Alekseenko, Anastasia Anatoyevna

Alekseenko A.A., Paperzh K.O., Pavlets A.S., Belenov S.V., Moguchikh E.A., Nevelskaya A.K., Bayan Y.A., Danilenko M.V., Pankov I.V., Guterman V.E.

Guterman V., Alekseenko A., Belenov S., Menshikov V., Moguchikh E., Novomlinskaya I., Paperzh K., Pankov I.

Bimetallic platinum-containing catalysts are deemed promising for electrolyzers and proton-exchange membrane fuel cells (PEMFCs). A significant number of laboratory studies and commercial offers are related to PtNi/C and PtCo/C electrocatalysts. The behavior of PtPd/C catalysts has been studied much less, although palladium itself is the metal closest to platinum in its properties. Using a series of characterization methods, this paper presents a comparative study of structural characteristics of the commercial PtPd/C catalysts containing 38% wt. of precious metals and the well-known HiSpec4000 Pt/C catalyst. The electrochemical behavior of the catalysts was studied both in a three-electrode electrochemical cell and in the membrane electrode assemblies (MEAs) of hydrogen–air PEMFCs. Both PtPd/C samples demonstrated higher values of the electrochemically active surface area, as well as greater specific and mass activity in the oxygen reduction reaction in comparison with conventional Pt/C, while not being inferior to the latter in durability. The MEA based on the best of the PtPd/C catalysts also exhibited higher performance in single tests and long-term durability testing. The results of this study conducted indicate the prospects of using bimetallic PtPd/C materials for cathode catalysts in PEMFCs.

Paperzh K., Bayan Y., Gerasimov E., Pankov I., Konstantinov A., Menshcikov V., Mauer D., Beskopylny Y., Alekseenko A.

To accelerate the implementation of zero-emission power installations based on proton-exchange membrane fuel cells, it is necessary to maximize the power characteristics of these devices. For this purpose, we have obtained and tested a new N-doped carbon support and a synthesized Pt/C catalyst based on it with a platinum loading of about 37.3 %. A comparison of the degradation resistance of the initial support and the N-doped one has shown greater stability of the latter. At the same time, Raman spectroscopy has confirmed the presence of the C–N bond, which indicates the successful doping of carbon with nitrogen. The resulting Pt/C catalyst based on an N-doped support is characterized by a substantially narrow size dispersion and an ultra-small nanoparticle size of about 2.6 nm. The high-angle annular dark-field scanning transmission electron microscopy images of the synthesized catalyst have confirmed the presence of individual platinum atoms/clusters uniformly distributed over the surface of the support, and their presence is due to nitrogen embedded into the carbon structure. This material is characterized by a 50 m2 gPt-1 larger electrochemically active surface area and a 227 A gPt-1 greater mass activity compared to the commercial JM40 analog (40 % platinum loading). Meanwhile, the electrochemical parameters remaining after the accelerated stress testing are almost 2 times higher than those of JM40. And the power characteristics in the membrane electrode assembly for the catalyst synthesized by the facile one-pot synthesis method are 13 % (575 mW cm-2) higher than those of the commercial analog (500 mW cm-2). The Pt/C catalyst obtained during the research is deemed promising for commercial use in proton-exchange membrane fuel cells.

Pavlets A., Pankov I., Moguchikh E., Suprun E., Gerasimov E., Guterman V., Alekseenko A.

Pavlets A., Tolstunov M., Pankov I., Belenov S., Alekseenko D., Alekseenko A.

A high-performance electrocatalyst based on bimetallic platinum-containing nanoparticles for PEMFCs has been presented. The combination of bimetallic nanoparticles and an N-doped carbon support ensures high ORR activity and stability of the catalyst. The single-reactor method to obtain the material and its higher functional characteristics allow considering the resulting PtCu/C-N electrocatalyst as a promising commercial product. An extended study of morphological characteristics has been conducted to understand the processes of evolution for this material. The in-situ IL-TEM research has allowed studying in detail the degradation process for the material during high-temperature treatment by analyzing changes in the type of histograms of the nanoparticles size distribution and testing the method for calculating the number of their intersections to assess the dynamics of the material degradation.

Bayan Y., Paperzh K., Pankov I., Alekseenko A.

There are numerous carbon materials that are deemed promising for use as supports in electrocatalysts for PEMFCs. We have carried out a comparative analysis of compositional, morphological and electrochemical characteristics of the platinum–carbon catalysts synthesized by a single method on various carbon supports (Vulcan XC-72, Ketjenblack EC-300 J, Ketjenblack EC-600JD and N-doped Ketjenblack EC-600JD) and the commercial electrocatalyst. The Pt/C materials obtained on highly dispersed supports (from 800 m2 g−1) exhibit almost 1.5 times greater ORR activity compared to those with a specific surface area of less than 250 m2 g−1. Doping of a highly dispersed support with nitrogen leads to a 30 % increase in the durability of the catalysts based thereon. The resulting Pt/C on the N-doped support exhibits an ESA of more than 110 m2 g−1 and an ORR mass activity of about 430 A g-1Pt, which correspond to the DOE targets and are 1.6 and 1.7 times higher than those of the commercial analog.

Belenov S., Mauer D., Moguchikh E., Gavrilova A., Nevelskaya A., Beskopylny E., Pankov I., Nikulin A., Alekseenko A.

The presented study is concerned with a new multi-step method to synthesize PtCo/C materials based on composite CoxOy/C that combines the advantages of different liquid-phase synthesis methods. Based on the results of studying the materials at each stage of synthesis with the TG, XRD, TEM, SEI, TXRF, CV and LSV methods, a detailed overview of the sequential changes in catalyst composition and structure at each stage of the synthesis is presented. The PtCo/C catalyst synthesized with the multi-step method is characterized by a uniform distribution of bimetallic nanoparticles of about 3 nm in size over the surface of the support, which result in its high ESA and ORR activity. The activity study for the synthesized PtCo/C catalyst in an MEA showed better current–voltage characteristics and a higher maximum specific power compared with an MEA based on a commercial Pt/C catalyst. Therefore, the results of the presented study demonstrate high prospects for the developed approach to the multi-step synthesis of PtM/C catalysts, which may enhance the characteristics of proton-exchange membrane fuel cells (PEMFCs).

Nevelskaya A.K., Belenov S.V., Pavlets A.S., Menshikov V.S., Pankov I.V., Nikolskiy A.V., Kozakov A.T., Moguchikh E.A., Alekseenko A.A.

In this article, we have studied the influence of the heat treatment in an inert atmosphere on the structure and catalytic activity of the PtCu/C catalysts with an architecture of bimetallic nanoparticles obtained by a multi-step synthesis method. The transformation of the structure obtained by a multi-step synthesis method into a solid solution during the heat treatment at 350 °C has been shown by the methods of high-resolution TEM and XPS. It has been found that regardless of the type of a carbon support used, the heat treatment leads to an increase in the specific mass activity by 1.4–1.6 times. The increase in the catalytic activity after the heat treatment is achieved due to a change in the chemical composition of the surface and an increase in the degree of alloying of metal components. Due to the combination of the heat treatment and the use of a nitrogen-doped carbon support, we have succeeded in obtaining the PtCu/C catalyst, the ORR activity of which is 6.4 times higher than that of the commercial analog. Testing of the most promising samples as part of the MEA has confirmed the high quality of the materials obtained, the maximum power being 696 W/g (Pt) for the PtCu/C catalyst after the heat treatment.

Moguchikh E.A., Pavlets A.S., Novomlinskaya I.A., Pankov I.V., Aydakov E.E., Kaichev V.V., Nikolskiy A.V., Kozakov A.T., Alekseenko D.V., Alekseenko A.A.

Bayan Y., Paperzh K., Danilenko M., Alekseenko D., Pankova Y., Pankov I., Alekseenko A.

One of the key components of low-temperature fuel cells with a proton-exchange membrane is an electrocatalyst contained in the porous electrodes. The most widespread synthesis methods are the liquid-phase ones that allow controlling the microstructure of the catalyst and, thus, its functional parameters. We have investigated the influence of various conditions of the liquid-phase synthesis on the morphological and electrochemical characteristics of the resulting platinum–carbon catalysts. An increase in the synthesis temperature has been established to allow for the narrowing of the size dispersion and the decrease in the average size of platinum nanoparticles. It has been found that the presence of a carbon support during the synthesis makes it possible to enhance the uniformity of the Pt NPs’ distribution over the surface of the support and decreasing the average particle size. As a result, the values of the active surface area grow almost 1.2–2 times compared to the homogeneous synthesis, during which the resulting colloid of platinum particles is deposited on the carbon support after the reduction. When using the molar ratio of hydroxyl groups/platinum in the range from 5 to 20 during the synthesis, the resulting Pt/C catalysts are characterized by an active surface area of more than 85 m2·g−1Pt. The possibility of scaling the synthesis method to obtain at least 1 g of the catalyst, which is not inferior in functional parameters to its commercial analog both before stress testing and after its completion, is also shown.

Pavlets A., Kozhokar E., Astravukh Y., Pankov I., Nikulin A., Alekseenko A.

Production of highly efficient platinum-containing catalysts for PEMFC cathode is an urgent task for the development of hydrogen energy. Fifteen bimetallic catalysts for the ORR were synthesized by various modified borohydride synthesis methods using de-alloying treatment. Of these, 33.3% PtNi/C and 33.3% PtCu/C materials were subjected to acid treatment, 13.3% PtNi/C and 20% PtCu/C were subjected to electrochemical leaching. A comprehensive assessment of the composition and structure of the catalysts was carried out using TEM, STEM, XRD, TXRF, and EDX methods. The electrochemical behavior of the materials was estimated by cyclic and linear voltammetry. The resulting bimetallic catalysts exceed the commercial Pt/C analogue in the ORR mass activity by 1.2–4.3 times. Most of the studied PtM/C catalysts (66.6%) exceed the DOE target 2025 (440 A/gPt). According to the results of the study, PtCu/C catalysts, subjected to electrochemical de-alloying, are considered promising for use in PEMFC MEA.

Alekseenko A., Belenov S., Mauer D., Moguchikh E., Falina I., Bayan J., Pankov I., Alekseenko D., Guterman V.

Studying the ORR activity of platinum-based electrocatalysts is an urgent task in the development of materials for proton-exchange membrane fuel cells. The catalytic ink composition and the formation technique of a thin layer at the RDE play a significant role in studying ORR activity. The use of a polymer ionomer in the catalytic ink provides viscosity as well as proton conductivity. Nafion is widely used as an ionomer for research both at the RDE and in the MEA. The search for ionomers is a priority task in the development of the MEA components to replace Nafion. The study also considers the possibility of using the LF4-SK polymer as an alternative ionomer. The comparative results on the composition and techniques of applying the catalytic layer using LF4-SK and Nafion ionomers are presented, and the influence of the catalytic ink composition on the electrochemical characteristics of commercial platinum–carbon catalysts and a highly efficient platinum catalyst based on an N-doped carbon support is assessed.

Paperzh K., Alekseenko A., Pankov I., Guterman V.

The degradation of the nanostructured platinum-based electrocatalysts during their operation poses a major problem for the performance and durability of PEMFCs and devices based on them. Therefore, the methodological aspects of research related to the quantitative assessment of the materials’ degradation as well as the mechanism of the processes causing it are gaining increasing attention. The degradation processes of the same Pt/C catalyst containing the nanoparticles of similar size uniformly distributed over the surface of the carbon support were studied using eight relevant protocols of the accelerated stress testing. Special attention was paid to electron microscopy examination of the catalyst’s microstructure before and after stress tests as well as to determination of the electrochemically active surface area and the activity of the catalyst in the ORR after the stress testing. We also studied the influence of the atmosphere, in which testing was performed, as well as the effect of the electrode rotation on the degradation rate. The results of the study carried out demonstrate the features of the catalyst’s degradation in different modes and facilitate the choice of optimal protocols and stress testing conditions.

Pavlets A., Titskaya E., Alekseenko A., Pankov I., Ivanchenko A., Falina I.

This work is aimed at studying the electrochemical behavior of the MEA containing the bimetallic catalysts with an alloy structure. The relevance of the study is associated with application of a simple method to synthesize the bimetallic catalysts using the acid post-treatment to obtain de-alloyed nanoparticles with an increased activity in the oxygen reduction reaction, a performance stability during the long-term stress testing, and a composition stability during the operation. The novelty of the work consists in a detailed consideration of the mechanisms of poisoning the MEA's components by copper cations formed during a selective dissolution of the catalysts' components as well as the mechanisms of the proton-exchange membrane degradation.

Bayan Y.A., Paperzh K.O., Pankov I.V., Pavlets A.S., Moguchikh E.A., Alekseenko A.A.

Finding the optimal substrate for electrocatalysts used as electrodes in fuel cells is an urgent task for the development of hydrogen energetics. The composition and the morphological and electrochemical properties of platinum–carbon catalysts synthesized according to a common method on various carbon supports (Vulcan XC-72, Vulcan XC-72R, Ketjenblack EC-300J, Ketjenblack EC-600JD, and modified Ketjenblack EC-600JD) and of a JM-20 commercial electrocatalyst are analyzed comparatively. It is found that highly dispersed supports (from 800 m2/g) make it possible to increase the catalytic activity of Pt/C materials in the electroreduction reaction of oxygen by two times compared to those with a specific surface area of less than 250 m2/g. The preliminary treatment of a carbon support with melamine increases the stability of catalysts based on it by 40%. A platinum-carbon catalyst with a 1.6-times-higher electrochemically active surface area and 1.7-times-higher mass activity in the reaction of oxygen electroreduction compared to a commercial analogue is obtained.

Gao Y., Cao J., Chen C.

Chen J., Liu J., Zhu Y., Shi J., Cai W., Lu L.

Choi J., Lee E., Woo S., Whang Y., Kwon Y., Seo M., Cho E., Park G.

Chen C.H., Coats M., Chabot F., Morimoto Y., Atanassov P., Tamura N., Braaten J., Stühmeier B.M., Johnston C., Pylypenko S., Cheng L., Zenyuk I.V.

AbstractAs an emerging technology, polymer electrolyte fuel cells (PEFCs) powered by clean hydrogen can be a great source of renewable power generation with flexible utilization because of high gravimetric energy density of hydrogen. To be used in real‐life applications, PEFCs need to maintain their performance for long‐term use under a wide range of conditions. Therefore, it's important to understand the degradation of the PEFC under protocols that are closely related to the catalyst lifetime. Alloying Pt with transitional metal improves catalyst activity. It is also crucial to understand Pt alloys degradation mechanisms to improve their durability. To study durability of Pt alloys, accelerated stress tests (ASTs) are performed on Pt−Co catalyst supported on two types of carbon. Two different AST protocols were being studied: Membrane Electrolyte Assembly (MEA) AST based on the protocol introduced by the Million Mile Fuel Cell Truck consortium in 2023 and Catalyst AST, adopted from the U.S. Department of Energy (DoE).

Meléndez-González P.C., Méndez-Vázquez J.F., Pech-Rodríguez W.J., Rodríguez-Varela F.J., Karinjilottu-Padmadas P.

Alekseenko A.A., Paperzh K.O., Pavlets A.S., Belenov S.V., Moguchikh E.A., Nevelskaya A.K., Bayan Y.A., Danilenko M.V., Pankov I.V., Guterman V.E.

Santiago-Ramírez C.R., Hernández-Pichardo M.L., Manzo-Robledo A., Acuña-Leal D.A., Gracia-Pinilla M.A.

The electrocatalytic reduction of nitric oxide and nitrogen dioxide (NOx) remains a significant challenge due to the need for stable, efficient, and cost-effective materials. This study presents a novel support system for NOx reduction in alkaline media, composed of ZrO2-WO3-C (ZWC), synthesized via coprecipitation. Platinum nanoparticles (10 wt.%) were loaded onto ZWC and Vulcan carbon support, using similar methods for comparison. Comprehensive physicochemical and electrochemical analyses (N2 physisorption, XRD, XPS, SEM, TEM, and cyclic and linear voltammetry) revealed that PtZWC outperformed PtC and commercial PtEtek in NOx electrocatalysis. Notably, PtZWC exhibited the highest total electric charge for NOx reduction. At the same time, the hydrogen evolution reaction (HER) was shifted to more negative cathodic potentials, indicating reduced hydrogen coverage and a modified dissociative Tafel mechanism on platinum. Additionally, the combination of WO3 and ZrO2 in ZWC enhanced electron transfer and suppressed HER by reducing NO and hydrogen atom adsorption competition. While the incorporation of WO3 and ZrO2 lowered the surface area to 96 m2/g, it significantly improved pore properties, facilitating better Pt nanoparticle dispersion (3.06 ± 0.85 nm, as confirmed by SEM and TEM). XRD analysis identified graphite and Pt phases, with monoclinic WO3 broadening PtZWC peaks (20–25°). At the same time, XPS confirmed oxidation states of Pt, W, and Zr and tungsten-related oxygen vacancies, ensuring chemical stability and enhanced catalytic activity.

Astravukh Y.V., Pavlets A.S., Beskopylny E.R., Pankov I.V., Guterman V.E., Alekseenko A.A.

Seo D., Park D., Park S., Gu Y., Lim D., Hong C., Han J., Kim J., Jang J., Kim E., Yun J., Jo H., Park K.

Fuentez-Torres M.O., Rodríguez-Varela F.J., Sánchez-Castro M.E., Escobar-Morales B., Pech-Rodríguez W.J., Alonso-Lemus I.L.

In this study, Vulcan XC-72 (C) and sewage sludge-derived biocarbon (SSB) are functionalized with mesitylcopper (Cu-mes) and implemented to produce the low-Pt content and thus low-cost (5 wt %) Pt/CCu-mes10, Pt/CCu-mes20, Pt/SSBCu-mes10, and Pt/SSBCu-mes20 nanocatalysts. This approach facilitates the generation of various functional groups along with the CuO and Cu2O phases. The nanocatalysts show the formation of the PtCu3 alloy, with the two first having an atomic fraction of Cu alloyed (XCu) of 55 and 67%, respectively. Pt/CCu-mes10 shows a comparable catalytic activity for the oxygen reduction reaction (ORR) before and after an accelerated degradation test (ADT) to 20 wt % Pt/C and 5 wt % Pt/C. It also shows the highest performance for the oxygen evolution reaction (OER), with remarkable electrochemical stability. The outstanding performance of Pt/CCu-mes10 is attributed to the presence of Cu-phases, its high degree of alloying and its d-band center which favorably promotes the adsorption of O-species and their further reaction. Specifically, the PtCu3 alloy promotes the kinetics of the reactions by modulating the electronic properties of Pt and creating dual active sites. Meanwhile, Pt/SSB demonstrates an encouraging performance for the reactions before ADT, with electrochemical parameters similar to those of 20 wt % Pt/C. However, its stability is poor, with low catalytic activity after ADT. Therefore, it is found that there is a significant effect of the electrochemical behavior of the carbon support on the performance and stability of the nanocatalysts. The potential application of Pt/CCu-mes10 in water splitting devices is identified.

Kastsova Angelina G., Krasnova Anna O., Glebova Nadezhda V., Pelageikina Anna O., Nechitailov Andrey A.

The review addresses the problem of durability of operation of low-temperature proton exchange membrane fuel cells. Fuel cells are of considerable interest for the transition to renewable energy sources; however, the durability of these devices is still not sufficiently long (10 to 40 thousand hours). The increase in the durability is a relevant task. The review presents a systematic account and evaluation of the methods used for stabilization of electrochemical energy conversion systems with a proton exchange membrane and defines promising approaches to increase their lifetime.The bibliography includes 197 references.

Şahin N.E., Pech‐Rodríguez W.J.

Palladium nanoparticles supported on a pretreated carbon substrate (Pd/C) were synthesized from a surfactant‐free microwave‐heated ethylene glycol without any external reducing agent and characterized by high‐resolution electron transmission microscopy, thermogravimetric analysis, and X‐ray diffraction analysis. Cyclic voltammetry was effectively employed to scrutinize the electrochemical processes such as Pd hydrogen interactions including hydrogen adsorption, absorption, desorption, and hydrogen evolution as well as Pd–oxygen interactions like the oxide formation and the subsequent reduction of the oxide layer. The electrochemical oxidation of palladium was clearly indicated at the potential ranging from 0.78 to 1.20 V versus reversible hydrogen electrode (RHE) in the anodic scan direction whereas the corresponding reduction peak was observed with a broad peak centered at 0.79 V versus RHE in the reverse scan. Therefore, an accurate evaluation of the EASA measurements on ultrathin film palladium (Pd/C) electrodes in acidic (0.5 mol L−1 H2SO4, pH ∼ 1) media was successfully conducted. Moreover, the steady‐state cyclic voltammetry (CV) measurements have been conducted at the lowest scan rate of 1 mV s−1, enabling obtaining of hydrogen adsorption, absorption, and desorption reaction features without concurrent. Besides, Pd/C electrocatalyst exhibited 129 mV overpotential yielding a cathodic current density of 10 mA cm−2 toward hydrogen evolution reaction. This study outlines the description of practical experimental conditions essential for accurately determining the EASA that facilitates a comprehensive evaluation of their electrochemical performance.

Liu Y., Li S., Zhang Y., Tian X., Wang H., Huo L.

Luo C., Wan K., Wang J., Li B., Yang D., Ming P., Zhang C.

Che Ramli Z.A., Pasupuleti J., Nik Zaiman N.F., Tengku Saharuddin T.S., Samidin S., Wan Isahak W.N., Sofiah A.G., Kamarudin S.K., Tiong S.K.

This comprehensive review article highlights recent advancements of Pt and Pd-based electrocatalysts, covering Pt and Pd alloys, Pt-M and Pd-M core-shell structures, nanosize/nanostructure effects, addition of support material, doping effects, and post-treatment for the oxygen reduction reaction (ORR) and hydrogen oxidation reaction (HOR) in Proton exchange membrane fuel cell (PEMFC). Additionally, it delves into other precious metals such as Gold (Au) and Silver (Ag) for ORR and HOR in PEMFC. The role and contribution of incorporating other elements or materials such as metal oxides, metal carbides, transition metal oxides, carbon support, and non-carbon support are thoroughly discussed. The most promising methods are also described, with a special emphasis on narrow particle size, nanostructure, and low loading of novel Pt- and Pd-based catalysts. Furthermore, the advantages and shortcomings of these catalysts for electrocatalysis are analyzed, along with the influence of the nanostructure and morphology of the electrocatalyst materials on electrochemical performance.

Zhang L., Lu P., Yin M., Li R., Wang B., Ma X., Jiao M., Ma W., Zhou Z.

Designing advanced electrocatalysts with high methanol tolerance in the oxygen reduction reaction process is crucial for the sustainable implementation of direct methanol fuel cells. Herein, we present a Pt/C catalyst modified with black phosphorus (BP) nanodots (BPNDs-Pt/C) by using a facile ultrasonic mixing method. Experimental and computational investigations reveal that the electron transfer from BP to Pt leads to weak adsorption of hydroxyl groups on the Pt surface. As a result, the BPNDs-Pt/C catalyst exhibits efficient activity and anti-methanol ability for cathodic oxygen reduction electrocatalysis in an acidic medium. Additionally, it demonstrates high activity for oxygen reduction reaction (ORR) in an alternative alkaline system with cation exchange membrane and eliminable methanol penetration. This work highlights the feasibility of using non-metallic elements to regulate the electronic structure and surface properties of Pt-based nanomaterials. Furthermore, the designed BPNDs-Pt/C electrocatalyst, with controllable ORR performance, can be applied across various scenarios based on demand.

Narayana Sarma R., Sambasivam B., Sundararaman M.

Hydrogen can be a clean energy carrier, the utilization of which can help to reduce emissions and can potentially help in decarbonization of various sectors. The current study presents a technoeconomic analysis of hydrogen production using three electrolyzer technologies—alkaline electrolysis, polymer electrolyte membrane electrolysis and solid oxide electrolysis. The study considers the electricity system of Karnataka, a leader in renewable energy in India. The work considers hydrogen from solar, wind, hydro, mini hydel, biomass and cogeneration sources of electricity as green, that from thermal, net Central Generating Stations (CGS) import (coal) as grey and nuclear as purple. The work presents an analysis of the Karnataka grid for the year 2022. Seasonal variation in electricity and its effect on the amount of hydrogen production is discussed. A detailed discussion on the green and grey hydrogen production costs is presented. When the demand of electricity is less than the maximum electricity that can be generated, excess electricity can be used for hydrogen production. The study presents an approach for quickly estimating the minimum selling price of hydrogen, based on the type of electrolysis. For the conditions considered in the present study, the average cost of grey hydrogen can be obtained to be about Rs. 356, Rs. 326 and Rs. 215 for alkaline electrolysis, polymer electrolyte membrane electrolysis and solid oxide electrolysis, respectively, and green hydrogen, with 10% subsidy, can even be about Rs. 275, Rs. 252 and Rs. 166 for alkaline electrolysis, polymer electrolyte membrane electrolysis and solid oxide electrolysis, respectively. The work points to the possibility of generating green hydrogen in a cost-effective way, by suitable management of the energy grid. This study points to the need for effective grid management strategies for high renewable resource electricity grids, to meet the energy demands, and to achieve carbon neutrality. Suitable electrolysis technologies can be selected, based on Capital Expenditure (CAPEX) and Operation Expenditure (OPEX), and can be operated on cheaper green electricity for clean hydrogen generation.

Li W., Zhu J., Cai H., Tong Z., Wang X., Wei Y., Wang X., Hu C., Zhao X., Zhang X.

Electrochemical water splitting, a sustainable method for hydrogen production, faces the challenge of slow oxygen evolution reaction (OER) kinetics. Iridium oxide (IrO2) is widely regarded as the most effective catalyst for OER due to its excellent properties. Compared to nanoparticles, IrO2 thin films exhibit significant advantages in OER, including a uniform and stable catalytic interface and excellent mechanical strength. This paper reviews recent advancements in one-step deposition techniques for the preparation of IrO2 thin films and their application in OER. Additionally, it analyzes the advantages and disadvantages of various methods and the latest research achievements, and briefly outlines the future trends and applications.

Paperzh K., Bayan Y., Gerasimov E., Pankov I., Konstantinov A., Menshcikov V., Mauer D., Beskopylny Y., Alekseenko A.

To accelerate the implementation of zero-emission power installations based on proton-exchange membrane fuel cells, it is necessary to maximize the power characteristics of these devices. For this purpose, we have obtained and tested a new N-doped carbon support and a synthesized Pt/C catalyst based on it with a platinum loading of about 37.3 %. A comparison of the degradation resistance of the initial support and the N-doped one has shown greater stability of the latter. At the same time, Raman spectroscopy has confirmed the presence of the C–N bond, which indicates the successful doping of carbon with nitrogen. The resulting Pt/C catalyst based on an N-doped support is characterized by a substantially narrow size dispersion and an ultra-small nanoparticle size of about 2.6 nm. The high-angle annular dark-field scanning transmission electron microscopy images of the synthesized catalyst have confirmed the presence of individual platinum atoms/clusters uniformly distributed over the surface of the support, and their presence is due to nitrogen embedded into the carbon structure. This material is characterized by a 50 m2 gPt-1 larger electrochemically active surface area and a 227 A gPt-1 greater mass activity compared to the commercial JM40 analog (40 % platinum loading). Meanwhile, the electrochemical parameters remaining after the accelerated stress testing are almost 2 times higher than those of JM40. And the power characteristics in the membrane electrode assembly for the catalyst synthesized by the facile one-pot synthesis method are 13 % (575 mW cm-2) higher than those of the commercial analog (500 mW cm-2). The Pt/C catalyst obtained during the research is deemed promising for commercial use in proton-exchange membrane fuel cells.

Xu X., Zhong Y., Wajrak M., Bhatelia T., Jiang S.P., Shao Z.

AbstractElectrochemical transformation processes involving carbon, hydrogen, oxygen, nitrogen, and small‐molecule chemistries represent a promising means to store renewable energy sources in the form of chemical energy. However, their widespread deployment is hindered by a lack of efficient, selective, durable, and affordable electrocatalysts. Recently, grain boundary (GB) engineering as one category of defect engineering, has emerged as a viable and powerful pathway to achieve improved electrocatalytic performances. This review presents a timely and comprehensive overview of recent advances in GB engineering for efficient electrocatalysis. The beneficial effects of introducing GBs into electrocatalysts are discussed, followed by an overview of the synthesis and characterization of GB‐enriched electrocatalysts. Importantly, the latest developments in leveraging GB engineering for enhanced electrocatalysis are thoroughly examined, focusing on the electrochemical utilization cycles of carbon, hydrogen, oxygen, and nitrogen. Future research directions are proposed to further advance the understanding and application of GB engineering for improved electrocatalysis.image

Shen Z., Tang J., Shen X.

Developing highly active and durable platinum-based catalysts is crucial for electrochemical renewable energy conversion technologies but the limited supply and high cost of platinum have hindered their widespread implementation. The incorporation of non-noble metals, particularly copper, into Pt catalysts has been demonstrated as an effective solution to reduce Pt consumption while further promoting their performance, making them promising for various electrocatalytic reactions. This review summarizes the latest advances in PtCu-based alloy catalysts over the past several years from both synthetic and applied perspectives. In the synthesis section, the selection of support and reagents, synthesis routes, as well as post-treatment methods at high temperatures are reviewed. The application section focuses not only on newly proposed electrochemical reactions such as nitrogen-related reactions and O2 reduction but also extends to device-level applications. The discussion in this review aims to provide further insights and guidance for the development of PtCu electrocatalysts for practical applications.

Paperzh K., Alekseenko A., Pankov I., Guterman V.

The degradation of the nanostructured platinum-based electrocatalysts during their operation poses a major problem for the performance and durability of PEMFCs and devices based on them. Therefore, the methodological aspects of research related to the quantitative assessment of the materials’ degradation as well as the mechanism of the processes causing it are gaining increasing attention. The degradation processes of the same Pt/C catalyst containing the nanoparticles of similar size uniformly distributed over the surface of the carbon support were studied using eight relevant protocols of the accelerated stress testing. Special attention was paid to electron microscopy examination of the catalyst’s microstructure before and after stress tests as well as to determination of the electrochemically active surface area and the activity of the catalyst in the ORR after the stress testing. We also studied the influence of the atmosphere, in which testing was performed, as well as the effect of the electrode rotation on the degradation rate. The results of the study carried out demonstrate the features of the catalyst’s degradation in different modes and facilitate the choice of optimal protocols and stress testing conditions.

Wang C., Feng L.

Recent advances and perspectives of Ir-based anode catalysts in PEM water electrolysis are highlighted, and it is concluded that the anti-dissolution and stability improvement of Ir active species should be carefully considered for catalyst design in the future.

Yasutake M., Noda Z., Matsuda J., Lyth S.M., Nishihara M., Ito K., Hayashi A., Sasaki K.

Novel Ru-core Ir-shell catalyst-integrated porous transport electrodes (PTEs) for polymer electrolyte membrane water electrolysis (PEMWE) cells are prepared, in which Ru-core Ir-shell catalyst nanostructures are directly deposited onto a porous transport layer (PTL) via arc plasma deposition (APD). The PTL has a nanostructured TiO2 surface prepared via NaOH etching, acting as a catalyst support. The performance and durability of these Ru-core Ir-shell catalysts depend strongly on the ratio of Ir and Ru. The current-voltage (I–V) characteristics of PEMWE cells were improved by applying these core-shell catalysts with a low Ir loading of around 0.1 mg cm−2. The core-shell catalyst-integrated PTEs can operate at current densities of up to 10 A cm−2 without exhibiting limiting current behavior. This unique combination of the core-shell catalyst and the PTE structure enables PEMWE cell operation with low iridium loading and high current density, potentially reducing the cost of green hydrogen.

Wallnöfer-Ogris E., Poimer F., Köll R., Macherhammer M., Trattner A.

This paper focuses on the main chemical, electrochemical, and mechanical degradation mechanisms and poisoning effects that influence the life-time, the performance, and the functionality of PEM (polymer electrolyte membrane) fuel cell stack components reversibly and irreversibly. The underlying causes are explained, possible influencing factors are listed, and the effects of degradation on fuel cell operation and state of health are described. Based on this, further consequences as well as mitigation strategies are presented. The summary gives an overview of the affected causes of voltage decay, the influence of operating conditions, strategies, and events on each specific degradation mechanism, and additionally the influence of initial degradation on any further degradation.

Moguchikh E.A., Alekseenko A.A., Pankov I.V., Alekseenko D.V., Guterman V.E.

A comparative analysis of the microstructure and electrochemical behavior of platinum–carbon electrocatalysts containing 20 and 40% platinum from different manufacturers for fuel cells with a proton-exchange membrane is carried out. The degree of degradation of the catalysts during accelerated stress testing in laboratory conditions is assessed based on the results of not only residual functional characteristics, but also microstructural parameters after electrochemical tests. It is determined that 20 and 40% PM series catalysts contain smaller platinum nanoparticles, characterized by a narrower size and more uniform spatial distribution, compared to analogues of the HiSPEC series. Due to these microstructural features, a PM-series platinum–carbon catalysts are characterized by a higher electrochemically active surface area (EASA) and mass activity values initially and after stress testing.

Pethaiah S.S., Jayakumar A., Palanichamy K.

The membrane electrode assembly (MEA) encompassing the polymer electrolyte membrane (PEM) and catalyst layers are the key components in Polymer Electrolyte Membrane Fuel Cells (PEMFCs). The cost of the PEMFC stacks has been limiting its commercialization due to the inflated price of conventional platinum (Pt)-based catalysts. As a consequence, the authors of this paper focus on developing novel bi-metallic (Pt-Co) nano-alloy-catalyzed MEAs using the non-equilibrium impregnation–reduction (NEIR) approach with an aim to reduce the Pt content, and hence, the cost. Herein, the MEAs are fabricated on a Nafion® membrane with a 0.4 mgPtcm−2 Pt:Co electrocatalyst loading at three atomic ratios, viz., 90:10, 70:30, and 50:50. The High Resolution-Scanning Electron Microscopic (HR-SEM) characterization of the MEAs show a favorable surface morphology with a uniform distribution of Pt-Co alloy particles with an average size of about 15–25 µm. Under standard fuel cell test conditions, an MEA with a 50:50 atomic ratio of Pt:Co exhibited a peak power density of 0.879 Wcm−2 for H2/O2 and 0.727 Wcm−2 for H2/air systems. The X-ray diffractometry (XRD), SEM, EDX, Cyclic Voltammetry (CV), impedance, and polarization studies validate that Pt:Co can be a potential affordable alternative to high-cost Pt. Additionally, a high degree of stability in the fuel cell performance was also demonstrated with Pt50:Co50.

Sun G., Cao Y., Hu M., Liang X., Wang Z., Cai Z., Shen F., He H., Wang Z., Zhou K.

The electrocatalytic reduction of CO2 to CO is an attractive approach for converting the greenhouse gas to value-added chemicals. However, current catalysts still suffer from low catalytic reactivity and low CO selectivity. Here, we report the synthesis of a series of N-doped carbon catalysts by thermal annealing of the mixture of urea and carbon in argon under varied temperatures, enabling the rational modulation of N species in carbon. The as-prepared NC-650 catalyst with pyrrolic N as the dominant N species can preferentially reduce CO2 to CO with almost 100% CO selectivity over a broad potential range (−0.45 to −1.05 V), coupled with remarkable long-term stability for over 300 h. DFT calculations reveal that the pyrrolic N site is unsaturated (valence state), which favors the formation of the N–COOH unit geometrically and electronically via proton-coupled electron transfer while inhibit hydrogen liberation, resulting in high CO2RR reactivity and CO selectivity of the NC-650 catalyst.

Mishra K., Devi N., Siwal S.S., Thakur V.K.

In the modern era, we all depend on energy for everything. However, we have limited traditional energy sources like coal, petroleum etc. Various alternative energy sources have been developed to fulfill the energy requirements from time to time. Despite this, we are in continuous need of energy sources that are of low cost and cause less environmental pollution. To overwhelm prospective energy concerns, when the world is exploring ways for net carbon zero or negative carbon emissive energy techniques FCs are predicted as one of the clean energy origins with low operating temperatures and high energy modifications. Nevertheless, a superior and steady catalyst for the electrodes is essential for the electrochemical reactions in FCs to work efficiently. Noble and non-noble metal electrocatalysts are extensively utilized as catalysts for the transformation of energy within fuel cells (FCs). For many years many pieces of research have been done to enhance the performance of FC technology. The literature review shows the role of various metal/ polymer-based nanomaterials as anode catalysts to robust fuel cell performance by the electro-oxidation of alcohols. Here, we have demonstrated the different morphology of the stimulus (such as nanowires and nanospheres, nanotubes, nanodendrites, nanofibers and nanosheets) and fabrication methods (such as electrodeposition, electrospinning, wet chemical, chemical vapor deposition, solvothermal, reduction, microwave-assisted polyol synthesis method) in detail. Further, the role of different noble and non-noble metal catalysts in FC application in FC technology and the relationship between morphology, synthesis and composition of catalysts have been discussed. Finally, the advantages of the fuel cell, current challenges, and prospects in this field, with concluding remarks, have been presented at the end.

Alekseenko A.A., Pavlets A.S., Mikheykin A.S., Belenov S.V., Guterman E.V.

The PtCu NPs supported on carbon have been synthesized using a unique one-pot gradient synthesis approach. The facile acid treatment has been conducted to obtain the de-alloyed structure of NPs. The de-alloyed catalysts have exhibited the 3 times higher ORR activity in TF-RDE compared to the commercial Pt/C analog (the 20% loading, Johnson Matthey). The composition and structure have been estimated by the XRF, XRD, EDX, TEM, and STEM methods. The synchrotron experimental data have been processed using spherical harmonics, which has allowed modeling the particles with a nonuniform distribution of the alloy components over the depth. The integrated approach to studying the NPs’ structure has allowed for the explanation of a higher activity of the NPs with a complex structure. The materials presented may become novel commercial catalysts for PEMFCs. The gram-scale method to obtain the catalyst in the amount of 1 g, which should maintain its structural and electrochemical characteristics, has also been proposed.