Coherent Workflows for Sustainable Electrocatalytic Hydrogenation Reactions with Pentlandite Catalysts
Authors: Kraenbring Mena-Alexander , Wickert Leon , Hansen Meinert , Sanden Sebastian , Pellumbi Kevinjeorjios , Wolf Jonas , Siegmund Daniel , Özcan Fatih , Apfel Ulf-Peter , Segets Doris 
Published: December 2024

The hydrogenation of organic substances is a central process type in various industries[1]. The usage of gaseous hydrogen, which is primarily sourced from fossil fuels, entails the release of CO2 during its production. In addition, the usage of gaseous hydrogen also carries a safety risk, which should be reduced as much as possible. An alternative approach is direct electrochemical hydrogenation with water or other protic liquids, where the required hydrogen is produced in situ and directly utilized. If this is driven by renewable energy, it represents a sustainable synthesis method that does not require stoichiometric reduction agents or high-temperature conditions[2].

Transition metal chalcogenides, particularly pentlandites (FexCoyNizSaSeb, x+y+z=9, a+b=8), exhibit high conductivity and serve as efficient and affordable electrocatalysts for this purpose. The utilization of hierarchical functional layers in the final electrode greatly enhances their efficiency[3, 4]. A comprehensive approach to analyzing the vast and complex electrode production parameter space, encompassing process parameters and material variables for ink formulation and layer deposition, is critical for understanding the intricate mechanisms within the manufacturing process chain and to maximize the electrochemical conversion efficiency. For this purpose, a time-saving and cost-effective coherent workflow was developed which enables a systematic analysis of several parameters, maximizing the knowledge gained from each experiment while minimizing the total amount of experiments. The workflow can be seen in Figure 1. In step 1, the materials and substrates to be investigated are first selected. Then, in step 2, catalyst inks are formulated, examined, and optimized concerning their sedimentation stability and compatibility with different binders and organic additives. Subsequently, in step 3, substrates are coated with the optimized catalyst inks and coating parameters such as catalyst mass loading are varied at the same time. In the fourth and final step, the resulting electrodes are tested electrochemically and with the help of imaging methods to shed light on process-structure-property relationships. The described procedure enables successive optimization and establishment of efficient membrane-electrode-assemblies for electroorganic reactions, offering new avenues for efficient, green, and sustainable synthesis pathways. These methods are also readily adaptable for scalable industrial applications.

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[2] Ya Zhang, Weibin Qiu, Yongjun Ma, Yonglan Luo, Ziqi Tian, Guanwei Cui, Fengyu Xie, Liang Chen, Tingshuai Li, and Xuping Sun, High-Performance Electrohydrogenation of N2 to NH3 Catalyzed by Multishelled Hollow Cr2O3 Microspheres under Ambient Conditions, ACS Catalysis (2018)

[3] David Tetzlaff, Kevinjeorjios Pellumbi, Daniel M. Baier, Lucas Hoof, Harikumar Shastry Barkur, Mathias Smialkowski, Hatem M. A. Amin, Sven Grätz, Daniel Siegmund, Lars Borchardt and Ulf-Peter Apfel, Sustainable and rapid preparation of nanosized of Fe/Ni-pentlandite particles by mechanochemistry, Chemical Science (2020)

[4] Daniel Siegmund, Sebastian Metz, Volker Peinecke, Terence E. Warner, Carsten Cremers, Anna Grevé, Tom Smolinka, Doris Segets and Ulf-Peter Apfel, Crossing the Valley of Death: From Fundamental to Applied Research in Electrolysis, JACS Au (2021)

[5] Mena-Alexander Kräenbring, Leon Wickert, Meinert Hansen, Sebastian Sanden, Kevinjeorjios Pellumbi, Jonas Wolf, Daniel Siegmund, Fatih Özcan, Ulf-Peter Apfel, and Doris Segets. Navigating through Complexity: Optimizing Cathodes for Organic Electrohydrogenation through Coherent Workflows, ChemCatChem (2023)

Figure 1