Investigating the voltaic efficiency of 3D-printed macro-patterned electrodes for hydrogen evolution reactions in water electrolysis

Conventional electrodes of water electrolysis face limitations in mass transport and bubble detachment, hindering sustainable hydrogen production. This study investigates the enhancement of hydrogen evolution reaction (HER) efficiency in water electrolysis using 3D-printed macro-patterned 17-4 PH-grade stainless steel electrodes. Leveraging additive manufacturing, stainless steel-based electrodes were fabricated via 3D printing, debinding and sintering, featuring three distinct macro-patterns namely small and large semi-spherical dimples, as well as pyramidal pits. Electrochemical testing using chronoamperometry and efficiency calculations, using KOH electrolyte in a H-cell setup, revealed that patterned electrodes significantly outperformed their flat counterparts. Results show up to a 6.5-percentage point higher voltaic efficiency, and visual observation revealed enhanced bubble detachment. Scanning Electron Micrography (SEM) imaging confirmed inherent microporosity from 3D printing, increasing active surface area. The pyramidal-pit electrode initiated HER at lower voltages, while dimpled designs achieved higher peak current densities. The experimentally measured current densities showed good agreement with the Butler–Volmer model with electrode surface bubble coverage considered. An empirical model developed, shows a strong correlation between the cell’s normalised voltaic efficiency, the non-dimensional current density and the non-dimensional surface area, highlighting the critical role of surface geometry in the efficiency of electrolysis cells. Gold coating reduced ohmic losses but did not consistently improve hydrogen yield. These results add to the growing experimental evidence that 3D-printed macro-patterns are beneficial, and in this case, enabled by an innovative metal additive manufacturing process. HER voltaic efficiency is boosted by at least 5 percentage points for a flat electrode of the same form factor through optimised bubble management and surface area. The study hence underlines the importance of patterned electrodes for industrial green hydrogen production with attendant tangible economic and sustainability benefits.