Optimization of Three-Dimensional-Printed Catalytic Electrodes for Alkaline Water Electrolysis Guided by the Experimental Design Methodology
Résumé
Dihydrogen (H$_2$) is considered nowadays as a sustainable energy carrier and exhibits a high energy density in its highly compressed state. Different countries in the world are developing industrial production and are scaling up water electrolysis processes with clear roadmaps. Alkaline water electrolysis is an affordable technology that avoids the use of platinum group metals with a good compromise of efficiency because of the development of new cost-effective and Earth-abundant materials of electrodes and new anion-exchange membranes. Here, we report on the use of emerging and selective laser melting (SLM) technology for the three-dimensional (3D) printing of binary alloyed NiFe, NiMo, NiCr, and NiCo electrode materials at an applied scale. These materials are preliminarily tested for hydrogen and oxygen evolution half-reactions in alkaline conditions to select the most promising combinations of cathode/anode combinations for overall water electrolysis. On the basis of three key performance metrics (KPMs, namely, overpotential values at 10 and 50 mA cm$^–$$^2$ and the stability in operation over 6 days at 50 mA cm$^–$$^2$), NiCr and NiCo are preferred for the cathode, whereas the anode is NiMo or NiFe. Moreover, to facilitate the release of the electrogenerated gas bubbles, the patterning of 3D-printed electrodes with either roughly conical holes or ramps is considered as a third experimental factor. The water electrolysis process is then fully optimized using the formalism of design of experiments (DOE), which allows to reduce the number of experiments without loss in the quality of conclusions. This study reveals that NiCo and NiMo will be preferentially used as the cathode and anode, respectively, to decrease the cell overvoltage, whereas NiFe as the anode yields the best stability in operation. Besides, the impact of the patterns printed by SLM on the KPMs is somewhat limited, even though the presence of holes is rather beneficial for decreasing cell overvoltage. Interestingly, an approximate calculation of the consumed energy for the production of 1 kg of H$_2$ from the combination of NiCo/NiMo/holes as the cathode/anode/pattern yields 50.6 kWh/kg of H$_2$, which is quite promising if one refers to the 48 kWh industrial target set by European Union for 2030.
Domaines
Autre
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