Three-dimensional-printed Ni-based scaffold design accelerates bubble escape for ampere-level alkaline hydrogen evolution reaction

Abstract

Alkaline hydrogen evolution reaction (HER) for scalable hydrogen production largely hinges on addressing the sluggish bubble-involved kinetics on the traditional Ni-based electrode, especially for ampere-level current densities and beyond. Herein, 3D-printed Ni-based sulfide (3DPNS) electrodes with varying scaffolds are designed and fabricated. In situ observations at microscopic levels demonstrate that the bubble escape velocity increases with the number of hole sides (HS) in the scaffolds. Subsequently, we conduct multiphysics field simulations to illustrate that as the hole shapes transition from square, pentagon, and hexagon to circle, where a noticeable reduction in the bubble-attached HS length and the pressure balance time around the bubbles results in a decrease in bubble size and an acceleration in the rate of bubble escape. Ultimately, the 3DPNS electrode with circular hole configurations exhibits the most favorable HER performance with an overpotential of 297 mV at the current density of up to 1000 mA cm⁻² for 120 h. The present study highlights a scalable and effective electrode scaffold design that promotes low-cost and low-energy green hydrogen production through the ampere-level alkaline HER.