Enhanced Optoelectronic and Electrocatalytic Properties of Cerium-Doped Nickel Oxide Nanostructures for Efficient Water Splitting

The search for high-performance, non-precious metal oxide nanomaterials is crucial for advancing energy conversion technologies, include ing optoelectronics and electrocatalysis. In this work, we report the synthesis and characterization of a series of cerium-doped nickel oxide (NiO) nanostructures, denoted as NiO, Ce-NiO-1, Ce-NiO-2, and Ce-NiO-3, via a facile hydrothermal method. Comprehensive structural analysis using XRD and SEM confirmed the successful incorporation of Ce ions into the NiO lattice, leading to well-defined morphological evolution from nanowires to layered nanosheets, which directly influences their electronic and interfacial properties. Electrochemical investigations revealed that the Ce-NiO-3 sample exhibited exceptional bifunctional activity for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Specifically, it achieved low overpotentials of 285.4, 310.4, and 331.4 mV for HER, and 264.6, 310.6, and 348.6 mV for OER at current densities of −100/−150/−200 and 100/150/200 mA cm −2 , respectively. Notably, it also displayed a small Tafel slope of 19.39 mV dec −1 for OER, indicating favorable reaction kinetics. Electrochemical impedance spectroscopy further supported enhanced charge transfer characteristics in Ce-doped samples. The correlation between the modulated nanoscale morphology, improved electronic structure, and the resulting electrocatalytic performance underscores the potential of these cerium-doped NiO nanostructures not only in electrolytic water splitting but also as promising candidates for nanoelectronic and optoelectronic devices where tunable charge transport and surface activity are required.