Gold Nanodots-Decorated Nickel Hydroxide Nanoflowers for Enhanced Electrochemical Oxygen Evolution Activity

Abstract

Oxygen evolution reaction (OER) is considered a major challenge in the production of efficient electrochemical water splitting devices. To overcome the challenge, the development of inexpensive electrochemical catalysts with high energy conversion efficiencies is vital. Nanohybrids composed of noble metal nanoparticles and transition metal hydroxides often possess catalytically active sites that are beneficial for OER performance. In this study, we report a successful synthesis of Ni(OH)2 nanoflowers with a high degree of crystallinity and uniformity. The as-prepared Ni(OH)2 nanoflowers are employed as templates for effective and controllable loading of Au nanodots to obtain Ni(OH)2@Au nanohybrids. An examination of the OER activity reveals that Ni(OH)2@Au nanohybrids exhibit a considerably lower overpotential (η) value (390 mV) at a current density of 5 mA cm–2 and a smaller Tafel slope (120 mV dec–1) than those of Ni(OH)2 nanoflowers (540 mV and 324 mV dec–1, respectively). The OER enhancement effect is mainly attributed to the decoration of Au nanodots, inducing charge transfer from Ni to Au and thereby stabilizing the Ni species at high oxidation levels. Moreover, the uniform loading of Au nanodots on the anisotropic Ni(OH)2 nanoflowers provides more active interfacial surfaces, which are expedient to OER.