Ilias , Dinh Cao Thang , Lehnert Werner , Pasel Joachim , Shviro Meital 
Published: February 2024

The development of low-cost and stable catalysts is important for lowering the capital and operational cost of CO2 electro-reduction (ECR). Zinc (Zn) is an earth-abundant metal, with promising performance for the CO2-to-CO conversion.1 Zinc oxide (ZnO) has been recently employed for the CO2-to-CO conversion, recording promising selectivity (FECO) but short-term stability, in Flow-Cell configuration.2,3 ZnO phase has been proven critical for competent ECR performance, since both the oxidation state of Zn and the Zn/ZnO interface are proven critical for high FECO. 4,5In our work 6, we have synthesised various ZnO allotropes, the properties of which induced differences in their ECR performance. We have identified the ZnO nanorods (ZnO-NR) as the best performing catalyst. The latter was implemented in a zero-gap ECR electrolyser (MEA), recording partial current density for CO (jCO) of 160 mA cm-2 at cell voltage of 3.6 V. We have correlated the depletion of the ZnO phase in the MEA with the degradation of the performance (initially 15 h stability). We applied a periodic oxidation protocol in the MEA, causing the regeneration of ZnO-phase, allowing us to prolong the life-time of the catalyst. Through our strategy we were able to record 82% CO selectivity (FECO) for over 100 h, at -160 mA cm-2. This work provides an approach of practical use of inexpensive Zn-based catalysts for large-scale ECR applications.
(1) Luo, W.; Zhang, J.; Li, M.; Züttel, A. Boosting CO Production in Electrocatalytic CO2 Reduction on Highly Porous Zn Catalysts. ACS Catal.
2019, 9 (5), 3783–3791. https://doi.org/10.1021/acscatal.8b05109.
(2) Zeng, J.; Fontana, M.; Sacco, A.; Sassone, D.; Pirri, C. F. A Study of the Effect of Electrode Composition on the Electrochemical Reduction of CO2. Catalysis Today
2021. https://doi.org/10.1016/j.cattod.2021.07.014.
(3) Zong, X.; Jin, Y.; Li, Y.; Zhang, X.; Zhang, S.; Xie, H.; Zhang, J.; Xiong, Y. Morphology-Controllable ZnO Catalysts Enriched with Oxygen-Vacancies for Boosting CO2 Electroreduction to CO. Journal of CO2 Utilization
2022, 61, 102051. https://doi.org/10.1016/j.jcou.2022.102051.
(4) Nguyen, D. L. T.; Jee, M. S.; Won, D. H.; Jung, H.; Oh, H.-S.; Min, B. K.; Hwang, Y. J. Selective CO2 Reduction on Zinc Electrocatalyst: The Effect of Zinc Oxidation State Induced by Pretreatment Environment. ACS Sustainable Chem. Eng.
2017, 5 (12), 11377–11386. https://doi.org/10.1021/acssuschemeng.7b02460.
(5) Geng, Z.; Kong, X.; Chen, W.; Su, H.; Liu, Y.; Cai, F.; Wang, G.; Zeng, J. Oxygen Vacancies in ZnO Nanosheets Enhance CO2 Electrochemical Reduction to CO. Angewandte Chemie International Edition
2018, 57 (21), 6054–6059. https://doi.org/10.1002/anie.201711255.
(6) Stamatelos, I.; Dinh, C.-T.; Lehnert, W.; Shviro, M. Zn-Based Catalysts for Selective and Stable Electrochemical CO2 Reduction at High Current Densities. ACS Appl. Energy Mater.
2022. https://doi.org/10.1021/acsaem.2c02557.

Figure 1
Understanding Performance Fading during CO Electrolysis in Zero Gap Electrolyzers
Authors: Ayyub Mohd Monis , Serfőző Andrea , Endrődi Balázs , Janaky Csaba 
Published: February 2024

Electrochemical CO reduction (ECOR) can act as a potential bridge between CO2-to-CO technologies and renewable production of C2+ chemicals. Copper has been the most widely studied cathode catalyst for ECOR because of its unique ability to produce multicarbon products. Iridium and nickel are the most-widely used anode materials for acidic and alkaline electrolysis, respectively. However, recent reports on the instability of Ir in alkaline conditions and Ni in near neutral conditions has made it imperative to understand the anodic processes for achieving stable long term operation at high current densities for CO2/CO electrolysers.
In this work, our aim was to investigate anode catalysts for ECOR at high current densities in zero gap electrolyser. Commercial Cu nanoparticles (25 nm) was used as the cathode catalysts with Ir black anode in alkaline conditions. Initially, CORR was studied in a hybrid cell with a catalyst coated anion exchange membrane and recirculated catholyte and anolyte. In this cell configuration we observe stable production of ethylene, acetate and ethanol for a total current density of upto 500 mA cm-2. However, in the zero gap electrolyser the catalytic activity decays rapidly (2-3 minutes) and leads to predominance of hydrogen evolution reaction (HER).
Analysis of the cathode and anolyte after electrolysis reveals the dissolution of Ir and subsequent deposition at the cathode. This rapid decay is counter intuitive since the dissolution of Ir in alkaline solutions is very slow and should take a few hours to affect the catalytic activity. More importantly this dissolution of Ir does not happen when Ar is circulated at the cathode instead of CO, which indicates that the Ir dissolution is not entirely due to the alkaline environment. NMR analysis of the anolyte shows the presence of CO reduction products acetate and ethanol. Therefore, it is possible that the presence of CO reduction products could aggravate the Ir dissolution. This study is currently underway to analyse the possible Ir dissolution mechanisms. This is an important observations since Ir is still the most widely used anode catalyst for CO electrolysis. This also stresses on the need to explore alternative anode catalysts and/or design strategies that can circumvent the migration of reduction products to the anode.
(Keynote) Single Atom Co-Catalysts in Photocatalytic H2 Generation
Authors: Schmuki Patrik 
Published: February 2024

Photocatalytic H2 generation has been a highly investigated topic ever since Fujishima und Honda (1972) reported on the use of TiO2 as a solar-illuminated semiconductor for the splitting of water into H2 and O2. Generally, in a fully photocatalytic setting (when photogenerated electron and hole are transferred from a solution-suspended TiO2 nanoparticle to an aqueous electrolyte), a reasonable electron transfer rate can only be established when a noble metal co-catalyst is attached to the TiO2. Mostly this is a Pt nanoparticle that is deposited onto the TiO2 by various reductive treatments. Over the years numerous efforts have been devoted to the shrinkage of the particle to enhance the usage of the noble metal. Evidently the most extreme case shrinkage is the use of an insulated single atom of Pt. The use of such isolated atoms as a co-catalyst in photocatalysis has in recent years attracted strong interest, not only because the single atom state represents a maximized surface to volume efficiency, but also because single atom reactivity allows for unprecedented reaction pathways. In the presentation we discuss the use of Pt dispersed and anchored as single atoms on TiO2 nanocrystallites, powders and nanotubes as a co-catalyst in photocatalytic H2 generation. We discuss various trapping and stabilization approaches of SAs on photocatalysts and report on a SA-Pt photocatalyst with a higher photocatalytic activity than observed for classic arrangements of co-catalyst on the semiconductive substrate. Moreover, we show that a small fraction of the totally deposited Pt that is stably trapped SAs provides virtually all photocatalytic reactivity of a Pt decorated catalyst.

References

1) C. Gao, J. Low, R. Long, T. Kong, J. Zhu and Y. Xiong, Chem. Rev., 2020, 120, 12175-12216.
2) N. Denisov, S. Qin, J. Will,, T. Yokosawa, .. and P. Schmuki, Adv. Mater., 2022, n/a, 2206569.
3) S. Hejazi, ..O. Tomanec, S. Kment, and P. Schmuki, Adv.
Mater., 2020, 32, 1908505.
4) S. Qin, N. Denisov, J. Will, ..E. Spiecker and P. Schmuki, Solar RRL, 2022, 6, 2101026.
5) S. Qin, J. Will, H. Kim, N. Denisov, S. Carl, E. Spiecker and P. Schmuki, ACS Energy Lett., 2023, DOI: 10.1021/acsenergylett.2c02801, 1209-1214.
6) I. Hwang, A. Mazare, ..and P. Schmuki, Adv. Funct. Mater., 2022, n/a, 2207849.
(Invited) DFT Studies on Interactions between Heteropolyacids, Noble Metal Ions, and TiO2 Support
Authors: Tokarz-Sobieraj Renata , Niemiec Piotr , Rutkowska-Zbik Dorota 
Published: February 2024

Heteropolycompounds of Keggin structure have been used as homogeneous and heterogeneous catalysts for decades. Recently, they gained popularity in photo- and electrocatalysis where they can be used as components of complex materials e.g., composed of metal ions/heteropolyacids/oxide-based supports.
The aim of the current theoretical studies is to characterize systems comprising of free and TiO2-supported heteropolyanions (PW12O40
3-, PMo12O40
3-) with embedded noble metal ions (Ag, Au, Cu, Pd, and Pt) acting as single atom catalysts. Their ground-state geometric and electronic structures were elucidated. Next, their redox and photochemical properties were determined: frontier (HOMO, LUMO) orbitals were defined, energy gaps and UV-VIS spectra were calculated, total and partial density of states were plotted and analysed. The interactions between components of the systems, in particular the influence of the support on the heteropolycompound electronic structure, were investigated. Next, the reactivity of the noble metal cations towards typical reagents (CO, H2, CH3, and C6H6) was studied.
The performed calculations demonstrated that the type of the metal and its oxidation state determines the energetics and character of the frontier orbitals, bond lengths and bond orders in their first coordination sphere, incl. the strength of their interactions with common reagents. The presence of TiO2 as the support is manifested by the emergence of new metal ion sitting sites, usually located at the interface between the heteropolyacid and the support, and modification of the redox properties of the systems.
Acknowledgements: This work was supported by the National Science Centre, Poland within Solar-Driven Chemistry project no 2019/01/Y/ST4/00024.