Remarkable gas bubble transport driven by capillary pressure in 3D printing-enabled anisotropic structures for efficient hydrogen evolution electrocatalysts

Additive manufacturing technologies have been proved as a promising method to achieve electrocatalysts with periodic micro-size pores, while the nano-sized interspace of the material structures and their corresponding gas bubbles transfer process are not explored in detail. Herein, we employ the shear force alignment in additive manufacturing to design NiMo-based structures with anisotropic porous channels as electrocatalysts for hydrogen evolution reaction (HER) in seawater. Based on the complementary experimental and theoretical investigation, the unique anisotropic structure not only fully exposes the active sites in the electrolyte, but also facilitates the rapid electrolyte-hydrogen phase conversion during electrochemical reactions. In this case, the obtained 3D electrode exhibits superior electrocatalytic performance and excellent long-term operational stability with an extremely low overpotential of ∼150 mV at a current density of 500 mA/cm2 in 1 M KOH seawater. This work will provide a practical scenario for designing highly-efficient HER electrocatalysts.