Digital light processing of Zr-doped NiFe self-supported electrodes for efficient and stable high-current-density oxygen evolution

The development of efficient and durable oxygen evolution reaction (OER) catalysts is essential for advancing large-scale electrochemical water splitting. Here, we report for the first time the fabrication of NiFe self-supported electrodes via digital light processing (DLP) using NiSO4 and FeSO4 precursors, followed by a redox conversion process. Compositional optimisation through precise tuning of the Ni-to-Fe atomic ratio, coupled with the incorporation of functional dopants (Zr, Co, Nb) and electrochemical activation, yielded an optimised Zr-doped NiFe electrode exhibiting an overpotential as low as 193 mV at 100 mA/cm2. Transmission electron microscopy revealed that the performance enhancement originates from the formation of nanocrystalline ZrO2 embedded in an amorphous NiFe-OOH matrix, which increases the electrochemically active surface area and accelerates reaction kinetics. Furthermore, rational three-dimensional structural engineering using triply periodic minimal surface architectures demonstrated that the gyroid geometry delivers superior catalytic performance and long-term stability under high-current operation, benefiting from improved bubble removal, mass transport, and structural robustness. This work establishes a versatile and scalable platform for the additive manufacturing of high-performance NiFe-based self-supported OER electrodes via commercially available DLP, providing new design principles for advanced functional metal-based materials in sustainable energy applications.