Architected 3D-Printed Electrodes with NiFe-LDH Coatings for Alkaline Oxygen Evolution

Abstract Alkaline water electrolysis requires electrodes that combine high oxygen evolution reaction (OER) activity with manufacturability. In this work, we fabricate OER-architected titanium electrodes via selective laser sintering and functionalize them with Ni- and NiFe-layered double hydroxides (LDHs). We observe that without a Ni seed layer, NiFe-LDH grows only weakly on the Ti architecture. This is evidenced by comparing the Ti architecture, the Ti architecture coated with Ni (Ti@Ni), the Ti architecture coated with LDH (Ti@LDH), and the full-layer assembly of the Ti architecture coated with Ni, followed by LDH growth (Ti@Ni/LDH). Morphological and chemical characterization using SEM−EDX, XRD, XPS, and STEM confirms the presence of a NiFe-LDH coating throughout the complex metallic architecture. Electrochemical double-layer capacitance indicates that functionalization modifies the electrochemical surface area, increasing from 57.23 cm2 for the Ti@Ni/LDH architecture to 69.90 cm2 for the Ti@Ni architecture. Although the electrochemical surface area varies slightly between architectures, the electrochemical overpotential remains the lowest for the Ti@Ni/LDH architecture, ca. 362 mV. Furthermore, the architectures influence reaction kinetics, with Tafel slopes decreasing from 203 mV dec−1 for the bare Ti electrode to 119 mV dec−1 with Ti@Ni and then improving with LDH deposition to 47 mV dec−1. The results demonstrate that the composition of 3D metal electrodes influences NiFe-LDH growth and, in turn, electrochemical surface area, overpotential, and interfacial charge transport. The results are expected to establish additively manufactured metallic-coated substrates as a viable platform for water-electrolysis electrodes in OER.