Tartrate-Assisted Hydrothermal Calcination Strategy for Compositionally Tunable Doped ZnO: Synthesis and Representative OER Evaluation

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Metal doping provides an effective means of regulating the structure, defect chemistry, and functional properties of ZnO. Here, we report a tartrate-assisted hydrothermal-calcination strategy for preparing metal-doped ZnO with tunable compositions. Zn and dopant metal salts are reacted in the presence of tartrate under hydrothermal conditions to generate tartrate-derived precursors, which are subsequently converted into doped ZnO by calcination in air. Using Mn, Fe, Co, Ni, and Cu as representative dopants, the method was demonstrated for five single-element-doped ZnO samples and representative binary, ternary, quaternary, and quinary compositions. X-ray diffraction confirmed the formation of hexagonal wurtzite ZnO without detectable secondary crystalline phases, while energy-dispersive X-ray spectroscopy and elemental mapping verified the incorporation and distribution of dopant elements. Oxygen evolution reaction measurements were used to evaluate dopant-dependent catalytic behavior. Among the tested samples, Fe-ZnO exhibited the highest activity, requiring an overpotential of 297 mV at 10 mA cm–2 with a Tafel slope of 36.81 mV dec–1. Structural and spectroscopic analyses indicate that Fe incorporation induces lattice distortion, oxygen-related defects, and improved interfacial charge transfer. This work provides a flexible, precursor-based approach for constructing compositionally tunable doped ZnO materials.