Nanoscale electrocatalyst design for alkaline hydrogen evolution reaction through activity descriptor identification

Baek, Du San; Lee, Jin Young; Lim, June Sung; Joo, Sang Hoon

doi:10.1039/d1qm00183c

Cited by 22 publications

(20 citation statements)

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“…Furthermore, useful information about the reaction kinetics and mechanism was obtained by extracting Tafel slope values from the LSV polarization curves (Figure b). The HER in alkaline media is more complex than in an acidic electrolyte due to the additional energy that is needed to break the strong covalent H–O–H bond before the adsorption of H* and thus to start the reaction. , Hence, the alkaline HER starts with the adsorption of protons onto the electrocatalyst surface via a reduction process (Volmer step), followed by the evolution of molecular H 2 , either through the desorption of adsorbed hydrogen atoms onto the electrode (Heyrovsky step) or through the recombination of two adsorbed protons (Tafel step), with an additional dissociation step of water molecules, to produce hydrogen during Volmer and Heyrovsky steps. , In this manner, the Tafel slope value for MoSe 2 –MnP is 256 mV/dec, indicating that adsorption of protons onto the electrode surface via a reduction process rate limits the HER. Meanwhile, Tafel slope values for MoSe 2 , f-MoSe 2 , and MnP, ca.…”

Section: Resultsmentioning

confidence: 99%

Molybdenum Diselenide–Manganese Porphyrin Bifunctional Electrocatalyst for the Hydrogen Evolution Reaction and Selective Hydrogen Peroxide Production

et al. 2022

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Electrochemical reactions for hydrogen and hydrogen peroxide production are essential for energy conversion to diminish the energy crisis but still lack efficient electrocatalysts. Development of non-noble metal bifunctional electrocatalysts for the hydrogen evolution reaction and 2e − oxygen reduction reaction to ease reaction kinetics is a challenging task. Integration of single components by employing easy strategies provides a key step toward the realization of highly active electrocatalysts. In this vein, MoSe 2 owns catalytic active sites and a high specific surface area but suffers from insufficient conductivity and high catalytic performance that noble metals provide. Herein, MoSe 2 was used as a platform for the incorporation of manganese-metalated porphyrin (MnP). The developed hybrid, namely, MoSe 2 −MnP, obtained by the initial metal−ligand coordination and the subsequent grafting with MnP was fully characterized and electrochemically assessed. The bifunctional electrocatalyst lowered the overpotential toward hydrogen evolution, improved the reaction kinetics and charge transfer processes, and was extremely stable after 10,000 ongoing cycles. Simultaneously, rotating ring disk electrode analysis showed that oxygen reduction proceeds through the 2e − pathway for the selective production of hydrogen peroxide with a high yield of 97%. The new facile modification route can be applied in diverse transition metal dichalcogenides and will help the development of new advanced functional materials.

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Section: Resultsmentioning

confidence: 99%

Molybdenum Diselenide–Manganese Porphyrin Bifunctional Electrocatalyst for the Hydrogen Evolution Reaction and Selective Hydrogen Peroxide Production

et al. 2022

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“…Several Reviews on the topic of AEM‐WEs were recently published and detailed below. The development of PGM‐ and/or CRM‐free electrocatalysts for the HER and OER in alkaline medium was described recently [10–17] . The recent development of AEM and anion‐exchange ionomers for AEM‐WE or AEM fuel cell application was reviewed in Refs.…”

Section: Introductionmentioning

confidence: 99%

“…AEM-WE is already more efficient compared to A-WE and has the potential to operate in high-pH environments without CRM and PGM, and without alkaline electrolyte. [10][11][12][13][14] AEM-WEs have key advantages over A-WEs: (i) they operate at higher current densities due to lower ohmic resistance and consequently have a smaller volumetric footprint while utilizing fewer materials that in turn lead to a smaller carbon footprint; (ii) they allow pressurizing hydrogen electrochemically, thus facilitating its subsequent storage, distribution, and final utilization; (iii) with a non-porous polymeric membrane, the safety of the system is significantly improved. Moreover, AEM-WEs have key advantages over PEM-WEs of: (i) reducing the EU dependence on CRMs throughout the entire balance of materials, and (ii) reducing the environmental footprint over the entire life cycle of the product.…”

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What is Next in Anion‐Exchange Membrane Water Electrolyzers? Bottlenecks, Benefits, and Future

et al. 2022

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As highlighted by the recent roadmaps from the European Union and the United States, water electrolysis is the most valuable high‐intensity technology for producing green hydrogen. Currently, two commercial low‐temperature water electrolyzer technologies exist: alkaline water electrolyzer (A‐WE) and proton‐exchange membrane water electrolyzer (PEM‐WE). However, both have major drawbacks. A‐WE shows low productivity and efficiency, while PEM‐WE uses a significant amount of critical raw materials. Lately, the use of anion‐exchange membrane water electrolyzers (AEM‐WE) has been proposed to overcome the limitations of the current commercial systems. AEM‐WE could become the cornerstone to achieve an intense, safe, and resilient green hydrogen production to fulfill the hydrogen targets to achieve the 2050 decarbonization goals. Here, the status of AEM‐WE development is discussed, with a focus on the most critical aspects for research and highlighting the potential routes for overcoming the remaining issues. The Review closes with the future perspective on the AEM‐WE research indicating the targets to be achieved.

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“…Pt-based catalysts exhibit the best activity for acidic HER with their optimized hydrogen binding energy; however, they exhibit sluggish kinetics for alkaline HER owing to the additionally required water dissociation step. Multidirectional efforts were made to enhance the alkaline HER activity. − Notable strategies include the use of an oxophilic catalyst (e.g., Ru) − or a cocatalyst [e.g., Ni(OH) 2 ] − that facilitated the kinetics of the water dissociation step. Recently, the Ma group demonstrated that α-MoC 1– x -supported catalysts exhibited higher activity than β-Mo 2 C-supported catalysts in aqueous phase methanol-reforming and water-gas shift reactions, suggesting the excellent water dissociation capability of the metastable α-MoC 1– x phase. − Inspired by these studies, we hypothesized that α-MoC 1– x itself can serve as a potential electrocatalyst for the alkaline HER; however, selective formation of the metastable, face-centered cubic (fcc) α-MoC 1– x phase is challenging .…”

Section: Introductionmentioning

confidence: 99%

Metastable Phase-Controlled Synthesis of Mesoporous Molybdenum Carbides for Efficient Alkaline Hydrogen Evolution

2022

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Transition metal carbides (TMCs) have shown great promise as nonprecious metal electrocatalysts for electrochemical energy conversion reactions owing to their Pt-like catalytic activity. The major challenges in the synthesis of TMCs include the selective formation of a catalytically active phase, enlargement of the catalytically active surface area, and control of the carbonaceous overlayer, all of which collectively influence their catalytic reactivity. Herein, we present a systematic study on the catalytically active metastable phase-selective synthesis of mesoporous molybdenum carbides with controlled carbon overlayer thickness for efficient alkaline hydrogen evolution reaction (HER) electrocatalysis. The synthesis of molybdenum carbides was explored by controlling the types of Mo and C precursors and carburization conditions and the use of a mesoporous silica template. The choice of the Mo precursor and the nanospace-confined carburization were identified as critical factors for the formation of mesoporous molybdenum carbides of the metastable α-MoC1–x phase (MMC) with a large catalytically active surface area. The thickness of the carbon overlayer on the surfaces of the molybdenum carbides increased proportionally with the carburization temperature and decreased substantially with H2 post annealing. Among the prepared catalysts, the H2-annealed MMC (MMC-H2) exhibited the highest alkaline HER activity and reaction kinetics, which is one of the best among the meal carbide alkaline HER catalysts reported so far and compared favorably with a commercial Pt/C catalyst. The MMC-H2 also demonstrated superior durability and stability as compared to MMC and Pt/C catalysts.

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Nanoscale electrocatalyst design for alkaline hydrogen evolution reaction through activity descriptor identification

Abstract: The hydrogen evolution reaction (HER) is the cathodic half-reaction of water electrolysers for producing hydrogen (H2) gas in a carbon-neutral manner. In the pursuit of system-level H2 production that occurs...

Cited by 22 publications

References 100 publications

Molybdenum Diselenide–Manganese Porphyrin Bifunctional Electrocatalyst for the Hydrogen Evolution Reaction and Selective Hydrogen Peroxide Production

Molybdenum Diselenide–Manganese Porphyrin Bifunctional Electrocatalyst for the Hydrogen Evolution Reaction and Selective Hydrogen Peroxide Production

What is Next in Anion‐Exchange Membrane Water Electrolyzers? Bottlenecks, Benefits, and Future

Metastable Phase-Controlled Synthesis of Mesoporous Molybdenum Carbides for Efficient Alkaline Hydrogen Evolution

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