3D Printed Microlattices of Transition Metal/Metal Oxides for Highly Stable and Efficient Water Splitting

AbstractDeveloping affordable electrocatalysts is crucial for driving the sustainable energy transition to green hydrogen. Here, a generalizable method known as polymer infusion additive manufacturing is reported for transforming 3D‐printed photopolymers into core–shell micro lattice electrodes for electrocatalytic water splitting with transition metal/metal oxides/carbon heterointerfaces. The optimized free‐standing architectures integrate Cu/CuOx on carbon (Cu/CuOx/C) microlattices, yielding high electrocatalytic activity (overpotential of 145 mV at 10 mA cm−2 and a Tafel slope of 134 mV dec−1) and excellent durability for the hydrogen evolution reaction (HER) (>100 h), surpassing state‐of‐the‐art Cu foams. Additionally, for the oxygen evolution reaction (OER), Co/CoOx on carbon (Co/CoOx/C) microlattices display exceptional activity with the lowest overpotential (1.40 V to gain 10 mA cm−2) among all reported PGM‐free electrodes. The study explores the gas phase mass‐transport properties of these 3D microlattices via microscopic imaging of bubble evolution, finding that the outstanding electrocatalytic performance and long‐term stability of microlattice electrodes leverages their mesoscale (100–300 µm) pores, providing accessibility of electrolytes, maximizing utilization of active sites, and ensuring rapid evolution of gas bubbles. Thus, a simple but pioneering method is introduced for manufacturing 3D mesostructured electrocatalysts with deep control of liquid and gas phase mass‐transport, enhancing the efficacy of alkaline water electrolysis.