Generalized Preparation of Au NP @ Ni(OH)2 Yolk-Shell NPs and Their Enhanced Catalytic Activity

ABSTRACT Yolk-shell nanostructures have attracted considerable attention because of their unique properties and promising applications. Yet, synthesis of well-defined yolk-shell structures with controllable composition remains a major challenge. Here, we report a general method to fabricate Au NP @ Ni(OH)2 yolk-shell NPs. Au cores with various diameters and shapes can be successfully encapsulated into the Ni(OH)2 shells by a similar approach. When the diameter of the core Au NPs changed from ∼15 to ∼90 nm, the size of the yolk-shell NPs accordingly grew from ∼110 to ∼380 nm, however, the shell thickness of the final yolk-shell NPs is in the narrow range of 18∼20 nm. The synergistic contribution from both Au and Ni(OH)2 has endowed the yolk-shell heterostructure with enhanced catalytic activity. As shown in the oxygen-evolution reactions (OER) tests, the OER activity of Au NP @ Ni(OH)2 yolk-shell NPs is 8.7 and 86-fold higher than that of hollow Ni(OH)2 NPs alone and Au NP @C (5%) (Au NPs (5%) mixed with Carbon Black), respectively. In general, our method provides a simple and novel strategy towards the fabrication of yolk-shell structures with superior catalytic activity for OER.