bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) Nitrogen-Doped High-Entropy Alloy as Efficient and Stable Electrocatalyst
Authors: Zhao Xueru , Cheng Hao , Chen Xiaobo , Zhang Qi , Li Chenzhao , Xie Jian , Marinkovic Nebojsa S. , Ma Lu , Zheng Jin-Cheng , Sasaki Kotaro 
Published: August 2024

The development of Pt-based catalysts for use in fuel cells that meet performance targets of high activity, maximized stability, and low cost remains a huge challenge. The high-entropy alloy (HEA) is one of the most promising candidates for electrocatalysts, owing to their unique properties involving the high entropy effect, lattice distortion effect, sluggish diffusion effect, and “cocktail” effect.1 Alternatively, nitrogen (N)-doping effects have been well documented and demonstrated in our previous studies, which further fine-tune the adsorption energetics of intermediates and improve the corrosion resistance by the pinning effect of metal-nitrogen bonds.2-3 Combining the HEA and N-doping strategies, the tailored lattice and interstice atomic sites lead to the formation of chemically stable multiple metal-nitrogen (M-N) bonds and the generation of the possible synergistic effect on promoting ORR performance. Herein, we report a N-doped high-entropy alloy (HEA) electrocatalyst that consists of a Pt-rich shell and a N-doped PtCoFeNiCu core on a carbon support (denoted as N-Pt/HEA/C). The N-Pt/HEA/C catalyst showed high mass activity of 1.34 A mgPt
-1 at 0.9 V for the oxygen reduction reaction (ORR), which substantially outperformed commercial Pt/C and most of the other binary/ternary Pt-based catalysts. The N-Pt/HEA/C catalyst also demonstrated excellent stability in both rotating disk electrode (RDE) and membrane electrode assembly (MEA) testing. Using operando X-ray absorption spectroscopy (XAS) measurements and theoretical calculations, we revealed that the enhanced ORR activity of N-Pt/HEA/C originated from the optimized adsorption energy of intermediates, consequent of the tailored electronic structure formed upon the N-doping. Furthermore, we showed that the multiple metal-nitrogen bonds formed synergistically improved the corrosion resistance of the 3d transition metals and enhanced the ORR durability.
References

Yao, Y.; Dong, Q.; Brozena, A.; Luo, J.; Miao, J.; Chi, M.; Wang, C.; Kevrekidis, I. G.; Ren, Z. J.; Greeley, J.; Wang, G.; Anapolsky, A.; Hu, L., High-entropy nanoparticles: Synthesis-structure-property relationships and data-driven discovery. Science
2022,
376 (6589), eabn3103.

Zhao, X.; Xi, C.; Zhang, R.; Song, L.; Wang, C.; Spendelow, J. S.; Frenkel, A. I.; Yang, J.; Xin, H. L.; Sasaki, K., High-Performance Nitrogen-Doped Intermetallic PtNi Catalyst for the Oxygen Reduction Reaction. ACS Catalysis
2020,
10 (18), 10637-10645.

Zhao, X.; Cheng, H.; Song, L.; Han, L.; Zhang, R.; Kwon, G.; Ma, L.; Ehrlich, S. N.; Frenkel, A. I.; Yang, J.; Sasaki, K.; Xin, H. L., Rhombohedral Ordered Intermetallic Nanocatalyst Boosts the Oxygen Reduction Reaction. ACS Catalysis
2020,
11 (1), 184-192.
Enhancing Anode Reversal Tolerance by Low-Carbon and Carbon-Free Anode Catalyst Layers for Proton Exchange Membrane Fuel Cells
Authors: Li Zheng , Huang Haodong , Lin Xiao , Zhang Zijie , Zhao Tianshou , Zeng Lin 
Published: August 2024

Proton exchange membrane fuel cells (PEMFCs), as the main hydrogen utilization device, are considered a powerful tool for accelerating a carbon-neutral society. However, durability and cost are the two main obstacles to the commercialization of PEMFCs. Specifically, the anode reversal has been extensively studied as a severe issue that deteriorates the performance and durability of PEMFCs and leads to cell failure. Commercially, iridium oxide (IrOx) or iridium black is intensively utilized as oxygen evolution reaction catalysts to fabricate reversal tolerant anodes (RTAs) despite the slight performance loss. However, previous studies concentrated on investigating the origin or phenomena during the cell-reversal, the key factors and mechanisms affecting the anti-reversal performance, and the interaction among the anode catalyst layer components are still yet to be explored.
Hence, we systematically studied the performance using three typical carbon supports with three metal contents and different metal deposition orders by experiments and model calculations. First, we synthesized Ir outside Ir/Pt/C and Pt outside Pt/It/C with uniform nanoparticle size and distribution and characterized them comprehensively. A new parameter, “relative metal coverage”, is put forward to evaluate and predict the anti-reversal ability, showing that higher relative metal coverage results in a longer reversal time and lower polarization performance degradation rate. In addition, Ir outside Ir/Pt/C shows better reversal tolerance than Pt outside Pt/It/C, which has been rarely mentioned in previous studies. Further, the experimental results show that even though the metal coverage is high, the performance degradation caused by carbon corrosion is still inevitable. On this basis, we synthesized a high specific surface area conductive oxide Ti4O7 as the anode catalyst support to eliminate the adverse effects of carbon corrosion. Previously, the initial performance of Ti4O7-supported catalyst was obstructed by the disadvantaged electrical conductivity of Ti4O7. We obtain a comparable polarization performance after optimizing the Ti4O7-supported anode catalyst layer parameters by shortening the electron transfer pathway and increasing metal coverage. Typically, the Ir@IrOx/Pt/Ti4O7-fabricated RTA with low Ir loading displays approximately ten times longer reversal time (6 hours) and two orders of magnitude lower degradation rate than a conventional carbon-supported counterpart. The degradation origin of the Ti4O7-supported anodes is also studied by postmortem characterizations, pointing to the Pt oxidation caused by the formation of TiOx thin layers on the Pt surface. These two works aim to promote the development of highly durable and reversal tolerance anode and provide a bright perspective for practical high-performance, low-degradation, and cost-friendly RTA fabrication.
Advancements in Electrocatalysts for Low-Temperature CO2 Electrolysis: Progress and Insights from the ECO2Fuel Project
Authors: Huq Faria 
Published: August 2024

The Electrochemical CO2 Reduction Reaction (CO2RR) represents a cutting-edge approach for converting CO2 into valuable chemicals and fuels, marking a significant stride in energy storage through chemical bonds. This innovative method ingeniously merges the well-established water splitting reaction with Fischer-Tropsch synthesis, traditionally dependent on high temperatures and pressures. However, uniquely, CO2RR facilitates this process under ambient conditions, combining hydrogenation with water splitting at room temperature and normal atmospheric pressure. In this context, the ECO2Fuel project, an initiative under the European Green Deal, aims to develop, implement, and validate the first-ever 1MW low-temperature direct electrochemical CO2 conversion system, poised to produce economically viable and sustainable e-fuels and chemicals.
Despite its transformative potential, the ECO2Fuel project acknowledges and addresses several pivotal challenges, including enhancing catalyst performance and selectivity, electrode longevity, mass transport optimization, averting electrolyte flooding, and mitigating the hydrogen evolution reaction.
This presentation will predominantly concentrate on refining the gas diffusion electrode at the cathode, for large-scale fuel and alcohol production via CO2RR. This electrode is composed of a gas diffusion layer, ensuring efficient CO2 transport; a catalyst layer where the reduction transpires; and a top adhesion layer to prevent catalyst delamination. These components collectively influence the electrode’s selectivity, durability, and stability.
Our discourse will delve into the intricate aspects of the catalyst layer and porous transport layer design, along with electrode manufacturing techniques, demonstrating their critical roles in achieving high faradaic efficiencies for carbonaceous fuel production. Furthermore, we will explore the nuanced operational modalities of the CO2 electrolyzer cell, focusing on strategies to curtail the parasitic side reaction of hydrogen evolution, thereby enhancing the system's overall efficiency and productivity.
This project has received funding from the European Union’s Horizon 2020 research and Innovation program under grant agreement no. 202037389.
Theoretical Investigation of the Adsorbate and Potential-Induced Stability of Cu Facets during Electrochemical CO2 and CO Reduction
Authors: Varley Joel , Yu Henry , Govindarajan Nitish , Weitzner Stephen Eric , Akhade Sneha A 
Published: August 2024

The activity and product selectivity of electrocatalysts for reactions like the carbon dioxide and carbon monoxide reduction reactions (CO2RR and CORR) are intimately dependent on the catalyst’s structure and composition. While engineering catalytic surfaces can improve performance, discovering the key sets of rational design principles remains challenging due to limitations in modeling catalyst stability under operating conditions. Herein, we perform first-principles density functional calculations adopting implicit solvation methods with potential control to study the influence of adsorbates and applied potential on the stability of different facets of model Cu electrocatalysts. Using coverage dependencies extracted from microkinetic models, we describe an approach for calculating potential and adsorbate-dependent contributions to surface energies under reaction conditions, where Wulff constructions are used to understand the morphological evolution of Cu electrocatalysts under CO2RR and CORR conditions. We identify that CO*, a key reaction intermediate, exhibits higher kinetically and thermodynamically accessible coverages on (100) relative to (111) facets, which can translate into an increased relative stabilization of the (100) facet during CO2RR. Our results support the known tendency for increased (111) faceting of Cu nanoparticles under more reducing conditions and that the relative increase in (100) faceting observed under CO2RR conditions is likely attributed to differences in CO* coverage between these facets.
This work was partially performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 and partially supported by the U.S. DOE, Office of Energy Efficiency and Renewable Energy, Advanced Materials & Manufacturing Office.
(Invited) Dynamic Operation of Solid Oxide Electrolyzers
Authors: Tucker Mike C , Zhu Zhikuan 
Published: August 2024

Electrolysis of steam to generate hydrogen is expected to be a highly dynamic operation if renewable resources such as wind and solar are used as the electrical power input. Rapid fluctuation of input power and intermittent operation of the solid oxide electrolysis stack will result in transient operating conditions at the cell level. All operating variables such as temperature, steam content, voltage, flow rate, etc. may change rapidly in these conditions.
To address this situation, this work operates Ni/YSZ-supported and metal-supported cells under highly dynamic conditions, with individual variables isolated. The cells are remarkably robust to dynamic operation. A safe range is found for each operating variable, with accelerated degradation observed outside that range in certain cases. For example, cycling Ni/YSZ-supported cells between 1.3 V and 1.6V at 750°C and 50:50 H2O:H2 is tolerated well, but increasing the upper voltage to 1.7 V and higher leads to increased degradation. Additionally, Steam:hydrogen ratio is cycled between 3:97 and 75:25. Temperature is cycled between 150 and 800°C. Operation is cycled between fuel cell and electrolysis modes, with synchronized steam content. Metal-supported cells tolerate steam cycling, voltage cycling, temperature cycling and redox cycling, and results for button cells and 50 cm2 planar cells will be reported. In many cases, hold times are 1 minute, allowing thousands of cycles to be accumulated over hundreds of hours of operation.
Figure 1. Dynamic cycling of a Ni/YSZ-supported button cell at 750C. (Top) Cycling between 1.3 and 1.7V with 1 min holds and 50/50 H2/H2O. (Bottom) Cycling between various steam contents at 1.3 V.

Figure 1
A Direct Dry Synthesis Route for High Purity Catalytic Nanoporous Metallic Films
Authors: Barad Hannah , Kwon Hyunah , Silva Olaya Alex Ricardo , Alárcon-Correa Mariana , Wittstock Gunther , Fischer Peer , Bartl Johannes D. 
Published: August 2024

Control of catalyst morphology is important because it affects many catalytic related properties such as, active sites, surface energy, and surface area, which can lead to tunable catalytic activity. Nanoporous metallic networks (NPMs), a morphology of interest for catalysis, contain many uncoordinated atoms at the surface and highly curved ligaments that can have a large effect on catalytic performance. Nanoporous self-supported metal structures have been synthesized in the past by dealloying of a master alloy,[1] which is a wet chemical method. This technique uses an Au-Ag alloy, from which Ag is etched away and which always results in NPMs containing residual amounts of the sacrificial metal (Ag) preventing the formation of high-purity structures. It follows that the catalytic properties of pure NPMs formed by dealloying can not be studied due to metal 'impurities' remaining in the structure. Although these 'impurities' contribute to catalytic activity and stability, it is difficult to control their amount and the systematic investigation of the 'impurity' effect is almost impossible for these NPMs.
Here, we present results obtained by using physical vapor deposition, in the form of glancing angle deposition (GLAD), together with plasma etching to form nanoporous ultra-thin metal mesh structures, in a unique and facile dry synthesis method,[2] unlike most wet chemical synthesis methods used to prepare catalysts, which result chemical waste. The nanostructured metal mesh films are suitable for catalysis as they are extremely pure and highly porous, and contain high curvature ligaments, different crystal motifs, and many grain boundaries. We present nanoporous gold films (NPGF) prepared by our method as an example material. We show that the electrochemical structural stability of the NPGF is remarkably higher than that of dealloyed nanoporous gold, which is a result of the high amount of grain boundaries. Furthermore, the electrocatalytic performance of CH3OH oxidation is measured and the results show high catalytic activity for pure NPGF.[3] Our GLAD method can be applied to various metals and enables precise mixing or doping of different materials composing the NPMs. The high porosity, active sites, and potential elemental mixing will lead to new catalysts, especially suitable for CO2 reduction to fuels and value-added chemicals.
[1] G. Wittstock, M. Bäumer, W. Dononelli, T. Klüner, L. Lührs, C. Mahr, L. V. Moskaleva, M. Oezaslan, T. Risse, A. Rosenauer, A. Staubitz, J. Weissmüller, A. Wittstock, Chem. Rev.
2023, 123, 6716.
[2] H. Kwon, H.-N. Barad, A. R. Silva Olaya, M. Alarcón-Correa, K. Hahn, G. Richter, G. Wittstock, P. Fischer, ACS Appl. Mater. Interfaces
2023, 15, 5620.
[3] H. Kwon, H.-N. Barad, A. R. Silva Olaya, M. Alarcón-Correa, K. Hahn, G. Richter, G. Wittstock, P. Fischer, ACS Catal.
2023, 11656.
Quantitative Study of Dislocation Density Effects on (100)-Orientated Cu in CO2RR
Authors: Zhang Caiwei , Wong Andrew Barnabas 
Published: August 2024

For the electrochemical CO2 reduction reaction, (CO2RR) structural defects have been reported to create key active sites. Previous reports have demonstrated the relationship between structural defects and CO2RR activities. However, an in-depth understanding of the connection between defect structure and selectivity study has proved challenging.
In this presentation, we elucidate the relationship between dislocation density, activity, and selectivity on Cu in CO2RR.
To accomplish this, we successfully synthesized (100)-oriented Cu samples with dislocation densities varying by a factor of 9, and we quantitatively studied the relationship between dislocation density and CO2RR performance.
In this work, we employ (100)-oriented Cu prepared by physical vapor deposition. This approach creates an atomically smooth surface that eliminates the differences in the relative influence based on differences in surface reconstruction and roughness factor. A suite of X-ray-based methods are applied to characterize the defect structure. Here, X-ray diffraction pole figures confirm the good epitaxial growth of Cu (100). X-ray diffraction (XRD) θ/2θ symmetrical scan are applied to facilitate calculation of the dislocation density. Unlike TEM and metallographic etching, this method provides precise structure information over large areas of the Cu catalyst.
It is demonstrated that under the potential of -1.04 V vs. RHE, the sample with the largest dislocation density favors HER more. With high dislocation density, HER and C1 products are dominant. The situation changes with the dropping dislocation density, and the best CO2RR performance is achieved at a medium dislocation density changing from 1.668 x 1015 m-2 to 1.106 x 1015 m-2, indicating a favorable catalyst surface for C-C coupled products. Here, a combination of mechanistic study via electrochemical methods and X-ray absorption spectroscopy suggests that a combination of low- and full-coordinated Cu sites is more beneficial for C-C coupling.

Figure 1
Electrochemistry of Diquinonyl Amines with an Internal Proton Source
Authors: Becker James Y. 
Published: August 2024

It is well established that quinones play an important role in various biological systems. Studying electrochemical properties of quinones affords fundamental knowledge of semi-quinone radicals formation in vivo and in vitro in different media.
Following our previous work on electrochemical properties of various quinonyl amines [1], Scheme 1 below describes seven diquinonyl amines. Noteworthy that six of them (1-6) contain an internal proton donor (‘NH’) except for the seventh one (7), in which both quinone moieties are attached to ‘NMe’ group. Their redox potentials were measured by cyclic voltammetry in dichloromethane [2].
The results show a strong dependence of the nature of substituent on the first reduction potentials, and that protonation of diquinonyl amines is feasible by internal proton source even in a non-polar medium.
References
[1] S. Bittner, S. Gorohovsky, O. Paz-Tal (Levi), J.Y. Becker, Amino Acids, 2002, 22,
71-93
[2] G. Temtsin-Krayz, S. Bittner, A. Dhiman and J.Y. Becker, "Electrochemistry of
Quinones with Respect to their Role in Biomedical Chemistry", Chem. Rec.,
2021, 21.

Figure 1
Electrochemical Hydrogenation in Action: Redefining the Production of Commodity and Fine Chemicals
Authors: Pellumbi Kevinjeorjios , Kleinhaus Julian Tobias , Wickert Leon , Wolf Jonas , junge Puring Kai , Apfel Ulf-Peter , Siegmund Daniel 
Published: August 2024

Electrocatalytic hydrogenation reactions (ECH) are increasingly recognized as promising approaches for the reductive production of both commodity and fine chemicals. Particularly when powered by renewable energies, ECH offers a sustainable alternative, avoiding the need for gaseous hydrogen, high-pressure conditions, and stoichiometric reducing agents, which often lead to excessive waste formation. Moreover, ECH processes can be conducted under mild conditions near room temperature, utilizing environmentally friendly solvents like water as a proton source. This marks them as a sustainable process for the future.1 Here, we discuss our latest advancements and challenges in advancing electrochemical hydrogenations towards significant industrial applications. We focus on critical aspects such as catalyst selection, electrode design, and the suitability of reactor concepts, illustrated through selected unsaturated organic substrates that are used industrially on a large scale. Specifically, we explore the selective semi-hydrogenation of internal and terminal alkynes as well as (di)aldehydes. Each substrate presents unique challenges and opportunities, showcasing potential pitfalls, unexpected reaction pathways, and serving as a source of inspiration for future ventures in electroorganic synthesis.1-3

References:
1) J. T. Kleinhaus, J. Wolf, K. Pellumbi, L. Wickert, S. C. Viswanathan, K. junge Puring, D. Siegmund*, U.-P. Apfel*, Chem. Soc. Rev.
2023, 52, 7305.
2) K. Pellumbi, L. Wickert, J. T. Kleinhaus, J. Wolf, A. Leonard, D. Tetzlaff, R. Goy, J. A. Medlock, K. junge Puring, R. Cao, S. Siegmund*, U.-P. Apfel*, Chem. Sci.
2022, 13, 12461.
3) J. Wolf, K. Pellumbi, S. Haridas, T. Kull, J. T. Kleinhaus, L. Wickert, U.-P. Apfel*, D. Siegmund*, Chem. Eur. J.
2023, e202303808.

Figure 1
Understanding the Role of Entropy in Promoting Electrocatalytic CO2 Reduction
Authors: Schreier Marcel , Noh Seonmyeong , Zhang Gong , Cho Yoon Jin 
Published: August 2024

A global push towards increased sustainability requires technologies that enable the long-term storage of renewable electricity and the sustainable synthesis of chemicals. The electrochemical reduction of CO2 to fuels and chemicals represents a promising avenue to meet these goals. Yet, despite extensive research, many fundamental aspects of the interfacial interactions that enable this reaction remain unclear. One simple question that has not been addressed to date is the mechanism through which the applied potential controls the rate of CO2 reduction. To provide insight, we measured CO2 reduction activation energies on Ag electrodes in the presence of different cations. Building on our earlier work (J. Am. Chem. Soc.
2016, 138, 25, 7820–7823), where some of us demonstrated the important role of structural modifications to imidazolium cations in controlling the rate of CO2 reduction reactions, we expected that these structural modifications impact the reaction rate through changes to the activation energy. However, our findings revealed a much more fascinating picture of the impact of imidazolium cations on CO2 reduction rates.
By measuring the activation energy in the presence of imidazolium cations with different structural features, we find that introducing 1-ethly-3-methylimidazolium (EMIM) results in an apparent activation energy of zero. Under these conditions, the applied potential modifies the reaction rate solely through changes to the pre-exponential factor of the Arrhenius equation.
Based on literature on homogeneous catalysis, we suggest that our finding indicates that the rate of CO2 reduction in the presence of EMIM is entirely controlled by the formation entropy of the CO2 reduction transition state, with the potential likely influencing the rate by modifying the degree of ordering of imidazolium cations at the electrode surface. We further show that proton abstraction from EMIM forms a neutral compound, resulting in the elimination of the rate enhancement. Our results provide important new insight into the mechanism through which the applied potential controls the rate of electrocatalytic reactions and we expect them to be of broad importance to a better understanding of the connection between interface structure and electrocatalytic rates.